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Document and Entity Information	3 Months Ended
Document and Entity Information	Mar. 31, 2018
Document And Entity Information [Abstract]
Document Type	S-4
Amendment Flag	false
Document Period End Date	Mar. 31, 2018
Trading Symbol	RBB
Entity Registrant Name	RBB BANCORP
Entity Central Index Key	0001499422
Entity Filer Category	Non-accelerated Filer

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets
Cash and due from banks	$ 53,535	$ 70,048	$ 74,213
Federal funds sold and other cash equivalents	25,000	80,000	44,500
Cash and cash equivalents	78,535	150,048	118,713
Interest-earning deposits in other financial institutions	600	600	345
Securities:
Available for sale	82,848	64,957	39,277
Held to maturity	9,998	10,009	6,214
Mortgage loans held for sale	183,391	125,847	44,345
Loans held for investment:
Real estate	871,073	839,230	755,301
Commercial	391,614	410,812	361,227
Total loans	1,262,687	1,250,042	1,116,528
Unaccreted discount on acquired loans	(2,410)	(2,762)	(8,085)
Deferred loan costs (fees), net	1,651	1,794	2,003
Total loans, gross	1,261,928	1,249,074	1,110,446
Allowance for loan losses	(13,957)	(13,773)	(14,162)
Net loans	1,247,971	1,235,301	1,096,284
Premises and equipment	6,687	6,583	6,585
Federal Home Loan Bank (FHLB) stock	6,770	6,770	6,770
Net deferred tax assets	6,460	6,086	11,097
Income tax receivable	272	272
Other real estate owned (OREO)	293	293	833
Cash surrender value of life insurance	32,980	32,782	21,958
Goodwill	29,940	29,940	29,940
Servicing assets	5,979	5,957	3,704
Core deposit intangibles	1,357	1,438	1,793
Accrued interest and other assets	21,023	14,176	7,693
Total assets	1,715,104	1,691,059	1,395,551
Deposits:
Noninterest-bearing demand	316,047	285,690	174,272
Savings, NOW and money market accounts	399,892	411,663	296,699
Time deposits under $250,000	292,887	293,471	310,969
Time deposits $250,000 and over	364,678	346,457	370,823
Total deposits	1,373,504	1,337,281	1,152,763
Reserve for unfunded commitments	575	282	604
Income tax payable	1,563		793
FHLB advances		25,000
Long-term debt	49,564	49,528	49,383
Subordinated debentures	3,447	3,424	3,334
Accrued interest and other liabilities	10,629	10,368	7,089
Total liabilities	1,439,282	1,425,883	1,213,966
Commitments and contingencies
Shareholders' equity:
Preferred Stock
Common Stock	210,595	205,927	142,651
Additional paid-in capital	7,429	8,426	8,417
Retained earnings	58,838	51,266	30,784
Accumulated other comprehensive income (loss)-net unrealized loss on securities available for sale, net	(1,040)	(443)	(267)
Total shareholders' equity	275,822	265,176	181,585
Total liabilities and shareholders' equity	$ 1,715,104	$ 1,691,059	$ 1,395,551

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Securities held to maturity, fair value	$ 10,020	$ 10,250	$ 6,553
Preferred stock, shares authorized	100,000,000	100,000,000	100,000,000
Preferred stock, par value
Preferred stock, shares outstanding	0	0	0
Common stock, shares authorized	100,000,000	100,000,000	100,000,000
Common stock, par value
Common stock, shares issued	16,288,928	15,908,893	12,827,803
Common stock, shares outstanding	16,288,928	15,908,893	12,827,803
Accumulated other comprehensive income (loss) - net unrealized loss on securities available for sale, tax	$ 437	$ 186	$ 186

CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($) $ in Thousands	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest and dividend income:
Interest and fees on loans	$ 19,074	$ 16,033	$ 70,289	$ 65,888	$ 41,026
Interest on interest-earning deposits	187	151	940	334	246
Interest on investment securities	560	278	1,406	872	553
Dividend income on FHLB stock	119	153	472	800	474
Interest on federal funds sold and other	237	144	997	295	214
Total interest income	20,177	16,759	74,104	68,189	42,513
Interest expense:
Interest on savings deposits, now and money market accounts	702	474	2,382	1,975	1,343
Interest on time deposits	2,046	1,849	7,891	6,968	5,592
Interest on subordinated debentures and other	913	905	3,629	2,547
Interest on other borrowed funds	71	17	36	217	1
Total interest expense	3,732	3,245	13,938	11,707	6,936
Net interest income	16,445	13,514	60,166	56,482	35,577
Provision (recapture) for credit losses	184		(1,053)	4,974	1,386
Net interest income after provision for credit losses	16,261	13,514	61,219	51,508	34,191
Noninterest income:
Service charges, fees and other	466	460	2,111	1,758	1,296
Gain on sale of loans	1,815	1,497	9,318	5,847	4,316
Loan servicing fees, net of amortization	(31)	262	722	615	272
Recoveries on loans acquired in business combinations	6	28	84	170	103
Increase in cash surrender value of life insurance	199	185	824	560	579
Gain on sale of securities				19	78
Gain on sale of OREO			142		1,218
Loss on sale of fixed assets				(3)
Total noninterest income	2,455	2,432	13,201	8,966	7,862
Noninterest expense:
Salaries and employee benefits	4,951	4,183	16,821	13,784	11,122
Occupancy and equipment expenses	791	744	2,940	3,098	2,359
Data processing	473	352	1,622	2,018	1,532
Legal and professional	258	(387)	331	1,565	954
Office expenses	171	154	679	598	353
Marketing and business promotion	203	182	837	542	475
Insurance and regulatory assessments	210	205	799	883	761
Amortization of intangibles	81	94	355	372	117
OREO expenses	7	14	28	28	(18)
Other expenses	1,144	1,037	3,211	5,018	2,429
Total noninterest expense	8,289	6,578	27,623	27,906	20,084
Income before income taxes	10,427	9,368	46,797	32,568	21,969
Income tax expense	1,580	3,875	21,269	13,489	8,996
Net income	$ 8,847	$ 5,493	$ 25,528	$ 19,079	$ 12,973
Net income per share
Basic	$ 0.55	$ 0.43	$ 1.81	$ 1.49	$ 1.02
Diluted	0.52	0.40	1.68	1.39	0.96
Cash dividends declared per common share	$ 0.08	$ 0.30	$ 0.38	$ 0.20	$ 0.25
Weighted-average common shares outstanding
Basic	16,082,895	12,827,803	14,078,281	12,800,990	12,761,832
Diluted	17,162,320	13,725,721	15,238,365	13,695,900	13,552,682

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 8,847	$ 5,493	$ 25,528	$ 19,079	$ 12,973
Other comprehensive income (loss):
Unrealized gains (losses) on securities available for sale, Change in unrealized gains (losses)	(853)	115	(176)	(107)	(161)
Unrealized gains (losses) on securities available for sale, Reclassification of gains recognized in net income				(19)	(78)
Unrealized gains (losses) on securities available for sale			(176)	(126)	(239)
Related income tax effect, Change in unrealized gains (losses)	256	(47)	72	44	66
Related income tax effect, Reclassification of gains recognized in net income				8	32
Related income tax effect			72	52	98
Total other comprehensive income (loss)	(597)	68	(104)	(74)	(141)
Total comprehensive income	$ 8,250	$ 5,561	$ 25,424	$ 19,005	$ 12,832

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Jan. 01, 2015	$ 151,981	$ 136,212	$ 6,373	$ 9,448	$ (52)
Balance, shares at Jan. 01, 2015		12,410,399
Net income	12,973			12,973
Stock-based compensation	1,455		1,455
Stock dividend		$ 5,048		(5,048)
Stock dividend, shares		311,443
Cash dividend	(3,114)			(3,114)
Stock options exercised, including tax benefits	491	$ 613	(122)
Stock options exercised including tax benefits, shares		48,729
Other comprehensive income, net of taxes	(141)				(141)
Balance at Dec. 31, 2015	163,645	$ 141,873	7,706	14,259	(193)
Balance, shares at Dec. 31, 2015		12,770,571
Net income	19,079			19,079
Stock-based compensation	894		894
Cash dividend	(2,554)			(2,554)
Stock options exercised, including tax benefits	595	$ 778	(183)
Stock options exercised including tax benefits, shares		57,232
Other comprehensive income, net of taxes	(74)				(74)
Balance at Dec. 31, 2016	$ 181,585	$ 142,651	8,417	30,784	(267)
Balance, shares at Dec. 31, 2016	12,827,803	12,827,803
Net income	$ 5,493			5,493
Stock-based compensation	198		198
Cash dividend	(3,848)			(3,848)
Other comprehensive income, net of taxes	68				68
Balance at Mar. 31, 2017	183,496	$ 142,651	8,615	32,429	(199)
Balance, shares at Mar. 31, 2017		12,827,803
Balance at Dec. 31, 2016	$ 181,585	$ 142,651	8,417	30,784	(267)
Balance, shares at Dec. 31, 2016	12,827,803	12,827,803
Net income	$ 25,528			25,528
Stock-based compensation	779		779
Cash dividend	(5,118)			(5,118)
Stock options exercised	$ 2,296	$ 3,066	(770)
Stock options exercised, shares	223,334	223,334
Issuance of common stock, net of issuance costs	$ 60,210	$ 60,210
Issuance of common stock, net of issuance costs, shares		2,857,756
Other comprehensive income, net of taxes	(104)				(104)
Reclassification of stranded tax effects from change in tax rates				72	(72)
Balance at Dec. 31, 2017	$ 265,176	$ 205,927	8,426	51,266	(443)
Balance, shares at Dec. 31, 2017	15,908,893	15,908,893
Net income	$ 8,847			8,847
Stock-based compensation	131		131
Cash dividend	(1,275)			(1,275)
Stock options exercised	3,540	$ 4,668	(1,128)
Stock options exercised, shares		380,035
Other comprehensive income, net of taxes	(597)				(597)
Balance at Mar. 31, 2018	$ 275,822	$ 210,595	$ 7,429	$ 58,838	$ (1,040)
Balance, shares at Mar. 31, 2018	16,288,928	16,288,928

CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY (Parenthetical) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Stockholders' Equity [Abstract]
Stock dividend, percentage	0.00%	0.00%	2.50%
Income tax benefits, stock options exercised		$ 10	$ 21
Issuance of common stock, net of issuance costs	$ 5,518

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net income	$ 8,847	$ 5,493	$ 25,528	$ 19,079	$ 12,973
Adjustments to reconcile net income to net cash from
Depreciation and amortization of premises, equipment and intangibles	295	338	1,273	1,360	1,020
Net amortization (accretion) of securities, loans, deposits, and other			(4,801)	(7,199)	(1,012)
Net (accretion) of securities, loans, deposits, and other	(88)	(1,020)
Amortization of affordable housing tax credits			316	14
Provision for credit losses	184		(1,053)	4,974	1,386
Stock-based compensation	131	198	779	894	1,455
Deferred tax expense			5,083	1,289	1,361
Gain on sale of securities				(19)	(78)
Gain on sale of loans	(1,815)	(1,497)	(9,318)	(5,847)	(4,316)
Gain on sale of OREO			(142)		(1,218)
Increase in cash surrender value of life insurance	(198)	(185)	(824)	(560)	(579)
Loans originated and purchased for sale	(88,790)	(43,500)	(254,629)	(184,030)	(157,409)
Proceeds from loans sold	57,453	24,780	265,497	221,328	176,744
Other items	2,478	2,950	1,074	4,936	(1,232)
Net cash from operating activities	(21,503)	(12,443)	28,783	56,219	29,095
Investing activities
Decrease in interest-earning deposits		245	(255)	9,437	(7,262)
Securities available for sale:
Purchases	(24,920)	(1,000)	(29,557)	(12,485)	(5,471)
Maturities, prepayments and calls	6,126	1,152	4,353	4,403	4,115
Sales			0	5,083	5,514
Securities Held to Maturity:
Purchases			(4,926)
Maturities, Prepayments and Calls			1,100
Purchase of FHLB stock and other equity securities, net	(4,549)	(5)	(837)	(3,265)	(766)
Purchase of investment in qualified affordable housing projects	(2,500)		(5,000)	(1,000)
Net (increase) decrease in loans	(37,377)	(30,712)	(218,897)	40,290	(103,128)
Proceeds from sales of OREO			257		2,086
Purchase of life insurance		(10,000)	(10,000)
Net cash paid in connection with acquisition				(35,051)
Purchases of premises and equipment	(277)	(124)	(684)	(210)	(468)
Net cash from investing activities	(63,497)	(40,444)	(264,446)	7,202	(105,380)
Financing activities
Net increase in demand deposits and savings accounts	18,586	70,270	226,382	(47,679)	65,761
Net increase in time deposits	17,636	25,299	(41,772)	(58,235)	20,343
Net (decrease) increase in FHLB advances	(25,000)	10,000	25,000
Cash dividends paid	(1,275)	(3,848)	(5,118)	(2,554)	(3,114)
Issuance of subordinated debentures, net of issuance costs				49,274
Issuance of common stock, net of issuance costs			60,210
Exercise of stock options	3,540		2,296	595	491
Net cash from financing activities	13,487	101,721	266,998	(58,599)	83,481
Net (decrease) increase in cash and cash equivalents	(71,513)	48,834	31,335	4,822	7,196
Cash and cash equivalents at beginning of period	150,048	118,713	118,713	113,891	106,695
Cash and cash equivalents at end of period	78,535	167,547	150,048	118,713	113,891
Cash paid during the period:
Interest paid			13,848	12,342	6,872
Taxes paid			16,935	12,515	7,120
Non-cash investing and financing activities:
Transfer of loan to available for sale securities			1,000
Transfer from loans to OREO				540
Transfer of loans to held for sale	23,989	25,046	165,651	71,626	53,127
Loan to facilitate OREO			425
Securities held to maturity transferred to available for sale				433
Net change in unrealized holding gain on securities available for sale	$ (853)	$ 115	$ (176)	$ (107)	$ (161)

Business Description	12 Months Ended
Business Description	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Description	NOTE 1—BUSINESS DESCRIPTION RBB Bancorp is a bank holding company registered under the Bank Holding Company Act of 1956, as amended. RBB Bancorp’s principal business is to serve as the holding company for its wholly-owned banking subsidiaries, Royal Business Bank (“Bank”) and RBB Asset Management Company (“RAM”), collectively referred to herein as “the Company”. At December 31, 2017, the Company had total assets of $1.7 billion, gross loans of $1.2 billion, total deposits of $1.3 billion and total stockholders’ equity of $265.2 million. On July 31, 2017, the Company completed its initial public offering of 3,750,000 shares at a price to the public of $23.00 per share. The Company’s stock trades on the Nasdaq Global Select Market under the symbol “RBB”. Royal Business Bank provides business banking services to the Chinese-American communities in Los Angeles County, Orange County, Ventura County and in Las Vegas, including remote deposit, E-banking, mobile banking, commercial and investor real estate loans, business loans and lines of credit, SBA 7A and 504 loans, mortgage loans, trade finance and a full range of depository accounts. RAM was formed to hold and manage problem assets acquired in business combinations. The Company operates full-service banking offices in Arcadia, Cerritos, Diamond Bar, Los Angeles, Monterey Park, Oxnard, Rowland Heights, San Gabriel, Silver Lake, Torrance, West Los Angeles, and Westlake Village, California and Las Vegas, Nevada and a loan production office in the City of Industry, California. The Company’s primary source of revenue is providing loans to customers, who are predominately small and middle-market businesses and individuals. The Company generates its revenue primarily from interest received on loans and leases and, to a lesser extent, from interest received on investment securities. The Company also derived income from noninterest sources, such as fees received in connection with various lending and deposit services, residential mortgage loan originations, loan servicing and gain on sales of loans. The Company’s principle expenses include interest expense on deposits and subordinated debentures, and operating expenses, such as salaries and employee benefits, occupancy and equipment, data processing, and income tax expense. The Company has completed four acquisitions from July 8, 2011 through February 19, 2016, including the acquisition of TFC Holding Company on February 19, 2016. The acquisitions have been accounted for using the acquisition method of accounting and, accordingly, the operating results of the acquired entities have been included in the consolidated financial statements from their respective acquisition dates. See Note 3. Acquisitions, for more information about the TFC acquisition.

Basis of Presentation and Summary of Significant Accounting Policies

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Presentation and Summary of Significant Accounting Policies

NOTE 1—BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The accompanying unaudited consolidated financial statements include the accounts of RBB Bancorp and its wholly-owned subsidiaries Royal Business Bank (Bank) and RBB Asset Management Company (RAM), collectively referred to herein as “the Company”, “we”, “our” or “us”. All significant intercompany accounts and transactions have been eliminated in consolidation. RBB Bancorp has no significant business activity other than its investments in Royal Business Bank and RAM.

The accompanying unaudited consolidated financial statements and notes thereto of the Company have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (SEC) for Form 10-Q and conform to practices within the banking industry and include all of the information and disclosures required by accounting principles generally accepted in the United States of America (GAAP) for interim financial reporting. The accompanying unaudited consolidated financial statements reflect all adjustments consisting only of normal recurring adjustments. That, in the opinion of management, are necessary to reflect a fair presentation of financial results for the interim periods presented. The results of operations for the three months ended March 31, 2018 are not necessarily indicative of the results for the full year. These interim unaudited financial statements should be read in conjunction with the audited consolidated financial statements and the notes thereto included in our Annual Report on Form 10-K for the year ended December 31, 2017 (the “2017 Annual Report”).

The Company accounts for its investments in its wholly owned special purpose TFC Statutory Trust under the equity method whereby the subsidiary’s net earnings are recognized in the Company’s statement of income.

Use of Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Summary of Significant Accounting Policies

The accompanying unaudited consolidated financial statements were compiled in accordance with the accounting policies set forth in Note 2—Summary of Significant Policies in our consolidated financial statements included in our 2017 Annual Report.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) 2014-09, Revenue from Contracts with Customers (Topic 606). This Update requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The following steps are applied in the updated guidance: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. These amendments are effective for public business entities for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period and one year later for nonpublic business entities. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that period. The Company plans to adopt ASU 2014-09 on January 1, 2019 utilizing the modified retrospective approach. Since the guidance does not apply to revenue associated with financial instruments such as loans and investments, which are accounted for under other provisions of GAAP, we do not expect it to impact interest income, our largest component of income. The Company will perform an overall assessment of revenue streams potentially affected by the ASU, including certain deposit related fees and interchange fees, to determine the impact this guidance will have on our consolidated financial statements.

In January 2016, the FASB issued ASU 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10). Changes made to the current measurement model primarily affect the accounting for equity securities and readily determinable fair values, where changes in fair value will impact earnings instead of other comprehensive income. The accounting for other financial instruments, such as loans, investments in debt securities, and financial liabilities is largely unchanged. The Update also changes the presentation and disclosure requirements for financial instruments including a requirement that public business entities use exit price when measuring the fair value of financial instruments measured at amortized cost for disclosure purposes. This Update is generally effective for public business entities in fiscal years beginning after December 15, 2017, including interim periods within those fiscal years and one year later for nonpublic business entities. Based upon an evaluation of the guidance in ASU 2016-01 the Company determined the ASU will not have a material impact on the Company’s consolidated financial statements as the accounting for other financial instruments, such as loans, investments in debt securities, and financial liabilities is largely unchanged. The Company adopted this ASU as of January 1, 2018 but will continue to monitor any updates to the guidance.

In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842). The most significant change for lessees is the requirement under the new guidance to recognize right-of-use assets and lease liabilities for all leases not considered short-term leases, which is generally defined as a lease term of less than 12 months. This change will result in lessees recognizing right-of-use assets and lease liabilities for most leases currently accounted for as operating leases under current lease accounting guidance. The amendments in this Update are effective for interim and annual periods beginning after December 15, 2018, for public business entities and one year later for all other entities. The Company has several lease agreements which are currently considered operating leases and are therefore not included on the Company’s Consolidated Balance Sheets. Under the new guidance the Company expects that some of the lease agreements will have to be recognized on the Consolidated Balance Sheets as a right-of-use asset with a corresponding lease liability. Based upon a preliminary evaluation the Company expects that the ASU will have an impact on the Company’s Consolidated Balance Sheets. The Company will continue to evaluate how extensive the impact will be under the ASU on the Company’s consolidated financial statements.

In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718.) ASU 2016-09 includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. Under ASU 2016-09, excess tax benefits and certain tax deficiencies will no longer be recorded in additional paid-in capital (APIC). Instead, they will record all excess tax benefits and tax deficiencies as income tax expense or benefit in the income statement, and APIC pools will be eliminated. In addition, the guidance requires excess tax benefits be presented as an operating activity on the statement of cash flows rather than as a financing activity. ASU 2016-09 also permits an accounting policy election for the impact of forfeitures on the recognition of expense for share-based payment awards. Forfeitures can be estimated, as required today, or recognized when they occur. This guidance is effective for public business entities for interim and annual reporting periods beginning after December 15, 2016, and for nonpublic business entities annual reporting periods beginning after December 15, 2017, and interim periods within the reporting periods beginning after December 15, 2018. Early adoption is permitted, but all of the guidance must be adopted in the same period. The Company early adopted the ASU as of January 1, 2017. The Company plans to recognize forfeitures as they occur. The early adoption of the ASU did not have a material effect on the company’s financial statements or disclosures.

In June 2016, the FASB issued ASU 2016-13, Measurement of Credit Losses on Financial Instrument (Topic 326). This ASU significantly changes how entities will measure credit losses for most financial assets and certain other instruments that aren’t measured at fair value through net income. In issuing the standard, the FASB is responding to criticism that today’s guidance delays recognition of credit losses. The standard will replace today’s “incurred loss” approach with an “expected loss” model. The new model, referred to as the current expected credit loss (CECL) model, will apply to: (1) financial assets subject to credit losses and measured at amortized cost, and (2) certain off-balance sheet credit exposures. This includes, but is not limited to, loans, leases, held to maturity securities, loan commitments, and financial guarantees. The CECL model does not apply to available for sale (AFS) debt securities. For AFS debt securities with unrealized losses, entities will measure credit losses in a manner similar to what they do today, except that the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. As a result, entities will recognize improvements to estimated credit losses immediately in earnings rather than as interest income over time, as they do today. The ASU also simplifies the accounting model for purchased credit-impaired debt securities and loans. ASU 2016-13also expands the disclosure requirements regarding an entity’s assumptions, models, and methods for estimating the allowance for loan and lease losses. In addition, public business entities will need to disclose the amortized cost balance for each class of financial asset by credit quality indicator, disaggregated by the year of origination. ASU No. 2016-13 is effective for interim and annual reporting periods beginning after December 15, 2019, for SEC filers, one year later for non SEC filing public business entities and annual reporting periods beginning after December 15, 2020, for nonpublic business entities and interim periods within the reporting periods beginning after December 15, 2021. Early adoption is permitted for interim and annual reporting periods beginning after December 15, 2018. Entities will apply the standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (i.e., modified retrospective approach). The Company has begun its evaluation of the impact of the implementation of ASU 2016-13. The implementation of the provisions of ASU No. 2016-13 will most likely impact the Company’s Consolidated Financial Statements as to the level of reserves that will be required for credit losses. The Company will continue to access the potential impact that this ASU will have on the Company’s consolidated financial statements.

In August 2016, the FASB issued ASU 2016-15, Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments (Topic 230). The new guidance clarifies the classification within the statement of cash flows for certain transactions, including debt extinguishment costs, zero-coupon debt, contingent consideration related to business combinations, insurance proceeds, equity method distributions and beneficial interests in securitizations. The guidance also clarifies that cash flows with aspects of multiple classes of cash flows that cannot be separated by source or use should be classified based on the activity that is likely to be the predominant source or use of cash flows for the item. This guidance is effective for fiscal years beginning after December 15, 2017 and will require application using a retrospective transition method. The Company adopted this statement as of January 1, 2018. The Company believes the requirement to separately identify cash flows and application of the predominance principle is the cash flow item currently applicable to the consolidated financial statements.

In January 2017, the FASB issued ASU 2017-01, Business Combinations: Clarifying the Definition of a Business (Topic 805). Currently, the ASU specifies three elements of a business – inputs, processes, and outputs. While an integrated set of assets and activities (collectively referred to as a “set”) that is a business usually has outputs, outputs are not required. In addition, all the inputs and processes that a seller uses in operating a set are not required if market participants can acquire the set and continue to produce outputs, for example, by integrating the acquired set with their own inputs and processes. This led many transactions to be accounted for as business combinations rather than asset purchases under legacy GAAP. The primary goal of ASU 2017-01 is to narrow the definition of a business, and the guidance in this update provides a screen to determine when a set is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The amendments in this update should be applied prospectively on or after the effective date. The Company adopted this ASU on January 1, 2018 and will be applied prospectively for any future business combinations.

In January 2017, the FASB issued ASU 2017-04, Intangibles—Goodwill and Other (Topic 350). This ASU simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The amendments in this Update are required for public business entities and other entities that have goodwill reported in their financial statements and have not elected the private company alternative for the subsequent measurement of goodwill. As a result, under the ASU, “an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit.” ASU No. 2017-14 is effective for annual and any interim impairment tests performed in periods beginning after December 15, 2019 for public business entities that are SEC filers, December 15, 2020 for business entities that are not SEC filers, and December 15, 2021 for all other entities. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company will continue to access the potential impact that this ASU will have on the Company’s consolidated financial statements.

In March 2017, the FASB issued ASU 2017-08, Receivables—Nonrefundable Fees and Other Costs: Premium Amortization on Purchased Callable Debt Securities (Subtopic 310-20), which is intended to enhance “the accounting for the amortization of premiums for purchased callable debt securities.” The ASU shortens the amortization period for certain callable debt securities purchased at a premium by requiring that the premium be amortized to the earliest call date. Under GAAP, entities generally amortize the premium as an adjustment of yield over the contractual life of the instrument. The amendments in this Update affects all entities that hold investments in callable debt securities that have an amortized cost basis in excess of the amount that is repayable by the issuer at the earliest call date (that is, at a premium). The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The ASU’s amendments are effective for public business entities for interim and annual periods beginning after December 15, 2018. For other entities, the amendments are effective for annual periods beginning after December 15, 2019, and interim periods thereafter. Early adoption is permitted, including adoption in an interim period. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity should apply the amendments in this Update on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. Additionally, in the period of adoption, an entity should provide disclosures about a change in accounting principle. The implementation of the provisions of ASU No. 2017-08 will most likely not have a material impact the Company’s consolidated financial statements. The Company will continue to access the potential impact that this ASU will have on the Company’s consolidated financial statements.

In May 2017, the FASB issued ASU 2017-09, Compensation—Stock Compensation: Scope of codification Accounting (Topic 718). The amendments in ASU 2017-09 provide guidance about which changes to the terms or conditions of a share- entity to apply modification accounting. An entity should account for the effects of a modification unless all the following are met: (1) The fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the modified award is the same as the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the original award immediately before the original award is modified. If the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification; (2) The vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified; (3) The classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified. The amendments in ASU No. 2017-09 are effective for annual periods, and interim within those annual reporting periods, beginning after December 15, 2017; early adoption is permitted. The amendments in this ASU should be applied prospectively to an award modified on or after the adoption date. The Company does not expect this ASU to have a material impact on the Company’s consolidated financial statements.

In July 2017, the FASB issued ASU 2017-13—Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842): Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments (SEC Update). At the July 20, 2017, EITF meeting, the SEC staff announced that it would not object when certain public business entities (PBEs) elect to use the non-PBE effective dates solely to adopt the FASB’s new standards on revenue (ASC 606) and leases (ASC 842). This ASU reflects comments made by the SEC. The Company will continue to evaluate how extensive the impact will be under the ASU on the Company’s consolidated financial statements.

In February 2018, the FASB issued ASU 2018-02—Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The amendments in this Update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act. Consequently, the amendments eliminate the stranded tax effects resulting from the Tax Cuts and Jobs Act and will improve the usefulness of information reported to financial statement users. However, because the amendments only relate to the reclassification of the income tax effects of the Tax Cuts and Jobs Act, the underlying guidance that requires that the effect of a change in tax laws or rates be included in income from continuing operations is not affected. The amendments in this Update also require certain disclosures about stranded tax effects. The amendments in this Update are effective for all entities for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption of the amendments in this Update is permitted, including adoption in any interim period, (1) for public business entities for reporting periods for which financial statements have not yet been issued and (2) for all other entities for reporting periods for which financial statements have not yet been made available for issuance. The amendments in this Update should be applied either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. The Company will continue to access the potential impact that this ASU will have on the Company’s consolidated financial statements.

NOTE 2—BASIS OF PRESENTATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

Basis of Presentation

The accompanying consolidated financial statements and notes thereto of the Company have been prepared in accordance with the rules and regulations of the Securities and Exchange Commission (“SEC”) for Form 10-K and conform to practices within the banking industry and include all of the information and disclosures required by accounting principles generally accepted in the United States of America (“GAAP”) for financial reporting.

Reclassifications

Certain amounts in the prior periods’ financial statements and related footnote disclosures have been reclassified to conform to the current presentation with no impact on previously reported net income or stockholders’ equity.

Principles of Consolidation and Nature of Operations

The accompanying consolidated financial statements include the accounts of RBB Bancorp and its wholly-owned subsidiaries Royal Business Bank (“Bank”) and RBB Asset Management Company (“RAM”), collectively referred to herein as “the Company”. All significant intercompany transactions have been eliminated.

RBB Bancorp was formed in January 2011 as a bank holding company. RAM was formed in 2012 to hold and manage problem assets acquired in business combinations.

RBB Bancorp has no significant business activity other than its investments in Royal Business Bank and RAM. Parent only condensed financial information on RBB Bancorp is provided in Note 22.

Use of Estimates in the Preparation of Financial Statements

The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Cash and Cash Equivalents

Cash and cash equivalents include cash and due from banks, term federal funds sold and interest-bearing deposits in other financial institutions with original maturities of less than 90 days. Net cash flows are reported for customer loan and deposit transactions and interest-bearing deposits in other financial institutions.

Cash and Due from Banks

Banking regulations require that banks maintain a percentage of their deposits as reserves in cash or on deposit with the Federal Reserve Bank. The reserves required to be held as of December 31, 2017 and 2016 were $19,664,000 and $9,811,000, respectively. The Company maintains amounts in due from bank accounts, which may exceed federally insured limits. The Company has not experienced any losses in such accounts.

Interest-Bearing Deposits in Other Financial Institutions

Interest-bearing deposits in other financial institutions not included in cash and cash equivalents are carried at cost.

Investment Securities

Debt securities are classified as held to maturity and carried at amortized cost when management has the positive intent and ability to hold them to maturity. Debt securities not classified as held to maturity are classified as available for sale. Equity securities with readily determinable fair values are classified as available for sale. Securities available for sale are carried at fair value, with unrealized holding gains and losses reported in other comprehensive income, net of tax.

Interest income includes amortization of purchase premiums or discounts. Premiums and discounts on securities are amortized on the level-yield method without anticipating prepayments. Gains and losses on sales are recorded on the trade date and determined using the specific identification method.

Management evaluates securities for other-than-temporary impairment (“OTTI”) on at least a semi-annual basis, and more frequently when economic or market conditions warrant such an evaluation. For securities in an unrealized loss position, management considers the extent and duration of the unrealized loss, and the financial condition and near-term prospects of the issuer. Management also assesses whether it intends to sell, or it is more likely than not that it will be required to sell, a security in an unrealized loss position before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the entire difference between amortized cost and fair value is recognized as impairment through earnings. For debt securities that do not meet the aforementioned criteria, the amount of impairment is split into two components as follows; OTTI related to credit loss, which must be recognized in the income statement and; OTTI related to other factors, which is recognized in other comprehensive income. The credit loss is defined as the difference between the present value of the cash flows expected to be collected and the amortized cost basis. For equity securities, the entire amount of impairment is recognized through earnings.

Loans Held For Sale

Mortgage loans originated or acquired and intended for sale in the secondary market are carried at the lower of aggregate cost or fair value, as determined by outstanding commitments from investors. Net unrealized losses, if any, are recorded as a valuation allowance and charged to earnings. Loans held for sale consist primarily of first trust deed mortgages on single-family residential properties located in California.

Mortgage loans held for sale are generally sold with servicing rights retained. The carrying value of mortgage loans sold is reduced by the amount allocated to the servicing right, when applicable. Gains and losses on sales of mortgage loans are based on the difference between the selling price and the carrying value of the related loans sold.

Loans

Loans receivable that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at their outstanding unpaid principal balances reduced by any charge-offs or specific valuation accounts and net of any deferred fees or costs on originated loans, or unamortized premiums or discounts on purchased loans. Loan origination fees and certain direct origination costs are deferred and recognized in interest income using the level-yield method without anticipating prepayments.

Premiums and discounts on loans purchased are grouped by type and certain common risk characteristics and amortized or accreted as an adjustment of yield over the weighted-average remaining contractual lives of each group of loans, adjusted for prepayments when applicable, using methodologies which approximate the interest method.

Loans on which the accrual of interest has been discontinued are designated as nonaccrual loans. The accrual of interest on loans is discontinued when principal or interest is past due 90 days or when, in the opinion of management, there is reasonable doubt as to collectability based on contractual terms of the loan. When loans are placed on nonaccrual status, all interest previously accrued but not collected is reversed against current period interest income. Income on nonaccrual loans is subsequently recognized only to the extent that cash is received and the loan’s principal balance is deemed collectible. Interest accruals are resumed on such loans only when they are brought current with respect to interest and principal and when, in the judgment of management, the loans are estimated to be fully collectible as to all principal and interest.

Allowance for Loan Losses

The allowance for loan losses is a valuation allowance for probable incurred credit losses. Loan losses are charged against the allowance when management believes the uncollectability of a loan balance is confirmed. Subsequent recoveries, if any, are credited to the allowance. Management estimates the allowance balance required using past loan loss experience, the nature and volume of the portfolio, information about specific borrower situations and estimated collateral values, economic conditions, and other factors. Allocations of the allowance may be made for specific loans, but the entire allowance is available for any loan that, in management’s judgment, should be charged-off. Amounts are charged-off when available information confirms that specific loans or portions thereof, are uncollectible. This methodology for determining charge-offs is consistently applied to each segment.

The Company determines a separate allowance for each portfolio segment. The allowance consists of specific and general reserves. Specific reserves relate to loans that are individually classified as impaired. A loan is impaired when, based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. Factors considered in determining impairment include payment status, collateral value and the probability of collecting all amounts when due. Measurement of impairment is based on the expected future cash flows of an impaired loan, which are to be discounted at the loan’s effective interest rate, or measured by reference to an observable market value, if one exists, or the fair value of the collateral for a collateral-dependent loan. The Company selects the measurement method on a loan-by-loan basis except that collateral-dependent loans for which foreclosure is probable are measured at the fair value of the collateral.

The Company recognizes interest income on impaired loans based on its existing methods of recognizing interest income on nonaccrual loans. Loans, for which the terms have been modified resulting in a concession, and for which the borrower is experiencing financial difficulties, are considered troubled debt restructurings and classified as impaired with measurement of impairment as described above.

If a loan is impaired, a portion of the allowance is allocated so that the loan is reported, net, at the present value of estimated future cash flows using the loan’s existing rate or at the fair value of collateral if repayment is expected solely from the collateral.

General reserves cover non-impaired loans and are based on historical loss rates of peer institutions for each portfolio segment, adjusted for the effects of qualitative or environmental factors that are likely to cause estimated credit losses as of the evaluation date to differ from the portfolio segment’s historical loss experience. Qualitative factors include consideration of the following: changes in lending policies and procedures; changes in economic conditions, changes in the nature and volume of the portfolio; changes in the experience, ability and depth of lending management and other relevant staff; changes in the volume and severity of past due, nonaccrual and other adversely graded loans; changes in the loan review system; changes in the value of the underlying collateral for collateral-dependent loans; concentrations of credit and the effect of other external factors such as competition and legal and regulatory requirements.

Portfolio segments identified by the Company include real estate and commercial loans. Relevant risk characteristics for these portfolio segments generally include debt service coverage, loan-to-value ratios, and financial performance.

Certain Acquired Loans

As part of business acquisitions, the Company acquires certain loans that have shown evidence of credit deterioration since origination. These acquired loans are recorded at the allocated fair value, such that there is no carryover of the seller’s allowance for loan losses. Such acquired loans are accounted for individually. The Company estimates the amount and timing of expected cash flows for each purchased loan, and the expected cash flows in excess of the allocated fair value is recorded as interest income over the remaining life of the loan (accretable yield). The excess of the loan’s contractual principal and interest over expected cash flows is not recorded (non-accretable difference). Over the life of the loan, expected cash flows continue to be estimated. If the present value of expected cash flows is less than the carrying amount, a loss is recorded through the allowance for loan losses. If the present value of expected cash flows is greater than the carrying amount, it is recognized as part of future interest income.

Servicing Rights

When mortgage and Small Business Administration (“SBA”) loans are sold with servicing retained, servicing rights are initially recorded at fair value with the income statement effect recorded in gains on sales of loans. Fair value is based on a valuation model that calculates the present value of estimated future net servicing income. All classes of servicing assets are subsequently measured using the amortization method which requires servicing rights to be amortized into noninterest income in proportion to, and over the period of, the estimated future net servicing income of the underlying loans.

Servicing rights are evaluated for impairment based upon the fair value of the rights as compared to carrying amount. Impairment is recognized through a valuation allowance for an individual grouping, to the extent that fair value is less than the carrying amount. If the Company later determines that all or a portion of the impairment no longer exists for a particular grouping, a reduction of the allowance may be recorded as an increase to income.

Servicing fee income, which is reported on the income statement as loan servicing fees, net of amortization , is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal. The amortization of mortgage servicing rights is netted against loan servicing fee income.

Transfers of Financial Assets

Transfers of financial assets are accounted for as sales, when control over the assets has been relinquished. Control over transferred assets is deemed to be surrendered when the assets have been isolated from the Company, the transferee obtains the right (free of conditions that constrain it from taking advantage of that right) to pledge or exchange the transferred assets, and the Company does not maintain effective control over the transferred assets through an agreement to repurchase them before their maturity.

Gains on sales of mortgage and SBA loans totaled $9.3 million, $5.8 million, and $4.3 million in 2017, 2016, and 2015, respectively. Gains on sale of mortgage loans totaled $3.7 million, $3.4 million, and $1.6 million, and gains on sale of SBA loans totaled $5.6 million, $2.4 million, and $2.7 million in 2017, 2016, and 2015 respectively.

Premises and Equipment

Land is carried at cost. Premises, leasehold improvements and equipment are carried at cost less accumulated depreciation and amortization. Depreciation is computed using the straight-line method over the estimated useful lives, which is thirty years for premises and ranges from three to ten years for leasehold improvements and equipment. Leasehold improvements are amortized using the straight-line method over the estimated useful lives of the improvements or the remaining lease term, whichever is shorter. Expenditures for betterments or major repairs are capitalized and those for ordinary repairs and maintenance are charged to operations as incurred.

Other Real Estate Owned

Real estate acquired by foreclosure or deed in lieu of foreclosure is recorded at fair value at the date of foreclosure, establishing a new cost basis by a charge to the allowance for loan losses, if necessary. Other real estate owned is carried at the lower of the Company’s carrying value of the property or its fair value, less estimated carrying costs and costs of disposition. Fair value is based on current appraisals less estimated selling costs. Any subsequent write-downs are charged against operating expenses and recognized as a valuation allowance. Operating expenses and related income of such properties and gains and losses on their disposition are included in other operating income and expenses.

Goodwill and Other Intangible Assets

Goodwill is generally determined as the excess of the fair value of the consideration transferred, plus the fair value of any noncontrolling interests in the acquiree, over the fair value of the net assets acquired and liabilities assumed as of the acquisition date. Goodwill resulting from whole bank acquisitions is not amortized, but tested for impairment at least annually. The Company has selected December 31 as the date to perform the annual impairment test. Goodwill amounted to $29.9 million as of December 31, 2017 and 2016, respectively, and is the only intangible asset with an indefinite life on the balance sheet. No impairment was recognized on goodwill during 2017 and 2016.

Other intangible assets consist of core deposit intangible (“CDI”) assets arising from whole bank acquisitions. CDI assets are amortized on an accelerated method over their estimated useful life of 8 to 10 years. CDI was recognized in the 2013 acquisition of Los Angeles National Bank and in the 2016 acquisition of TFC Holding Company. The unamortized balance as of December 31, 2017 and 2016 was $1,438,000 and $1,793,000, respectively. CDI amortization expense was $355,000, $372,000, and $117,000 in 2017, 2016 and 2015, respectively.

Estimated CDI amortization expense for the next 5 years is as follows (dollars in thousands):


Year ending December 31:
2018	$	311
2019		274
2020		244
2021		172
2022		129
Thereafter		308

Total	$	1,438

Bank Owned Life Insurance

The Company has purchased life insurance policies on a select group of employees and directors. Bank owned life insurance (BOLI) is recorded at the amount that can be realized under the insurance contract at the balance sheet date, which is the cash surrender value adjusted for other charges or other amounts due that are probable at settlement. Increases of the cash value of these policies, as well as insurance proceeds received, are recorded in the other noninterest income and are not subject to income tax for as long as they are held for the life of the covered employee and director.

Federal Home Loan Bank (“FHLB”) Stock

The Company is a member of the FHLB system. Members are required to own a certain amount of stock based on the level of borrowings and other factors, and may invest in additional amounts. FHLB stock is carried at cost, classified as a restricted security, and periodically evaluated for impairment based on ultimate recovery of par value. Both cash and stock dividends are reported as income.

Stock-Based Compensation

Compensation cost is recognized for stock options issued to employees and directors, based on the fair value of these awards at the date of grant. A Black-Scholes model is utilized to estimate the fair value of stock options. This cost is recognized over the period which an employee is required to provide services in exchange for the award, generally defined as the vesting period. When the options are exercised, the Company’s policy is to issue new shares of stock.

Income Taxes

The Company files its income taxes on a consolidated basis with its subsidiaries. The allocation of income tax expense represents each entity’s proportionate share of the consolidated provision for income taxes. Income tax expense is the total of the current year income tax due or refundable and the change in deferred tax assets and liabilities. Deferred tax assets and liabilities are the expected future tax amounts for the temporary differences between carrying amounts and tax bases of assets and liabilities, computed using enacted tax rates. A valuation allowance, if needed, reduces deferred tax assets to the amount expected to be realized. Tax effects from an uncertain tax position are recognized in the financial statements only if, based on its merits, the position is more likely than not to be sustained on audit by the taxing authorities. Interest and penalties related to uncertain tax positions are recorded as part of income tax expense.

Retirement Plans

The Company established a 401(k) plan in 2010. The Company contributed $272,000, $221,000, and $125,000 in 2017 , 2 016, and 2015, respectively .

Comprehensive Income

Comprehensive income consists of net income and other comprehensive income. Other comprehensive income includes unrealized gains and losses on securities available for sale.

Financial Instruments

In the ordinary course of business, the Company has entered into off-balance sheet financial instruments consisting of commitments to extend credit, commercial letters of credit, and standby letters of credit as described in Note 13. Such financial instruments are recorded in the financial statements when they are funded.

Earnings Per Share (“EPS”)

Basic EPS excludes dilution and is computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted EPS reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity.

Fair Value Measurement

Fair value is the exchange price that would be received for an asset or paid to transfer a liability (exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Current accounting guidance establishes a fair value hierarchy, which requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair values:

Level 1: Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date.

Level 2: Significant other observable inputs other than Level 1 prices such as quoted prices for similar assets or liabilities; quoted prices in markets that are not active; or other inputs that are observable or can be corroborated by observable market data.

Level 3: Significant unobservable inputs that reflect the Company’s own assumptions about the assumptions that market participants would use in pricing an asset or liability.

See Note 17 and Note 18 for more information and disclosures relating to the Company’s fair value measurements.

Operating Segments

Management has determined that since generally all of the banking products and services offered by the Company are available in each branch of the Bank, all branches are located within the same economic environment and management does not allocate resources based on the performance of different lending or transaction activities, it is appropriate to aggregate the Bank branches and report them as a single operating segment.

Recent Accounting Pronouncements

In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (Topic 606). This Update requires an entity to recognize revenue as performance obligations are met, in order to reflect the transfer of promised goods or services to customers in an amount that reflects the consideration the entity is entitled to receive for those goods or services. The following steps are applied in the updated guidance: (1) identify the contract(s) with a customer; (2) identify the performance obligations in the contract; (3) determine the transaction price; (4) allocate the transaction price to the performance obligations in the contract; and (5) recognize revenue when, or as, the entity satisfies a performance obligation. These amendments are effective for public business entities for annual reporting periods beginning after December 15, 2017, including interim periods within that reporting period and one year later for nonpublic business entities. Early adoption is permitted only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that period. The guidance does not apply to revenue associated with financial instruments and therefore the Company does not expect the new guidance to have a material impact on revenue closely associated with financial instruments, including interest income. The Company plans to adopt ASU 2014-09 on January 1, 2019 utilizing the modified retrospective approach. Since the guidance does not apply to revenue associated with financial instruments such as loans and investments, which are accounted for under other provisions of GAAP, we do not expect it to impact interest income, our largest component of income. The Company will perform an overall assessment of revenue streams potentially affected by the ASU, including certain deposit related fees and interchange fees, to determine the impact this guidance will have on our consolidated financial statements.

In January 2016, the FASB issued ASU 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10). Changes made to the current measurement model primarily affect the accounting for equity securities and readily determinable fair values, where changes in fair value will impact earnings instead of other comprehensive income. The accounting for other financial instruments, such as loans, investments in debt securities, and financial liabilities is largely unchanged. The Update also changes the presentation and disclosure requirements for financial instruments including a requirement that public business entities use exit price when measuring the fair value of financial instruments measured at amortized cost for disclosure purposes. This Update is generally effective for public business entities in fiscal years beginning after December 15, 2017, including interim periods within those fiscal years and one year later for nonpublic business entities. Based upon a preliminary evaluation of the guidance in ASU No. 2016-01 the Company does not believe that the ASU will have a material impact on the Company’s Consolidated Financial Statements. The Company will continue to monitor any updates to the guidance.

In February 2016, the FASB issued Accounting Standards Update (ASU) 2016-02, Leases (Topic 842). The most significant change for lessees is the requirement under the new guidance to recognize right-of-use assets and lease liabilities for all leases not considered short-term leases, which is generally defined as a lease term of less than 12 months. This change will result in lessees recognizing right-of-use assets and lease liabilities for most leases currently accounted for as operating leases under current lease accounting guidance. The amendments in this Update are effective for interim and annual periods beginning after December 15, 2018, for public business entities and one year later for all other entities. The Company has several lease agreements which are currently considered operating leases and are therefore not included on the Company’s Consolidated Balance Sheets. Under the new guidance the Company expects that some of the lease agreements will have to be recognized on the Consolidated Balance Sheets as a right-of-use asset with a corresponding lease liability. Based upon a preliminary evaluation the Company expects that the ASU will have an impact on the Company’s Consolidated Balance Sheets. The Company will continue to evaluate how extensive the impact will be under the ASU on the Company’s Consolidated Financial Statements.

In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718.) ASU 2016-09 includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. Under ASU 2016-09, excess tax benefits and certain tax deficiencies will no longer be recorded in additional paid-in capital (“APIC”). Instead, they will record all excess tax benefits and tax deficiencies as income tax expense or benefit in the income statement, and APIC pools will be eliminated. In addition, the guidance requires excess tax benefits be presented as an operating activity on the statement of cash flows rather than as a financing activity. ASU 2016-09 also permits an accounting policy election for the impact of forfeitures on the recognition of expense for share-based payment awards. Forfeitures can be estimated, as required today, or recognized when they occur. This guidance is effective for public business entities for interim and annual reporting periods beginning after December 15, 2016, and for nonpublic business entities annual reporting periods beginning after December 15, 2017, and interim periods within the reporting periods beginning after December 15, 2018. Early adoption is permitted, but all of the guidance must be adopted in the same period. The Company early adopted the ASU as of January 1, 2017. The Company plans to recognize forfeitures as they occur. The early adoption of the ASU did not have a material effect on the Company’s financial statements or disclosures.

In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instrument (Topic 326). This ASU significantly changes how entities will measure credit losses for most financial assets and certain other instruments that aren’t measured at fair value through net income. In issuing the standard, the FASB is responding to criticism that today’s guidance delays recognition of credit losses. The standard will replace today’s “incurred loss” approach with an “expected loss” model. The new model, referred to as the current expected credit loss (“CECL”) model, will apply to: (1) financial assets subject to credit losses and measured at amortized cost, and (2) certain off-balance sheet credit exposures. This includes, but is not limited to, loans, leases, held to maturity securities, loan commitments, and financial guarantees. The CECL model does not apply to available for sale (“AFS”) debt securities. For AFS debt securities with unrealized losses, entities will measure credit losses in a manner similar to what they do today, except that the losses will be recognized as allowances rather than reductions in the amortized cost of the securities. As a result, entities will recognize improvements to estimated credit losses immediately in earnings rather than as interest income over time, as they do today. The ASU also simplifies the accounting model for purchased credit-impaired debt securities and loans. ASU 2016-13 also expands the disclosure requirements regarding an entity’s assumptions, models, and methods for estimating the allowance for loan and lease losses. In addition, public business entities will need to disclose the amortized cost balance for each class of financial asset by credit quality indicator, disaggregated by the year of origination. ASU No. 2016-13 is effective for interim and annual reporting periods beginning after December 15, 2019, for SEC filers, one year later for non SEC filing public business entities and annual reporting periods beginning after December 15, 2020, for nonpublic business entities and interim periods within the reporting periods beginning after December 15, 2021. Early adoption is permitted for interim and annual reporting periods beginning after December 15, 2018. Entities will apply the standard’s provisions as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is effective (i.e., modified retrospective approach). The Company has begun its evaluation of the impact of the implementation of ASU 2016-13. The implementation of the provisions of ASU No. 2016-13 will most likely impact the Company’s Consolidated Financial Statements as to the level of reserves that will be required for credit losses. The Company will continue to access the potential impact that this ASU will have on the Company’s Consolidated Financial Statements.

In August 2016, the FASB issued ASU No. 2016-15, “Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments.” The new guidance clarifies the classification within the statement of cash flows for certain transactions, including debt extinguishment costs, zero-coupon debt, contingent consideration related to business combinations, insurance proceeds, equity method distributions and beneficial interests in securitizations. The guidance also clarifies that cash flows with aspects of multiple classes of cash flows that cannot be separated by source or use should be classified based on the activity that is likely to be the predominant source or use of cash flows for the item. This guidance is effective for fiscal years beginning after December 15, 2017 and will require application using a retrospective transition method. The Company is currently evaluating the impact of adoption of this ASU on its consolidated financial statements, and does not expect this ASU to have a material impact on the Company’s consolidated financial statements.

In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. Currently, Topic 805 specifies three elements of a business—inputs, processes, and outputs. While an integrated set of assets and activities (collectively referred to as a “set”) that is a business usually has outputs, outputs are not required. In addition, all the inputs and processes that a seller uses in operating a set are not required if market participants can acquire the set and continue to produce outputs, for example, by integrating the acquired set with their own inputs and processes. This led many transactions to be accounted for as business combinations rather than asset purchases under legacy GAAP. The primary goal of ASU 2017-01 is to narrow the definition of a business, and the guidance in this update provides a screen to determine when a set is not a business. The screen requires that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business. This screen reduces the number of transactions that need to be further evaluated. The amendments in this update are effective for public business entities for fiscal years beginning after December 15, 2017, including interim periods within those fiscal years. The amendments in this update should be applied prospectively on or after the effective date. The Company is currently evaluating this ASU to determine the impact on its consolidated financial statements.

In January 2017, the FASB issued ASU No. 2017-04, Intangibles—Goodwill and Other (Topic 350). This ASU simplifies how an entity is required to test goodwill for impairment by eliminating Step 2 from the goodwill impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The amendments in this Update are required for public business entities and other entities that have goodwill reported in their financial statements and have not elected the private company alternative for the subsequent measurement of goodwill. As a result, under the ASU, “an entity should perform its annual, or interim, goodwill impairment test by comparing the fair value of a reporting unit with its carrying amount and should recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value; however, the loss recognized should not exceed the total amount of goodwill allocated to that reporting unit.” ASU No. 2017-14 is effective for annual and any interim impairment tests performed in periods beginning after December 15, 2019 for public business entities that are SEC filers, December 15, 2020 for business entities that are not SEC filers, and December 15, 2021 for all other entities. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. The Company does not expect this ASU to have a material impact on the Company’s consolidated financial statements.

In March 2017, the FASB issued ASU No. 2017-08, Receivables—Nonrefundable Fees and Other Costs (Subtopic 310-20): Premium Amortization on Purchased Callable Debt Securities, which is intended to enhance “the accounting for the amortization of premiums for purchased callable debt securities.” The ASU shortens the amortization period for certain callable debt securities purchased at a premium by requiring that the premium be amortized to the earliest call date. Under current generally accepted accounting principles (GAAP), entities generally amortize the premium as an adjustment of yield over the contractual life of the instrument. The amendments in this Update affects all entities that hold investments in callable debt securities that have an amortized cost basis in excess of the amount that is repayable by the issuer at the earliest call date (that is, at a premium). The amendments do not require an accounting change for securities held at a discount; the discount continues to be amortized to maturity. The ASU’s amendments are effective for public business entities for interim and annual periods beginning after December 15, 2018. For other entities, the amendments are effective for annual periods beginning after December 15, 2019, and interim periods thereafter. Early adoption is permitted, including adoption in an interim period. If an entity early adopts the amendments in an interim period, any adjustments should be reflected as of the beginning of the fiscal year that includes that interim period. An entity should apply the amendments in this Update on a modified retrospective basis through a cumulative-effect adjustment directly to retained earnings as of the beginning of the period of adoption. Additionally, in the period of adoption, an entity should provide disclosures about a change in accounting principle. The implementation of the provisions of ASU No. 2017-08 will most likely not have a material impact the Company’s consolidated financial statements. The Company will continue to access the potential impact that this ASU will have on the Company’s consolidated financial statements.

In May 2017, the FASB issued ASU No. 2017-09, “Compensation—Stock Compensation (Topic 718): Scope of codification Accounting.” The amendments in ASU 2017-09 provide guidance about which changes to the terms or conditions of a share- entity to apply modification accounting. An entity should account for the effects of a modification unless all the following are met: (1) The fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the modified award is the same as the fair value (or calculated value or intrinsic value, if such an alternative measurement method is used) of the original award immediately before the original award is modified. If the modification does not affect any of the inputs to the valuation technique that the entity uses to value the award, the entity is not required to estimate the value immediately before and after the modification. (2) The vesting conditions of the modified award are the same as the vesting conditions of the original award immediately before the original award is modified. (3) The classification of the modified award as an equity instrument or a liability instrument is the same as the classification of the original award immediately before the original award is modified. The amendments in ASU No. 2017-09 are effective for annual periods, and interim within those annual reporting periods, beginning after December 15, 2017; early adoption is permitted. The amendments in this ASU should be applied prospectively to an award modified on or after the adoption date. The Company does not expect this ASU to have a material impact on the Company’s consolidated financial statements.

In July 2017, the FASB issued ASU 2017-13—Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842): Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments (SEC Update) . At the July 20, 2017, EITF meeting, the SEC staff announced that it would not object when certain public business entities (PBEs) elect to use the non-PBE effective dates solely to adopt the FASB’s new standards on revenue (ASC 606) and leases (ASC 842). This ASU reflects comments made by the SEC. The Company will continue to evaluate how extensive the impact will be under the ASU on the Company’s consolidated financial statements. The Company does not expect this ASU to have a material impact on the Company’s consolidated financial statements.

In February 2018, the FASB issued Accounting Standards Update (ASU) No. 2018-02, “Reclassification of Certain Tax Effects From Accumulated Other Comprehensive Income.” The ASU amends ASC 220, Income Statement—Reporting Comprehensive Income , to “allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act.” In addition, under the ASU, an entity will be required to provide certain disclosures regarding stranded tax effects. The ASU provides financial statement preparers with an option to reclassify stranded tax effects within AOCI to retained earnings in each period in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act (or portion thereof) is recorded. The amendments in this ASU affect any organization that is required to apply the provisions of Topic 220, Income Statement—Reporting Comprehensive Income, and has items of other comprehensive income for which the related tax effects are presented in other comprehensive income as required by GAAP. The amendments are effective for all organizations for fiscal years beginning after December 15, 2018, and interim periods within those fiscal years. Early adoption is permitted. Organizations should apply the proposed amendments either in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in the U.S. federal corporate income tax rate in the Tax Cuts and Jobs Act is recognized. The Company has adopted this ASU and included the reclassified stranded tax effects within AOCI to retained earnings in the amount of $72,000 in the Company’s consolidated financial statements as of December 31, 2017.

Acquisitions

12 Months Ended

Dec. 31, 2017

Business Combinations [Abstract]

Acquisitions

NOTE 3—ACQUISITIONS

TFC HOLDING COMPANY ACQUISITION:

On February 19, 2016, the Company acquired all the assets and assumed all the liabilities of TFC Holding Company in exchange for cash of $86.7 million. TFC Holding Company operated six branches in the Los Angeles metropolitan area. The Company acquired TFC Holding Company to strategically increase its existing presence in the Los Angeles area. Goodwill in the amount of $25.9 million was recognized in this acquisition. Goodwill represents the future economic benefits arising from net assets acquired that are not individually identified and separately recognized and is attributable to synergies expected to be derived from the combination of the two entities. Goodwill is not deductible for income tax purposes.

The following table represents the assets acquired and liabilities assumed of TFC Holding Company as of February 19, 2016 and the fair value adjustments and amounts recorded by the Company in 2016 under the acquisition method of accounting:


*(dollars in thousands)*	TFC Book Value			Fair Value Adjustments			Fair Value
Assets acquired
Cash and cash equivalents	$	51,613		$	—		$	51,613
Interest-bearing deposits in other financial Institutions		2,320			—			2,320
Net investments—available for sale		15,952			(106	)		15,846
Loans, gross		400,887			(13,211	)		387,676
Allowance for loan losses		(9,857	)		9,857			—
Bank premises and equipment		225			—			225
Deferred income taxes		4,027			858			4,885
Other assets		5,595			1,699			7,294

Total assets acquired	$	470,762		$	(903	)	$	469,859

Liabilities assumed
Deposits	$	404,465		$	848		$	405,313
Subordinated debentures		5,155			(1,900	)		3,255
Other liabilities		566			—			566

Total liabilities assumed		410,186			(1,052	)		409,134
Excess of assets acquired over liabilities assumed		60,576			149			60,725

	$	470,762		$	(903	)

Cash paid								86,664

Goodwill recognized							$	25,939

The Company accounted for the transaction under the acquisition method of accounting which requires purchased assets and liabilities assumed to be recorded at their respective fair values at the date of acquisition. The Company determined the fair value of loans, leases, core deposit intangible, deposits, and Subordinated Debentures with the assistance of a third party valuation.

The estimated fair values are subject to refinement as additional information relative to the closing date fair values becomes available through the measurement period. While additional significant changes to the closing date fair values are not expected, any information relative to the changes in these fair values will be evaluated to determine if such changes are due to events and circumstances that existed as of the acquisition date. During the measurement period, any such changes will be recorded as part of the closing date fair value.

In many cases, the fair values of assets acquired and liabilities assumed were determined by estimating the cash flows expected to result from those assets and liabilities and discounting them at appropriate market rates. The most significant category of assets for which this procedure was used was that of acquired loans. The excess of expected cash flows above the fair value of the majority of loans will be accreted to interest income over the remaining lives of the loans in accordance with Financial Accounting Standards Board (“FASB”) Accounting Standards Codification (“ASC”) 310-20.

For loans acquired, the contractual amounts due, expected cash flows to be collected, interest component and fair value as of the respective acquisition dates were as follows:


*(dollars in thousands)*	Acquired Loans
Contractual amounts due	$	441,275
Cash flows not expected to be collected		—

Expected cash flows		441,275
Interest component of expected cash flows		53,599

Fair value of acquired loans	$	387,676

None of the loans acquired had evidence of deterioration of credit quality since origination for which it was probable, at acquisition, that the Company would be unable to collect all contractually required payments receivable.

In accordance with generally accepted accounting principles there was no carryover of the allowance for loan losses that had been previously recorded by TFC Holding Company.

Investment Securities

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Investment Securities

NOTE 2—INVESTMENT SECURITIES

The following table summarizes the amortized cost and fair value of securities available for sale and held to maturity at March 31, 2018 and December 31, 2017, and the corresponding amounts of gross unrealized gains and losses recognized in accumulated other comprehensive income:


*(dollars in thousands)*	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
March 31, 2018
Available for sale
Government agency securities	$	7,746	$	—	$	(264	)	$	7,482
Mortgage-backed securities
Government sponsored agencies		38,843		—		(1,171	)		37,672
Corporate debt securities		37,736		145		(187	)		37,694

	$	84,325	$	145	$	(1,622	)	$	82,848

Held to maturity
Municipal taxable securities	$	4,294	$	165	$	—		$	4,459
Municipal securities		5,704		4		(147	)		5,561

	$	9,998	$	169	$	(147	)	$	10,020

December 31, 2017
Available for sale
Government agency securities	$	7,968	$	—	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		39,806		17		(608	)		39,215
Corporate debt securities		17,813		161		(48	)		17,926

	$	65,587	$	178	$	(808	)	$	64,957

Held to maturity
Municipal taxable securities	$	4,295	$	228	$	—		$	4,523
Municipal securities		5,714		32		(19	)		5,727

	$	10,009	$	260	$	(19	)	$	10,250

One security with a fair value of $759,000 and $796,000 was pledged to secure a local agency deposit at March 31, 2018 and December 31, 2017, respectively.

The amortized cost and fair value of the investment securities portfolio at March 31, 2018 are shown by expected maturity below. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties.


	Available for Sale				Held to Maturity
*(dollars in thousands)*	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due from one to five years	$	52,326	$	51,530	$	2,780	$	2,865
Due from five to ten years		27,958		27,333		2,397		2,481
Due from ten years and greater		4,041		3,985		4,821		4,674

	$	84,325	$	82,848	$	9,998	$	10,020

The following table summarizes available for sale securities with unrealized losses at March 31, 2018 and December 31, 2017, aggregated by major security type and length of time in a continuous unrealized loss position:


	Less than Twelve Months					Twelve Months or More					Total
*(dollars in thousands)*	Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value
March 31, 2018
Government agency securities	$	(112	)	$	3,873	$	(152	)	$	3,609	$	(264	)	$	7,482
Mortgage-backed securities
Government sponsored agencies		(786	)		25,484		(385	)		11,852		(1,171	)		37,336
Corporate debt securities		(119	)		9,660		(68	)		1,937		(187	)		11,597

Total available for sale	$	(1,017	)	$	39,017	$	(605	)	$	17,398	$	(1,622	)	$	56,415

Municipal securities	$	(147	)	$	4,674	$	—		$	—	$	(147	)	$	4,674

Total held to maturity	$	(147	)	$	4,674	$	—		$	—	$	(147	)	$	4,674

December 31, 2017
Government agency securities	$	(32	)	$	4,039	$	(120	)	$	3,777	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		(359	)		23,609		(249	)		11,887		(608	)		35,496
Corporate debt securities		(15	)		5,035		(33	)		1,972		(48	)		7,007

Total available for sale	$	(406	)	$	32,683	$	(402	)	$	17,636	$	(808	)	$	50,319

Municipal securities	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232

Total held to maturity	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232

Unrealized losses have not been recognized into income because the issuer bonds are of high credit quality, management does not intend to sell, it is not more likely than not that management would be required to sell the securities prior to their anticipated recovery and the decline in fair value is largely due to changes in interest rates. The fair value is expected to recover as the bonds approach maturity.

Management evaluates securities for other-than-temporary impairment (OTTI) on at least a quarterly basis, and more frequently when economic or market conditions warrant such an evaluation. For securities in an unrealized loss position, management considers the extent and duration of the unrealized loss, and the financial condition and near-term prospects of the issuer. Management also assesses whether it intends to sell, or it is more likely than not that it will be required to sell, a security in an unrealized loss position before recovery of its amortized cost basis. If either of the criteria regarding intent or requirement to sell is met, the entire difference between amortized cost and fair value is recognized as impairment through earnings.

NOTE 4—INVESTMENT SECURITIES

The following table summarizes the amortized cost and fair value of securities available for sale and held to maturity at December 31, 2017 and 2016, and the corresponding amounts of gross unrealized gains and losses recognized in accumulated other comprehensive income:


*(dollars in thousands)* *December 31, 2017*	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available for sale
Government agency securities	$	7,968	$	—	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		39,806		17		(608	)		39,215
Corporate debt securities		17,813		161		(48	)		17,926

	$	65,587	$	178	$	(808	)	$	64,957

Held to maturity
Municipal taxable securities	$	4,295	$	228	$	—		$	4,523
Municipal securities		5,714		32		(19	)		5,727

	$	10,009	$	260	$	(19	)	$	10,250


December 31, 2016
Available for sale
Government agency securities	$	5,453	$	—	$	(136	)	$	5,317
Mortgage-backed securities
Government sponsored agencies		23,913		38		(311	)		23,640
Corporate debt securities		10,364		21		(65	)		10,320

	$	39,730	$	59	$	(512	)	$	39,277

Held to maturity
Municipal taxable securities	$	5,301	$	328	$	—		$	5,629
Municipal securities		913		11		—			924

	$	6,214	$	339	$	—		$	6,553

The Company did not sell any securities in 2017. During 2016 and 2015 the Company sold $5.1 million and $5.5 million of securities available for sale, recognizing gross gains of $19,000 and $78,000, respectively.

One security with a fair value of $796,000 and $933,000 was pledged to secure a local agency deposit at December 31, 2017 and December 31, 2016, respectively.

The amortized cost and fair value of the investment securities portfolio as of December 31, 2017 are shown by expected maturity below. Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties.


	Available for Sale				Held to Maturity
*(dollars in thousands)*	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due from one to five years	$	35,221	$	34,825	$	2,780	$	2,897
Due from five to ten years		26,321		26,102		2,404		2,521
Due from ten years and greater		4,045		4,030		4,825		4,832

	$	65,587	$	64,957	$	10,009	$	10,250

The following table summarizes securities with unrealized losses at December 31, 2017 and December 31, 2016, aggregated by major security type and length of time in a continuous unrealized loss position. There were no held to maturity securities in a continuous unrealized loss position at December 31, 2016:


	Less than Twelve Months					Twelve Months or More					Total
*(dollars in thousands)*	Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value
December 31, 2017
Government agency securities	$	(32	)	$	4,039	$	(120	)	$	3,777	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		(359	)		23,609		(249	)		11,887		(608	)		35,496
Corporate debt securities		(15	)		5,035		(33	)		1,972		(48	)		7,007

Total available for sale	$	(406	)	$	32,683	$	(402	)	$	17,636	$	(808	)	$	50,319

Municipal securities	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232

Total held to maturity	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232

December 31, 2016
Government agency securities	$	(136	)	$	5,317	$	—		$	—	$	(136	)	$	5,317
Mortgage-backed securities
Government sponsored agencies		(221	)		16,231		(90	)		2,504		(311	)		18,735
Corporate debt securities		(65	)		5,147		—			—		(65	)		5,147

Total available for sale	$	(422	)	$	26,695	$	(90	)	$	2,504	$	(512	)	$	29,199

Loans and Allowance for Loan Losses

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Receivables [Abstract]

Loans and Allowance for Loan Losses

NOTE 3—LOANS AND ALLOWANCE FOR LOAN LOSSES

The Company’s loan portfolio consists primarily of loans to borrowers within Los Angeles, Ventura and Orange counties in California and Las Vegas (Clark County) in Nevada. Although the Company seeks to avoid concentrations of loans to a single industry or based upon a single class of collateral, real estate and real estate associated businesses are among the principal industries in the Company’s market area and, as a result, the Company’s loan and collateral portfolios are, to some degree, concentrated in those industries.

The following tables present the balance and activity related to the allowance for loan losses for held for investment loans by type for the periods presented.


	Three Months Ended March 31,
	2018										2017
(dollars in thousands)	Real Estate		Commercial			Unallocated			Total		Real Estate			Commercial		Unallocated		Total
Beginning balance	$	9,309	$	4,044		$	420		$	13,773	$	8,111		$	6,051	$	—	$	14,162
Additions (reductions) to the allowance charged to expense		653		(118	)		(351	)		184		(1,169	)		1,169		—		—
Recoveries on loans charged-off		—		—			—			—		—			—		—		—
Less loans charged-off		—		—			—			—		—			24		—		24

Ending balance	$	9,962	$	3,926		$	69		$	13,957	$	6,942		$	7,244	$	—	$	14,186

The following table presents the recorded investment in loans and impairment method as of and for the three months ended March 31, 2018 and March 31, 2017, and the activity in the allowance for loan losses for the year ended December 31, 2017, by portfolio segment:


*(dollars in thousands)* As of and for the three months ended March 31, 2018	Real Estate		Commercial		Unallocated		Total
Reserves:
Specific	$	—	$	—	$	—	$	—
General		9,962		3,926		69		13,957
Loans acquired with deteriorated credit quality		—		—		—		—

	$	9,962	$	3,926	$	69	$	13,957

Loans evaluated for impairment:
Individually	$	2,393	$	2,072	$	—	$	4,465
Collectively		866,176		390,974		—		1,257,150
Loans acquired with deteriorated credit quality		313		—		—		313

	$	868,882	$	393,046	$	—	$	1,261,928


As of and for the three months ended March 31, 2017	Real Estate		Commercial		Unallocated		Total
Reserves:
Specific	$	—	$	3,559	$	—	$	3,559
General		6,942		3,685		—		10,627
Loans acquired with deteriorated credit quality		—		—		—		—

	$	6,942	$	7,244	$	—	$	14,186

Loans evaluated for impairment:
Individually	$	2,550	$	3,559	$	—	$	6,109
Collectively		771,870		360,847		—		1,132,717
Loans acquired with deteriorated credit quality		737		—		—		737

	$	775,157	$	364,406	$	—	$	1,139,563


December 31, 2017	Real Estate		Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	8,111	$	6,051		$	—	$	14,162
Provisions		1,198		(2,671	)		420		(1,053	)
Charge-offs		—		(83	)		—		(83	)
Recoveries		—		747			—		747

	$	9,309	$	4,044		$	420	$	13,773

Reserves:
Specific	$	—	$	—		$	—	$	—
General		9,309		4,044			420		13,773
Loans acquired with deteriorated credit quality		—		—			—		—

	$	9,309	$	4,044		$	420	$	13,773

Loans evaluated for impairment:
Individually	$	2,420	$	155		$	—	$	2,575
Collectively		834,152		412,032			—		1,246,184
Loans acquired with deteriorated credit quality		315		—			—		315

	$	836,887	$	412,187		$	—	$	1,249,074

The Company categorizes loans into risk categories based on relevant information about the ability of borrowers to service their debt such as current financial information, historical payment experience, collateral adequacy, credit documentation, and current economic trends, among other factors. The Company analyzes loans individually by classifying the loans as to credit risk. This analysis typically includes larger, non-homogeneous loans such as commercial real estate and commercial and industrial loans. This analysis is performed on an ongoing basis as new information is obtained. The Company uses the following definitions for risk ratings:

Pass — Loans classified as pass include loans not meeting the risk ratings defined below.

Special Mention — Loans classified as special mention have a potential weakness that deserves management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loan or of the institution’s credit position at some future date.

Substandard — Loans classified as substandard are inadequately protected by the current net worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that the institution will sustain some loss if the deficiencies are not corrected.

Impaired — A loan is considered impaired, when, based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. Additionally, all loans classified as troubled debt restructurings (TDRs) are considered impaired.

The risk category of loans by class of loans was as follows at March 31, 2018 and December 31, 2017:


*(dollars in thousands)*	Pass		Special Mention		Substandard		Impaired		Total
March 31, 2018
Real estate:
Construction and land development	$	100,954	$	—	$	—	$	286	$	101,240
Commercial real estate		478,059		4,464		15,421		2,107		500,051
Single-family residential mortgages		267,591		—		—		—		267,591
Commercial:
Other		277,678		195		520		—		278,393
SBA		108,711		—		3,870		2,072		114,653

	$	1,232,993	$	4,659	$	19,811	$	4,465	$	1,261,928

December 31, 2017
Real estate:
Construction and land development	$	91,619	$	—	$	—	$	289	$	91,908
Commercial real estate		469,422		19,070		5,416		2,131		496,039
Single-family residential mortgages		248,940		—		—		—		248,940
Commercial:
Other		277,518		2,360		888		—		280,766
SBA		126,759		1,778		2,729		155		131,421

	$	1,214,258	$	23,208	$	9,033	$	2,575	$	1,249,074

The following table presents the aging of the recorded investment in past-due loans at March 31, 2018 and December 31, 2017 by class of loans:


*(dollars in thousands)*	30-59 Days		60-89 Days		90 Days Or More (2)		Total Past Due		Loans Not Past Due		Total Loans		Non- Accrual Loans (1)
March 31, 2018
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	101,240	$	101,240	$	—
Commercial real estate		—		—		—		—		500,051		500,051		—
Single-family residential mortgages		790		—		—		790		266,801		267,591		—
Commercial:
Other		689		—		—		689		277,704		278,393		—
SBA		1,462		—		586		2,048		112,605		114,653		2,001

	$	2,941	$	—	$	586	$	3,527	$	1,258,401	$	1,261,928	$	2,001

Real estate:
Single-family residential mortgages held for sale	$	696	$	—	$	—	$	696	$	182,695	$	183,391	$	—

December 31, 2017
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	91,908	$	91,908	$	—
Commercial real estate		—		—		—		—		496,039		496,039		—
Single-family residential mortgages		1,175		338		—		1,513		247,427		248,940		—
Commercial:
Other		—		—		—		—		280,766		280,766		—
SBA		—		1,426		84		1,510		129,911		131,421		155

	$	1,175	$	1,764	$	84	$	3,023	$	1,246,051	$	1,249,074	$	155

Real estate:
Single-family residential mortgages held for sale	$	697	$	—	$	—	$	697	$	125,150	$	125,847	$	—

(1)	Included in total loans.

(2)	As of March 31, 2018, there were no loans over 90 days past due and still accruing. There was one loan over 90 days past due and still accruing in the amount of $71,000 as of December 31, 2017.

Information relating to individually impaired loans presented by class of loans was as follows at March 31, 2018 and December 31, 2017:


*(dollars in thousands)*	Unpaid Principal Balance		Recorded Investment		Average Balance		Interest Income		Related Allowance
March 31, 2018
With no related allowance recorded
Real estate:
Construction and land development	$	286	$	286	$	288	$	6	$	—
Commercial real estate		2,108		2,108		2,119		51		—
Commercial—SBA		2,071		2,071		1,114		34		—

Total	$	4,465	$	4,465	$	3,521	$	91	$	—

December 31, 2017
With no related allowance recorded
Real estate:
Construction and land development	$	289	$	289	$	296	$	16	$	—
Commercial real estate		2,131		2,131		2,192		297		—
Commercial—SBA		155		155		78		15		—

Total	$	2,575	$	2,575	$	2,566	$	328	$	—

No interest income was recognized on a cash basis for the three months ended March 31, 2018 and for the year ended December 31, 2017.

The Company had five and four loans identified as TDRs at March 31, 2018 and December 31, 2017, respectively. There were no specific reserves on TDRs as of March 31, 2018 or December 31, 2017. There are no commitments to lend additional amounts at March 31, 2018 and December 31, 2017 to customers with outstanding loans that are classified as TDRs.

As of March 31, 2018, the terms of one loan was modified as TDR. The modification of the terms generally included loans where a moratorium on loan payments was granted. Such moratoriums ranged from three months to twelve months on the loans restructured in 2017 and 2016.

The following table presents loans by class modified as TDRs that occurred during the three months ended March 31, 2018. There were no TDRs for the year ended December 31, 2017.


*(dollars in thousands)*	Number of Loans		Pre-Modification Recorded Investment		Post-Modification Recorded Investment
March 31, 2018
Commercial		1	$	71	$	71

The Company has purchased loans as part of its whole bank acquisitions, for which there was at acquisition, evidence of deterioration of credit quality since origination and it was probable, at acquisition, that all contractually required payments would not be collected.

The outstanding balance and carrying amount of purchased credit-impaired loans at March 31, 2018 and December 31, 2017 were as follows:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Outstanding balance	$	319	$	322
Carrying amount	$	313	$	315

For these purchased credit-impaired loans, the Company did not increase the allowance for loan losses during the three months ended March 31, 2018 or for the year ended December 31, 2017, as there were no significant reductions in the expected cash flows.

Below is a summary of activity in the accretable yield on purchased credit-impaired loans for the three months ended March 31, 2018 and 2017:


*(dollars in thousands)*	March 31, 2018			March 31, 2017
Beginning balance	$	122		$	142
Accretion of income		(1	)		(20	)

Ending balance	$	121		$	122

NOTE 5—LOANS

The Company’s loan portfolio consists primarily of loans to borrowers within Los Angeles and Orange County, California. Although the Company seeks to avoid concentrations of loans to a single industry or based upon a single class of collateral, real estate and real estate associated businesses are among the principal industries in the Company’s market area and, as a result, the Company’s loan and collateral portfolios are, to some degree, concentrated in those industries.

A summary of the changes in the allowance for loan losses as of December 31 follows:


*(dollars in thousands)*	2017			2016			2015
Beginning balance	$	14,162		$	10,023		$	8,848
Additions (reductions) to the allowance charged to expense		(1,053	)		4,974			1,386
Recoveries on loans charged-off		747			—			211

		13,856			14,997			10,445
Less loans charged-off		(83	)		(835	)		(422	)

Ending balance	$	13,773		$	14,162		$	10,023

The following table presents the recorded investment in loans and impairment method as of December 31, 2017, 2016 and 2015 and the activity in the allowance for loan losses for the years then ended, by portfolio segment:


*(dollars in thousands)*
December 31, 2017	Real Estate		Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	8,111	$	6,051		$	—	$	14,162
Provisions		1,198		(2,671	)		420		(1,053	)
Charge-offs		—		(83	)		—		(83	)
Recoveries		—		747			—		747

	$	9,309	$	4,044		$	420	$	13,773

Reserves:
Specific	$	—	$	—		$	—	$	—
General		9,309		4,044			420		13,773
Loans acquired with deteriorated credit quality		—		—			—		—

	$	9,309	$	4,044		$	420	$	13,773

Loans evaluated for impairment:
Individually	$	2,420	$	155		$	—	$	2,575
Collectively		834,152		412,032			—		1,246,184
Loans acquired with deteriorated credit quality		315		—			—		315

	$	836,887	$	412,187		$	—	$	1,249,074


December 31, 2016	Real Estate		Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	5,788	$	4,235		$	—	$	10,023
Provisions		2,323		2,651			—		4,974
Charge-offs		—		(835	)		—		(835	)
Recoveries		—		—			—		—

	$	8,111	$	6,051		$	—	$	14,162

Reserves:
Specific	$	—	$	1,782		$	—	$	1,782
General		8,111		4,269			—		12,380
Loans acquired with deteriorated credit quality		—		—			—		—

	$	8,111	$	6,051		$	—	$	14,162

Loans evaluated for impairment:
Individually	$	2,556	$	3,577		$	—	$	6,133
Collectively		744,349		359,234			—		1,103,583
Loans acquired with deteriorated credit quality		730		—			—		730

	$	747,635	$	362,811		$	—	$	1,110,446


December 31, 2015	Real Estate			Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	5,696		$	3,152		$	—	$	8,848
Provisions		(108	)		1,494			—		1,386
Charge-offs		—			(422	)		—		(422	)
Recoveries		200			11			—		211

	$	5,788		$	4,235		$	—	$	10,023

Reserves:
Specific	$	—		$	—		$	—	$	—
General		5,788			4,235			—		10,023
Loans acquired with deteriorated credit quality		—			—			—		—

	$	5,788		$	4,235		$	—	$	10,023

Loans evaluated for impairment:
Individually	$	1,482		$	4,630		$	—	$	6,112
Collectively		519,963			264,610			—		784,573
Loans acquired with deteriorated credit quality		1,677			—			—		1,677

	$	523,122		$	269,240		$	—	$	792,362

Pass—Loans classified as pass include loans not meeting the risk ratings defined below.

Special Mention—Loans classified as special mention have a potential weakness that deserves management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects for the loan or of the institution’s credit position at some future date.

Substandard—Loans classified as substandard are inadequately protected by the current net worth and paying capacity of the obligor or of the collateral pledged, if any. Loans so classified have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that the institution will sustain some loss if the deficiencies are not corrected.

Impaired—A loan is considered impaired, when, based on current information and events, it is probable that the Company will be unable to collect all amounts due according to the contractual terms of the loan agreement. Additionally, all loans classified as troubled debt restructurings are considered impaired.

The risk category of loans by class of loans was as follows as of December 31, 2017 and 2016:


*(dollars in thousands)* December 31, 2017	Pass		Special Mention		Substandard		Impaired		Total
Real estate:
Construction and land development	$	91,619	$	—	$	—	$	289	$	91,908
Commercial real estate		469,422		19,070		5,416		2,131		496,039
Single-family residential mortgages		248,940		—		—		—		248,940
Commercial:
Other		277,518		2,360		888		—		280,766
SBA		126,759		1,778		2,729		155		131,421

	$	1,214,258	$	23,208	$	9,033	$	2,575	$	1,249,074


December 31, 2016
Real estate:
Construction and land development	$	87,174	$	1,932	$	—	$	303	$	89,409
Commercial real estate		475,499		4,562		19,484		2,253		501,798
Single-family residential mortgages		136,206		13,950		6,272		—		156,428
Commercial:
Other		194,227		—		9,616		—		203,843
SBA		151,066		1,934		2,391		3,577		158,968

	$	1,044,172	$	22,378	$	37,763	$	6,133	$	1,110,446

The following table presents the aging of the recorded investment in past-due loans as of December 31, 2017 and 2016 by class of loans:


*(dollars in thousands)* December 31, 2017	30-59 Days		60-89 Days		90 Days Or More (2)		Total Past Due		Loans Not Past Due		Total Loans		Non- Accrual Loans (1)
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	91,908	$	91,908	$	—
Commercial real estate		—		—		—		—		496,039		496,039		—
Single-family residential mortgages		1,175		338		—		1,513		247,427		248,940		—
Commercial:
Other		—		—		—		—		280,766		280,766		—
SBA		—		1,426		84		1,510		129,911		131,421		155

	$	1,175	$	1,764	$	84	$	3,023	$	1,246,051	$	1,249,074	$	155

Real estate:
Single-family residential mortgages held for sale	$	697	$	—	$	—	$	697	$	125,150	$	125,847	$	—


*December 31, 2016*
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	89,409	$	89,409	$	—
Commercial real estate		—		—		—		—		501,798		501,798		—
Single-family residential mortgages		—		—		—		—		156,428		156,428		—
Commercial:
Other		343		—		—		343		203,500		203,843		—
SBA		—		—		3,577		3,577		155,391		158,968		3,577

	$	343	$	—	$	3,577	$	3,920	$	1,106,526	$	1,110,446	$	3,577

Real estate:
Single-family residential mortgages held for sale	$	—	$	—	$	—	$	—	$	44,345	$	44,345	$	—

(1)	Included in total loans

(2)	As of December 31, 2017, there was one loan over 90 days past due and still accruing in the amount of $71,000.

Information relating to individually impaired loans presented by class of loans was as follows as of December 31, 2017, 2016 and 2015:


*(dollars in thousands)* December 31, 2017	Unpaid Principal Balance		Recorded Investment		Average Balance		Interest Income		Related Allowance
With no related allowance recorded
Construction and land development	$	289	$	289	$	296	$	16	$	—
Commercial real estate		2,131		2,131		2,192		297		—
Commercial—SBA		155		155		78		15		—

Total	$	2,575	$	2,575	$	2,566	$	328	$	—


December 31, 2016
With no related allowance recorded
Construction and land development	$	303	$	303	$	309	$	21	$	—
Commercial real estate		2,253		2,253		1,710		280		—
Commercial—SBA		18		18		93		—		—

Subtotal		2,574		2,574		2,112		301		—
With an allowance recorded
Commercial—SBA		3,559		3,559		3,559		—		1,782

Total	$	6,133	$	6,133	$	5,671	$	301	$	1,782


December 31, 2015
With no related allowance recorded
Construction and land development	$	315	$	315	$	320	$	4	$	—
Commercial real estate		1,167		1,167		1,145		195		—
Commercial—SBA		4,630		4,630		4,545		14		—

Total	$	6,112	$	6,112	$	6,010	$	213	$	—

No interest income was recognized on a cash basis as of December 31, 2017, 2016 and 2015.

The Company had four and six loans identified as troubled debt restructurings (“TDR’s”) at December 31, 2017 and 2016, respectively. There were no specific reserves allocated to the loans as of December 31, 2017. A specific reserve for $1,782,000 was allocated for one loan as of December 31, 2016. There were no commitments to lend additional amounts as of December 31, 2017 and 2016, respectively, to customers with outstanding loans that are classified as TDR’s.

During the year ended December 31, 2016, the terms of certain loans were modified as TDR’s. The modification of the terms generally included loans where a moratorium on loan payments was granted. Such moratoriums ranged from three months to six months on the loans restructured in 2016.

The following table presents loans by class modified as TDR’s that occurred during the year ended December 31, 2016:


*(dollars in thousands)* December 31, 2016	Number of Loans		Pre-Modification Recorded Investment		Post-Modification Recorded Investment
Commercial real estate		1	$	1,047	$	1,047

There were no loans modified as TDR’s during the year ended December 31, 2017.

There were no defaults of TDR’s in 2017 and 2016 where the loan was modified within the prior twelve months.

The outstanding balance and carrying amount of purchased credit-impaired loans as of December 31 were as follows:


*(dollars in thousands)*	2017		2016
Outstanding balance	$	322	$	878
Carrying amount	$	315	$	730

For these purchased credit-impaired loans, the Company did not increase the allowance for loan losses during 2017 or 2016 as there were no significant reductions in the expected cash flows.

Below is a summary of activity in the accretable yield on purchased credit-impaired loans for 2017, 2016 and 2015:


*(dollars in thousands)*	2017			2016			2015
Beginning balance	$	142		$	349		$	574
Disposals		—			—			(99	)
Restructuring as TDR		—			(22	)		—
Accretion of income		(135	)		(185	)		(126	)

Ending balance	$	7		$	142		$	349

- Definition

The entire disclosure for claims held for amounts due a entity, excluding financing receivables. Examples include, but are not limited to, trade accounts receivables, notes receivables, loans receivables. Includes disclosure for allowance for credit losses.

+ References + Details

Loan Servicing

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Text Block [Abstract]

Loan Servicing

NOTE 4—LOAN SERVICING

When mortgage and Small Business Administration (SBA) loans are sold with servicing retained, servicing rights are initially recorded at fair value with the income statement effect recorded in gains on sales of loans. Fair value is based on a valuation model that calculates the present value of estimated future net servicing income. All classes of servicing assets are subsequently measured using the amortization method which requires servicing rights to be amortized into noninterest income in proportion to, and over the period of, the estimated future net servicing income of the underlying loans.

Servicing fee income is recorded for fees earned for servicing loans. The fees are based on a contractual percentage of the outstanding principal. The amortization of mortgage servicing rights is netted against loan servicing fee income.

The principal balances of mortgage and SBA loans serviced for others at March 31, 2018 and December 31, 2017 are as follows:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Loans serviced for others:
Mortgage loans	$	406,559	$	384,437
SBA loans	$	174,282	$	175,919

Activity for servicing assets follows:


	Three Months Ended March 31, 2018						Three Months Ended March 31, 2017
(dollars in thousands)	Mortgage Loans			SBA Loans			Mortgage Loans			SBA Loans
Servicing assets:
Beginning of year	$	1,540		$	4,417		$	1,002		$	2,702
Additions		315			484			—			724
Disposals		(39	)		(425	)		—			—
Amortized to expense		(155	)		(158	)		(86	)		(119	)

End of period	$	1,661		$	4,318		$	916		$	3,307

The fair value of servicing assets for mortgage loans was $2,751,000 and $2,538,000 at March 31, 2018 and December 31, 2017, respectively. The fair value of servicing assets for SBA loans was $5,984,000 and $5,915,000 at March 31, 2018 and December 31, 2017, respectively.

Servicing fees net of servicing asset amortization totaled $(31,000) and $262,000 for the three months ended March 31, 2018 and 2017, respectively.

NOTE 6—LOAN SERVICING

Mortgage and SBA loans serviced for others are not reported as assets. The principal balances as of December 31 are as follows:


*(dollars in thousands)*	2017		2016
Loans serviced for others:
Mortgage loans	$	384,437	$	259,207
SBA loans	$	175,919	$	110,263

Activity for servicing assets follows:


	2017						2016						2015
*(dollars in thousands)*	Mortgage Loans			SBA Loans			Mortgage Loans			SBA Loans			Mortgage Loans			SBA Loans
Servicing assets:
Beginning of year	$	1,002		$	2,702		$	298		$	1,807		$	—		$	720
Additions		1,115			2,628			912			1,353			329			1,268
Disposals		(172	)		(367	)		—			—			—			—
Amortized to expense		(405	)		(546	)		(208	)		(458	)		(31	)		(181	)

End of period	$	1,540		$	4,417		$	1,002		$	2,702		$	298		$	1,807

The fair value of servicing assets for mortgage loans was $2,538,000 and $1,184,000 as of December 31, 2017 and 2016, respectively. Fair value at December 31, 2017 was determined using a discount rate of 12.50%, prepayment speeds ranging from 20.00% to 21.79%, depending on the stratification of the specific right, and a weighted-average default rate of 0.25%. Fair value at December 31, 2016 was determined using a discount rate of 12.50%, prepayment speeds ranging from 20.74% to 22.90%, depending on the stratification of the specific right, and a weighted-average default rate of 0.25%.

The fair value of servicing assets for SBA loans was $5,915,000 and $3,142,000 as of December 31, 2017 and 2016, respectively. Fair value at December 31, 2017 was determined using a discount rate of 8.50%, prepayment speeds ranging from 11.40% to 13.78%, depending on the stratification of the specific right, and a weighted-average default rate of 0.98%. Fair value at December 31, 2016 was determined using a discount rate of 8.50% and prepayment speeds ranging from 7.20% to 12.80%, depending on the stratification of the specific right.

Servicing fees net of servicing asset amortization totaled $722,000, $615,000, and $272,000 for the years ended December 31, 2017, 2016, and 2015, respectively.

Premises and Equipment

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Premises and Equipment

NOTE 7—PREMISES AND EQUIPMENT

A summary of premises and equipment as of December 31 follows:


*(dollars in thousands)*	2017			2016
Land	$	2,956		$	2,956
Building and improvements		2,467			2,467
Furniture, fixtures, and equipment		3,222			2,950
Leasehold improvements		2,872			2,865

	11,517			11,238
Less accumulated depreciation and amortization		(5,359	)		(4,673	)
Construction in progress		425			20

	$6,583			$6,585

Depreciation and amortization expense was $686,000, $750,000, and $625,000 for 2017, 2016, and 2015, respectively.

The Company leases several of its operating facilities under various noncancellable operating leases expiring at various dates through 2028. The Company is also responsible for common area maintenance, taxes and insurance at the various branch locations.

Future minimum rent payments on the Company’s leases were as follows as of December 31, 2017:


*(dollars in thousands)*
Year ending December 31:
2018	$	1,857
2019		1,625
2020		1,396
2021		1,312
2022		1,029
Thereafter		4,102

	$	11,321

The minimum rent payments shown above are given for the existing lease obligations and are not a forecast of future rental expense. Total rental expense, recognized on a straight-line basis, was $1.5 million, $1.6 million, and $1.2 million for 2017, 2016, and 2015, respectively.

The lease for the Company’s downtown headquarters expires in May 2018. In October 2017 the Company signed a lease for a new headquarters office at 1055 Wilshire Boulevard, Suite 1220, Los Angeles, California 90017, which the Company expects to occupy by June 2018. In February 2018 the Company signed a lease for a new office in Irvine which the Company expects to occupy in May 2018. In September 2017 the Company signed a lease to occupy a new location in Oxnard which the Company occupied on March 26, 2018. The future payments for all of the new leases are included in the schedule above.

Deposits

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Banking and Thrift [Abstract]

Deposits

NOTE 6—DEPOSITS

At March 31, 2018, the scheduled maturities of time deposits are as follows:


*(dollars in thousands)*
One year	$	651,067
Two to three years		6,498

	$657,565

NOTE 8—DEPOSITS

At December 31, 2017 the scheduled maturities of time deposits are as follows:


*(dollars in thousands)*
One year	$	627,665
Two to three years		12,263

	$	639,928

Long-term Debt

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Debt Disclosure [Abstract]

Long-term Debt

NOTE 7—LONG-TERM DEBT

In March 2016, the Company issued $50 million of 6.5% fixed to floating rate subordinated debentures, due March 31, 2026. The interest rate is fixed through March 31, 2021 and floats at 3 month London Interbank Offered Rate (LIBOR) plus 516 basis points thereafter. The subordinated debt is considered Tier-2 capital at the Company. The Company allocated $35 million to the Bank as Tier-1 capital.

At March 31, 2018 and December 31, 2017 the aggregate outstanding principal amount and unamortized debt issuance costs related to these subordinated debentures were as follows:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Principal	$	50,000	$	50,000

Unamortized debt issuance costs	$	436	$	472

NOTE 9—LONG-TERM DEBT

At December 31, 2017 and 2016, respectively, long-term debt—6.5% fixed-to-floating subordinated debentures, due March 31, 2026—were as follows:


*(dollars in thousands)*	2017		2016
Principal	$	50,000	$	50,000

Unamortized debt issuance costs	$	472	$	617

In March 2016, the Company issued $50 million of 6.5% fixed to floating rate subordinated debentures, due March 31, 2026. The interest rate is fixed through March 31, 2021 and floats at 3 month LIBOR plus 516 basis points thereafter. The Company can redeem these subordinated debentures beginning March 31, 2021. The sub-debt is considered Tier-two capital at the Company. The Company allocated $35 million to the Bank as Tier-one capital.

Subordinated Debentures	3 Months Ended	12 Months Ended
Subordinated Debentures	Mar. 31, 2018	Dec. 31, 2017
Brokers and Dealers [Abstract]
Subordinated Debentures	NOTE 8—SUBORDINATED DEBENTURES The Company, through the acquisition of TFC Bancorp, acquired TFC Statutory Trust (Trust). The Trust contained a pooled private offering of 5,000 Trust preferred securities with a liquidation amount of $1,000 per security. TFC Bancorp issued $5,000,000 of subordinated debentures to the Trust in exchange for ownership of all of the common security of the Trust and the proceeds of the preferred securities sold by the Trust. The Company is not considered the primary beneficiary of this Trust (variable interest entity), therefore the Trust is not consolidated in the Company’s financial statements, but rather the subordinated debentures are shown as a liability at market value as of the close of the acquisition which was $3,255,000. There was a $1,900,000 valuation reserve recorded to arrive at market value which is treated as a yield adjustment and is amortized over the life of the security. The amount of amortization expense recognized for the three months ended March 31, 2018 and 2017 was constant at $23,000. The Company also purchased an investment in the common stock of the Trust for $155,000 which is included in other assets. The Company may redeem the subordinated debentures, subject to prior approval by the Federal Reserve Bank on or after March 15, 2012, at 100% of the principal amount, plus accrued and unpaid interest. The subordinated debentures mature on March 15, 2037. The Company has the option to defer interest payments on the subordinated debentures from time to time for a period not to exceed five consecutive years. The Company has been paying interest on a quarterly basis. The subordinated debentures may be included in Tier 1 capital (with certain limitations applicable) under current regulatory guidelines and interpretations. The subordinated debentures have a variable rate of interest equal to the three month LIBOR plus 1.65%, which was 3.77% and 3.24% at March 31, 2018 and December 31, 2017, respectively.	NOTE 10—SUBORDINATED DEBENTURES The Company, through the acquisition of TFC Bancorp, acquired TFC Statutory Trust. The Trust contained a pooled private offering of 5,000 trust preferred securities with a liquidation amount of $1,000 per security. TFC Bancorp issued $5,000,000 of subordinated debentures to the trust in exchange for ownership of all of the common security of the trust and the proceeds of the preferred securities sold by the trust. The Company is not considered the primary beneficiary of this trust (variable interest entity), therefore the trust is not consolidated in the Company’s financial statements, but rather the subordinated debentures are shown as a liability at market value as of the close of the acquisition which was $3,255,000. There was a $1,900,000 valuation reserve recorded to arrive at market value which is treated as a yield adjustment and is amortized over the life of the security. The amount of amortization expense recognized in 2017 was $90,000 and in 2016 was $79,000. The Company also purchased an investment in the common stock of the trust for $155,000 which is included in other assets. The Company may redeem the subordinated debentures, subject to prior approval by the Federal Reserve Bank on or after March 15, 2012, at 100% of the principal amount, plus accrued and unpaid interest. The subordinated debentures mature on March 15, 2037. The Company has the option to defer interest payments on the subordinated debentures from time to time for a period not to exceed five consecutive years. The Company has been paying interest on a quarterly basis. The subordinated debentures may be included in Tier I capital (with certain limitations applicable) under current regulatory guidelines and interpretations. The subordinated debentures have a variable rate of interest equal to the three month London Interbank Offered Rate (LIBOR) plus 1.65%, which was 3.24% at December 31, 2017. In July 2017, British banking regulators announced plan to eliminate the LIBOR rate by the end of 2021, before these subordinated notes and debentures mature. For these subordinated notes and debentures, there are provisions for amendments to establish a new interest rate benchmark.

Borrowing Arrangements	3 Months Ended	12 Months Ended
Borrowing Arrangements	Mar. 31, 2018	Dec. 31, 2017
Debt Disclosure [Abstract]
Borrowing Arrangements	NOTE 9—BORROWING ARRANGEMENTS The Company has established secured and unsecured lines of credit. The Company may borrow funds from time to time on a term or overnight basis from the Federal Home Loan Bank of San Francisco (FHLB), the Federal Reserve Bank of San Francisco (“FRB”) and other financial institutions as indicated below. Federal Funds Arrangements with Commercial Banks. At March 31, 2018, the Company may borrow on an unsecured basis, up to $20.0 million, $10.0 million, $12.0 million and $5.0 million overnight from Zions Bank, Wells Fargo Bank, First Tennessee National Bank, and Pacific Coast Bankers’ Bank, respectively. Letter of Credit Arrangements. At March 31, 2018, the Company had an unsecured commercial letter of credit line with Wells Fargo Bank for $2.0 million. FRB Secured Line of Credit. The secured borrowing capacity of $13.8 million at March 31, 2018 is collateralized by loans pledged with a carrying value of $25.2 million. FHLB Secured Line of Credit. The secured borrowing capacity of $342.9 million at March 31, 2018 is collateralized by loans pledged with a carrying value of $392.2 million. There were no amounts outstanding under any of the arrangements above at March 31, 2018. At December 31, 2017, the Company had $25.0 million in short-term borrowings with the FHLB at 1.41% which was repaid on January 2, 2018.	NOTE 11—BORROWING ARRANGEMENTS The Company has established secured and unsecured lines of credit. The Company may borrow funds from time to time on a term or overnight basis from the Federal Home Loan Bank of San Francisco (“FHLB”), the Federal Reserve Bank of San Francisco (“FRB”) and other financial institutions as indicated below. Federal Funds Arrangements with Commercial Banks. As of December 31, 2017 the Company may borrow on an unsecured basis, up to $20 million, $10 million, $12 million and $5 million overnight from Zions Bank, Wells Fargo Bank, First Tennessee National Bank, and Pacific Coast Bankers’ Bank, respectively. Letter of Credit Arrangements. As of December 31, 2017 the Company had an unsecured commercial letter of credit line with Wells Fargo Bank for $2 million. FRB Secured Line of Credit. The secured borrowing capacity of $14 million at December 31, 2017 is collateralized by loans pledged with a carrying value of $25.8 million. FHLB Secured Line of Credit. The secured borrowing capacity of $323.3 million at December 31, 2017 is collateralized by loans pledged with a carrying value of $368.1 million. At December 31, 2017, the Company had $25.0 million in short-term borrowings with the FHLB at 1.41% which was repaid on January 2, 2018. There were no amounts outstanding under any of the other borrowing arrangements above as of December 31, 2017 and 2016.

Income Taxes

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Income Taxes

NOTE 10—INCOME TAXES

The asset and liability method is used in accounting for income taxes. Under this method, deferred tax assets and liabilities are determined based on differences between financial reporting and tax bases of assets and liabilities and are measured using the enacted tax rates and laws that will be in effect when the differences are expected to reverse.

During the three months ended March 31, 2018 and 2017, the Company recorded an income tax provision of $1.6 million and $3.9 million, respectively, reflecting and effective tax rate of 15.2% and 41.4% for the three months ended March 31, 2018 and 2017, respectively.

NOTE 12—INCOME TAXES

Income tax expense consists of the following:


*(dollars in thousands)*	2017		2016		2015
Current:
Federal	$	12,097	$	9,345	$	5,662
State		3,773		2,841		1,973

		15,870		12,186		7,635
Deferred		2,492		1,289		1,361
Deferred tax adjustment for enacted change in tax rate		2,591		—		—
Affordable housing tax credits		316		14		—

	$	21,269	$	13,489	$	8,996

A comparison of the federal statutory income tax rates to the Company’s effective income tax rates as of December 31 follows:


	2017						2016						2015
*(dollars in thousands)*	Amount			Rate			Amount			Rate			Amount			Rate
Statutory federal tax	$	16,379			35.0	%	$	11,399			35.0	%	$	7,469			34.0	%
State franchise tax, net of federal benefit		3,135			6.7	%		2,281			7.0	%		1,550			7.1	%
Tax-exempt income		(297	)		-0.6	%		(202	)		-0.6	%		(203	)		-0.9	%
Tax impact from enacted change in tax rate		2,591			5.5	%		—			0.0	%		—			0.0	%
Other items, net		(539	)		-1.2	%%		11			0.0	%		180			0.8	%

Actual tax expense	$	21,269			45.4	%	$	13,489			41.4	%	$	8,996			41.0	%

On December 22, 2017, the U.S. government enacted comprehensive tax legislation commonly referred to as the Tax Cuts and Jobs Act (“Tax Act”). Among other changes, the Tax Act reduces the U.S. federal corporate tax rate from 35% to 21%. The Company has recorded an income tax expense of $2.6 million related to the re-measurement of federal net deferred tax assets resulting from the permanent reduction in the U.S. statutory corporate tax rate to 21% from 35%.

Deferred taxes are a result of differences between income tax accounting and generally accepted accounting principles with respect to income and expense recognition. The following is a summary of the components of the net deferred tax asset accounts recognized in the accompanying balance sheets as of December 31:


*(dollars in thousands)*	2017			2016
Deferred tax assets:
Pre-opening expenses	$	173		$	287
Allowance for loan losses		4,072			5,954
Stock-based compensation		1,973			2,576
Off balance sheet reserve		83			254
Operating loss carryforwards		285			693
Other real estate owned		10			17
Acquisition accounting fair value adjustments		—			1,779
Unrealized loss on AFS securities		186			186
Other		1,968			2,520

		8,750			14,266
Deferred tax liabilities:
Depreciation		(511	)		(917	)
Acquisition accounting fair value adjustments		(145	)		—
Other		(2,008	)		(2,252	)

		(2,664	)		(3,169	)

Net deferred tax assets	$	6,086		$	11,097

The Company has net operating loss carryforwards from acquisitions of approximately $37,000 for federal income and approximately $3.2 million for California franchise tax purposes. Net operating loss carry forwards, to the extent not used will begin to expire in 2027. Net operating loss carryforwards available from acquisitions are substantially limited by Section 382 of the Internal Revenue Code and benefits not expected to be realized due to the limitation have been excluded from the deferred tax asset and net operating loss carryforward amounts noted above. The Company acquired operating loss carryforwards in its acquisitions that were subject to limitations under Section 382 of the Internal Revenue Code. The amount of net operating loss carry forwards the Company was able to utilize amounted to $3.8 million and $11.4 million for federal income and California franchise tax purposes, respectively. These operating loss carryforwards expire in 2031 through 2033.

The Company is subject to federal income tax and franchise tax of the state of California. Income tax returns for the years ended after December 31, 2013 are open to audit by the federal authorities and for the years ended after December 31, 2012 are open to audit by California state authorities.

There were no recorded interest or penalties related to uncertain tax positions as part of income tax for the years ended December 31, 2017, 2016, and 2015, respectively. The Company has determined that as of December 31, 2017 all tax positions taken to date are highly certain and, accordingly, no accounting adjustment has been made to the consolidated financial statements.

Commitments

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Commitments

NOTE 11—COMMITMENTS

Future minimum rent payments on the Company’s leases were as follows at March 31, 2018:


*(dollars in thousands)*
Year ending December 31:
2018 remaining	$	1,338
2019		1,625
2020		1,396
2021		1,312
2022		1,089
Thereafter		4,117

	$	10,877

The minimum rent payments shown above are given for the existing lease obligation and are not a forecast of future rental expense. Total rental expense, recognized on a straight-line basis, was $437,000 and $381,000 for the three months ended March 31, 2018 and 2017, respectively.

In the ordinary course of business, the Company enters into financial commitments to meet the financing needs of its customers. These financial commitments include commitments to extend credit, unused lines of credit, commercial and similar letters of credit and standby letters of credit. Those instruments involve to varying degrees, elements of credit and interest rate risk not recognized in the Company’s financial statements.

The Company’s exposure to loan loss in the event of nonperformance on these financial commitments is represented by the contractual amount of those instruments. The Company uses the same credit policies in making commitments as it does for loans reflected in the financial statements.

At March 31, 2018 and December 31, 2017, the Company had the following financial commitments whose contractual amount represents credit risk:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Commitments to make loans	$	103,354	$	101,960
Unused lines of credit		119,964		99,217
Commercial and similar letters of credit		4,700		3,013
Standby letters of credit		1,575		1,575

	$	229,593	$	205,765

Commitments to extend credit are agreements to lend to a customer as long as there is no violation of any condition established in the contract. Since many of the commitments are expected to expire without being drawn upon, the total amounts do not necessarily represent future cash requirements. The Company evaluates each client’s credit worthiness on a case-by-case basis. The amount of collateral obtained if deemed necessary by the Company is based on management’s credit evaluation of the customer.

The Company is involved in various matters of litigation which have arisen in the ordinary course of business and accruals for estimates of potential losses have been provided when necessary and appropriate under GAAP. In the opinion of management, the disposition of such pending litigation will not have a material effect on the Company’s financial statements.

NOTE 13—COMMITMENTS

As of December 31, 2017 and 2016, the Company had the following financial commitments whose contractual amount represents credit risk:


	2017				2016
*(dollars in thousands)*	Fixed Rate		Variable Rate		Fixed Rate		Variable Rate
Commitments to make loans	$	19,438	$	82,522	$	54,812	$	13,191
Unused lines of credit		58,291		40,926		38,943		53,435
Commercial and similar letters of credit		3,013		—		8,966		—
Standby letters of credit		1,225		350		1,100		150

	$81,967		$123,798		$103,821		$66,776

The Company is involved in various matters of litigation which have arisen in the ordinary course of business and accruals for estimates of potential losses have been provided when necessary and appropriate under generally accepted accounting principles. In the opinion of management, the disposition of such pending litigation will not have a material effect on the Company’s financial statements.

Related Party Transactions

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Related Party Transactions

NOTE 12—RELATED PARTY TRANSACTIONS

Loans to principal officers, directors, and their affiliates were as follows:


*(dollars in thousands)*	March 31, 2018			December 31, 2017
Beginning balance	$	2,300		$	3,445
New loans and advances		300			2,200
Repayments		(500	)		(3,345	)

Ending balance	$	2,100		$	2,300

Loan commitments outstanding to executive officers, directors and their related interests with whom they are associated totaled approximately $1.8 million and $2.1 million at March 31, 2018 and December 31, 2017, respectively.

Deposits from principal officers, directors, and their affiliates at March 31, 2018 and December 31, 2017 were $43.9 million and $43.8 million, respectively.

NOTE 14—RELATED PARTY TRANSACTIONS

Loans to principal officers, directors, and their affiliates were as follows:


*(dollars in thousands)*	2017			2016
Beginning balance	$	3,445		$	3,971
New loans and advances		2,200			1,274
Repayments		(3,345	)		(1,800	)

Ending balance	$	2,300		$	3,445

Loan commitments outstanding to executive officers, directors and their related interests with whom they are associated totaled approximately $2.1 million and $2.3 million as of December 31, 2017 and 2016, respectively.

Deposits from principal officers, directors, and their affiliates at year-end 2017 and 2016 were $43.8 million and $37.2 million.

Stock-based Compensation

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Stock-based Compensation

NOTE 13—STOCK-BASED COMPENSATION

RBB Bancorp 2017 Omnibus Stock Incentive Plan.

The 2017 Omnibus Stock Incentive Plan, or OSIP, was adopted by the Company’s board of directors on January 18, 2017 and approved by the Company’s shareholders at the Company’s annual meeting on May 23, 2017. The OSIP was designed to ensure continued availability of equity awards that will assist the Company in attracting and retaining competent managerial personnel and rewarding key employees, directors and other service providers for high levels of performance. Pursuant to the OSIP, the Company’s board of directors are allowed to grant awards to eligible persons in the form of qualified and non-qualified stock options, restricted stock, restricted stock units, stock appreciation rights and other incentive awards. The Company has reserved up to 30% of issued and outstanding shares of common stock as of the date the Company adopted the 2017 OSIP, or 3,848,341 shares. This represents 24% of the issued and outstanding shares of the Company’s common stock as of March 31, 2018. As of March 31, 2018, there were 1,353,207 shares of common stock available for issuance under the OSIP. Awards vest, become exercisable and contain such other terms and conditions as determined by the board of directors and set forth in individual agreements with the employees receiving the awards. The OSIP enables the board of directors to set specific performance criteria that must be met before an award vests. The OSIP allows for acceleration of vesting and exercise privileges of grants if a participant’s termination of employment is due to a change in control, death or total disability. If a participant’s job is terminated for cause, then all awards expire at the date of termination.

RBB Bancorp 2010 Stock Option Plan

Under the 2010 Plan, the Company was permitted to grant awards to eligible persons in the form of qualified and non-qualified stock options. The Company reserved up to 30% of the issued and outstanding shares of common stock as of the date the Company adopted the 2010 Plan or 3,494,478 shares, for issuance under the 2010 Plan. After approval of the OSIP at the Company’s annual meeting on May 23, 2017, no additional grants will be made under the 2010 Plan. The 2010 Plan has terminated and options that were granted under that Plan have become subject to the OSIP. Awards that were granted under the 2010 Plan will remain exercisable pursuant to the terms and conditions set forth in individual award agreements, but such awards will be assumed and administered under the OSIP. The 2010 Plan award agreements allow for acceleration of exercise privileges of grants upon occurrence of a change in control of the Company. If a participant’s job is terminated for cause, then all unvested awards expire at the date of termination.

The Company recognized stock-based compensation expense of $131,000 and recognized income tax benefits on that expense of $1.2 million for the three months ended March 31, 2018. The Company recognized stock-based compensation expense of $198,000 and recognized income tax benefits on that expense of $61,000 for the three months ended March 31, 2017.

NOTE 15—STOCK OPTION PLAN

Under the terms of the Company’s 2017 Omnibus Stock Incentive Plan, officers and key employees may be granted both nonqualified and incentive stock options and directors and organizers, who are not also an officer or employee, may only be granted nonqualified stock options. The Plan provides for options to purchase up to 30 percent of the outstanding common stock at a price not less than 100 percent of the fair market value of the stock on the date of the grant. Stock options expire no later than ten years from the date of the grant and generally vest over three years.

At December 31, 2017, 1,586,541 shares were available under the 2017 Omnibus Stock Incentive Plan for future grants.

The Company adopted ASU 2016-09 in 2017 where all excess tax benefits and tax deficiencies from share based payments are recognized as income tax expense or benefit in the income statement instead of the previous accounting which credited excess tax benefits to additional paid-in capital and tax deficiencies as a charge to income tax expense or as an offset to accumulated excess tax benefits, if any.

The Company recognized stock-based compensation expense of $779,000, $894,000, and $1.5 million in 2017, 2016, and 2015 and recognized income tax benefits on that expense of $246,000, $267,000, and $482,000, respectively.

The fair value of each option grant was estimated on the date of grant using the Black-Scholes option pricing model with the following weighted-average assumptions presented below for 2016 and 2015. There were no stock options granted in 2017.


	2016			2015
Expected volatility		35.0	%		35.0	%
Expected term		6.0 years			6.0 years
Expected dividends		None			None
Risk free rate		1.93	%		1.84	%
Grant date fair value	$	6.76		$	6.29

Since the Company had a limited amount of historical stock activity in 2016, the expected volatility was based on the historical volatility of similar banks that had a longer trading history. The expected term represents the estimated average period of time that the options remain outstanding. Since the Company did not have sufficient historical data on the exercise of stock options in 2016, the expected term was based on the “simplified” method that measures the expected term as the average of the vesting period and the contractual term. The risk free rate of return reflects the grant date interest rate offered for zero coupon U.S. Treasury bonds over the expected term of the options.

A summary of the status of the Company’s stock option plan as of December 31, 2017 and changes during the year then ended is presented below:


*(dollars in thousands, except for share amounts)*	Shares			Weighted- Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
Outstanding at beginning of year		2,495,134		$	11.26
Granted		—		$	—
Exercised		(223,334	)	$	10.28
Forfeited or expired		(10,000	)	$	18.25

Outstanding at end of year		2,261,800		$	11.32		3.8 years	$	36,297

Options exercisable		2,097,804		$	10.80		3.4 years	$	34,755

As of December 31, 2017 there was approximately $637,000 of total unrecognized compensation cost related to outstanding stock options that will be recognized over a weighted-average period of 1.2 years. The intrinsic value of options exercised was $2,808,000, $216,000, and $231,000 in 2017, 2016, and 2015, respectively.

The total fair value of the shares vested was $930,000, $1,511,000, and $1,454,000 in 2017, 2016, and 2015, respectively. The number of nonvested stock options were 163,996 and 328,826 with a weighted average grant date fair value of $6.53 and $6.28 as of December 31, 2017 and 2016.

Cash received from the exercise of 223,334 share options was $2.3 million for the period ended December 31, 2017 with a related tax benefit of $573,000.

Regulatory Matters

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Regulated Operations [Abstract]

Regulatory Matters

NOTE 14—REGULATORY MATTERS

Holding companies (with assets over $1 billion at the beginning of the year) and banks are subject to various regulatory capital requirements administered by the federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory—and possibly additional discretionary—actions by regulators that, if undertaken, could have a direct material effect on the Company’s financial statements.

In July 2013, the federal bank regulatory agencies approved the final rules implementing the Basel Committee on Banking Super vision’s capital guidelines for U.S. banks. The new rules became effective on January 1, 2015, with certain of the requirements phased-in over a multi-year schedule. Under the rules, minimum requirements increased for both the quantity and quality of capital held by the Bank. The rules include a new common equity Tier 1 (“CET1”) capital to risk-weighted assets ratio with minimums for capital adequacy and prompt corrective action purposes of 4.5% and 6.5%, respectively. The minimum Tier 1 capital to risk-weighted assets ratio was raised from 4.0% to 6.0% under the capital adequacy framework and from 6.0% to 8.0% to be well-capitalized under the prompt corrective action framework. In addition, the rules introduced the concept of a “conservation buffer” of 2.5% applicable to the three capital adequacy risk-weighted asset ratios (CET1, Tier 1, and Total). The implementation of the capital conservation buffer began on January 1, 2016 at 0.625% and will be phased in over a four-year period (increasing by that amount on each subsequent January 1, until it reaches 2.5% on January 1, 2019). If the capital adequacy minimum ratios plus the phased-in conservation buffer amount exceed actual risk-weighted capital ratios, then dividends, share buybacks, and discretionary bonuses to executives could be limited in amount.

Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Bank must meet specific capital guidelines that involve quantitative measures of the Bank’s assets, liabilities, and certain off-balance-sheet items as calculated under regulatory accounting practices. Capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Quantitative measures established by regulation to ensure capital adequacy require the Bank to maintain minimum amounts and ratios (set forth in the table below) of total, Tier 1 and CET1 capital to risk-weighted assets, and of Tier 1 capital to average assets. As permitted by the regulators for financial institutions that are not deemed to be “advanced approaches” institutions, the Company has elected to opt out of the Basel III requirement to include accumulated other comprehensive income in risk-based capital. Management believes, at March 31, 2018 and December 31, 2017, that the Bank meets all capital adequacy requirements to which it is subject.

As defined in applicable regulations and set forth in the tables below, the Company and the Bank continue to exceed the regulatory capital minimum requirements and the Bank continues to exceed the “well capitalized” standards at the dates indicated:


						Amount of Capital Required
	Actual					Minimum Required for Capital Adequacy Purposes					To Be Well- Capitalized Under Prompt Corrective Provisions
*(dollars in thousands)*	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of March 31, 2018:
Tier 1 Leverage Ratio
Consolidated	$	249,304		15.24	%	$	65,439		4.00	%	$	81,798		5.00	%
Bank	$	242,192		14.84	%	$	65,283		4.00	%	$	81,604		5.00	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	245,857		17.95	%	$	61,620		4.50	%	$	89,007		6.50	%
Bank	$	242,192		17.72	%	$	61,502		4.50	%	$	88,837		6.50	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	249,304		18.21	%	$	82,161		6.00	%	$	109,547		8.00	%
Bank	$	242,192		17.72	%	$	82,003		6.00	%	$	109,338		8.00	%
Total Risk-Based Capital Ratio
Consolidated	$	313,402		22.89	%	$	109,547		8.00	%	$	136,934		10.00	%
Bank	$	256,725		18.78	%	$	109,338		8.00	%	$	136,672		10.00	%
As of December 31, 2017:
Tier 1 Leverage Ratio
Consolidated	$	238,219		14.35	%	$	66,423		4.00	%	$	83,029		5.00	%
Bank	$	232,765		14.50	%	$	64,214		4.00	%	$	80,267		5.00	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	234,794		17.54	%	$	60,233		4.50	%	$	87,003		6.50	%
Bank	$	232,765		17.42	%	$	60,122		4.50	%	$	86,843		6.50	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	238,219		17.80	%	$	80,311		6.00	%	$	107,081		8.00	%
Bank	$	232,765		17.42	%	$	80,163		6.00	%	$	106,884		8.00	%
Total Risk-Based Capital Ratio
Consolidated	$	301,802		22.55	%	$	107,081		8.00	%	$	133,851		10.00	%
Bank	$	246,820		18.47	%	$	106,884		8.00	%	$	133,605		10.00	%

The California Financial Code generally acts to prohibit banks from making a cash distribution to its shareholders in excess of the lesser of the bank’s undivided profits or the bank’s net income for its last three fiscal years less the amount of any distribution made by the bank’s shareholders during the same period.

The California General Corporation Law generally acts to prohibit companies from paying dividends on common stock unless its retained earnings, immediately prior to the dividend payment, equals or exceeds the amount of the dividend. If a company fails this test, then it may still pay dividends if after giving effect to the dividend the company’s assets are at least 125% of its liabilities.

Additionally, the Federal Reserve Bank has issued guidance which requires that they be consulted before payment of a dividend if a bank holding company does not have earnings over the prior four quarters of at least equal to the dividend to be paid, plus other holding company obligations.

NOTE 16—REGULATORY MATTERS

In July, 2013, the federal bank regulatory agencies approved the final rules implementing the Basel Committee on Banking Supervision’s capital guidelines for U.S. banks. The new rules became effective on January 1, 2015, with certain of the requirements phased-in over a multi-year schedule. Under the rules, minimum requirements increased for both the quantity and quality of capital held by the Bank. The rules include a new common equity Tier 1 (“CET1”) capital to risk-weighted assets ratio with minimums for capital adequacy and prompt corrective action purposes of 4.5% and 6.5%, respectively. The minimum Tier 1 capital to risk-weighted assets ratio was raised from 4.0% to 6.0% under the capital adequacy framework and from 6.0% to 8.0% to be well-capitalized under the prompt corrective action framework. In addition, the rules introduced the concept of a “conservation buffer” of 2.5% applicable to the three capital adequacy risk-weighted asset ratios (CET1, Tier 1, and Total). The conservation buffer will be phased-in on a pro rata basis over a four year period beginning in 2016. If the capital adequacy minimum ratios plus the phased-in conservation buffer amount exceed actual risk-weighted capital ratios, then dividends, share buybacks, and discretionary bonuses to executives could be limited in amount.

Under capital adequacy guidelines and the regulatory framework for prompt corrective action, the Bank must meet specific capital guidelines that involve quantitative measures of the Bank’s assets, liabilities, and certain off-balance-sheet items as calculated under regulatory accounting practices. Capital amounts and classification are also subject to qualitative judgments by the regulators about components, risk weightings, and other factors. Quantitative measures established by regulation to ensure capital adequacy require the Bank to maintain minimum amounts and ratios (set forth in the table below) of total, Tier 1 and CET1 capital (as defined in the regulations) to risk-weighted assets (as defined), and of Tier 1 capital (as defined) to average assets (as defined).

The Company’s capital conservation buffer for 2017 is 11.80%. The net unrealized gain or loss on available for sale securities is not included in computing regulatory capital. Management believes, as of December 31, 2017 and 2016, that the Bank meets all capital adequacy requirements to which it is subject.

As of December 31, 2017, the most recent notification from the FDIC categorized the Bank as well-capitalized under the regulatory framework for prompt corrective action (there are no conditions or events since that notification that management believes have changed the Bank’s category). To be categorized as well-capitalized, the Bank must maintain minimum ratios as set forth in the table below.

The following table sets forth RBB Bancorp’s consolidated and the Bank’s actual capital amounts and ratios and related regulatory requirements for the Bank as of December 31, 2017:


						Amount of Capital Required
	Actual					For Capital Adequacy Purposes					To Be Well- Capitalized Under Prompt Corrective Provisions
*(dollars in thousands)*	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of December 31, 2017:
Tier 1 Leverage Ratio
Consolidated	$	238,219		14.35	%		NA		NA			NA		NA
Bank	$	232,765		14.50	%	$	64,214		4.0	%	$	80,267		5.0	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	234,794		17.54	%		NA		NA			NA		NA
Bank	$	232,765		17.42	%	$	60,122		4.5	%	$	86,843		6.5	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	238,219		17.80	%		NA		NA			NA		NA
Bank	$	232,765		17.42	%	$	80,163		6.0	%	$	106,884		8.0	%
Total Risk-Based Capital Ratio
Consolidated	$	301,802		22.55	%		NA		NA			NA		NA
Bank	$	246,820		18.47	%	$	106,884		8.0	%	$	133,605		10.0	%

The following table sets forth RBB Bancorp’s consolidated and the Bank’s actual capital amounts and ratios and related regulatory requirements for the Bank as of December 31, 2016:


						Amount of Capital Required
	Actual					For Capital Adequacy Purposes					To Be Well- Capitalized Under Prompt Corrective Provisions
*(dollars in thousands)*	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of December 31, 2016:
Tier 1 Leverage Ratio
Consolidated	$	153,682		10.99	%		NA		NA			NA		NA
Bank	$	178,645		12.81	%	$	55,777		4.0	%	$	69,722		5.0	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	150,786		13.30	%		NA		NA			NA		NA
Bank	$	178,645		15.81	%	$	50,860		4.5	%	$	73,464		6.5	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	153,682		13.55	%		NA		NA			NA		NA
Bank	$	178,645		15.81	%	$	67,813		6.0	%	$	90,417		8.0	%
Total Risk-Based Capital Ratio
Consolidated	$	217,244		19.16	%		NA		NA			NA		NA
Bank	$	192,784		17.06	%	$	90,417		8.0	%	$	113,021		10.0	%

The California general corporation law generally acts to prohibit companies from paying dividends on common stock unless its retained earnings, immediately prior to the dividend payment, equals or exceeds the amount of the dividend. If a company fails this test, then it may still pay dividends if after giving effect to the dividend the company’s assets are at least 125% of its liabilities.

Fair Value Measurements

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value Measurements

NOTE 15—FAIR VALUE MEASUREMENTS

The following is a description of valuation methodologies used for assets and liabilities recorded at fair value:

Securities: The fair values of securities available for sale are determined by obtaining quoted prices on nationally recognized securities exchanges (Level 1) or matrix pricing, which is a mathematical technique used widely in the industry to value debt securities without relying exclusively on quoted prices for specific securities but rather by relying on the securities’ relationship to other benchmark quoted securities (Level 2).

Other Real Estate Owned: Nonrecurring adjustments to certain commercial and residential real estate properties classified as other real estate owned are measured at the lower of carrying amount or fair value, less costs to sell. In cases where the carrying amount exceeds the fair value, less costs to sell, an impairment loss is recognized. Fair values are generally based on third party appraisals of the property which are commonly adjusted by management to reflect an expectation of the amount to be ultimately collected and selling costs (Level 3).

Appraisals for other real estate owned are performed by state licensed appraisers (for commercial properties) or state certified appraisers (for residential properties) whose qualifications and licenses have been reviewed and verified by the Company. When a Notice of Default is recorded, an appraisal report is ordered. Once received, a member of the credit administration department reviews the assumptions and approaches utilized in the appraisal as well as the overall resulting fair value in comparison to independent data sources such as recent market data or industry wide-statistics for residential appraisals. Commercial appraisals are sent to an independent third party to review. The Company also compares the actual selling price of collateral that has been sold to the most recent appraised value to determine what additional adjustments, if any, should be made to the appraisal values on any remaining other real estate owned to arrive at fair value. If the existing appraisal is older than twelve months a new appraisal report is ordered. No significant adjustments to appraised values have been made as a result of this comparison process as of March 31, 2018.

The following table provides the hierarchy and fair value for each major category of assets and liabilities measured at fair value at March 31, 2018 and December 31, 2017:


	Fair Value Measurements Using:
*(dollars in thousands)*	Level 1		Level 2		Level 3		Total
March 31, 2018
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	7,482			$	7,482
Mortgage-backed securities
Government sponsored agencies				37,672				37,672
Corporate debt securities				37,694				37,694

	$	—	$	82,848	$	—	$	82,848

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	293	$	293

December 31, 2017
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	7,816				7,816
Mortgage-backed securities
Government sponsored agencies				39,215				39,215
Corporate debt securities				17,926				17,926

	$	—	$	64,957	$	—	$	64,957

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	293	$	293

No write-downs to OREO were recorded in for the three months ended March 31, 2018 or for the year ended December 31, 2017.

Quantitative information about the Company’s non-recurring Level 3 fair value measurements at March 31, 2018 and December 31, 2017 is as follows:


*(dollars in thousands)*	Fair Value Amount		Valuation Technique		Unobservable Input	Adjustment Range			Weighted- Average Adjustment
March 31, 2018
Other real estate owned	$	293		Third Party Appraisals	Management Adjustments to Reflect Current Conditions and Selling Costs		21	%		21	%
December 31, 2017
Other real estate owned	$	293		Third Party Appraisals	Management Adjustments to Reflect Current Conditions and Selling Costs		21	%		21	%

NOTE 17—FAIR VALUE MEASUREMENTS

The following is a description of valuation methodologies used for assets and liabilities recorded at fair value:

The following table provides the hierarchy and fair value for each major category of assets and liabilities measured at fair value at December 31, 2017 and 2016:


*(dollars in thousands)*	Fair Value Measurements Using:
December 31, 2017	Level 1		Level 2		Level 3		Total
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	7,816			$	7,816
Mortgage-backed securities								—
Government sponsored agencies				39,215				39,215
Corporate debt securities				17,926				17,926

	$	—	$	64,957	$	—	$	64,957

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	293	$	293


December 31, 2016
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	5,317				5,317
Mortgage-backed securities
Government sponsored agencies				23,640				23,640
Corporate debt securities				10,320				10,320

	$	—	$	39,277	$	—	$	39,277

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	833	$	833

No write-downs to OREO were recorded in 2017 or 2016.

Quantitative information about the Company’s non-recurring Level 3 fair value measurements as of December 31, 2017 and 2016 is as follows:

(dollars in thousands)

December 31, 2017

Fair Value
Amount

Valuation

Technique

Unobservable Input

Adjustment
Range

Weighted-
Average
Adjustment

Other real estate owned

293

Third party

appraisals

Management adjustments to reflect current conditions and selling costs

21%

December 31, 2016

Other real estate owned

833

Third party

appraisals

Management adjustments to reflect current conditions and selling costs

10% - 15%

12%

Fair Value of Financial Instruments

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

NOTE 16—FAIR VALUE OF FINANCIAL INSTRUMENTS

The fair value of a financial instrument is the amount at which the asset or obligation could be exchanged in a current transaction between willing parties, other than in a forced or liquidation sale. Fair value estimates are made at a specific point in time based on relevant market information and information about the financial instrument. These estimates do not reflect any premium or discount that could result from offering for sale at one time the entire holdings of a particular financial instrument. Because no market value exists for a significant portion of the financial instruments, fair value estimates are based on judgments regarding future expected loss experience, current economic conditions, risk characteristics of various financial instruments, and other factors. These estimates are subjective in nature, involve uncertainties and matters of judgment and, therefore, cannot be determined with precision. Changes in assumptions could significantly affect the estimates.

Fair value estimates are based on financial instruments both on and off the balance sheet without attempting to estimate the value of anticipated future business and the value of assets and liabilities that are not considered financial instruments. Additionally, tax consequences related to the realization of the unrealized gains and losses can have a potential effect on fair value estimates and have not been considered in many of the estimates.

Fair value measurement and disclosure standards also establish a framework for measuring fair values. Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability, in an orderly transaction between market participants on the measurement date. Further, the standards establish a fair value hierarchy that encourages an entity to maximize the use of observable inputs and limit the use of unobservable inputs when measuring fair values. The standards describe three levels of inputs that may be used to measure fair values:

•

Level 1: Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date.

•

Level 2: Significant observable inputs other than Level 1 prices, such as quoted prices for similar assets or liabilities, quoted prices in markets that are not active, and other inputs that are observable or can be corroborated by observable market data.

•

Level 3: Significant unobservable inputs that reflect a company’s own assumptions about the factors that market participants would likely consider in pricing an asset or liability.

Fair value estimates are made at a specific point in time based on relevant market data and information about the financial instruments. The estimates incorporate our assumptions with regard to the impact of prepayments on future cash flows and credit quality adjustments based on risk characteristics of various financial instruments, among other things. The estimates are subjective and involve uncertainties and matters of significant judgment, and therefore cannot be determined with precision. Changes in assumptions could significantly alter the fair values presented.

The fair value hierarchy level and estimated fair value of significant financial instruments at March 31, 2018 and December 31, 2017 are summarized as follows:


			March 31,				December 31,
			2018				2017
*(dollars in thousands)*	Fair Value Hierarchy		Carrying Value		Fair Value		Carrying Value		Fair Value
Financial Assets:
Cash and due from banks		Level 1	$	53,535	$	53,535	$	70,048	$	70,048
Federal funds sold and other cash equivalents		Level 1		25,000		25,000		80,000		80,000
Interest-earning deposits in other financial institutions		Level 1		600		600		600		600
Investment securities—AFS		Level 2		82,848		82,848		64,957		64,957
Investment securities—HTM		Level 2		9,998		10,020		10,009		10,250
Mortgage loans held for sale		Level 1		183,391		128,491		125,847		128,972
Loans, net		Level 3		1,247,971		1,288,740		1,235,301		1,236,289
Financial Liabilities:
Deposits		Level 2		1,373,504		1,371,213	$	1,337,281	$	1,336,353
FHLB advances		Level 2		—		—		25,000		25,000
Long-term debt		Level 2		49,564		41,950		49,528		44,319
Subordinated debentures		Level 3		3,447		3,625		3,424		3,348

NOTE 18—FAIR VALUE OF FINANCIAL INSTRUMENTS

The following methods and assumptions were used to estimate the fair value of significant financial instruments not previously presented:

Cash and Cash Equivalents

The carrying amounts of cash and short-term instruments approximate fair values.

Time Deposits in Other Banks

Fair values for time deposits with other banks are estimated using discounted cash flow analyses, using interest rates currently being offered with similar terms.

Loans

For variable rate loans that reprice frequently and with no significant change in credit risk, fair values are based on carrying amounts. The fair values for all other loans are estimated using discounted cash flow analyses, using interest rates currently being offered for loans with similar terms to borrowers with similar credit quality. The methods utilized to estimate the fair value of loans do not necessarily represent an exit price.

Mortgage Loans Held for Sale

The Company records mortgage loans held for sale at fair value based on the net premium received on recent sales of mortgage loans for identical pools of loans.

Deposits

The fair values disclosed for demand deposits, including interest and non-interest demand accounts, savings, and certain types of money market accounts are, by definition based on carrying value. Fair value for fixed-rate certificates of deposit is estimated using a discounted cash flow calculation that applies interest rates currently being offered on certificates to a schedule of aggregate expected monthly maturities on time deposits. Early withdrawal of fixed-rate certificates of deposit is not expected to be significant.

FHLB Advances

The carrying amounts of short-term debt with maturities of less than ninety days, such as FHLB Advances, approximate their fair values.

Long-Term Debt

The fair values of the Company’s long-term borrowings are estimated using discounted cash flow analyses based on the current borrowing rates for similar types of borrowing arrangements resulting in a Level 2 classification.

Subordinated Debentures

The fair values of the Company’s Subordinated Debentures are estimated using discounted cash flow analyses based on the current borrowing rates for similar types of borrowing arrangements resulting in a Level 3 classification.

Off-Balance Sheet Financial Instruments

The fair value of commitments to extend credit and standby letters of credit is estimated using the fees currently charged to enter into similar agreements. The fair value of these financial instruments is not material.

The fair value hierarchy level and estimated fair value of significant financial instruments at December 31, 2017 and 2016 are summarized as follows:


			2017				2016
*(dollars in thousands)*	Fair Value Hierarchy		Carrying Value		Fair Value		Carrying Value		Fair Value
Financial Assets:
Cash and due from banks		Level 1	$	70,048	$	70,048	$	74,213	$	74,213
Federal funds sold and other cash equivalents		Level 1		80,000		80,000		44,500		44,500
Interest-earning deposits in other financial institutions		Level 1		600		600		345		345
Investment securities—AFS		Level 2		64,957		64,957		39,277		39,277
Investment securities—HTM		Level 2		10,009		10,250		6,214		6,553
Mortgage loans held for sale		Level 2		125,847		128,972		44,345		45,433
Loans, net		Level 3		1,235,301		1,236,289		1,096,284		1,095,944
Financial Liabilities:
Deposits		Level 2	$	1,337,281	$	1,336,353	$	1,152,763	$	1,140,707
FHLB advances		Level 2		25,000		25,000		—		—
Long-term debt		Level 2		49,528		44,319		49,383		48,447
Subordinated debentures		Level 3		3,424		3,348		3,334		3,334

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Earnings Per Share (EPS)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Earnings Per Share [Abstract]

Earnings Per Share (EPS)

NOTE 17—EARNINGS PER SHARE (EPS)

The following is a reconciliation of net income and shares outstanding to the income and number of shares used to compute EPS:


	Three Months Ended
	March 31
	2018					2017
*(dollars in thousands except per share amounts)*	Income		Shares			Income		Shares
Net income as reported	$	8,847				$	5,493
Shares outstanding				16,288,928					12,827,803
Impact of weighting shares				(206,033	)				—

Used in basic EPS		8,847		16,082,895			5,493		12,827,803
Dilutive effect of outstanding
Stock options				1,079,425					897,918

Used in dilutive EPS	$	8,847		17,162,320		$	5,493		13,725,721

Basic earnings per common share	$	0.55				$	0.43
Diluted earnings per common share	$	0.52				$	0.40

NOTE 19—EARNINGS PER SHARE (“EPS”)

The following is a reconciliation of net income and shares outstanding to the income and number of shares used to compute EPS:


	2017					2016					2015
*(dollars in thousands except per share amounts)*	Income		Shares			Income		Shares			Income		Shares
Net income as reported	$	25,528				$	19,079				$	12,973
Shares outstanding				15,908,893					12,827,803					12,770,571
Impact of weighting shares				(1,830,612	)				(26,813	)				(8,739	)

Used in basic EPS		25,528		14,078,281			19,079		12,800,990			12,973		12,761,832
Dilutive effect of outstanding
Stock options				1,160,084					894,910					790,850

Used in dilutive EPS	$	25,528		15,238,365		$	19,079		13,695,900		$	12,973		13,552,682

Basic earnings per common share	$	1.81				$	1.49				$	1.02
Diluted earnings per common share	$	1.68				$	1.39				$	0.96

Stock options for 321,000 and 139,225 shares of common stock were not considered in computing diluted earnings per common share for 2016 and 2015, respectively, because they were anti-dilutive. There were no anti-dilutive stock options in 2017.

Stock Dividends	12 Months Ended
Stock Dividends	Dec. 31, 2017
Text Block [Abstract]
Stock Dividends	NOTE 20—STOCK DIVIDENDS The Company issued a 2.5% stock dividend in 2015. No stock dividends were issued in 2017 or 2016. The per share data in the statements of income and the footnotes have been adjusted to give retroactive effect to these dividends.

Qualified Affordable Housing Project Investments	3 Months Ended	12 Months Ended
Qualified Affordable Housing Project Investments	Mar. 31, 2018	Dec. 31, 2017
Federal Home Loan Banks [Abstract]
Qualified Affordable Housing Project Investments	NOTE 18—QUALIFIED AFFORDABLE HOUSING PROJECT INVESTMENTS The Company began investing in qualified housing projects in 2016. At March 31, 2018 and December 31, 2017, the balance of the investment for qualified affordable housing projects was $8,031,000 and $5,670,000, respectively. This balance is reflected in the accrued interest and other assets line on the consolidated balance sheets. Total unfunded commitments related to the investments in qualified housing projects totaled $6,264,000 and $4,194,000 at March 31, 2018 and December 31, 2017, respectively. The Company expects to fulfill these commitments during the years ending 2027 and 2028. For the three months ended March 31, 2018 and 2017, the Company recognized amortization expense of $139,000 and $22,000, respectively, which was included within income tax expense on the consolidated statements of income.	NOTE 21—QUALIFIED AFFORDABLE HOUSING PROJECT INVESTMENTS The Company began investing in qualified affordable housing projects in 2016. At December 31, 2017 the balance of the investment for qualified affordable housing projects was $5,670,000. This balance is reflected in the accrued interest and other assets line on the consolidated balance sheets. Total unfunded commitments related to the investments in qualified affordable housing projects totaled $4,194,000 at December 31, 2017. The Company expects to fulfill these commitments during the year ending 2027. During the years ending December 31, 2017 and 2016, the Company recognized amortization expense of $316,000 and $14,000, respectively, which was included within income tax expense on the consolidated statements of income. During the years ended December 31, 2017 and 2016, the Company recognized tax credits from its investment in affordable housing tax credits of $275,000 and $6,000, respectively. The Company had no impairment losses during the years ended December 31, 2017 and 2016. Additionally, during the years ended December 31, 2017 and 2016, the Company recognized tax credits and other benefits from its investment in affordable housing tax credits of $275,000 and $12,000, respectively.

Parent Only Condensed Financial Information

12 Months Ended

Dec. 31, 2017

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Parent Only Condensed Financial Information

NOTE 22—PARENT ONLY CONDENSED FINANCIAL INFORMATION


*(Dollars in Thousands)*	2017			2016
ASSETS
Cash and cash equivalents	$	45,769		$	17,497
Investment in Bank		263,022			209,727
Investment in RAM		6,268			6,125
Other assets		3,538			1,455

Total assets	$	318,597		$	234,804

LIABILITIES AND SHAREHOLDERS’ EQUITY
Long term debt		49,528			49,383
Subordinated debentures		3,424			3,334
Other liabilities		36			8

Total liabilities		52,989			52,725
Shareholders’ equity:
Common stock		205,927			142,651
Additional paid-in capital		8,426			8,417
Retained earnings		51,697			31,278
Accumulated other comprehensive income (loss)		(443	)		(267	)

Total shareholders’ equity		265,608			182,079

Total liabilities and shareholders’ equity	$	318,597		$	234,804


*(Dollars in Thousands)*	2017			2016			2015
Interest expense	$	3,629		$	2,728		$	—
Noninterest expense		704			123			298
Loss before equity in undistributed income of subsidiaries		(4,334	)		(2,851	)		(298	)
Equity in undistributed income of:
Bank		27,620			20,483			12,310
RAM		143			274			804

Income before income taxes		23,430			17,906			12,816
Income tax benefit		2,036			1,173			125

Net income		25,466			19,079			12,941

Other comprehensive income (loss)		(104	)		(74	)		(141	)

Total comprehensive income	$	25,362		$	19,005		$	12,800

Cash flows from operating activities:
Net income	$	25,466		$	19,079		$	12,941
Net amortization of other		235			188			—
Provision for deferred income taxes		1,807			(1,172	)		(125	)
Undistributed income of subsidiaries		(27,763	)		(20,757	)		(13,114	)
Change in other assets and liabilities		(3,861	)		(159	)		135

		(4,116	)		(2,821	)		(163	)
Cash flows from investment activities:
Outlays for business acquisitions		—			(839	)		—
Investment in subsidiaries		(25,000	)		(35,000	)		5,000

		(25,000	)		(35,839	)		5,000
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs		—			49,274			—
Issuance of common stock, net of issuance costs		60,210			—			—
Dividends paid		(5,118	)		(2,554	)		(3,114	)
Stock options exercised		2,296			585			470

		57,388			47,305			(2,644	)
Increase in cash and cash equivalents		28,272			8,645			2,193
Cash and cash equivalents beginning of year		17,497			8,852			6,659

Cash and cash equivalents end of year	$	45,769		$	17,497		$	8,852

- Definition

The entire disclosure for condensed financial information, including the financial position, cash flows, and the results of operations of the registrant (parent company) as of the same dates or for the same periods for which audited consolidated financial statements are being presented. Alternatively, the details of this disclosure can be reported by the specific parent company taxonomy elements, indicating the appropriate date and period contexts in an instance document.

+ References + Details

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2017
Subsequent Events [Abstract]
Subsequent Events	NOTE 23—SUBSEQUENT EVENTS On January 17, 2018, the Company announced that the Board of Directors had declared a cash dividend of $0.08 per common share. The cash dividend is payable on February 15, 2018 to stockholders of record at the close of business on January 31, 2018 in the amount of $1,275,000.

Goodwill and Intangibles

3 Months Ended

Mar. 31, 2018

Goodwill and Intangible Assets Disclosure [Abstract]

Goodwill and Intangibles

NOTE 5—GOODWILL AND INTANGIBLES

Goodwill is generally determined as the excess of the fair value of the consideration transferred, plus the fair value of any noncontrolling interests in the acquiree, over the fair value of the net assets acquired and liabilities assumed as of the acquisition date. Goodwill resulting from whole bank acquisitions is not amortized, but tested for impairment at least annually. The Company has selected December 31st as the date to perform the annual impairment test. Goodwill amounted to $29.9 million at March 31, 2018 and December 31, 2017, and is the only intangible asset with an indefinite life on the balance sheet. There were no impairment losses recognized on goodwill during the three months ended March 31, 2018 and 2017.

Other intangible assets consist of core deposit intangible (“CDI”) assets arising from whole bank acquisitions. CDI assets are amortized on an accelerated method over their estimated useful life of 8 to 10 years. CDI was recognized in the 2013 acquisition of Los Angeles National Bank and in the 2016 acquisition of TFC Holding Company. The unamortized balance at March 31, 2018 and December 31, 2017 was $1,357,000 and $1,438,000, respectively, for both Los Angeles National Bank and TFC Holding Company. CDI amortization expense was $81,000 and $94,000 for the three months ended March 31, 2018 and March 31, 2017, respectively, for both Los Angeles National Bank and TFC Holding Company.

Estimated CDI amortization expense for future years is as follows (dollars in thousands):


Year ending December 31:
2018 remaining	$	230
2019		274
2020		244
2021		172
2022		129
Thereafter		308

Total	$	1,357

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References + Details

Recent Developments	3 Months Ended
Recent Developments	Mar. 31, 2018
Text Block [Abstract]
Recent Developments	NOTE 19—RECENT DEVELOPMENTS On April 18, 2018, RBB Bancorp declared a cash dividend of $0.09 per share for the first quarter of 2018. The dividend is payable on May 15, 2018 to common shareholders of record as of April 30, 2018. On April 23, 2018, RBB Bancorp and First American International Corporation, New York, New York (FAIC) entered into an Agreement and Plan of Merger (the Merger Agreement), providing for the merger of FAIC with and into RBB Bancorp, with RBB Bancorp as the surviving corporation (the Merger). Immediately following the effectiveness of the Merger, First American International Bank, a wholly-owned subsidiary of FAIC (FAIB) will be merged with and into the Bank, with the Bank being the surviving bank in the merger (the Bank Merger). Pursuant to the terms and subject to the conditions of the Merger Agreement, at the effective time of the Merger (the Effective Time), each share of the common stock of FAIC will be convertible into the right to receive (i) 1.3472 shares of the common stock, no par value per share, of RBB Bancorp and (ii) $15.30 in cash (such consideration set forth in clauses (i) and (ii), the Per Share Merger Consideration). Holders of in-the-money FAIC stock options (FAIC Stock Options) will receive an amount equal to (1) $51.00 minus (2) the exercise price per share with respect to the corresponding FAIC Stock Option. Pursuant to the terms of the Merger Agreement, RBB Bancorp and FAIC have agreed that FAIC will repurchase its currently outstanding $17 million of preferred stock held by the U.S. Department of the Treasury and issued under the Troubled Asset Relief Program prior to completion of the Merger (the TARP Redemption) and that the Bank will assist in financing such repurchase, if necessary. Royal Business Bank has committed to lend FAIC $17 million for up to one month, if necessary. The Merger is expected to close in the second half of 2018, subject to the satisfaction of customary closing conditions, including regulatory approvals and approval of FAIC’s shareholders. Each director of FAIC has entered into an agreement with RBB Bancorp pursuant to which they have committed to vote their shares of FAIC common stock in favor of the proposed acquisition.

Basis of Presentation and Summary of Significant Accounting Policies (Policies)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Accounting Policies [Abstract]

Basis of Presentation

Reclassifications

Principles of Consolidation and Nature of Operations

RBB Bancorp was formed in January 2011 as a bank holding company. RAM was formed in 2012 to hold and manage problem assets acquired in business combinations.

RBB Bancorp has no significant business activity other than its investments in Royal Business Bank and RAM. Parent only condensed financial information on RBB Bancorp is provided in Note 22.

Use of Estimates in the Preparation of Financial Statements

Cash and Cash Equivalents

Cash and Due from Banks

Interest-Bearing Deposits in Other Financial Institutions

Interest-bearing deposits in other financial institutions not included in cash and cash equivalents are carried at cost.

Investment Securities

Loans Held For Sale

Loans

Allowance for Loan Losses

Certain Acquired Loans

Servicing Rights

Transfers of Financial Assets

Premises and Equipment

Other Real Estate Owned

Goodwill and Other Intangible Assets

Estimated CDI amortization expense for the next 5 years is as follows (dollars in thousands):


Year ending December 31:
2018	$	311
2019		274
2020		244
2021		172
2022		129
Thereafter		308

Total	$	1,438

Bank Owned Life Insurance

Federal Home Loan Bank (FHLB) Stock

Federal Home Loan Bank (“FHLB”) Stock

Stock-Based Compensation

Income Taxes

Retirement Plans

The Company established a 401(k) plan in 2010. The Company contributed $272,000, $221,000, and $125,000 in 2017 , 2 016, and 2015, respectively .

Comprehensive Income

Comprehensive income consists of net income and other comprehensive income. Other comprehensive income includes unrealized gains and losses on securities available for sale.

Financial Instruments

Earnings Per Share ("EPS")

Earnings Per Share (“EPS”)

Fair Value Measurement

Level 1: Quoted prices (unadjusted) for identical assets or liabilities in active markets that the entity has the ability to access as of the measurement date.

Level 3: Significant unobservable inputs that reflect the Company’s own assumptions about the assumptions that market participants would use in pricing an asset or liability.

See Note 17 and Note 18 for more information and disclosures relating to the Company’s fair value measurements.

Operating Segments

Recent Accounting Pronouncements

In January 2016, the FASB issued ASU 2016-01, Financial Instruments-Overall: Recognition and Measurement of Financial Assets and Financial Liabilities (Subtopic 825-10). Changes made to the current measurement model primarily affect the accounting for equity securities and readily determinable fair values, where changes in fair value will impact earnings instead of other comprehensive income. The accounting for other financial instruments, such as loans, investments in debt securities, and financial liabilities is largely unchanged. The Update also changes the presentation and disclosure requirements for financial instruments including a requirement that public business entities use exit price when measuring the fair value of financial instruments measured at amortized cost for disclosure purposes. This Update is generally effective for public business entities in fiscal years beginning after December 15, 2017, including interim periods within those fiscal years and one year later for nonpublic business entities. Based upon a preliminary evaluation of the guidance in ASU No. 2016-01 the Company does not believe that the ASU will have a material impact on the Company’s Consolidated Financial Statements. The Company will continue to monitor any updates to the guidance.

In March 2016, the FASB issued ASU 2016-09, Improvements to Employee Share-Based Payment Accounting (Topic 718.) ASU 2016-09 includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. Under ASU 2016-09, excess tax benefits and certain tax deficiencies will no longer be recorded in additional paid-in capital (“APIC”). Instead, they will record all excess tax benefits and tax deficiencies as income tax expense or benefit in the income statement, and APIC pools will be eliminated. In addition, the guidance requires excess tax benefits be presented as an operating activity on the statement of cash flows rather than as a financing activity. ASU 2016-09 also permits an accounting policy election for the impact of forfeitures on the recognition of expense for share-based payment awards. Forfeitures can be estimated, as required today, or recognized when they occur. This guidance is effective for public business entities for interim and annual reporting periods beginning after December 15, 2016, and for nonpublic business entities annual reporting periods beginning after December 15, 2017, and interim periods within the reporting periods beginning after December 15, 2018. Early adoption is permitted, but all of the guidance must be adopted in the same period. The Company early adopted the ASU as of January 1, 2017. The Company plans to recognize forfeitures as they occur. The early adoption of the ASU did not have a material effect on the Company’s financial statements or disclosures.

In July 2017, the FASB issued ASU 2017-13—Revenue Recognition (Topic 605), Revenue from Contracts with Customers (Topic 606), Leases (Topic 840), and Leases (Topic 842): Amendments to SEC Paragraphs Pursuant to the Staff Announcement at the July 20, 2017 EITF Meeting and Rescission of Prior SEC Staff Announcements and Observer Comments (SEC Update) . At the July 20, 2017, EITF meeting, the SEC staff announced that it would not object when certain public business entities (PBEs) elect to use the non-PBE effective dates solely to adopt the FASB’s new standards on revenue (ASC 606) and leases (ASC 842). This ASU reflects comments made by the SEC. The Company will continue to evaluate how extensive the impact will be under the ASU on the Company’s consolidated financial statements. The Company does not expect this ASU to have a material impact on the Company’s consolidated financial statements.

Summary of Significant Accounting Policies

Goodwill and Intangibles (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Goodwill and Intangible Assets Disclosure [Abstract]

Schedule of Future Estimated Amortization Expense

Estimated CDI amortization expense for future years is as follows (dollars in thousands):


Year ending December 31:
2018 remaining	$	230
2019		274
2020		244
2021		172
2022		129
Thereafter		308

Total	$	1,357

Estimated CDI amortization expense for the next 5 years is as follows (dollars in thousands):


Year ending December 31:
2018	$	311
2019		274
2020		244
2021		172
2022		129
Thereafter		308

Total	$	1,438

Acquisitions (Tables) - TFC Holding Company

12 Months Ended

Dec. 31, 2017

Schedule of Assets Acquired and Liabilities Assumed and Fair Value Adjustments


*(dollars in thousands)*	TFC Book Value			Fair Value Adjustments			Fair Value
Assets acquired
Cash and cash equivalents	$	51,613		$	—		$	51,613
Interest-bearing deposits in other financial Institutions		2,320			—			2,320
Net investments—available for sale		15,952			(106	)		15,846
Loans, gross		400,887			(13,211	)		387,676
Allowance for loan losses		(9,857	)		9,857			—
Bank premises and equipment		225			—			225
Deferred income taxes		4,027			858			4,885
Other assets		5,595			1,699			7,294

Total assets acquired	$	470,762		$	(903	)	$	469,859

Liabilities assumed
Deposits	$	404,465		$	848		$	405,313
Subordinated debentures		5,155			(1,900	)		3,255
Other liabilities		566			—			566

Total liabilities assumed		410,186			(1,052	)		409,134
Excess of assets acquired over liabilities assumed		60,576			149			60,725

	$	470,762		$	(903	)

Cash paid								86,664

Goodwill recognized							$	25,939

Schedule of Loans Acquired Contractual Amounts Due Expected Cash Flow Interest Component and Fair Value

For loans acquired, the contractual amounts due, expected cash flows to be collected, interest component and fair value as of the respective acquisition dates were as follows:


*(dollars in thousands)*	Acquired Loans
Contractual amounts due	$	441,275
Cash flows not expected to be collected		—

Expected cash flows		441,275
Interest component of expected cash flows		53,599

Fair value of acquired loans	$	387,676

Investment Securities (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Investments, Debt and Equity Securities [Abstract]

Summary of Amortized Cost and Fair Value of Securities Available for Sale and Held to Maturity


*(dollars in thousands)*	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
March 31, 2018
Available for sale
Government agency securities	$	7,746	$	—	$	(264	)	$	7,482
Mortgage-backed securities
Government sponsored agencies		38,843		—		(1,171	)		37,672
Corporate debt securities		37,736		145		(187	)		37,694

	$	84,325	$	145	$	(1,622	)	$	82,848

Held to maturity
Municipal taxable securities	$	4,294	$	165	$	—		$	4,459
Municipal securities		5,704		4		(147	)		5,561

	$	9,998	$	169	$	(147	)	$	10,020

December 31, 2017
Available for sale
Government agency securities	$	7,968	$	—	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		39,806		17		(608	)		39,215
Corporate debt securities		17,813		161		(48	)		17,926

	$	65,587	$	178	$	(808	)	$	64,957

Held to maturity
Municipal taxable securities	$	4,295	$	228	$	—		$	4,523
Municipal securities		5,714		32		(19	)		5,727

	$	10,009	$	260	$	(19	)	$	10,250


*(dollars in thousands)* *December 31, 2017*	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Value
Available for sale
Government agency securities	$	7,968	$	—	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		39,806		17		(608	)		39,215
Corporate debt securities		17,813		161		(48	)		17,926

	$	65,587	$	178	$	(808	)	$	64,957

Held to maturity
Municipal taxable securities	$	4,295	$	228	$	—		$	4,523
Municipal securities		5,714		32		(19	)		5,727

	$	10,009	$	260	$	(19	)	$	10,250


December 31, 2016
Available for sale
Government agency securities	$	5,453	$	—	$	(136	)	$	5,317
Mortgage-backed securities
Government sponsored agencies		23,913		38		(311	)		23,640
Corporate debt securities		10,364		21		(65	)		10,320

	$	39,730	$	59	$	(512	)	$	39,277

Held to maturity
Municipal taxable securities	$	5,301	$	328	$	—		$	5,629
Municipal securities		913		11		—			924

	$	6,214	$	339	$	—		$	6,553

Amortized Cost and Fair Value of Investment Securities Portfolio Expected Maturity

Expected maturities may differ from contractual maturities if borrowers have the right to call or prepay obligations with or without call or prepayment penalties.


	Available for Sale				Held to Maturity
*(dollars in thousands)*	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due from one to five years	$	52,326	$	51,530	$	2,780	$	2,865
Due from five to ten years		27,958		27,333		2,397		2,481
Due from ten years and greater		4,041		3,985		4,821		4,674

	$	84,325	$	82,848	$	9,998	$	10,020


	Available for Sale				Held to Maturity
*(dollars in thousands)*	Amortized Cost		Fair Value		Amortized Cost		Fair Value
Due from one to five years	$	35,221	$	34,825	$	2,780	$	2,897
Due from five to ten years		26,321		26,102		2,404		2,521
Due from ten years and greater		4,045		4,030		4,825		4,832

	$	65,587	$	64,957	$	10,009	$	10,250

Summary of Available for Sale Securities With Unrealized Losses


	Less than Twelve Months					Twelve Months or More					Total
*(dollars in thousands)*	Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value
March 31, 2018
Government agency securities	$	(112	)	$	3,873	$	(152	)	$	3,609	$	(264	)	$	7,482
Mortgage-backed securities
Government sponsored agencies		(786	)		25,484		(385	)		11,852		(1,171	)		37,336
Corporate debt securities		(119	)		9,660		(68	)		1,937		(187	)		11,597

Total available for sale	$	(1,017	)	$	39,017	$	(605	)	$	17,398	$	(1,622	)	$	56,415

Municipal securities	$	(147	)	$	4,674	$	—		$	—	$	(147	)	$	4,674

Total held to maturity	$	(147	)	$	4,674	$	—		$	—	$	(147	)	$	4,674

December 31, 2017
Government agency securities	$	(32	)	$	4,039	$	(120	)	$	3,777	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		(359	)		23,609		(249	)		11,887		(608	)		35,496
Corporate debt securities		(15	)		5,035		(33	)		1,972		(48	)		7,007

Total available for sale	$	(406	)	$	32,683	$	(402	)	$	17,636	$	(808	)	$	50,319

Municipal securities	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232

Total held to maturity	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232


	Less than Twelve Months					Twelve Months or More					Total
*(dollars in thousands)*	Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value		Unrealized Losses			Estimated Fair Value
December 31, 2017
Government agency securities	$	(32	)	$	4,039	$	(120	)	$	3,777	$	(152	)	$	7,816
Mortgage-backed securities
Government sponsored agencies		(359	)		23,609		(249	)		11,887		(608	)		35,496
Corporate debt securities		(15	)		5,035		(33	)		1,972		(48	)		7,007

Total available for sale	$	(406	)	$	32,683	$	(402	)	$	17,636	$	(808	)	$	50,319

Municipal securities	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232

Total held to maturity	$	(19	)	$	2,232	$	—		$	—	$	(19	)	$	2,232

December 31, 2016
Government agency securities	$	(136	)	$	5,317	$	—		$	—	$	(136	)	$	5,317
Mortgage-backed securities
Government sponsored agencies		(221	)		16,231		(90	)		2,504		(311	)		18,735
Corporate debt securities		(65	)		5,147		—			—		(65	)		5,147

Total available for sale	$	(422	)	$	26,695	$	(90	)	$	2,504	$	(512	)	$	29,199

Loans and Allowance for Loan Losses (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Receivables [Abstract]

Summary of Balance and Activity Related to Allowance for Loan Losses for Held for Investment Loans and the Recorded Investments in Loans and Impairment method by Portfolio Segment

The following tables present the balance and activity related to the allowance for loan losses for held for investment loans by type for the periods presented.


	Three Months Ended March 31,
	2018										2017
(dollars in thousands)	Real Estate		Commercial			Unallocated			Total		Real Estate			Commercial		Unallocated		Total
Beginning balance	$	9,309	$	4,044		$	420		$	13,773	$	8,111		$	6,051	$	—	$	14,162
Additions (reductions) to the allowance charged to expense		653		(118	)		(351	)		184		(1,169	)		1,169		—		—
Recoveries on loans charged-off		—		—			—			—		—			—		—		—
Less loans charged-off		—		—			—			—		—			24		—		24

Ending balance	$	9,962	$	3,926		$	69		$	13,957	$	6,942		$	7,244	$	—	$	14,186


*(dollars in thousands)* As of and for the three months ended March 31, 2018	Real Estate		Commercial		Unallocated		Total
Reserves:
Specific	$	—	$	—	$	—	$	—
General		9,962		3,926		69		13,957
Loans acquired with deteriorated credit quality		—		—		—		—

	$	9,962	$	3,926	$	69	$	13,957

Loans evaluated for impairment:
Individually	$	2,393	$	2,072	$	—	$	4,465
Collectively		866,176		390,974		—		1,257,150
Loans acquired with deteriorated credit quality		313		—		—		313

	$	868,882	$	393,046	$	—	$	1,261,928


As of and for the three months ended March 31, 2017	Real Estate		Commercial		Unallocated		Total
Reserves:
Specific	$	—	$	3,559	$	—	$	3,559
General		6,942		3,685		—		10,627
Loans acquired with deteriorated credit quality		—		—		—		—

	$	6,942	$	7,244	$	—	$	14,186

Loans evaluated for impairment:
Individually	$	2,550	$	3,559	$	—	$	6,109
Collectively		771,870		360,847		—		1,132,717
Loans acquired with deteriorated credit quality		737		—		—		737

	$	775,157	$	364,406	$	—	$	1,139,563


December 31, 2017	Real Estate		Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	8,111	$	6,051		$	—	$	14,162
Provisions		1,198		(2,671	)		420		(1,053	)
Charge-offs		—		(83	)		—		(83	)
Recoveries		—		747			—		747

	$	9,309	$	4,044		$	420	$	13,773

Reserves:
Specific	$	—	$	—		$	—	$	—
General		9,309		4,044			420		13,773
Loans acquired with deteriorated credit quality		—		—			—		—

	$	9,309	$	4,044		$	420	$	13,773

Loans evaluated for impairment:
Individually	$	2,420	$	155		$	—	$	2,575
Collectively		834,152		412,032			—		1,246,184
Loans acquired with deteriorated credit quality		315		—			—		315

	$	836,887	$	412,187		$	—	$	1,249,074

A summary of the changes in the allowance for loan losses as of December 31 follows:


*(dollars in thousands)*	2017			2016			2015
Beginning balance	$	14,162		$	10,023		$	8,848
Additions (reductions) to the allowance charged to expense		(1,053	)		4,974			1,386
Recoveries on loans charged-off		747			—			211

		13,856			14,997			10,445
Less loans charged-off		(83	)		(835	)		(422	)

Ending balance	$	13,773		$	14,162		$	10,023


*(dollars in thousands)*
December 31, 2017	Real Estate		Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	8,111	$	6,051		$	—	$	14,162
Provisions		1,198		(2,671	)		420		(1,053	)
Charge-offs		—		(83	)		—		(83	)
Recoveries		—		747			—		747

	$	9,309	$	4,044		$	420	$	13,773

Reserves:
Specific	$	—	$	—		$	—	$	—
General		9,309		4,044			420		13,773
Loans acquired with deteriorated credit quality		—		—			—		—

	$	9,309	$	4,044		$	420	$	13,773

Loans evaluated for impairment:
Individually	$	2,420	$	155		$	—	$	2,575
Collectively		834,152		412,032			—		1,246,184
Loans acquired with deteriorated credit quality		315		—			—		315

	$	836,887	$	412,187		$	—	$	1,249,074


December 31, 2016	Real Estate		Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	5,788	$	4,235		$	—	$	10,023
Provisions		2,323		2,651			—		4,974
Charge-offs		—		(835	)		—		(835	)
Recoveries		—		—			—		—

	$	8,111	$	6,051		$	—	$	14,162

Reserves:
Specific	$	—	$	1,782		$	—	$	1,782
General		8,111		4,269			—		12,380
Loans acquired with deteriorated credit quality		—		—			—		—

	$	8,111	$	6,051		$	—	$	14,162

Loans evaluated for impairment:
Individually	$	2,556	$	3,577		$	—	$	6,133
Collectively		744,349		359,234			—		1,103,583
Loans acquired with deteriorated credit quality		730		—			—		730

	$	747,635	$	362,811		$	—	$	1,110,446


December 31, 2015	Real Estate			Commercial			Unallocated		Total
Allowance for loan losses:
Beginning of year	$	5,696		$	3,152		$	—	$	8,848
Provisions		(108	)		1,494			—		1,386
Charge-offs		—			(422	)		—		(422	)
Recoveries		200			11			—		211

	$	5,788		$	4,235		$	—	$	10,023

Reserves:
Specific	$	—		$	—		$	—	$	—
General		5,788			4,235			—		10,023
Loans acquired with deteriorated credit quality		—			—			—		—

	$	5,788		$	4,235		$	—	$	10,023

Loans evaluated for impairment:
Individually	$	1,482		$	4,630		$	—	$	6,112
Collectively		519,963			264,610			—		784,573
Loans acquired with deteriorated credit quality		1,677			—			—		1,677

	$	523,122		$	269,240		$	—	$	792,362

Summary of Risk Category of Loans by Class of Loans

The risk category of loans by class of loans was as follows at March 31, 2018 and December 31, 2017:


*(dollars in thousands)*	Pass		Special Mention		Substandard		Impaired		Total
March 31, 2018
Real estate:
Construction and land development	$	100,954	$	—	$	—	$	286	$	101,240
Commercial real estate		478,059		4,464		15,421		2,107		500,051
Single-family residential mortgages		267,591		—		—		—		267,591
Commercial:
Other		277,678		195		520		—		278,393
SBA		108,711		—		3,870		2,072		114,653

	$	1,232,993	$	4,659	$	19,811	$	4,465	$	1,261,928

December 31, 2017
Real estate:
Construction and land development	$	91,619	$	—	$	—	$	289	$	91,908
Commercial real estate		469,422		19,070		5,416		2,131		496,039
Single-family residential mortgages		248,940		—		—		—		248,940
Commercial:
Other		277,518		2,360		888		—		280,766
SBA		126,759		1,778		2,729		155		131,421

	$	1,214,258	$	23,208	$	9,033	$	2,575	$	1,249,074

The risk category of loans by class of loans was as follows as of December 31, 2017 and 2016:


*(dollars in thousands)* December 31, 2017	Pass		Special Mention		Substandard		Impaired		Total
Real estate:
Construction and land development	$	91,619	$	—	$	—	$	289	$	91,908
Commercial real estate		469,422		19,070		5,416		2,131		496,039
Single-family residential mortgages		248,940		—		—		—		248,940
Commercial:
Other		277,518		2,360		888		—		280,766
SBA		126,759		1,778		2,729		155		131,421

	$	1,214,258	$	23,208	$	9,033	$	2,575	$	1,249,074


December 31, 2016
Real estate:
Construction and land development	$	87,174	$	1,932	$	—	$	303	$	89,409
Commercial real estate		475,499		4,562		19,484		2,253		501,798
Single-family residential mortgages		136,206		13,950		6,272		—		156,428
Commercial:
Other		194,227		—		9,616		—		203,843
SBA		151,066		1,934		2,391		3,577		158,968

	$	1,044,172	$	22,378	$	37,763	$	6,133	$	1,110,446

Summary of Aging Recorded Investment Past-due Loans

The following table presents the aging of the recorded investment in past-due loans at March 31, 2018 and December 31, 2017 by class of loans:


*(dollars in thousands)*	30-59 Days		60-89 Days		90 Days Or More (2)		Total Past Due		Loans Not Past Due		Total Loans		Non- Accrual Loans (1)
March 31, 2018
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	101,240	$	101,240	$	—
Commercial real estate		—		—		—		—		500,051		500,051		—
Single-family residential mortgages		790		—		—		790		266,801		267,591		—
Commercial:
Other		689		—		—		689		277,704		278,393		—
SBA		1,462		—		586		2,048		112,605		114,653		2,001

	$	2,941	$	—	$	586	$	3,527	$	1,258,401	$	1,261,928	$	2,001

Real estate:
Single-family residential mortgages held for sale	$	696	$	—	$	—	$	696	$	182,695	$	183,391	$	—

December 31, 2017
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	91,908	$	91,908	$	—
Commercial real estate		—		—		—		—		496,039		496,039		—
Single-family residential mortgages		1,175		338		—		1,513		247,427		248,940		—
Commercial:
Other		—		—		—		—		280,766		280,766		—
SBA		—		1,426		84		1,510		129,911		131,421		155

	$	1,175	$	1,764	$	84	$	3,023	$	1,246,051	$	1,249,074	$	155

Real estate:
Single-family residential mortgages held for sale	$	697	$	—	$	—	$	697	$	125,150	$	125,847	$	—

(1)	Included in total loans.

(2)	As of March 31, 2018, there were no loans over 90 days past due and still accruing. There was one loan over 90 days past due and still accruing in the amount of $71,000 as of December 31, 2017.

The following table presents the aging of the recorded investment in past-due loans as of December 31, 2017 and 2016 by class of loans:


*(dollars in thousands)* December 31, 2017	30-59 Days		60-89 Days		90 Days Or More (2)		Total Past Due		Loans Not Past Due		Total Loans		Non- Accrual Loans (1)
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	91,908	$	91,908	$	—
Commercial real estate		—		—		—		—		496,039		496,039		—
Single-family residential mortgages		1,175		338		—		1,513		247,427		248,940		—
Commercial:
Other		—		—		—		—		280,766		280,766		—
SBA		—		1,426		84		1,510		129,911		131,421		155

	$	1,175	$	1,764	$	84	$	3,023	$	1,246,051	$	1,249,074	$	155

Real estate:
Single-family residential mortgages held for sale	$	697	$	—	$	—	$	697	$	125,150	$	125,847	$	—


*December 31, 2016*
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	89,409	$	89,409	$	—
Commercial real estate		—		—		—		—		501,798		501,798		—
Single-family residential mortgages		—		—		—		—		156,428		156,428		—
Commercial:
Other		343		—		—		343		203,500		203,843		—
SBA		—		—		3,577		3,577		155,391		158,968		3,577

	$	343	$	—	$	3,577	$	3,920	$	1,106,526	$	1,110,446	$	3,577

Real estate:
Single-family residential mortgages held for sale	$	—	$	—	$	—	$	—	$	44,345	$	44,345	$	—

(1)	Included in total loans

(2)	As of December 31, 2017, there was one loan over 90 days past due and still accruing in the amount of $71,000.

Summary of Individually Impaired Loans Presented by Class of Loans

Information relating to individually impaired loans presented by class of loans was as follows at March 31, 2018 and December 31, 2017:


*(dollars in thousands)*	Unpaid Principal Balance		Recorded Investment		Average Balance		Interest Income		Related Allowance
March 31, 2018
With no related allowance recorded
Real estate:
Construction and land development	$	286	$	286	$	288	$	6	$	—
Commercial real estate		2,108		2,108		2,119		51		—
Commercial—SBA		2,071		2,071		1,114		34		—

Total	$	4,465	$	4,465	$	3,521	$	91	$	—

December 31, 2017
With no related allowance recorded
Real estate:
Construction and land development	$	289	$	289	$	296	$	16	$	—
Commercial real estate		2,131		2,131		2,192		297		—
Commercial—SBA		155		155		78		15		—

Total	$	2,575	$	2,575	$	2,566	$	328	$	—

Information relating to individually impaired loans presented by class of loans was as follows as of December 31, 2017, 2016 and 2015:


*(dollars in thousands)* December 31, 2017	Unpaid Principal Balance		Recorded Investment		Average Balance		Interest Income		Related Allowance
With no related allowance recorded
Construction and land development	$	289	$	289	$	296	$	16	$	—
Commercial real estate		2,131		2,131		2,192		297		—
Commercial—SBA		155		155		78		15		—

Total	$	2,575	$	2,575	$	2,566	$	328	$	—


December 31, 2016
With no related allowance recorded
Construction and land development	$	303	$	303	$	309	$	21	$	—
Commercial real estate		2,253		2,253		1,710		280		—
Commercial—SBA		18		18		93		—		—

Subtotal		2,574		2,574		2,112		301		—
With an allowance recorded
Commercial—SBA		3,559		3,559		3,559		—		1,782

Total	$	6,133	$	6,133	$	5,671	$	301	$	1,782


December 31, 2015
With no related allowance recorded
Construction and land development	$	315	$	315	$	320	$	4	$	—
Commercial real estate		1,167		1,167		1,145		195		—
Commercial—SBA		4,630		4,630		4,545		14		—

Total	$	6,112	$	6,112	$	6,010	$	213	$	—

Summary of Loans Class Modified as TDRs

The following table presents loans by class modified as TDRs that occurred during the three months ended March 31, 2018. There were no TDRs for the year ended December 31, 2017.


*(dollars in thousands)*	Number of Loans		Pre-Modification Recorded Investment		Post-Modification Recorded Investment
March 31, 2018
Commercial		1	$	71	$	71

The following table presents loans by class modified as TDR’s that occurred during the year ended December 31, 2016:


*(dollars in thousands)* December 31, 2016	Number of Loans		Pre-Modification Recorded Investment		Post-Modification Recorded Investment
Commercial real estate		1	$	1,047	$	1,047

Summary of Outstanding Balance and Carrying Amount of Purchased Credit-impaired Loans

The outstanding balance and carrying amount of purchased credit-impaired loans at March 31, 2018 and December 31, 2017 were as follows:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Outstanding balance	$	319	$	322
Carrying amount	$	313	$	315

The outstanding balance and carrying amount of purchased credit-impaired loans as of December 31 were as follows:


*(dollars in thousands)*	2017		2016
Outstanding balance	$	322	$	878
Carrying amount	$	315	$	730

Summary of Activity in Accretable Yield on Purchased Credit-impaired Loans

Below is a summary of activity in the accretable yield on purchased credit-impaired loans for the three months ended March 31, 2018 and 2017:


*(dollars in thousands)*	March 31, 2018			March 31, 2017
Beginning balance	$	122		$	142
Accretion of income		(1	)		(20	)

Ending balance	$	121		$	122

Below is a summary of activity in the accretable yield on purchased credit-impaired loans for 2017, 2016 and 2015:


*(dollars in thousands)*	2017			2016			2015
Beginning balance	$	142		$	349		$	574
Disposals		—			—			(99	)
Restructuring as TDR		—			(22	)		—
Accretion of income		(135	)		(185	)		(126	)

Ending balance	$	7		$	142		$	349

Loan Servicing (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Text Block [Abstract]

Schedule of Principal Balances of Mortgage and SBA Loans Serviced for Others

The principal balances of mortgage and SBA loans serviced for others at March 31, 2018 and December 31, 2017 are as follows:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Loans serviced for others:
Mortgage loans	$	406,559	$	384,437
SBA loans	$	174,282	$	175,919

Mortgage and SBA loans serviced for others are not reported as assets. The principal balances as of December 31 are as follows:


*(dollars in thousands)*	2017		2016
Loans serviced for others:
Mortgage loans	$	384,437	$	259,207
SBA loans	$	175,919	$	110,263

Schedule of Activity for Servicing Assets

Activity for servicing assets follows:


	Three Months Ended March 31, 2018						Three Months Ended March 31, 2017
(dollars in thousands)	Mortgage Loans			SBA Loans			Mortgage Loans			SBA Loans
Servicing assets:
Beginning of year	$	1,540		$	4,417		$	1,002		$	2,702
Additions		315			484			—			724
Disposals		(39	)		(425	)		—			—
Amortized to expense		(155	)		(158	)		(86	)		(119	)

End of period	$	1,661		$	4,318		$	916		$	3,307

Activity for servicing assets follows:


	2017						2016						2015
*(dollars in thousands)*	Mortgage Loans			SBA Loans			Mortgage Loans			SBA Loans			Mortgage Loans			SBA Loans
Servicing assets:
Beginning of year	$	1,002		$	2,702		$	298		$	1,807		$	—		$	720
Additions		1,115			2,628			912			1,353			329			1,268
Disposals		(172	)		(367	)		—			—			—			—
Amortized to expense		(405	)		(546	)		(208	)		(458	)		(31	)		(181	)

End of period	$	1,540		$	4,417		$	1,002		$	2,702		$	298		$	1,807

Premises and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Summary of Premises and Equipment

A summary of premises and equipment as of December 31 follows:


*(dollars in thousands)*	2017			2016
Land	$	2,956		$	2,956
Building and improvements		2,467			2,467
Furniture, fixtures, and equipment		3,222			2,950
Leasehold improvements		2,872			2,865

	11,517			11,238
Less accumulated depreciation and amortization		(5,359	)		(4,673	)
Construction in progress		425			20

	$6,583			$6,585

Commitments (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Commitments and Contingencies Disclosure [Abstract]

Schedule of Future Minimum Rent Payments on Company's Leases

Future minimum rent payments on the Company’s leases were as follows at March 31, 2018:


*(dollars in thousands)*
Year ending December 31:
2018 remaining	$	1,338
2019		1,625
2020		1,396
2021		1,312
2022		1,089
Thereafter		4,117

	$	10,877

Future minimum rent payments on the Company’s leases were as follows as of December 31, 2017:


*(dollars in thousands)*
Year ending December 31:
2018	$	1,857
2019		1,625
2020		1,396
2021		1,312
2022		1,029
Thereafter		4,102

	$	11,321

Schedule of Financial Commitments whose Contractual Amount Represents Credit Risk

At March 31, 2018 and December 31, 2017, the Company had the following financial commitments whose contractual amount represents credit risk:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Commitments to make loans	$	103,354	$	101,960
Unused lines of credit		119,964		99,217
Commercial and similar letters of credit		4,700		3,013
Standby letters of credit		1,575		1,575

	$	229,593	$	205,765

As of December 31, 2017 and 2016, the Company had the following financial commitments whose contractual amount represents credit risk:


	2017				2016
*(dollars in thousands)*	Fixed Rate		Variable Rate		Fixed Rate		Variable Rate
Commitments to make loans	$	19,438	$	82,522	$	54,812	$	13,191
Unused lines of credit		58,291		40,926		38,943		53,435
Commercial and similar letters of credit		3,013		—		8,966		—
Standby letters of credit		1,225		350		1,100		150

	$81,967		$123,798		$103,821		$66,776

Deposits (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Banking and Thrift [Abstract]

Schedule of Maturities of Time Deposits

At March 31, 2018, the scheduled maturities of time deposits are as follows:


*(dollars in thousands)*
One year	$	651,067
Two to three years		6,498

	$657,565

NOT

At December 31, 2017 the scheduled maturities of time deposits are as follows:


*(dollars in thousands)*
One year	$	627,665
Two to three years		12,263

	$	639,928

Long-term Debt (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Debt Disclosure [Abstract]

Schedule of Aggregate Outstanding Principal Amount and Unamortized Debt Issuance Cost Related to Subordinated Debentures

At March 31, 2018 and December 31, 2017 the aggregate outstanding principal amount and unamortized debt issuance costs related to these subordinated debentures were as follows:


*(dollars in thousands)*	March 31, 2018		December 31, 2017
Principal	$	50,000	$	50,000

Unamortized debt issuance costs	$	436	$	472

At December 31, 2017 and 2016, respectively, long-term debt—6.5% fixed-to-floating subordinated debentures, due March 31, 2026—were as follows:


*(dollars in thousands)*	2017		2016
Principal	$	50,000	$	50,000

Unamortized debt issuance costs	$	472	$	617

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2017

Income Tax Disclosure [Abstract]

Components of Income Tax Expense

Income tax expense consists of the following:


*(dollars in thousands)*	2017		2016		2015
Current:
Federal	$	12,097	$	9,345	$	5,662
State		3,773		2,841		1,973

		15,870		12,186		7,635
Deferred		2,492		1,289		1,361
Deferred tax adjustment for enacted change in tax rate		2,591		—		—
Affordable housing tax credits		316		14		—

	$	21,269	$	13,489	$	8,996

Comparison of Federal Statutory Income Tax Rates to Effective Income Tax Rates

A comparison of the federal statutory income tax rates to the Company’s effective income tax rates as of December 31 follows:


	2017						2016						2015
*(dollars in thousands)*	Amount			Rate			Amount			Rate			Amount			Rate
Statutory federal tax	$	16,379			35.0	%	$	11,399			35.0	%	$	7,469			34.0	%
State franchise tax, net of federal benefit		3,135			6.7	%		2,281			7.0	%		1,550			7.1	%
Tax-exempt income		(297	)		-0.6	%		(202	)		-0.6	%		(203	)		-0.9	%
Tax impact from enacted change in tax rate		2,591			5.5	%		—			0.0	%		—			0.0	%
Other items, net		(539	)		-1.2	%%		11			0.0	%		180			0.8	%

Actual tax expense	$	21,269			45.4	%	$	13,489			41.4	%	$	8,996			41.0	%

Components of Net Deferred Tax Asset

The following is a summary of the components of the net deferred tax asset accounts recognized in the accompanying balance sheets as of December 31:


*(dollars in thousands)*	2017			2016
Deferred tax assets:
Pre-opening expenses	$	173		$	287
Allowance for loan losses		4,072			5,954
Stock-based compensation		1,973			2,576
Off balance sheet reserve		83			254
Operating loss carryforwards		285			693
Other real estate owned		10			17
Acquisition accounting fair value adjustments		—			1,779
Unrealized loss on AFS securities		186			186
Other		1,968			2,520

		8,750			14,266
Deferred tax liabilities:
Depreciation		(511	)		(917	)
Acquisition accounting fair value adjustments		(145	)		—
Other		(2,008	)		(2,252	)

		(2,664	)		(3,169	)

Net deferred tax assets	$	6,086		$	11,097

Related Party Transactions (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Schedule of Related Party Transactions

Loans to principal officers, directors, and their affiliates were as follows:


*(dollars in thousands)*	March 31, 2018			December 31, 2017
Beginning balance	$	2,300		$	3,445
New loans and advances		300			2,200
Repayments		(500	)		(3,345	)

Ending balance	$	2,100		$	2,300

Loans to principal officers, directors, and their affiliates were as follows:


*(dollars in thousands)*	2017			2016
Beginning balance	$	3,445		$	3,971
New loans and advances		2,200			1,274
Repayments		(3,345	)		(1,800	)

Ending balance	$	2,300		$	3,445

Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2017

Disclosure of Compensation Related Costs, Share-based Payments [Abstract]

Schedule of Weighted Average Assumption for Fair Value of Option Grant Estimated Using Black-Scholes Option Pricing Model

There were no stock options granted in 2017.


	2016			2015
Expected volatility		35.0	%		35.0	%
Expected term		6.0 years			6.0 years
Expected dividends		None			None
Risk free rate		1.93	%		1.84	%
Grant date fair value	$	6.76		$	6.29

Summary of Stock Option Plan

A summary of the status of the Company’s stock option plan as of December 31, 2017 and changes during the year then ended is presented below:


*(dollars in thousands, except for share amounts)*	Shares			Weighted- Average Exercise Price		Weighted Average Remaining Contractual Term		Aggregate Intrinsic Value
Outstanding at beginning of year		2,495,134		$	11.26
Granted		—		$	—
Exercised		(223,334	)	$	10.28
Forfeited or expired		(10,000	)	$	18.25

Outstanding at end of year		2,261,800		$	11.32		3.8 years	$	36,297

Options exercisable		2,097,804		$	10.80		3.4 years	$	34,755

Regulatory Matters (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Regulated Operations [Abstract]

Summary of Company and Bank Continue to Exceed Regulatory Capital Minimum Requirements and Bank Continues to Exceed Well Capitalized Standards


						Amount of Capital Required
	Actual					Minimum Required for Capital Adequacy Purposes					To Be Well- Capitalized Under Prompt Corrective Provisions
*(dollars in thousands)*	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of March 31, 2018:
Tier 1 Leverage Ratio
Consolidated	$	249,304		15.24	%	$	65,439		4.00	%	$	81,798		5.00	%
Bank	$	242,192		14.84	%	$	65,283		4.00	%	$	81,604		5.00	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	245,857		17.95	%	$	61,620		4.50	%	$	89,007		6.50	%
Bank	$	242,192		17.72	%	$	61,502		4.50	%	$	88,837		6.50	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	249,304		18.21	%	$	82,161		6.00	%	$	109,547		8.00	%
Bank	$	242,192		17.72	%	$	82,003		6.00	%	$	109,338		8.00	%
Total Risk-Based Capital Ratio
Consolidated	$	313,402		22.89	%	$	109,547		8.00	%	$	136,934		10.00	%
Bank	$	256,725		18.78	%	$	109,338		8.00	%	$	136,672		10.00	%
As of December 31, 2017:
Tier 1 Leverage Ratio
Consolidated	$	238,219		14.35	%	$	66,423		4.00	%	$	83,029		5.00	%
Bank	$	232,765		14.50	%	$	64,214		4.00	%	$	80,267		5.00	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	234,794		17.54	%	$	60,233		4.50	%	$	87,003		6.50	%
Bank	$	232,765		17.42	%	$	60,122		4.50	%	$	86,843		6.50	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	238,219		17.80	%	$	80,311		6.00	%	$	107,081		8.00	%
Bank	$	232,765		17.42	%	$	80,163		6.00	%	$	106,884		8.00	%
Total Risk-Based Capital Ratio
Consolidated	$	301,802		22.55	%	$	107,081		8.00	%	$	133,851		10.00	%
Bank	$	246,820		18.47	%	$	106,884		8.00	%	$	133,605		10.00	%

The following table sets forth RBB Bancorp’s consolidated and the Bank’s actual capital amounts and ratios and related regulatory requirements for the Bank as of December 31, 2017:


						Amount of Capital Required
	Actual					For Capital Adequacy Purposes					To Be Well- Capitalized Under Prompt Corrective Provisions
*(dollars in thousands)*	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of December 31, 2017:
Tier 1 Leverage Ratio
Consolidated	$	238,219		14.35	%		NA		NA			NA		NA
Bank	$	232,765		14.50	%	$	64,214		4.0	%	$	80,267		5.0	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	234,794		17.54	%		NA		NA			NA		NA
Bank	$	232,765		17.42	%	$	60,122		4.5	%	$	86,843		6.5	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	238,219		17.80	%		NA		NA			NA		NA
Bank	$	232,765		17.42	%	$	80,163		6.0	%	$	106,884		8.0	%
Total Risk-Based Capital Ratio
Consolidated	$	301,802		22.55	%		NA		NA			NA		NA
Bank	$	246,820		18.47	%	$	106,884		8.0	%	$	133,605		10.0	%

The following table sets forth RBB Bancorp’s consolidated and the Bank’s actual capital amounts and ratios and related regulatory requirements for the Bank as of December 31, 2016:


						Amount of Capital Required
	Actual					For Capital Adequacy Purposes					To Be Well- Capitalized Under Prompt Corrective Provisions
*(dollars in thousands)*	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of December 31, 2016:
Tier 1 Leverage Ratio
Consolidated	$	153,682		10.99	%		NA		NA			NA		NA
Bank	$	178,645		12.81	%	$	55,777		4.0	%	$	69,722		5.0	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	150,786		13.30	%		NA		NA			NA		NA
Bank	$	178,645		15.81	%	$	50,860		4.5	%	$	73,464		6.5	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	153,682		13.55	%		NA		NA			NA		NA
Bank	$	178,645		15.81	%	$	67,813		6.0	%	$	90,417		8.0	%
Total Risk-Based Capital Ratio
Consolidated	$	217,244		19.16	%		NA		NA			NA		NA
Bank	$	192,784		17.06	%	$	90,417		8.0	%	$	113,021		10.0	%

Fair Value Measurements (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of Hierarchy and Fair Value for Each Major Category of Assets and Liabilities Measured at Fair Value

The following table provides the hierarchy and fair value for each major category of assets and liabilities measured at fair value at March 31, 2018 and December 31, 2017:


	Fair Value Measurements Using:
*(dollars in thousands)*	Level 1		Level 2		Level 3		Total
March 31, 2018
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	7,482			$	7,482
Mortgage-backed securities
Government sponsored agencies				37,672				37,672
Corporate debt securities				37,694				37,694

	$	—	$	82,848	$	—	$	82,848

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	293	$	293

December 31, 2017
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	7,816				7,816
Mortgage-backed securities
Government sponsored agencies				39,215				39,215
Corporate debt securities				17,926				17,926

	$	—	$	64,957	$	—	$	64,957

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	293	$	293

The following table provides the hierarchy and fair value for each major category of assets and liabilities measured at fair value at December 31, 2017 and 2016:


*(dollars in thousands)*	Fair Value Measurements Using:
December 31, 2017	Level 1		Level 2		Level 3		Total
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	7,816			$	7,816
Mortgage-backed securities								—
Government sponsored agencies				39,215				39,215
Corporate debt securities				17,926				17,926

	$	—	$	64,957	$	—	$	64,957

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	293	$	293


December 31, 2016
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	5,317				5,317
Mortgage-backed securities
Government sponsored agencies				23,640				23,640
Corporate debt securities				10,320				10,320

	$	—	$	39,277	$	—	$	39,277

On a non-recurring basis:
Other real estate owned	$	—	$	—	$	833	$	833

Summary of Quantitative Information About Non-recurring Level 3 Fair Value Measurements

Quantitative information about the Company’s non-recurring Level 3 fair value measurements at March 31, 2018 and December 31, 2017 is as follows:


*(dollars in thousands)*	Fair Value Amount		Valuation Technique		Unobservable Input	Adjustment Range			Weighted- Average Adjustment
March 31, 2018
Other real estate owned	$	293		Third Party Appraisals	Management Adjustments to Reflect Current Conditions and Selling Costs		21	%		21	%
December 31, 2017
Other real estate owned	$	293		Third Party Appraisals	Management Adjustments to Reflect Current Conditions and Selling Costs		21	%		21	%

Quantitative information about the Company’s non-recurring Level 3 fair value measurements as of December 31, 2017 and 2016 is as follows:

(dollars in thousands)

December 31, 2017

Fair Value
Amount

Valuation

Technique

Unobservable Input

Adjustment
Range

Weighted-
Average
Adjustment

Other real estate owned

293

Third party

appraisals

Management adjustments to reflect current conditions and selling costs

21%

December 31, 2016

Other real estate owned

833

Third party

appraisals

Management adjustments to reflect current conditions and selling costs

10% - 15%

12%

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Fair Value of Financial Instruments (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Fair Value Disclosures [Abstract]

Schedule of Fair Value Hierarchy Level and Estimated Fair Value of Significant Financial Instruments

The fair value hierarchy level and estimated fair value of significant financial instruments at March 31, 2018 and December 31, 2017 are summarized as follows:


			March 31,				December 31,
			2018				2017
*(dollars in thousands)*	Fair Value Hierarchy		Carrying Value		Fair Value		Carrying Value		Fair Value
Financial Assets:
Cash and due from banks		Level 1	$	53,535	$	53,535	$	70,048	$	70,048
Federal funds sold and other cash equivalents		Level 1		25,000		25,000		80,000		80,000
Interest-earning deposits in other financial institutions		Level 1		600		600		600		600
Investment securities—AFS		Level 2		82,848		82,848		64,957		64,957
Investment securities—HTM		Level 2		9,998		10,020		10,009		10,250
Mortgage loans held for sale		Level 1		183,391		128,491		125,847		128,972
Loans, net		Level 3		1,247,971		1,288,740		1,235,301		1,236,289
Financial Liabilities:
Deposits		Level 2		1,373,504		1,371,213	$	1,337,281	$	1,336,353
FHLB advances		Level 2		—		—		25,000		25,000
Long-term debt		Level 2		49,564		41,950		49,528		44,319
Subordinated debentures		Level 3		3,447		3,625		3,424		3,348

The fair value hierarchy level and estimated fair value of significant financial instruments at December 31, 2017 and 2016 are summarized as follows:


			2017				2016
*(dollars in thousands)*	Fair Value Hierarchy		Carrying Value		Fair Value		Carrying Value		Fair Value
Financial Assets:
Cash and due from banks		Level 1	$	70,048	$	70,048	$	74,213	$	74,213
Federal funds sold and other cash equivalents		Level 1		80,000		80,000		44,500		44,500
Interest-earning deposits in other financial institutions		Level 1		600		600		345		345
Investment securities—AFS		Level 2		64,957		64,957		39,277		39,277
Investment securities—HTM		Level 2		10,009		10,250		6,214		6,553
Mortgage loans held for sale		Level 2		125,847		128,972		44,345		45,433
Loans, net		Level 3		1,235,301		1,236,289		1,096,284		1,095,944
Financial Liabilities:
Deposits		Level 2	$	1,337,281	$	1,336,353	$	1,152,763	$	1,140,707
FHLB advances		Level 2		25,000		25,000		—		—
Long-term debt		Level 2		49,528		44,319		49,383		48,447
Subordinated debentures		Level 3		3,424		3,348		3,334		3,334

Earnings Per Share (EPS) (Tables)

3 Months Ended

12 Months Ended

Mar. 31, 2018

Dec. 31, 2017

Earnings Per Share [Abstract]

Reconciliation of Net Income and Shares Outstanding to Income and Number of Shares Used to Compute EPS

The following is a reconciliation of net income and shares outstanding to the income and number of shares used to compute EPS:


	Three Months Ended
	March 31
	2018					2017
*(dollars in thousands except per share amounts)*	Income		Shares			Income		Shares
Net income as reported	$	8,847				$	5,493
Shares outstanding				16,288,928					12,827,803
Impact of weighting shares				(206,033	)				—

Used in basic EPS		8,847		16,082,895			5,493		12,827,803
Dilutive effect of outstanding
Stock options				1,079,425					897,918

Used in dilutive EPS	$	8,847		17,162,320		$	5,493		13,725,721

Basic earnings per common share	$	0.55				$	0.43
Diluted earnings per common share	$	0.52				$	0.40

The following is a reconciliation of net income and shares outstanding to the income and number of shares used to compute EPS:


	2017					2016					2015
*(dollars in thousands except per share amounts)*	Income		Shares			Income		Shares			Income		Shares
Net income as reported	$	25,528				$	19,079				$	12,973
Shares outstanding				15,908,893					12,827,803					12,770,571
Impact of weighting shares				(1,830,612	)				(26,813	)				(8,739	)

Used in basic EPS		25,528		14,078,281			19,079		12,800,990			12,973		12,761,832
Dilutive effect of outstanding
Stock options				1,160,084					894,910					790,850

Used in dilutive EPS	$	25,528		15,238,365		$	19,079		13,695,900		$	12,973		13,552,682

Basic earnings per common share	$	1.81				$	1.49				$	1.02
Diluted earnings per common share	$	1.68				$	1.39				$	0.96

Parent Only Condensed Financial Information (Tables)

12 Months Ended

Dec. 31, 2017

Condensed Financial Information of Parent Company Only Disclosure [Abstract]

Schedule of Parent Only Condensed Balance Sheets


*(Dollars in Thousands)*	2017			2016
ASSETS
Cash and cash equivalents	$	45,769		$	17,497
Investment in Bank		263,022			209,727
Investment in RAM		6,268			6,125
Other assets		3,538			1,455

Total assets	$	318,597		$	234,804

LIABILITIES AND SHAREHOLDERS’ EQUITY
Long term debt		49,528			49,383
Subordinated debentures		3,424			3,334
Other liabilities		36			8

Total liabilities		52,989			52,725
Shareholders’ equity:
Common stock		205,927			142,651
Additional paid-in capital		8,426			8,417
Retained earnings		51,697			31,278
Accumulated other comprehensive income (loss)		(443	)		(267	)

Total shareholders’ equity		265,608			182,079

Total liabilities and shareholders’ equity	$	318,597		$	234,804

Schedule of Parent Only Condensed Statements of Income

*(Dollars in Thousands)*	2017			2016			2015
Interest expense	$	3,629		$	2,728		$	—
Noninterest expense		704			123			298
Loss before equity in undistributed income of subsidiaries		(4,334	)		(2,851	)		(298	)
Equity in undistributed income of:
Bank		27,620			20,483			12,310
RAM		143			274			804

Income before income taxes		23,430			17,906			12,816
Income tax benefit		2,036			1,173			125

Net income		25,466			19,079			12,941

Other comprehensive income (loss)		(104	)		(74	)		(141	)

Total comprehensive income	$	25,362		$	19,005		$	12,800

Schedule of Parent Only Condensed Statements of Cash Flows

(Dollars in Thousands)

Cash flows from operating activities:
Net income	$	25,466		$	19,079		$	12,941
Net amortization of other		235			188			—
Provision for deferred income taxes		1,807			(1,172	)		(125	)
Undistributed income of subsidiaries		(27,763	)		(20,757	)		(13,114	)
Change in other assets and liabilities		(3,861	)		(159	)		135

		(4,116	)		(2,821	)		(163	)
Cash flows from investment activities:
Outlays for business acquisitions		—			(839	)		—
Investment in subsidiaries		(25,000	)		(35,000	)		5,000

		(25,000	)		(35,839	)		5,000
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs		—			49,274			—
Issuance of common stock, net of issuance costs		60,210			—			—
Dividends paid		(5,118	)		(2,554	)		(3,114	)
Stock options exercised		2,296			585			470

		57,388			47,305			(2,644	)
Increase in cash and cash equivalents		28,272			8,645			2,193
Cash and cash equivalents beginning of year		17,497			8,852			6,659

Cash and cash equivalents end of year	$	45,769		$	17,497		$	8,852

Business Description - Additional Information (Detail) $ / shares in Units, $ in Thousands		55 Months Ended
	Jul. 31, 2017 $ / shares shares	Feb. 19, 2016 Acquisition	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Jan. 01, 2015 USD ($)
Description Of Business [Line Items]
Total assets			$ 1,715,104	$ 1,691,059		$ 1,395,551
Gross loans			1,261,928	1,249,074		1,110,446
Total deposits			1,373,504	1,337,281		1,152,763
Total stockholders' Equity			$ 275,822	$ 265,176	$ 183,496	$ 181,585	$ 163,645	$ 151,981
Number of acquisitions \| Acquisition		4
Initial Public Offering
Description Of Business [Line Items]
Issuance of common stock, net of issuance costs, shares \| shares	3,750,000
Share price per share \| $ / shares	$ 23.00

Basis of Presentation and Summary of Significant Accounting Policies - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cash and due from banks, reserves required to be held			$ 19,664,000	$ 9,811,000
Securities evaluation for other-than-temporary impairment, measurement basis			semi-annual
Threshold period past due principal or interest, to discontinue accrual of interest on loans			90 days
Gain on sale of loans	$ 1,815,000	$ 1,497,000	$ 9,318,000	5,847,000	$ 4,316,000
Gains on sale of mortgage loans, total			3,700,000	3,400,000	1,600,000
Gains on sale of SBA loans, total			5,600,000	2,400,000	2,700,000
Goodwill	29,940,000		29,940,000	29,940,000
Impairment losses recognized on goodwill	0	0	0	0
Amortization of intangibles	81,000	94,000	355,000	372,000	117,000
Accounting Standards Update 2018-02
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Reclassified stranded tax effects within AOCI to retained earnings			72,000
401(k) Plan
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Contributions to plan			272,000	221,000	125,000
Core Deposit Intangible
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Unamortized balance of intangible assets	1,357,000		1,438,000	1,793,000
Amortization of intangibles	$ 81,000	$ 94,000	$ 355,000	372,000	117,000
Premises
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets			30 years
Mortgage and SBA
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Gain on sale of loans			$ 9,300,000	$ 5,800,000	$ 4,300,000
Maximum
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Cash and cash equivalents maturity period			90 days
Maximum \| Core Deposit Intangible
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, estimated useful life	10 years		10 years
Maximum \| Leasehold Improvements
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets			10 years
Maximum \| Equipment
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets			10 years
Minimum \| Core Deposit Intangible
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Intangible assets, estimated useful life	8 years		8 years
Minimum \| Leasehold Improvements
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets			3 years
Minimum \| Equipment
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated useful life of assets			3 years

Goodwill and Intangibles - Schedule of Future Estimated Amortization Expense (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Goodwill And Intangible Assets Disclosure [Abstract]
2018		$ 311
2018 remaining	$ 230
2019	274	274
2020	244	244
2021	172	172
2022	129	129
Thereafter	308	308
Total	$ 1,357	$ 1,438

Acquisitions - Additional Information (Detail)	Feb. 19, 2016 USD ($) Branch	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 29,940,000	$ 29,940,000	$ 29,940,000
TFC Holding Company
Business Acquisition [Line Items]
Cash consideration	$ 86,700,000
Number of branches operated \| Branch	6
Goodwill	$ 25,900,000
Loans acquired for deterioration of credit quality	$ 0

Acquisitions - Schedule of Assets Acquired and Liabilities Assumed and Fair Value Adjustments (Detail) - USD ($) $ in Thousands	Feb. 19, 2016	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill recognized		$ 29,940	$ 29,940	$ 29,940
TFC Holding Company
Business Acquisition [Line Items]
Cash paid	$ 86,700
Goodwill recognized	25,900
TFC Holding Company \| Book Value
Business Acquisition [Line Items]
Cash and cash equivalents	51,613
Interest-bearing deposits in other financial Institutions	2,320
Net investments - available for sale	15,952
Loans, gross	400,887
Allowance for loan losses	(9,857)
Bank premises and equipment	225
Deferred income taxes	4,027
Other assets	5,595
Total assets acquired	470,762
Deposits	404,465
Subordinated debentures	5,155
Other liabilities	566
Total liabilities assumed	410,186
Excess of assets acquired over liabilities assumed	60,576
Business combination, Recognized identifiable assets acquired and liabilities assumed, net	470,762
TFC Holding Company \| Fair Value Adjustments
Business Acquisition [Line Items]
Net investments - available for sale	(106)
Loans, gross	(13,211)
Allowance for loan losses	9,857
Deferred income taxes	858
Other assets	1,699
Total assets acquired	(903)
Deposits	848
Subordinated debentures	(1,900)
Total liabilities assumed	(1,052)
Excess of assets acquired over liabilities assumed	149
Business combination, Recognized identifiable assets acquired and liabilities assumed, net	(903)
TFC Holding Company \| Fair Value
Business Acquisition [Line Items]
Cash and cash equivalents	51,613
Interest-bearing deposits in other financial Institutions	2,320
Net investments - available for sale	15,846
Loans, gross	387,676
Bank premises and equipment	225
Deferred income taxes	4,885
Other assets	7,294
Total assets acquired	469,859
Deposits	405,313
Subordinated debentures	3,255
Other liabilities	566
Total liabilities assumed	409,134
Excess of assets acquired over liabilities assumed	60,725
Cash paid	86,664
Goodwill recognized	$ 25,939

Acquisitions - Schedule of Loans Acquired Contractual Amounts Due Expected Cash Flow Interest Component and Fair Value (Detail) $ in Thousands	Feb. 19, 2016 USD ($)
Business Combinations [Abstract]
Contractual amounts due	$ 441,275
Expected cash flows	441,275
Interest component of expected cash flows	53,599
Fair value of acquired loans	$ 387,676

Investment Securities - Summary of Amortized Cost and Fair Value of Securities Available for Sale and Held to Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Available for sale, Amortized Cost	$ 84,325	$ 65,587	$ 39,730
Available for sale, Gross Unrealized Gains	145	178	59
Available for sale, Gross Unrealized Losses	(1,622)	(808)	(512)
Available for sale, Fair Value	82,848	64,957	39,277
Held to maturity, Amortized Cost	9,998	10,009	6,214
Held to maturity, Gross Unrealized Gains	169	260	339
Held to maturity, Gross Unrealized Losses	(147)	(19)
Securities held to maturity, fair value	10,020	10,250	6,553
Municipal Taxable Securities
Schedule Of Available For Sale Securities [Line Items]
Held to maturity, Amortized Cost	4,294	4,295	5,301
Held to maturity, Gross Unrealized Gains	165	228	328
Securities held to maturity, fair value	4,459	4,523	5,629
Municipal Securities
Schedule Of Available For Sale Securities [Line Items]
Held to maturity, Amortized Cost	5,704	5,714	913
Held to maturity, Gross Unrealized Gains	4	32	11
Held to maturity, Gross Unrealized Losses	(147)	(19)
Securities held to maturity, fair value	5,561	5,727	924
Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale, Amortized Cost	7,746	7,968	5,453
Available for sale, Gross Unrealized Losses	(264)	(152)	(136)
Available for sale, Fair Value	7,482	7,816	5,317
Government Sponsored Agencies
Schedule Of Available For Sale Securities [Line Items]
Available for sale, Amortized Cost	38,843	39,806	23,913
Available for sale, Gross Unrealized Gains		17	38
Available for sale, Gross Unrealized Losses	(1,171)	(608)	(311)
Available for sale, Fair Value	37,672	39,215	23,640
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Available for sale, Amortized Cost	37,736	17,813	10,364
Available for sale, Gross Unrealized Gains	145	161	21
Available for sale, Gross Unrealized Losses	(187)	(48)	(65)
Available for sale, Fair Value	$ 37,694	$ 17,926	$ 10,320

Investment Securities - Additional Information (Detail)	12 Months Ended
Investment Securities - Additional Information (Detail)	Dec. 31, 2017 USD ($) Security	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Mar. 31, 2018 USD ($) Security
Investments Debt And Equity Securities [Abstract]
Securities available for sale, sold	$ 0	$ 5,083,000	$ 5,514,000
Securities available for sale, recognizing gross gains		19,000	$ 78,000
Number of investment securities pledged as collateral \| Security	1			1
Fair value of securities pledged to secure local agency deposit	$ 796,000	$ 933,000		$ 759,000

Investment Securities - Amortized Cost and Fair Value of Investment Securities Portfolio Expected Maturity (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Due from one to five years, Available for sale, Amortized Cost	$ 52,326	$ 35,221
Due from five to ten years, Available for sale, Amortized Cost	27,958	26,321
Due from ten years and greater, Available for sale, Amortized Cost	4,041	4,045
Available for sale, Amortized Cost	84,325	65,587	$ 39,730
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Due from one to five years, Available for sale, Fair Value	51,530	34,825
Due from five to ten years, Available for sale, Fair Value	27,333	26,102
Due from ten years and greater, Available for sale, Fair Value	3,985	4,030
Available for sale, Fair value	82,848	64,957	39,277
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Due from one to five years, Held to Maturity, Amortized Cost	2,780	2,780
Due from five to ten years, Held to Maturity, Amortized Cost	2,397	2,404
Due from ten years and greater, Held to Maturity, Amortized Cost	4,821	4,825
Held to maturity, Amortized Cost	9,998	10,009	6,214
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Due from one to five years, Held to Maturity, Fair Value	2,865	2,897
Due from five to ten years, Held to Maturity, Fair Value	2,481	2,521
Due from ten years and greater, Held to Maturity, Fair Value	4,674	4,832
Securities held to maturity, fair value	$ 10,020	$ 10,250	$ 6,553

Investment Securities - Summary of Available for Sale Securities With Unrealized Losses (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses	$ (1,017)	$ (406)	$ (422)
Less than Twelve Months Estimated Fair Value	39,017	32,683	26,695
Twelve Months or More Unrealized Losses	(605)	(402)	(90)
Twelve Months or More Estimated Fair Value	17,398	17,636	2,504
Total Unrealized Losses	(1,622)	(808)	(512)
Total Estimated Fair Value	56,415	50,319	29,199
Held to maturity, Less than Twelve Months Unrealized Losses	(147)	(19)
Held to maturity, Less than Twelve Months Estimated Fair Value	4,674	2,232
Held to maturity, Total Unrealized Losses	(147)	(19)
Held to maturity, Total Estimated Fair Value	4,674	2,232
Municipal Securities
Schedule Of Available For Sale Securities [Line Items]
Held to maturity, Less than Twelve Months Unrealized Losses	(147)	(19)
Held to maturity, Less than Twelve Months Estimated Fair Value	4,674	2,232
Held to maturity, Total Unrealized Losses	(147)	(19)
Held to maturity, Total Estimated Fair Value	4,674	2,232
Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses	(112)	(32)	(136)
Less than Twelve Months Estimated Fair Value	3,873	4,039	5,317
Twelve Months or More Unrealized Losses	(152)	(120)
Twelve Months or More Estimated Fair Value	3,609	3,777
Total Unrealized Losses	(264)	(152)	(136)
Total Estimated Fair Value	7,482	7,816	5,317
Government Sponsored Agencies
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses	(786)	(359)	(221)
Less than Twelve Months Estimated Fair Value	25,484	23,609	16,231
Twelve Months or More Unrealized Losses	(385)	(249)	(90)
Twelve Months or More Estimated Fair Value	11,852	11,887	2,504
Total Unrealized Losses	(1,171)	(608)	(311)
Total Estimated Fair Value	37,336	35,496	18,735
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses	(119)	(15)	(65)
Less than Twelve Months Estimated Fair Value	9,660	5,035	5,147
Twelve Months or More Unrealized Losses	(68)	(33)
Twelve Months or More Estimated Fair Value	1,937	1,972
Total Unrealized Losses	(187)	(48)	(65)
Total Estimated Fair Value	$ 11,597	$ 7,007	$ 5,147

Loans and Allowance for Loan Losses - Summary of Balance and Activity Related to Allowance for Loan Losses for Held for Investment Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, Beginning balance	$ 13,773	$ 14,162	$ 14,162	$ 10,023	$ 8,848
Additions (reductions) to the allowance charged to expense	184		(1,053)	4,974	1,386
Recoveries on loans charged-off			747		211
Allowance for loan losses before charged off			13,856	14,997	10,445
Less loans charged-off		24	(83)	(835)	(422)
Allowance for loan losses, Ending balance	13,957	14,186	13,773	14,162	10,023
Real Estate
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, Beginning balance	9,309	8,111	8,111	5,788	5,696
Additions (reductions) to the allowance charged to expense	653	(1,169)
Recoveries on loans charged-off					200
Allowance for loan losses, Ending balance	9,962	6,942	9,309	8,111	5,788
Commercial
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, Beginning balance	4,044	6,051	6,051	4,235	3,152
Additions (reductions) to the allowance charged to expense	(118)	1,169
Recoveries on loans charged-off			747		11
Less loans charged-off		24	(83)	(835)	(422)
Allowance for loan losses, Ending balance	3,926	$ 7,244	4,044	$ 6,051	$ 4,235
Unallocated
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for loan losses, Beginning balance	420
Additions (reductions) to the allowance charged to expense	(351)
Allowance for loan losses, Ending balance	$ 69		$ 420

Loans and Allowance for Loan Losses - Summary of Recorded Investment in Loans Impairment Method and Activity in Allowance for Loan Losses by Portfolio Segment (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reserves:
Loan losses, Reserves	$ 13,957	$ 14,186	$ 13,773	$ 14,162	$ 10,023
Loans evaluated for impairment:
Loans, Individually evaluated for impairment	4,465	6,109	2,575	6,133	6,112
Loans, Collectively evaluated for impairment	1,257,150	1,132,717	1,246,184	1,103,583	784,573
Total loans, gross	1,261,928	1,139,563	1,249,074	1,110,446	792,362
Allowance for loan losses:
Allowance for loan losses, Beginning balance	13,773	14,162	14,162	10,023	8,848
Allowance for loan losses, Provisions	184		(1,053)	4,974	1,386
Allowance for loan losses, Charge-offs		24	(83)	(835)	(422)
Allowance for loan losses, Recoveries			747		211
Allowance for loan losses, Ending balance	13,957	14,186	13,773	14,162	10,023
Loans Acquired with Deteriorated Credit Quality
Loans evaluated for impairment:
Loans acquired	313	737	315	730	1,677
Specific Reserves
Reserves:
Loan losses, Reserves		3,559		1,782
General Reserves
Reserves:
Loan losses, Reserves	13,957	10,627	13,773	12,380	10,023
Real Estate
Reserves:
Loan losses, Reserves	9,962	6,942	9,309	8,111	5,788
Loans evaluated for impairment:
Loans, Individually evaluated for impairment	2,393	2,550	2,420	2,556	1,482
Loans, Collectively evaluated for impairment	866,176	771,870	834,152	744,349	519,963
Total loans, gross	868,882	775,157	836,887	747,635	523,122
Allowance for loan losses:
Allowance for loan losses, Beginning balance	9,309	8,111	8,111	5,788	5,696
Allowance for loan losses, Provisions			1,198	2,323	(108)
Allowance for loan losses, Recoveries					200
Allowance for loan losses, Ending balance	9,962	6,942	9,309	8,111	5,788
Real Estate \| Loans Acquired with Deteriorated Credit Quality
Loans evaluated for impairment:
Loans acquired	313	737	315	730	1,677
Real Estate \| General Reserves
Reserves:
Loan losses, Reserves	9,962	6,942	9,309	8,111	5,788
Commercial
Reserves:
Loan losses, Reserves	3,926	7,244	4,044	6,051	4,235
Loans evaluated for impairment:
Loans, Individually evaluated for impairment	2,072	3,559	155	3,577	4,630
Loans, Collectively evaluated for impairment	390,974	360,847	412,032	359,234	264,610
Total loans, gross	393,046	364,406	412,187	362,811	269,240
Allowance for loan losses:
Allowance for loan losses, Beginning balance	4,044	6,051	6,051	4,235	3,152
Allowance for loan losses, Provisions			(2,671)	2,651	1,494
Allowance for loan losses, Charge-offs		24	(83)	(835)	(422)
Allowance for loan losses, Recoveries			747		11
Allowance for loan losses, Ending balance	3,926	7,244	4,044	6,051	4,235
Commercial \| Specific Reserves
Reserves:
Loan losses, Reserves		3,559		1,782
Commercial \| General Reserves
Reserves:
Loan losses, Reserves	3,926	$ 3,685	4,044	$ 4,269	$ 4,235
Unallocated
Reserves:
Loan losses, Reserves	69		420
Allowance for loan losses:
Allowance for loan losses, Beginning balance	420
Allowance for loan losses, Provisions			420
Allowance for loan losses, Ending balance	69		420
Unallocated \| General Reserves
Reserves:
Loan losses, Reserves	$ 69		$ 420

Loans and Allowance for Loan Losses - Summary of Risk Category of Loans by Class of Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 1,261,928	$ 1,249,074	$ 1,110,446
Real Estate \| Construction and Land Development
Accounts Notes And Loans Receivable [Line Items]
Total loans	101,240	91,908	89,409
Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	500,051	496,039	501,798
Real Estate \| Single-family Residential Mortgages
Accounts Notes And Loans Receivable [Line Items]
Total loans	267,591	248,940	156,428
Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	278,393	280,766	203,843
Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	114,653	131,421	158,968
Pass
Accounts Notes And Loans Receivable [Line Items]
Total loans	1,232,993	1,214,258	1,044,172
Pass \| Real Estate \| Construction and Land Development
Accounts Notes And Loans Receivable [Line Items]
Total loans	100,954	91,619	87,174
Pass \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	478,059	469,422	475,499
Pass \| Real Estate \| Single-family Residential Mortgages
Accounts Notes And Loans Receivable [Line Items]
Total loans	267,591	248,940	136,206
Pass \| Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	277,678	277,518	194,227
Pass \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	108,711	126,759	151,066
Special Mention
Accounts Notes And Loans Receivable [Line Items]
Total loans	4,659	23,208	22,378
Special Mention \| Real Estate \| Construction and Land Development
Accounts Notes And Loans Receivable [Line Items]
Total loans			1,932
Special Mention \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	4,464	19,070	4,562
Special Mention \| Real Estate \| Single-family Residential Mortgages
Accounts Notes And Loans Receivable [Line Items]
Total loans			13,950
Special Mention \| Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	195	2,360
Special Mention \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans		1,778	1,934
Substandard
Accounts Notes And Loans Receivable [Line Items]
Total loans	19,811	9,033	37,763
Substandard \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	15,421	5,416	19,484
Substandard \| Real Estate \| Single-family Residential Mortgages
Accounts Notes And Loans Receivable [Line Items]
Total loans			6,272
Substandard \| Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	520	888	9,616
Substandard \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	3,870	2,729	2,391
Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans	4,465	2,575	6,133
Impaired \| Real Estate \| Construction and Land Development
Accounts Notes And Loans Receivable [Line Items]
Total loans	286	289	303
Impaired \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	2,107	2,131	2,253
Impaired \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 2,072	$ 155	$ 3,577

Loans and Allowance for Loan Losses - Summary of Aging Recorded Investment Past-due Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 3,527	$ 3,023	$ 3,920
Loans Not Past Due	1,258,401	1,246,051	1,106,526
Total Loans	1,261,928	1,249,074	1,110,446
Non-Accrual Loans	2,001	155	3,577
30-59 Days
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,941	1,175	343
60-89 Days
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,764
90 Days Or More
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	586	84	3,577
Real Estate \| Construction and Land Development
Financing Receivable Recorded Investment Past Due [Line Items]
Loans Not Past Due	101,240	91,908	89,409
Total Loans	101,240	91,908	89,409
Real Estate \| Commercial Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Loans Not Past Due	500,051	496,039	501,798
Total Loans	500,051	496,039	501,798
Real Estate \| Single-family Residential Mortgages
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	790	1,513
Loans Not Past Due	266,801	247,427	156,428
Total Loans	267,591	248,940	156,428
Real Estate \| Single Family Residential Mortgages Loans Held For Sale
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	696	697
Loans Not Past Due	182,695	125,150	44,345
Total Loans	183,391	125,847	44,345
Real Estate \| 30-59 Days \| Single-family Residential Mortgages
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	790	1,175
Real Estate \| 30-59 Days \| Single Family Residential Mortgages Loans Held For Sale
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	696	697
Real Estate \| 60-89 Days \| Single-family Residential Mortgages
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		338
Commercial \| Other
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	689		343
Loans Not Past Due	277,704	280,766	203,500
Total Loans	278,393	280,766	203,843
Commercial \| SBA
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,048	1,510	3,577
Loans Not Past Due	112,605	129,911	155,391
Total Loans	114,653	131,421	158,968
Non-Accrual Loans	2,001	155	3,577
Commercial \| 30-59 Days \| Other
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	689		343
Commercial \| 30-59 Days \| SBA
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,462
Commercial \| 60-89 Days \| SBA
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		1,426
Commercial \| 90 Days Or More \| SBA
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 586	$ 84	$ 3,577

Loans and Allowance for Loan Losses - Summary of Aging Recorded Investment Past-due Loans (Parenthetical) (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
90 Days Or More
Financing Receivable Recorded Investment Past Due [Line Items]
Loan over 90 days past due and still accruing	$ 0	$ 71,000

Loans and Allowance for Loan Losses - Summary of Individually Impaired Loans Presented by Class of Loans (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded	$ 4,465	$ 2,575	$ 2,574	$ 6,112
Recorded Investment, With no related allowance recorded	4,465	2,575	2,574	6,112
Average Balance, With no related allowance recorded	3,521	2,566	2,112	6,010
Interest Income, With no related allowance recorded	91	328	301	213
Unpaid Principal Balance, With an allowance recorded			6,133
Recorded Investment, With an allowance recorded			6,133
Average Balance, With an allowance recorded			5,671
Interest Income, With an allowance recorded			301
Related Allowance, With an allowance recorded			1,782
Construction and Land Development
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded	286	289	303	315
Recorded Investment, With no related allowance recorded	286	289	303	315
Average Balance, With no related allowance recorded	288	296	309	320
Interest Income, With no related allowance recorded	6	16	21	4
Commercial Real Estate
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded	2,108	2,131	2,253	1,167
Recorded Investment, With no related allowance recorded	2,108	2,131	2,253	1,167
Average Balance, With no related allowance recorded	2,119	2,192	1,710	1,145
Interest Income, With no related allowance recorded	51	297	280	195
Commercial \| SBA
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded	2,071	155	18	4,630
Recorded Investment, With no related allowance recorded	2,071	155	18	4,630
Average Balance, With no related allowance recorded	1,114	78	93	4,545
Interest Income, With no related allowance recorded	$ 34	$ 15		$ 14
Unpaid Principal Balance, With an allowance recorded			3,559
Recorded Investment, With an allowance recorded			3,559
Average Balance, With an allowance recorded			3,559
Related Allowance, With an allowance recorded			$ 1,782

Loans and Allowance for Loan Losses - Additional Information (Detail)	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($) Loan	Dec. 31, 2017 USD ($) Loan	Dec. 31, 2016 USD ($) Loan	Dec. 31, 2015 USD ($)	Mar. 31, 2017 USD ($)
Financing Receivable Recorded Investment [Line Items]
Interest income recognized on cash basis	$ 0	$ 0	$ 0	$ 0
Number of loans identified as troubled debt restructurings \| Loan	5	4	6
Specific reserve	$ 13,957,000	$ 13,773,000	$ 14,162,000	$ 10,023,000	$ 14,186,000
Commitments to lend an additional amounts of outstanding loans are classified as TDR's	$ 0	$ 0	$ 0
Description of loans modified as troubled debt restructuring	As of March 31, 2018, the terms of one loan was modified as TDR. The modification of the terms generally included loans wherea moratorium on loan payments was granted. Such moratoriums ranged from three months to twelve months on the loans restructured in 2017 and 2016.	During the year ended December 31, 2016, the terms of certain loans were modified as TDR's. The modification of the terms generally included loans wherea moratorium on loan payments was granted. Suchmoratoriums ranged from three months to six monthson the loans restructured in 2016.
Number of loans defaulted \| Loan		0	0
Increase in allowance for loan losses under purchased credit-impaired loans	$ 0	$ 0	$ 0
Significant reductions in allowance for loan losses under purchased credit-impaired loans	$ 0	0	$ 0
Minimum
Financing Receivable Recorded Investment [Line Items]
Moratorium on loan payments period granted	3 months		3 months
Maximum
Financing Receivable Recorded Investment [Line Items]
Moratorium on loan payments period granted	12 months		6 months
One Loan
Financing Receivable Recorded Investment [Line Items]
Specific reserve	$ 0	$ 0	$ 1,782,000

Loans and Allowance for Loan Losses - Summary of Loans Class Modified as TDRs (Detail) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018 USD ($) Loan	Dec. 31, 2017 Loan	Dec. 31, 2016 USD ($) Loan
Financing Receivable Recorded Investment [Line Items]
Number of Loans \| Loan	5	4	6
Commercial
Financing Receivable Recorded Investment [Line Items]
Number of Loans \| Loan	1		1
Pre- Modification Recorded Investment \| $	$ 71		$ 1,047
Post- Modification Recorded Investment \| $	$ 71		$ 1,047

Loans and Allowance for Loan Losses - Summary of Outstanding Balance and Carrying Amount of Purchased Credit-impaired Loans (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Outstanding balance	$ 319	$ 322	$ 878
Carrying amount	$ 313	$ 315	$ 730

Loans and Allowance for Loan Losses - Summary of Activity in Accretable Yield on Purchased Credit-impaired Loans (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	$ 122	$ 142	$ 142	$ 349	$ 574
Disposals					(99)
Restructuring as TDR				(22)
Accretion of income	(1)	(20)	(135)	(185)	(126)
Ending balance	121	$ 122	122	$ 142	$ 349
Scenario, Previously Reported [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Beginning balance	$ 7
Ending balance			$ 7

Loan Servicing- Schedule of Principal Balances of Mortgage and SBA Loans Serviced for Others (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Mortgage Loans
Schedule Of Mortgage And Small Business Administration Loans Serviced [Line Items]
Loans serviced for others	$ 406,559	$ 384,437	$ 259,207
SBA
Schedule Of Mortgage And Small Business Administration Loans Serviced [Line Items]
Loans serviced for others	$ 174,282	$ 175,919	$ 110,263

Loan Servicing - Schedule of Activity for Servicing Assets (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Mortgage Loans
Servicing assets:
Beginning of year	$ 1,540	$ 1,002	$ 1,002	$ 298
Additions	315		1,115	912	$ 329
Disposals	(39)		(172)
Amortized to expense	(155)	(86)	(405)	(208)	(31)
End of period	1,661	916	1,540	1,002	298
SBA
Servicing assets:
Beginning of year	4,417	2,702	2,702	1,807	720
Additions	484	724	2,628	1,353	1,268
Disposals	(425)		(367)
Amortized to expense	(158)	(119)	(546)	(458)	(181)
End of period	$ 4,318	$ 3,307	$ 4,417	$ 2,702	$ 1,807

Loan Servicing - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	$ 5,979,000		$ 5,957,000	$ 3,704,000
Loan servicing fees, net of amortization	(31,000)	$ 262,000	722,000	615,000	$ 272,000
Mortgage Loans
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	2,751,000		$ 2,538,000	$ 1,184,000
Fair value discount rate			12.50%	12.50%
Fair value weighted average default rate			0.25%	0.25%
SBA
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	$ 5,984,000		$ 5,915,000	$ 3,142,000
Fair value discount rate			8.50%	8.50%
Fair value weighted average default rate			0.98%
Minimum \| Mortgage Loans
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value prepayment rate			20.00%	20.74%
Minimum \| SBA
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value prepayment rate			11.40%	7.20%
Maximum \| Mortgage Loans
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value prepayment rate			21.79%	22.90%
Maximum \| SBA
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value prepayment rate			13.78%	12.80%

Premises and Equipment - Summary of Premises and Equipment (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Line Items]
Premises and equipment, gross		$ 11,517	$ 11,238
Less accumulated depreciation and amortization		(5,359)	(4,673)
Construction in progress		425	20
Premises and equipment	$ 6,687	6,583	6,585
Land
Property Plant And Equipment [Line Items]
Premises and equipment, gross		2,956	2,956
Building and Improvements
Property Plant And Equipment [Line Items]
Premises and equipment, gross		2,467	2,467
Leasehold Improvements
Property Plant And Equipment [Line Items]
Premises and equipment, gross		2,872	2,865
Furnitures, Fixtures and Equipment
Property Plant And Equipment [Line Items]
Premises and equipment, gross		$ 3,222	$ 2,950

Premises and Equipment - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Abstract]
Depreciation and amortization expense			$ 686,000	$ 750,000	$ 625,000
Total rental expense, recognized on straight-line basis	$ 437,000	$ 381,000	$ 1,500,000	$ 1,600,000	$ 1,200,000
Operating lease expiration date			2018-05

Premises and Equipment - Schedule of Future Minimum Rent Payments on Company's Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
2018		$ 1,857
2019	$ 1,625	1,625
2020	1,396	1,396
2021	1,312	1,312
2022	1,089	1,029
Thereafter	4,117	4,102
Total	$ 10,877	$ 11,321

Deposits - Schedule of Maturities of Time Deposits (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Maturities Of Time Deposits [Abstract]
One year	$ 651,067	$ 627,665
Two to three years	6,498	12,263
Time deposits	$ 657,565	$ 639,928

Long-term Debt - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt instrument, face amount		$ 50,000,000	$ 50,000,000	$ 50,000,000
6.5% Fixed to Floating Rate Subordinated Debentures, Due March 31, 2026
Debt Instrument [Line Items]
Long-term debt, fixed interest rate	6.50%		6.50%	6.50%
Debt instrument, due date	Mar. 31, 2026		Mar. 31, 2026	Mar. 31, 2026
Debt instrument, face amount	$ 50,000,000
Debt instrument, fixed to floating interest rate conversion date	Mar. 31, 2021
Debt instrument, floating rate description		3 month London Interbank Offered Rate (LIBOR) plus 516 basis points	3 month LIBOR plus 516 basis points
Debt instrument, basis points	5.16%
Tier-1 capital		$ 35,000,000	$ 35,000,000
Debt instrument, redemption period, start date			Mar. 31, 2021

Long-term Debt - Schedule of Aggregate Outstanding Principal Amount and Unamortized Debt Issuance Cost Related to Subordinated Debentures (Detail) - USD ($)	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instruments [Abstract]
Principal	$ 50,000,000	$ 50,000,000	$ 50,000,000
Unamortized debt issuance costs	$ 436,000	$ 472,000	$ 617,000

Subordinated Debentures - Additional Information (Detail) - USD ($)			3 Months Ended		12 Months Ended
	Feb. 19, 2016	Mar. 15, 2012	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt instrument, face amount			$ 50,000,000		$ 50,000,000	$ 50,000,000
Subordinated Debentures
Debt Instrument [Line Items]
Percentage of principal amount redeemed		100.00%
Debt instrument redemption period			Mar. 15, 2012		Mar. 15, 2012
Debt instrument maturity period			Mar. 15, 2037		Mar. 15, 2037
Defer interest payments maximum period			5 years		5 years
Debt instrument interest rate description			three month LIBOR plus 1.65%, which was 3.77% and 3.24% at March 31, 2018 and December 31, 2017		three month London Interbank Offered Rate (LIBOR) plus 1.65%, which was 3.24% at December 31, 2017.
Debt instrument interest percentage			3.77%		3.24%
TFC Statutory Trust \| Private Offering
Debt Instrument [Line Items]
Number of trust preferred securities	5,000
Trust preferred securities liquidation amount per preferred security	$ 1,000
TFC Statutory Trust \| Subordinated Debentures
Debt Instrument [Line Items]
Debt instrument, face amount	$ 5,000,000
Debt valuation reserve	1,900,000		$ 1,900,000
Debt amortization expense			23,000	$ 23,000	$ 90,000	$ 79,000
TFC Statutory Trust \| Fair Value, Inputs, Level 1
Debt Instrument [Line Items]
Subordinated debenture liability	$ 3,255,000
Other Assets
Debt Instrument [Line Items]
Investment in common stock			$ 155,000		$ 155,000
London Interbank Offered Rate \| Subordinated Debentures
Debt Instrument [Line Items]
Debt instrument, basis points			1.65%		1.65%

Borrowing Arrangements - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2017	Mar. 31, 2018	Dec. 31, 2016
Debt Instrument [Line Items]
Line of credit amount outstanding	$ 0		$ 0
FRB Secured Line of Credit
Debt Instrument [Line Items]
Secured borrowing capacity	14,000,000	$ 13,800,000
Carrying value of collateral loan pledged	25,800,000	25,200,000
FHLB Secured Line of Credit
Debt Instrument [Line Items]
Secured borrowing capacity	323,300,000	342,900,000
Carrying value of collateral loan pledged	368,100,000	392,200,000
FHLB
Debt Instrument [Line Items]
Short-term borrowings	$ 25,000,000
Short-term borrowings interest percentage	1.41%
Short-term borrowings repayment date	Jan. 02, 2018
Zions Bank \| Maximum
Debt Instrument [Line Items]
Borrowings of unsecured loan	$ 20,000,000	20,000,000
Wells Fargo Bank \| Maximum
Debt Instrument [Line Items]
Borrowings of unsecured loan	10,000,000	10,000,000
Wells Fargo Bank \| Letter of Credit
Debt Instrument [Line Items]
Borrowings of unsecured loan	2,000,000	2,000,000
First Tennessee National Bank \| Maximum
Debt Instrument [Line Items]
Borrowings of unsecured loan	12,000,000	12,000,000
Pacific Coast Bankers' Bank \| Maximum
Debt Instrument [Line Items]
Borrowings of unsecured loan	$ 5,000,000	$ 5,000,000

Income Taxes - Components of Income Tax Expense (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current:
Federal			$ 12,097	$ 9,345	$ 5,662
State			3,773	2,841	1,973
Current			15,870	12,186	7,635
Deferred			2,492	1,289	1,361
Deferred tax adjustment for enacted change in tax rate			2,591
Affordable housing tax credits			316	14
Income tax expense	$ 1,580	$ 3,875	$ 21,269	$ 13,489	$ 8,996

Income Taxes - Comparison of Federal Statutory Income Tax Rates to Effective Income Tax Rates (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amount
Statutory federal tax			$ 16,379	$ 11,399	$ 7,469
State franchise tax, net of federal benefit			3,135	2,281	1,550
Tax-exempt income			(297)	(202)	(203)
Tax impact from enacted change in tax rate			2,591
Other items, net			(539)	11	180
Income tax expense	$ 1,580	$ 3,875	$ 21,269	$ 13,489	$ 8,996
Rate
Statutory federal tax			35.00%	35.00%	34.00%
State franchise tax, net of federal benefit			6.70%	7.00%	7.10%
Tax-exempt income			(0.60%)	(0.60%)	(0.90%)
Tax impact from enacted change in tax rate			5.50%	0.00%	0.00%
Other items, net			(1.20%)	0.00%	0.80%
Income tax expense	15.20%	41.40%	45.40%	41.40%	41.00%

Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax [Line Items]
Net deferred tax assets as result of enactment of tax rate				$ 2,600,000
Statutory federal tax				35.00%	35.00%	34.00%
Net operating loss carry forwards expiration, description				begin to expire in 2027
Net operating loss carry forwards expiration year start				2027
Net operating loss carryforwards utilized expiration, description				expire in 2031 through 2033
Net operating loss carryforwards utilized expiration year start				2031
Net operating loss carryforwards utilized expiration year end				2033
Income tax return examination, description				Income tax returns for the years ended after December 31, 2013 are open to audit by the federal authorities and for the years ended after December 31, 2012 are open to audit by California state authorities.
Interest or penalties related to uncertain tax positions				$ 0	$ 0	$ 0
Adjustment to uncertain tax position				0
Income tax expense	$ 1,580,000	$ 3,875,000		$ 21,269,000	$ 13,489,000	$ 8,996,000
Effective tax rate	15.20%	41.40%		45.40%	41.40%	41.00%
California Franchise Tax
Income Tax [Line Items]
Net operating loss carryforwards				$ 3,200,000
Net operating loss carryforwards utilized				11,400,000
Federal
Income Tax [Line Items]
Net operating loss carryforwards				37,000
Net operating loss carryforwards utilized				$ 3,800,000
Scenario Forecast
Income Tax [Line Items]
Statutory federal tax			21.00%

Income Taxes - Components of Net Deferred Tax Asset (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred tax assets:
Pre-opening expenses		$ 173	$ 287
Allowance for loan losses		4,072	5,954
Stock-based compensation		1,973	2,576
Off balance sheet reserve		83	254
Operating loss carryforwards		285	693
Other real estate owned		10	17
Acquisition accounting fair value adjustments			1,779
Unrealized loss on AFS securities		186	186
Other		1,968	2,520
Deferred tax assets		8,750	14,266
Deferred tax liabilities:
Depreciation		(511)	(917)
Acquisition accounting fair value adjustments		(145)
Other		(2,008)	(2,252)
Deferred tax liabilities		(2,664)	(3,169)
Net deferred tax assets	$ 6,460	$ 6,086	$ 11,097

Commitments - Schedule of Financial Commitments whose Contractual Amount Represents Credit Risk (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Mar. 31, 2018
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	$ 81,967	$ 103,821
Financial commitments, contractual amount, Variable Rate	123,798	66,776
Financial commitments, contractual amount	205,765		$ 229,593
Commitments to Make Loans
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	19,438	54,812
Financial commitments, contractual amount, Variable Rate	82,522	13,191
Financial commitments, contractual amount	101,960		103,354
Unused Lines of Credit
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	58,291	38,943
Financial commitments, contractual amount, Variable Rate	40,926	53,435
Financial commitments, contractual amount	99,217		119,964
Commercial and Similar Letters of Credit
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	3,013	8,966
Financial commitments, contractual amount	3,013		4,700
Standby Letters of Credit
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	1,225	1,100
Financial commitments, contractual amount, Variable Rate	350	$ 150
Financial commitments, contractual amount	$ 1,575		$ 1,575

Related Party Transactions - Schedule of Related Party Transactions (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transactions [Abstract]
Beginning balance	$ 2,300	$ 3,445	$ 3,971
New loans and advances	300	2,200	1,274
Repayments	(500)	(3,345)	(1,800)
Ending balance	$ 2,100	$ 2,300	$ 3,445

Related Party Transactions - Additional Information (Detail) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Executive Officers, Directors and their Related Interests
Related Party Transaction [Line Items]
Due to related parties	$ 1.8	$ 2.1	$ 2.3
Principal Officers, Directors and their Affiliates
Related Party Transaction [Line Items]
Deposits from related parties	$ 43.9	$ 43.8	$ 37.2

Stock-based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 18, 2017
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense	$ 131,000	$ 198,000	$ 779,000	$ 894,000	$ 1,500,000
Income tax benefits recognized	1,200,000	$ 61,000	$ 246,000	267,000	482,000
Stock options granted			0
Total unrecognized compensation cost			$ 637,000
Unrecognized compensation costs, weighted-average recognition period			1 year 2 months 12 days
Option exercised of intrinsic value			$ 2,808,000	216,000	231,000
Total fair of share vested			$ 930,000	$ 1,511,000	1,454,000
Number of nonvested stock options			163,996	328,826
Weighted average grant date fair value, nonvested stock options			$ 6.53	$ 6.28
Stock options exercised, shares			223,334
Stock options exercised	$ 3,540,000		$ 2,296,000	$ 595,000	$ 491,000
Excess tax benefit			$ 573,000
Omnibus Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved as percentage of issued and outstanding shares	24.00%
Stock option expiration period from date of grant			10 years
Stock option vesting period			3 years
Available for issuance of common stock	1,353,207		1,586,541
Common stock reserved for issuance						3,848,341
Maximum \| Omnibus Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved as percentage of issued and outstanding shares			30.00%
Percentage of fair market value stock on date of the grant			100.00%
Common stock reserved as percentage of issued and outstanding shares						30.00%
Maximum \| 2010 Stock Option Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Common stock reserved as percentage of issued and outstanding shares	30.00%
Common stock reserved for issuance	3,494,478
Additional shares of common stock available for grant	0

Stock Option Plan - Schedule of Weighted Average Assumption for Fair Value of Option Grant Estimated Using Black-Scholes Option Pricing Model (Detail) - $ / shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected volatility	35.00%	35.00%
Expected term	6 years	6 years
Expected dividends	0.00%	0.00%
Risk free rate	1.93%	1.84%
Grant date fair value	$ 6.76	$ 6.29

Stock Option Plan - Summary of Stock Option Plan (Detail) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2017 USD ($) $ / shares shares
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning Balance, Shares	2,495,134
Granted, Shares	0
Exercised, Shares	(223,334)
Forfeited or expired, Shares	(10,000)
Ending Balance, Shares	2,261,800
Options exercisable, Shares	2,097,804
Beginning Balance, Weighted Average Exercise Price \| $ / shares	$ 11.26
Exercised, Weighted Average Exercise Price \| $ / shares	10.28
Forfeited or expired, Weighted Average Exercise Price \| $ / shares	18.25
Ending Balance, Weighted Average Exercise Price \| $ / shares	11.32
Options exercisable, Weighted Average Exercise Price \| $ / shares	$ 10.80
Ending Balance, Weighted Average Remaining Contractual Term	3 years 9 months 18 days
Options exercisable, Weighted Average Remaining Contractual Term	3 years 4 months 24 days
Ending Balance, Aggregate Intrinsic Value \| $	$ 36,297
Options exercisable, Aggregate Intrinsic Value \| $	$ 34,755

Regulatory Matters - Additional Information (Detail) - USD ($)	Jan. 02, 2016	Jan. 01, 2019	Mar. 31, 2018	Jan. 01, 2018	Dec. 31, 2017	Jan. 02, 2017	Dec. 31, 2016	Jan. 01, 2015
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Common equity Tier 1 capital to risk-weighted assets ratio with minimum for capital adequacy								4.50%
Common equity Tier 1 capital to risk-weighted assets ratio with minimum for prompt corrective action purposes								6.50%
Tier 1 capital to risk-weighted assets ratio with minimum for capital adequacy			6.00%		6.00%		6.00%	4.00%
Increased Tier 1 capital to risk-weighted assets ratio with minimum for capital adequacy								6.00%
Tier 1 capital to risk-weighted assets ratio with minimum for prompt corrective action purposes			8.00%		8.00%		8.00%	6.00%
Increased Tier 1 capital to risk-weighted assets ratio with minimum for prompt corrective action purposes								8.00%
Capital conservation buffer	0.625%			2.50%	11.80%	2.50%		2.50%
Capital conservation buffer phased-in on pro rata basis period	4 years
Scenario Forecast
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer		2.50%
Minimum
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Regulatory assets							$ 1,000,000,000
Required assets to liabilities ratio after dividend effect			125.00%		125.00%

Regulatory Matters - Summary of Company and Bank Continue to Exceed Regulatory Capital Minimum Requirements and Bank Continues to Exceed Well Capitalized Standards (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2015
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 Risk-Based Capital Ratio, Amount	$ 242,192	$ 232,765	$ 178,645
Tier 1 Risk-Based Capital Ratio, Ratio	17.72%	17.42%	15.81%
Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 82,003	$ 80,163	$ 67,813
Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Ratio	6.00%	6.00%	6.00%	4.00%
Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 109,338	$ 106,884	$ 90,417
Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	8.00%	8.00%	8.00%	6.00%
Total Risk-Based Capital Ratio, Amount	$ 256,725	$ 246,820	$ 192,784
Total Risk-Based Capital Ratio, Ratio	18.78%	18.47%	17.06%
Total Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 109,338	$ 106,884	$ 90,417
Total Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Ratio	8.00%	8.00%	8.00%
Total Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 136,672	$ 133,605	$ 113,021
Total Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	10.00%	10.00%	10.00%
RBB Bancorp
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 Leverage Ratio, Amount	$ 249,304	$ 238,219	$ 153,682
Tier 1 Leverage Ratio, Ratio	15.24%	14.35%	10.99%
Tier 1 Leverage Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 65,439	$ 66,423
Tier 1 Leverage Ratio, Minimum Required for Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 Leverage Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 81,798	$ 83,029
Tier 1 Leverage Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	5.00%	5.00%
Common Equity Tier 1 Risk-Based Capital Ratio, Amount	$ 245,857	$ 234,794	$ 150,786
Common Equity Tier 1 Risk-Based Capital Ratio, Ratio	17.95%	17.54%	13.30%
Common Equity Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 61,620	$ 60,233
Common Equity Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Ratio	4.50%	4.50%
Common Equity Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 89,007	$ 87,003
Common Equity Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	6.50%	6.50%
Tier 1 Risk-Based Capital Ratio, Amount	$ 249,304	$ 238,219	$ 153,682
Tier 1 Risk-Based Capital Ratio, Ratio	18.21%	17.80%	13.55%
Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 82,161	$ 80,311
Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Ratio	6.00%	6.00%
Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 109,547	$ 107,081
Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	8.00%	8.00%
Total Risk-Based Capital Ratio, Amount	$ 313,402	$ 301,802	$ 217,244
Total Risk-Based Capital Ratio, Ratio	22.89%	22.55%	19.16%
Total Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 109,547	$ 107,081
Total Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Ratio	8.00%	8.00%
Total Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 136,934	$ 133,851
Total Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	10.00%	10.00%
Royal Business Bank
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 Leverage Ratio, Amount	$ 242,192	$ 232,765	$ 178,645
Tier 1 Leverage Ratio, Ratio	14.84%	14.50%	12.81%
Tier 1 Leverage Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 65,283	$ 64,214	$ 55,777
Tier 1 Leverage Ratio, Minimum Required for Capital Adequacy Purposes Ratio	4.00%	4.00%	4.00%
Tier 1 Leverage Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 81,604	$ 80,267	$ 69,722
Tier 1 Leverage Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	5.00%	5.00%	5.00%
Common Equity Tier 1 Risk-Based Capital Ratio, Amount	$ 242,192	$ 232,765	$ 178,645
Common Equity Tier 1 Risk-Based Capital Ratio, Ratio	17.72%	17.42%	15.81%
Common Equity Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Amount	$ 61,502	$ 60,122	$ 50,860
Common Equity Tier 1 Risk-Based Capital Ratio, Minimum Required for Capital Adequacy Purposes Ratio	4.50%	4.50%	4.50%
Common Equity Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 88,837	$ 86,843	$ 73,464
Common Equity Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	6.50%	6.50%	6.50%

Fair Value Measurements - Schedule of Hierarchy and Fair Value for Each Major Category of Assets and Liabilities Measured at Fair Value (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Assets measured at fair value:
Assets measured at fair value on recurring basis	$ 82,848	$ 64,957	$ 39,277
Other Real Estate Owned
Assets measured at fair value:
Assets measured at fair value on a non-recurring basis	293	293	833
Government Agency Securities
Assets measured at fair value:
Assets measured at fair value on recurring basis	7,482	7,816	5,317
Government Sponsored Agencies
Assets measured at fair value:
Assets measured at fair value on recurring basis	37,672	39,215	23,640
Corporate Debt Securities
Assets measured at fair value:
Assets measured at fair value on recurring basis	37,694	17,926	10,320
Fair Value Measurements Using Level 2
Assets measured at fair value:
Assets measured at fair value on recurring basis	82,848	64,957	39,277
Fair Value Measurements Using Level 2 \| Government Agency Securities
Assets measured at fair value:
Assets measured at fair value on recurring basis	7,482	7,816	5,317
Fair Value Measurements Using Level 2 \| Government Sponsored Agencies
Assets measured at fair value:
Assets measured at fair value on recurring basis	37,672	39,215	23,640
Fair Value Measurements Using Level 2 \| Corporate Debt Securities
Assets measured at fair value:
Assets measured at fair value on recurring basis	37,694	17,926	10,320
Fair Value Measurements Using Level 3 \| Other Real Estate Owned
Assets measured at fair value:
Assets measured at fair value on a non-recurring basis	$ 293	$ 293	$ 833

Fair Value Measurements - Additional Information (Detail) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Write-downs to OREO	$ 0	$ 0	$ 0

Fair Value Measurements - Summary of Quantitative Information About Non-recurring Level 3 Fair Value Measurements (Detail) - Other Real Estate Owned - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Amount	$ 293	$ 293	$ 833
Fair Value Measurements Using Level 3
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Amount	293	293	833
Fair Value Measurements Using Level 3 \| Third Party Appraisals
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Amount	$ 293	$ 293	$ 833
Fair Value Adjustment	21.00%	21.00%
Fair Value Measurements Using Level 3 \| Third Party Appraisals \| Weighted Average
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Adjustment	21.00%	21.00%	12.00%
Fair Value Measurements Using Level 3 \| Third Party Appraisals \| Minimum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Adjustment			10.00%
Fair Value Measurements Using Level 3 \| Third Party Appraisals \| Maximum
Fair Value Inputs Assets Quantitative Information [Line Items]
Fair Value Adjustment			15.00%

Fair Value of Financial Instruments - Schedule of Fair Value Hierarchy Level and Estimated Fair Value of Significant Financial Instruments (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financial Assets:
Cash and due from banks	$ 53,535	$ 70,048	$ 74,213
Federal funds sold and other cash equivalents	25,000	80,000	44,500
Interest-earning deposits in other financial institutions	600	600	345
Investment securities - AFS	82,848	64,957	39,277
Investment securities - HTM	9,998	10,009	6,214
Mortgage loans held for sale	183,391	125,847	44,345
Loans, net	1,247,971	1,235,301	1,096,284
Investment securities - HTM	10,020	10,250	6,553
Financial Liabilities:
Deposits	1,373,504	1,337,281	1,152,763
FHLB advances		25,000
Long-term debt	49,564	49,528	49,383
Subordinated debentures	3,447	3,424	3,334
Fair Value, Inputs, Level 1 \| Fair Value
Financial Assets:
Cash and due from banks	53,535	70,048	74,213
Federal funds sold and other cash equivalents	25,000	80,000	44,500
Interest-earning deposits in other financial institutions	600	600	345
Mortgage loans held for sale	128,491	128,972
Fair Value Measurements Using Level 2 \| Fair Value
Financial Assets:
Investment securities - AFS	82,848	64,957	39,277
Investment securities - HTM	10,020	10,250	6,553
Mortgage loans held for sale		128,972	45,433
Financial Liabilities:
Deposits	1,371,213	1,336,353	1,140,707
FHLB advances		25,000
Long-term debt	41,950	44,319	48,447
Fair Value Measurements Using Level 3 \| Fair Value
Financial Assets:
Loans, net	1,288,740	1,236,289	1,095,944
Financial Liabilities:
Subordinated debenture liability	$ 3,625	$ 3,348	$ 3,334

Earnings Per Share (EPS) - Computation of Basic and Diluted Earnings Per Share (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Earnings Per Share [Abstract]
Net income as reported	$ 8,847	$ 5,493	$ 25,528	$ 19,079	$ 12,973
Shares outstanding	16,288,928	12,827,803	15,908,893	12,827,803	12,770,571
Impact of weighting shares	(206,033)		(1,830,612)	(26,813)	(8,739)
Used in basic EPS, Income	$ 8,847	$ 5,493	$ 25,528	$ 19,079	$ 12,973
Used in basic EPS, Shares	16,082,895	12,827,803	14,078,281	12,800,990	12,761,832
Dilutive effect of outstanding
Stock options, Shares	1,079,425	897,918	1,160,084	894,910	790,850
Used in dilutive EPS, Income	$ 8,847	$ 5,493	$ 25,528	$ 19,079	$ 12,973
Used in dilutive EPS, Shares	17,162,320	13,725,721	15,238,365	13,695,900	13,552,682
Basic earnings per common share	$ 0.55	$ 0.43	$ 1.81	$ 1.49	$ 1.02
Diluted earnings per common share	$ 0.52	$ 0.40	$ 1.68	$ 1.39	$ 0.96

Earnings Per Share ("EPS") - Additional Information (Detail) - shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Stock options \| Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Excluded common stock for computation of diluted earnings per share	0	321,000	139,225

Stock Dividends - Additional Information (Detail)	12 Months Ended
Stock Dividends - Additional Information (Detail)	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Dividends Stock [Abstract]
Stock dividend issued percentage	0.00%	0.00%	2.50%

Qualified Affordable Housing Project Investments - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016
Schedule Of Equity Method Investments [Line Items]
Investment for qualified affordable housing projects	$ 8,031,000		$ 5,670,000
Unfunded commitments related to the investments in qualified affordable housing projects	6,264,000		$ 4,194,000
Expected year in which commitments are fulfilled			2027
Amortization expense	$ 139,000	$ 22,000	$ 316,000	$ 14,000
Recognized tax credits from its investment in affordable housing tax credits			275,000	6,000
Impairment losses			0	0
Recognized tax credits and other benefits from its investment in affordable housing tax credits			$ 275,000	$ 12,000
Maximum
Schedule Of Equity Method Investments [Line Items]
Expected year in which commitments are fulfilled	2028
Minimum
Schedule Of Equity Method Investments [Line Items]
Expected year in which commitments are fulfilled	2027

Parent Only Condensed Financial Information - Schedule of Parent Only Condensed Balance Sheets (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 01, 2015
Assets
Cash and cash equivalents	$ 53,535	$ 70,048		$ 74,213
Total assets	1,715,104	1,691,059		1,395,551
Liabilities and Shareholders' Equity
Long-term debt	49,564	49,528		49,383
Subordinated debentures	3,447	3,424		3,334
Total liabilities	1,439,282	1,425,883		1,213,966
Shareholders' equity:
Common Stock	210,595	205,927		142,651
Additional paid-in capital	7,429	8,426		8,417
Retained earnings	58,838	51,266		30,784
Accumulated other comprehensive income (loss)	(1,040)	(443)		(267)
Total shareholders' equity	275,822	265,176	$ 183,496	181,585	$ 163,645	$ 151,981
Total liabilities and shareholders' equity	$ 1,715,104	1,691,059		1,395,551
RBB Bancorp
Assets
Cash and cash equivalents		45,769		17,497
Other assets		3,538		1,455
Total assets		318,597		234,804
Liabilities and Shareholders' Equity
Long-term debt		49,528		49,383
Subordinated debentures		3,424		3,334
Other liabilities		36		8
Total liabilities		52,989		52,725
Shareholders' equity:
Common Stock		205,927		142,651
Additional paid-in capital		8,426		8,417
Retained earnings		51,697		31,278
Accumulated other comprehensive income (loss)		(443)		(267)
Total shareholders' equity		265,608		182,079
Total liabilities and shareholders' equity		318,597		234,804
RBB Bancorp \| Royal Business Bank
Assets
Investment		263,022		209,727
RBB Bancorp \| Royal Asset Management
Assets
Investment		$ 6,268		$ 6,125

Parent Only Condensed Financial Information - Schedule of Parent Only Condensed Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Statements of Income and Comprehensive Income
Interest expense	$ 3,732	$ 3,245	$ 13,938	$ 11,707	$ 6,936
Noninterest expense	8,289	6,578	27,623	27,906	20,084
Income before income taxes	10,427	9,368	46,797	32,568	21,969
Income tax benefit	(1,580)	(3,875)	(21,269)	(13,489)	(8,996)
Net income	8,847	5,493	25,528	19,079	12,973
Other comprehensive income (loss)	(597)	68	(104)	(74)	(141)
Total comprehensive income	$ 8,250	$ 5,561	25,424	19,005	12,832
RBB Bancorp
Consolidated Statements of Income and Comprehensive Income
Interest expense			3,629	2,728
Noninterest expense			704	123	298
Loss before equity in undistributed income of subsidiaries			(4,334)	(2,851)	(298)
Income before income taxes			23,430	17,906	12,816
Income tax benefit			2,036	1,173	125
Net income			25,466	19,079	12,941
Other comprehensive income (loss)			(104)	(74)	(141)
Total comprehensive income			25,362	19,005	12,800
RBB Bancorp \| Royal Business Bank
Consolidated Statements of Income and Comprehensive Income
Equity in undistributed income			27,620	20,483	12,310
RBB Bancorp \| Royal Asset Management
Consolidated Statements of Income and Comprehensive Income
Equity in undistributed income			$ 143	$ 274	$ 804

Parent Only Condensed Financial Information - Schedule of Parent Only Condensed Statements of Cash Flows (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net income	$ 8,847	$ 5,493	$ 25,528	$ 19,079	$ 12,973
Net cash from operating activities	(21,503)	(12,443)	28,783	56,219	29,095
Cash flows from investment activities:
Net cash from investing activities	(63,497)	(40,444)	(264,446)	7,202	(105,380)
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs				49,274
Issuance of common stock, net of issuance costs			60,210
Cash dividends paid	(1,275)	(3,848)	(5,118)	(2,554)	(3,114)
Stock options exercised	3,540		2,296	595	491
Net cash from financing activities	13,487	101,721	266,998	(58,599)	83,481
Net increase in cash and cash equivalents	(71,513)	48,834	31,335	4,822	7,196
RBB Bancorp
Cash flows from operating activities:
Net income			25,466	19,079	12,941
Net amortization of other			235	188
Provision for deferred income taxes			1,807	(1,172)	(125)
Undistributed income of subsidiaries			(27,763)	(20,757)	(13,114)
Change in other assets and liabilities			(3,861)	(159)	135
Net cash from operating activities			(4,116)	(2,821)	(163)
Cash flows from investment activities:
Outlays for business acquisitions				(839)
Investment in subsidiaries			(25,000)	(35,000)	5,000
Net cash from investing activities			(25,000)	(35,839)	5,000
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs				49,274
Issuance of common stock, net of issuance costs			60,210
Cash dividends paid			(5,118)	(2,554)	(3,114)
Stock options exercised			2,296	585	470
Net cash from financing activities			57,388	47,305	(2,644)
Net increase in cash and cash equivalents			28,272	8,645	2,193
Cash and cash equivalents beginning of year	$ 45,769	$ 17,497	17,497	8,852	6,659
Cash and cash equivalents end of year			$ 45,769	$ 17,497	$ 8,852

Subsequent Events - Additional Information (Detail) - USD ($)			3 Months Ended		12 Months Ended
	Apr. 18, 2018	Jan. 17, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Jan. 31, 2018
Subsequent Event [Line Items]
Cash dividends declared per common share			$ 0.08	$ 0.30	$ 0.38	$ 0.20	$ 0.25
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared per common share		$ 0.08
Cash dividend declared date	Apr. 18, 2018	Jan. 17, 2018
Cash dividend payable date	May 15, 2018	Feb. 15, 2018
Cash dividend declared, record date	Apr. 30, 2018	Jan. 31, 2018
Cash dividend payable amount								$ 1,275,000

Goodwill and Intangibles - Additional information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule Of Finite Lived Intangible Assets And Goodwill [Line Items]
Goodwill	$ 29,940,000		$ 29,940,000	$ 29,940,000
Impairment losses recognized on goodwill	0	$ 0	0	0
Amortization of intangibles	81,000	94,000	355,000	372,000	$ 117,000
Core Deposit Intangible
Schedule Of Finite Lived Intangible Assets And Goodwill [Line Items]
Unamortized balance of intangible assets	1,357,000		1,438,000	1,793,000
Amortization of intangibles	$ 81,000	$ 94,000	$ 355,000	$ 372,000	$ 117,000
Core Deposit Intangible \| Minimum
Schedule Of Finite Lived Intangible Assets And Goodwill [Line Items]
Intangible assets, estimated useful life	8 years		8 years
Core Deposit Intangible \| Maximum
Schedule Of Finite Lived Intangible Assets And Goodwill [Line Items]
Intangible assets, estimated useful life	10 years		10 years

Commitments - Schedule of Future Minimum Rent Payments on Company's Leases (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Commitments And Contingencies Disclosure [Abstract]
2018 remaining	$ 1,338
2019	1,625	$ 1,625
2020	1,396	1,396
2021	1,312	1,312
2022	1,089	1,029
Thereafter	4,117	4,102
Total	$ 10,877	$ 11,321

Commitments - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
Commitments - Additional Information (Detail) - USD ($)	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Commitments And Contingencies Disclosure [Abstract]
Total rental expense, recognized on straight-line basis	$ 437,000	$ 381,000	$ 1,500,000	$ 1,600,000	$ 1,200,000

Recent Developments - Additional Information (Detail) - USD ($)				3 Months Ended
	Apr. 23, 2018	Apr. 18, 2018	Jan. 17, 2018	Sep. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Recent Developments [Line Items]
Common stock, par value
Subsequent Event
Recent Developments [Line Items]
Cash dividend declared date		Apr. 18, 2018	Jan. 17, 2018
Cash dividends declared per share		$ 0.09
Cash dividend payable date		May 15, 2018	Feb. 15, 2018
Cash dividend declared, record date		Apr. 30, 2018	Jan. 31, 2018
Subsequent Event \| Merger Agreement \| First American International Corporation
Recent Developments [Line Items]
Repurchase of outstanding preferred stock				$ 17,000,000
Amount committed to lend FAIC for repurchase of outstanding preferred stock				$ 17,000,000
Committed to lend FAIC for repurchase of outstanding preferred stock, maximum period				1 month
Subsequent Event \| Convertible Common Stock \| Merger Agreement
Recent Developments [Line Items]
Common stock shares issued	1.3472
Common stock, par value
Common stock purchase price, per share	$ 15.30
Exercise price of common stock options excluded from share price	$ 51.00