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Document and Entity Information - USD ($)	12 Months Ended
Document and Entity Information - USD ($)	Dec. 31, 2018	Mar. 18, 2019	Jun. 30, 2018
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2018
Document Fiscal Period Focus	FY
Trading Symbol	RBB
Entity Registrant Name	RBB BANCORP
Entity Central Index Key	0001499422
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		20,073,991
Entity Public Float			$ 391,057,685

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Assets
Cash and due from banks	$ 147,685	$ 70,048
Federal funds sold and other cash equivalents		80,000
Cash and cash equivalents	147,685	150,048
Interest-earning deposits in other financial institutions	600	600
Securities:
Available for sale	73,762	64,957
Held to maturity (fair value of $9,940 and $10,250 at December 31, 2018 and December 31, 2017, respectively)	9,961	10,009
Mortgage loans held for sale	434,522	125,847
Loans held for investment:
Real estate	1,762,864	839,230
Commercial	387,474	410,812
Total loans	2,150,338	1,250,042
Unaccreted discount on acquired loans	(9,229)	(2,762)
Deferred loan costs (fees), net	906	1,794
Total loans, gross	2,142,015	1,249,074
Allowance for loan losses	(17,577)	(13,773)
Net loans	2,124,438	1,235,301
Premises and equipment	17,307	6,583
Federal Home Loan Bank (FHLB) stock	9,707	6,770
Net deferred tax assets	4,642	6,086
Income tax receivable	656	272
Other real estate owned (OREO)	1,101	293
Bank owned life insurance (BOLI)	33,578	32,782
Goodwill	58,383	29,940
Servicing assets	17,370	5,957
Core deposit intangibles	7,601	1,438
Accrued interest and other assets	32,689	14,176
Total assets	2,974,002	1,691,059
Deposits:
Noninterest-bearing demand	438,764	285,690
Savings, NOW and money market accounts	579,247	411,663
Time deposits under $250,000	532,395	293,471
Time deposits $250,000 and over	593,635	346,457
Total deposits	2,144,041	1,337,281
Reserve for unfunded commitments	688	282
FHLB advances	319,500	25,000
Long-term debt, net of debt issuance costs	103,708	49,528
Subordinated debentures	9,506	3,424
Accrued interest and other liabilities	21,938	10,368
Total liabilities	2,599,381	1,425,883
Commitments and contingencies - Note 7 and 13
Shareholders' equity:
Preferred Stock - 100,000,000 shares authorized, no par value; none outstanding
Common Stock - 100,000,000 shares authorized, no par value; 20,000,022 shares issued and outstanding at December 31, 2018 and 15,908,893 shares at December 31, 2017	288,610	205,927
Additional paid-in capital	5,659	8,426
Retained earnings	81,618	51,266
Non-controlling interest	72
Accumulated other comprehensive income (loss) - net unrealized loss on securities available for sale, net of tax of $895 at December 31, 2018 and $104 December 31, 2017	(1,338)	(443)
Total shareholders’ equity	374,621	265,176
Total liabilities and shareholders’ equity	$ 2,974,002	$ 1,691,059

CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Statement Of Financial Position [Abstract]
Securities held to maturity, fair value	$ 9,940	$ 10,250
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, par value
Preferred stock, shares outstanding	0	0
Common stock, shares authorized	100,000,000	100,000,000
Common stock, par value
Common stock, shares issued	20,000,022	15,908,893
Common stock, shares outstanding	20,000,022	15,908,893
Accumulated other comprehensive income (loss) - net unrealized loss on securities available for sale, tax	$ 895	$ 104

CONSOLIDATED STATEMENTS OF INCOME - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF INCOME - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest and dividend income:
Interest and fees on loans	$ 97,480,000	$ 70,289,000	$ 65,888,000
Interest on interest-earning deposits	1,002,000	940,000	334,000
Interest on investment securities	2,351,000	1,406,000	872,000
Dividend income on FHLB stock	650,000	472,000	800,000
Interest on federal funds sold and other	632,000	997,000	295,000
Total interest income	102,115,000	74,104,000	68,189,000
Interest expense:
Interest on savings deposits, now and money market accounts	4,408,000	2,382,000	1,975,000
Interest on time deposits	12,548,000	7,891,000	6,968,000
Interest on subordinated debentures and other	4,083,000	3,629,000	2,547,000
Interest on other borrowed funds	2,606,000	36,000	217,000
Total interest expense	23,645,000	13,938,000	11,707,000
Net interest income	78,470,000	60,166,000	56,482,000
Provision (recapture) for credit losses	4,469,000	(1,053,000)	4,974,000
Net interest income after provision (recapture) for credit losses	74,001,000	61,219,000	51,508,000
Noninterest income:
Service charges, fees and other	2,679,000	2,111,000	1,758,000
Gain on sale of loans	7,126,000	9,318,000	5,847,000
Loan servicing fees, net of amortization	850,000	722,000	615,000
Recoveries on loans acquired in business combinations	1,385,000	84,000	170,000
Increase in bank owned life insurance	797,000	824,000	560,000
Gain on sale of securities	5,000		19,000
Gain on sale of OREO		142,000
Loss on sale of fixed assets			(3,000)
Total noninterest income	12,842,000	13,201,000	8,966,000
Noninterest expense:
Salaries and employee benefits	23,254,000	16,821,000	13,784,000
Occupancy and equipment expenses	4,554,000	2,940,000	3,098,000
Data processing	2,323,000	1,622,000	2,018,000
Legal and professional	1,714,000	331,000	1,565,000
Office expenses	890,000	679,000	598,000
Marketing and business promotion	1,143,000	837,000	542,000
Insurance and regulatory assessments	951,000	799,000	883,000
Amortization of intangibles	575,000	355,000	372,000
OREO expenses	24,000	28,000	28,000
Merger expenses	1,658,000	37,000
Other expenses	3,551,000	3,174,000	5,018,000
Total noninterest expense	40,637,000	27,623,000	27,906,000
Income before income taxes	46,206,000	46,797,000	32,568,000
Income tax expense	10,101,000	21,269,000	13,489,000
Net income	$ 36,105,000	$ 25,528,000	$ 19,079,000
Net income per share
Basic	$ 2.11	$ 1.81	$ 1.49
Diluted	2.01	1.68	1.39
Cash dividends declared per common share	$ 0.35	$ 0.38	$ 0.20
Weighted-average common shares outstanding
Basic	17,151,222	14,078,281	12,800,990
Diluted	17,967,653	15,238,365	13,695,900

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 36,105	$ 25,528	$ 19,079
Other comprehensive (loss):
Unrealized gains (losses) on securities available for sale, Change in unrealized gains (losses)	(1,266)	(176)	(107)
Unrealized gains (losses) on securities available for sale, Reclassification of gains recognized in net income	(5)		(19)
Unrealized gains (losses) on securities available for sale	(1,271)	(176)	(126)
Related income tax effect, Change in unrealized gains (losses)	376	72	44
Related income tax effect, Reclassification of gains recognized in net income			8
Related income tax effect	376	72	52
Total other comprehensive (loss)	(895)	(104)	(74)
Total comprehensive income	$ 35,210	$ 25,424	$ 19,005

CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Non-Controlling Interest	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Beginning balance at Dec. 31, 2015	$ 163,645	$ 141,873	$ 7,706		$ 14,259	$ (193)
Beginning 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 loss, net of taxes	(74)					(74)
Ending balance at Dec. 31, 2016	181,585	$ 142,651	8,417		30,784	(267)
Ending balance, shares at Dec. 31, 2016		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
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 loss, net of taxes	(104)					(104)
Reclassification of stranded tax effects from change in tax rates					72	(72)
Ending balance at Dec. 31, 2017	$ 265,176	$ 205,927	8,426		51,266	(443)
Ending balance, shares at Dec. 31, 2017	15,908,893	15,908,893
Net income	$ 36,105				36,105
Stock-based compensation	684		684
Restricted stock award, shares		43,425
Cash dividend	(5,753)				(5,753)
Stock options exercised	$ 9,629	$ 13,080	(3,451)
Stock options exercised, shares	1,035,942	1,035,942
Issuance of common stock for acquisition	$ 69,603	$ 69,603
Issuance of common stock for acquisition, shares		3,011,762
Non-controlling interest	72			$ 72
Other comprehensive loss, net of taxes	(895)					(895)
Ending balance at Dec. 31, 2018	$ 374,621	$ 288,610	$ 5,659	$ 72	$ 81,618	$ (1,338)
Ending balance, shares at Dec. 31, 2018	20,000,022	20,000,022

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

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income	$ 36,105,000	$ 25,528,000	$ 19,079,000
Adjustments to reconcile net income to net cash from
Depreciation and amortization of premises, equipment and intangibles	1,681,000	1,273,000	1,360,000
Net amortization (accretion) of securities, loans, deposits, and other	(1,754,000)	(4,801,000)	(7,199,000)
Amortization of affordable housing tax credits	644,000	316,000	14,000
Provision (recapture) for loan losses	4,469,000	(1,053,000)	4,974,000
Stock-based compensation	684,000	779,000	894,000
Deferred tax expense (benefit)	(383,000)	5,083,000	1,289,000
Gain on sale of securities	(5,000)		(19,000)
Gain on sale of loans	(7,126,000)	(9,318,000)	(5,847,000)
Gain on sale of OREO		(142,000)
Increase in bank owned life insurance	(797,000)	(824,000)	(560,000)
Loans originated and purchased for sale	(413,450,000)	(254,629,000)	(184,030,000)
Proceeds from loans sold	301,894,000	265,497,000	221,328,000
Other items	(6,610,000)	1,074,000	4,936,000
Net cash from operating activities	(84,648,000)	28,783,000	56,219,000
Investing activities
Net (increase) decrease in interest-earning deposits		(255,000)	9,437,000
Securities available for sale:
Purchases	(74,171,000)	(29,557,000)	(12,485,000)
Maturities, prepayments and calls	64,008,000	4,353,000	4,403,000
Sales	44,591,000	0	5,083,000
Securities Held to Maturity:
Purchases		(4,926,000)
Maturities, Prepayments and Calls		1,100,000
Purchase of other equity securities, net	(8,140,000)
Purchase of FHLB stock	(2,937,000)	(837,000)	(3,265,000)
Purchase of investment in qualified affordable housing projects	(1,911,000)	(5,000,000)	(1,000,000)
Net (increase) decrease in loans	(366,415,000)	(218,897,000)	40,290,000
Proceeds from sales of OREO		257,000
Purchase of bank owned life insurance		(10,000,000)
Net cash acquired (paid) in connection with acquisition	25,073,000		(35,051,000)
Purchases of premises and equipment	(2,488,000)	(684,000)	(210,000)
Net cash from investing activities	(322,390,000)	(264,446,000)	7,202,000
Financing activities
Net (decrease) increase in demand deposits and savings accounts	(9,807,000)	226,382,000	(47,679,000)
Net increase (decrease) in time deposits	186,588,000	(41,772,000)	(58,235,000)
Net change in FHLB advances	170,000,000	25,000,000
Cash dividends paid	(5,753,000)	(5,118,000)	(2,554,000)
Issuance of subordinated debentures, net of issuance costs	54,018,000		49,274,000
Issuance of common stock, net of issuance costs		60,210,000
Stock options exercised	9,629,000	2,296,000	595,000
Net cash from financing activities	404,675,000	266,998,000	(58,599,000)
Net (decrease) increase in cash and cash equivalents	(2,363,000)	31,335,000	4,822,000
Cash and cash equivalents at beginning of period	150,048,000	118,713,000	113,891,000
Cash and cash equivalents at end of period	147,685,000	150,048,000	118,713,000
Cash paid during the period:
Interest paid	19,993,000	13,848,000	12,342,000
Taxes paid	9,335,000	16,935,000	12,515,000
Non-cash investing and financing activities:
Transfer of loan to available for sale securities		1,000,000
Transfer from loans to OREO	808,000		540,000
Transfer of loans to held for sale	186,503,000	165,651,000	71,626,000
Loan to facilitate OREO		425,000
Securities held to maturity transferred to available for sale			433,000
Net change in unrealized holding gain on securities available for sale	$ (1,276,000)	$ (176,000)	$ (107,000)

Business Description

12 Months Ended

Dec. 31, 2018

Business Description [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, 2018, the Company had total assets of $3.0 billion, gross loans of $2.1 billion, total deposits of $2.1 billion and total stockholders' equity of $374.6 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 and New York City metropolitan area, 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, Irvine, and Westlake Village, California; Las Vegas, Nevada; and Manhattan, Brooklyn, Flushing, and Elmhurst, New York. 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 derives income from noninterest sources, such as fees received in connection with various lending and deposit services, residential mortgage loan originations, loan servicing, gain on sales of loans and wealth management services. 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.

As part of the FAIC acquisition, the Company acquired FAIB Capital Corp. (FAICC) that was formed on January 29, 2014. FAICC is a real estate investment trust subsidiary of the Bank.

The Company has completed five acquisitions from July 8, 2011 through October 15, 2018, including the acquisition of TFC Holding Company on February 19, 2016 and First American International Corp. on October 15, 2018. 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 FAIC acquisition.

Basis of Presentation and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation and Summary of Significant Accounting Policies

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, and in 2018 changed to a financial holding company. RAM was formed in 2012 to hold and manage problem assets acquired in business combinations.

In connection with the 2018 acquisition of FAIC, the Company acquired a real estate investment trust (“REIT”) as a subsidiary of the Bank and is a New York State corporation. In addition to the REIT, the Company acquired four inactive subsidiaries: FAIC Insurance Services (a New York corporation formed in 2006), P4G8, LLC, FAIB Reacquisitions I, LLC and FAIB REO Acquisition II, LLC. These inactive subsidiaries are in the process of being dissolved.

We acquired two statutory business trusts: TFC Statutory Trust in 2016 and FAIC Statutory Trust in 2018. These trusts issued trust preferred securities representing undivided preferred beneficial interests in the assets of the Trusts. The proceeds of these trust preferred securities were invested in certain securities issued by us, with similar terms to the relevant series of securities issued by the Trusts, which we refer to as subordinated debentures.

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, 2018 and 2017 were $24.5 million and $19.7 million, 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

Investment 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 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. 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 $7.1 million, $9.3 million, and $5.8 million in 2018, 2017, and 2016, respectively. Gains on sale of mortgage loans totaled $4.3 million, $3.7 million, and $3.4 million, and gains on sale of SBA loans totaled $2.8 million, $5.6 million, and $2.4 million in 2018, 2017, and 2016 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 $58.4 million and $29.9 million as of December 31, 2018 and 2017, respectively, and is the only intangible asset with an indefinite life on the balance sheet. No impairment was recognized on goodwill during 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 and in the 2018 acquisition of FAIC. The unamortized balance as of December 31, 2018 and 2017 was $7.6 million and $1.4 million, respectively. CDI amortization expense was $575,000, $355,000, and $372,000 in 2018, 2017 and 2016, respectively.

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

Year ending December 31:
2019	$	1,501
2020		1,285
2021		1,056
2022		879
2023		749
Thereafter		2,131
Total	$	7,601

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.

FHLB Stock and Other Equity Securities

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.

The Company also owns equity investment in Pacific Coast Bankers’ Bank (“PCBB”) and Atlantic Community Bankers’ Bank (“ACBB”). The Company adopted ASU 2016-01 on January 1, 2019, and elected the measurement alternative for measuring equity securities without readily determinable fair values at cost less impairment, plus or minus observable price changes in orderly transactions. As of December 31, 2018, the carrying amount of equity securities without readily determinable fair values were $217,000 for PCBB and $60,000 for ACBB. An estimated gain of $107,000 from PCBB and $40,000 from ACBB based on observable activity in these securities will be recorded in the first quarter of 2019.

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 $341,000, $272,000, and $221,000 in 2018, 2017, and 2016, 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" or “Update”) 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. Our revenue is primarily comprised of net interest income on financial assets and financial liabilities, which is explicitly excluded from the scope of ASU 2014-09, and non-interest income. Accordingly, the majority of the Company’s revenues will not be affected. In addition, the standard does not materially impact the timing or measurement of the Company’s revenue recognition as it is consistent with the Company’s existing accounting for contracts within the scope of the standard. As an emerging growth company, the Company plans to adopt ASU 2014-09 as of January 1, 2019, utilizing the modified prospective approach. The Company performed 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. For the nine months ended September 30, 2018, the Company estimates approximately 20% of non-interest income (primarily fees on deposit accounts, other fees and other income) is within the scope of this ASU, with approximately 80% out-of-scope (primarily gains on loan sales, BOLI income, net loan servicing income and letter of credit commissions).

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. Investments in Federal Home Loan Bank (“FHLB”) and Federal Reserve Bank (“FRB”) stock issued to member financial institutions are not subject to this guidance. Instead, FHLB and FRB stock would continue to be accounted for at cost less impairment under ASC 942-325-35-3. The ASU’s impairment guidance on equity investments for which fair value is not readily determinable also does not apply to FHLB or FRB stock. This 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, 2019 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, 2019, for an emerging growth company. 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. The Company anticipates adopting this ASU 2016-02 beginning January 1, 2020.

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. 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. For available for sale (“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. 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 2016-13 is effective for interim and annual reporting periods for an emerging growth company beginning after December 15, 2020. 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 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 assess the potential impact that this Update will have on the Company’s consolidated financial statements. The Company anticipates adopting this ASU 2016-13 beginning January 1, 2021.

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 (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 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 Update 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 this Update, “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 2017-14 is effective for annual and any interim impairment tests performed in periods beginning after December 15, 2021 for an emerging growth company. Adoption of ASU 2017-04 is not expected to have a significant impact on the Company’s consolidated financial statements.

In March 2017, the FASB issued ASU 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.” This Update 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 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 emerging growth companies for interim and annual periods beginning after December 15, 2019. 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 principles. The implementation of the provisions of ASU 2017-08 will most likely not have a material impact the Company’s consolidated financial statements. As of December 31, 2018, the unamortized premium on purchased callable debt securities was an immaterial 0.91% of those securities book value. The Company will continue to assess 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 (Topic 718): Scope of Modification 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 2017-09 are effective for annual periods, and interim within those annual reporting periods, for an emerging growth company, beginning after December 15, 2018. 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 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. This Update allows a reclassification from accumulated other comprehensive income (“AOCI”) to retained earnings for stranded tax effects resulting from the new U.S. Federal corporate income tax rate enacted on December 22, 2017. The amendments in this Update are effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. The Company elected to early adopt ASU 2018-02 and elected to reclassify the income tax effects of the Tax Reform Act from AOCI to retained earnings. The amount of the reclassification is $72,000, which is the difference between the historical corporate income tax rate and the newly enacted 21% corporate income tax rate.

In June 2018, the FASB issued ASU 2018-07, Compensation—Stock Compensation (Topic 718): Improvements to Nonemployee Share-Based Payment Accounting. The amendments in this Update expand the scope of Topic 718 to include share-based payment transactions for acquiring goods and services from nonemployees. An entity should apply the requirements of Topic 718 to nonemployee awards except for specific guidance on inputs to an option pricing model and the attribution of cost (that is, the period of time over which share-based payment awards vest and the pattern of cost recognition over that period). The amendments specify that Topic 718 applies to all share-based payment transactions in which a grantor acquires goods or services to be used or consumed in a grantor’s own operations by issuing share-based payment awards. The amendments also clarify that Topic 718 does not apply to share-based payments used to effectively provide (1) financing to the issuer or (2) awards granted in conjunction with selling goods or services to customers as part of a contract accounted for under Topic 606, Revenue from Contracts with Customers. For emerging growth companies, the amendments are effective for fiscal years beginning after December 15, 2019, and interim periods within fiscal years beginning after December 15, 2020. This Update has the potential to only impact share-based payments to members of the Company’s board of directors. The Company will assess the potential impact that this ASU will have on the Company’s consolidated financial statements.

In June 2018, the FASB issued ASU 2018-09, Codification Improvements, which affects a wide variety of topics, including amendments to subtopics: 220-10, Income Statement—Reporting Comprehensive Income—Overall; 470-50, Debt—Modifications and Extinguishments; 480-10, Distinguishing Liabilities from Equity—Overall; 718-740, Compensation—Stock Compensation—Income Taxes; 805-740, Business Combinations—Income Taxes; and, 820-10, Fair Value Measurement—Overall. The transition and effective date guidance is based on the facts and circumstances of each amendment. Some of the amendments in ASU 2018-09 do not require transition guidance and will be effective upon issuance of ASU 2018-09. However, many of the amendments do have transition guidance with effective dates for annual periods beginning after December 15, 2018, for public business entities and after December 15, 2019 for emerging growth companies.

In August 2018, the FASB issued ASU 2018-13, Fair Value Measurement (Topic 820): Disclosure Framework – Changes to the Disclosure Requirements for fair Value Measurement. The amendments in this Update modify the disclosure requirements on fair value measurements in Topic 820, Fair Value Measurement, based on the concepts in the Concepts Statement, including the consideration of costs and benefits. These disclosure requirements were removed from the topic: (1) The amount of and reasons for transfers between Level 1 and Level 2 of the fair value hierarchy, (2) the policy for timing of transfers between levels, and (3) the valuation processes for Level 3 fair value measurements. These disclosure requirements were modified: (1) For investments in certain entities that calculate net asset value, an entity is required to disclose the timing of liquidation of an investee’s assets and the date when restrictions from redemption might lapse only if the investee has communicated the timing to the entity or announced the timing publicly, and (2) the amendments clarify that the measurement uncertainty disclosure is to communicate information about the uncertainty in measurement as of the reporting date. The following disclosure requirements were added: (1) The changes in unrealized gains and losses for the period included in other comprehensive income for recurring Level 3 fair value measurements held at the end of the reporting period, (2) the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements. For certain unobservable inputs, an entity may disclose other quantitative information (such as the median or arithmetic average) in lieu of the weighted average if the entity determines that other quantitative information would be a more reasonable and rational method to reflect the distribution of unobservable inputs used to develop Level 3 fair value measurements. In addition, the amendments eliminate “at a minimum” from the phrase “an entity shall disclose at a minimum to promote the appropriate exercise of discretion by entities when considering fair value measurement disclosures and to clarify that materiality is an appropriate consideration of entities and their auditors when evaluating disclosure requirements”. The amendments in this Update are effective for emerging growth companies for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements, and the narrative description of measurement uncertainty should be applied prospectively for only the most recent interim or annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. Early adoption is permitted upon issuance of this Update. An entity is permitted to early adopt any removed or modified disclosures upon issuance of this Update and delay adoption of the additional disclosures until their effective date. As an emerging growth company, RBB will adopt this Update on January 1, 2021.

In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. This Update provides additional guidance to ASU 2015-05, “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Fees Paid in a Cloud Computing Arrangement” (CCA), on the accounting for implementation, setup, and other upfront costs (collectively referred to as implementation costs) apply to entities that are a customer in a hosting arrangement. This Update applies to entities that are a customer in a hosting arrangement, which is a service contract. Costs for implementation activities in the application development stage are capitalized depending on the nature of the costs, while costs incurred during the preliminary project and post-implementation stages are expensed as the activities are performed. This Update also require the customer to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. This Update are effective for an emerging growth company for annual reporting periods beginning after December 15, 2020, and interim periods within annual periods beginning after December 15, 2021. Early adoption of the amendments in this Update is permitted, including adoption in any interim period, for all entities. The amendments in this Update should be applied either retrospectively or prospectively to all implementation costs incurred after the date of adoption. This Update could be material should RBB incur implementation costs for a CCA that is a service contract.

Acquisitions

12 Months Ended

Dec. 31, 2018

Business Combinations [Abstract]

Acquisitions

NOTE 3 – ACQUISITIONS

First American International Bancorp Acquisition:

On October 15, 2018, the Company acquired all the assets and assumed all the liabilities of First American International Bancorp in exchange for cash of $34.8 million and RBB stock valued at $69.6 million from issuance of 3,011,762 common shares at $23.11 per share. FAIC operated nine branches in the New York City metropolitan area. The Company acquired FAIC to strategically establish a presence in the New York area. Goodwill in the amount of $28.4 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 FAIC as of October 15, 2018 and the fair value adjustments and amounts recorded by the Company in 2018 under the acquisition method of accounting:

	FAIC			Fair Value			Fair
(dollars in thousands)	Book Value			Adjustments			Value
Assets acquired
Cash and cash equivalents	$	55,891		$	—		$	55,891
Fed funds sold		218			—			218
Interest-bearing deposits in other financial Institutions		3,801			—			3,801
Investments - held to maturity		30,814			(611	)		30,203
Investments - available for sale		14,388			—			14,388
Mortgage loans held for sale		1,915			—			1,915
Loans, gross		721,732			(6,161	)		715,571
Allowance for loan losses		(9,583	)		9,583			—
Bank premises and equipment		5,785			3,439			9,224
Mortgage servicing rights		11,274			(660	)		10,614
Core deposit premium		—			6,738			6,738
Other assets		3,518			(2,119	)		1,399
Total assets acquired	$	839,753		$	10,209		$	849,962
Liabilities assumed
Deposits	$	629,609		$	94		$	629,703
FHLB advances		124,500			—			124,500
Subordinated debentures		7,217			(1,241	)		5,976
Other liabilities		14,940			(1,153	)		13,787
Total liabilities assumed		776,266			(2,300	)		773,966
Excess of assets acquired over liabilities assumed		63,487			12,509			75,996
	$	839,753		$	10,209
Stock consideration								69,602
Cash paid								34,837
Goodwill recognized							$	28,443

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.

The fair value of net assets acquired includes fair value adjustments to certain receivables that were not considered impaired as of the acquisition date. The fair value adjustments were determined using discounted contractual cash flows. However, the Company believes that all contractual cash flows related to these financial instruments will be collected. As such, these receivables were not considered impaired at the acquisition date and were not subject to the guidance relating to purchased credit impaired loans, which have shown evidence of credit deterioration since acquisition. Receivables acquired that were not subject to these requirements include non-impaired loans and customer receivables with a fair value and gross contractual amounts receivable of $715.6 million and $721.7 million on the date of acquisition.

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 FAIC.

The operating results of the Company for the twelve months ending December 31, 2018 include the operating results of FAIC since its acquisition date of October 15, 2018. The following table presents the net interest and other income, net income and earnings per share as if the merger with FAIC was effective as of January 1, 2018. The unaudited pro forma information in the following table is intended for informational purpose only and is not necessarily indicative of our future operating results or operating results that would have occurred had the merger been completed at the beginning of the year. No assumptions have been applied to the pro forma results of operations regarding possible revenue enhancements, expense efficiencies or asset dispositions.

	Year Ended December 31,
	2018		2017		2016
Net interest and other income	$	122,640	$	120,778	$	103,966
Net income		37,084		31,559		23,665
Basic earnings per share		1.87		1.85		1.50
Diluted earnings per share		1.80		1.73		1.42

Investment Securities

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

Investment Securities

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, 2018 and 2017, and the corresponding amounts of gross unrealized gains and losses recognized in accumulated other comprehensive income:

			Gross		Gross
(dollars in thousands)	Amortized		Unrealized		Unrealized			Fair
December 31, 2018	Cost		Gains		Losses			Value
Available for sale
Government agency securities	$	1,873	$	—	$	(58	)	$	1,815
SBA agency securities		5,354		—		(185	)		5,169
Mortgage-backed securities
Government sponsored agencies		23,125		—		(584	)		22,541
Collateralized mortgage obligations		12,696		1		(631	)		12,066
Corporate debt securities		32,615		105		(549	)		32,171
	$	75,663	$	106	$	(2,007	)	$	73,762

Held to maturity
Municipal taxable securities	$	4,290	$	142	$	—		$	4,432
Municipal securities		5,671		1		(164	)		5,508
	$	9,961	$	143	$	(164	)	$	9,940

December 31, 2017
Available for sale
Government agency securities	$	2,052	$	—	$	(53	)	$	1,999
SBA agency securities		5,916		—		(99	)		5,817
Mortgage-backed securities
Government sponsored agencies		26,519		17		(324	)		26,212
Collateralized mortgage obligations		13,287		—		(284	)		13,003
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

The Company did not sell any securities in 2017. During 2018 and 2016 the Company sold $44.6 million and $5.1 million of securities, recognizing gross gains of $5,000 and $19,000, respectively. Following the 2018 FAIC acquisition, the Company sold $30.2 million of investment securities obtained from FAIC.

One security with a fair value of $697,000 and $796,000 was pledged to secure a local agency deposit at December 31, 2018 and December 31, 2017, respectively.

The amortized cost and fair value of the investment securities portfolio as of December 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
	Amortized		Fair		Amortized		Fair
(dollars in thousands)	Cost		Value		Cost		Value
Within one year	$	16,571	$	16,559	$	500	$	500
Due from one to five years		30,947		30,047		2,786		2,859
Due from five to ten years		24,116		23,538		1,870		1,940
Due from ten years and greater		4,029		3,618		4,805		4,641
	$	75,663	$	73,762	$	9,961	$	9,940

The following table summarizes securities with unrealized losses at December 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
	Unrealized			Estimated		No. of		Unrealized			Estimated		No. of		Unrealized			Estimated
(dollars in thousands)	Losses			Fair Value		Issuances		Losses			Fair Value		Issuances		Losses			Fair Value
December 31, 2018
Government agency securities	$	—		$	—		—	$	(58	)	$	1,815		2	$	(58	)	$	1,815
SBA securities		—			—		—		(185	)		5,169		4		(185	)		5,169
Mortgage-backed securities
Government sponsored agencies		(11	)		3,484		2		(573	)		23,928		25		(584	)		27,412
Collateralized mortgage obligations		—			—		—		(631	)		12,065		8		(631	)		12,065
Corporate debt securities		(61	)		4,600		4		(488	)		6,548		4		(549	)		11,148
Total available for sale	$	(72	)	$	8,084		6	$	(1,935	)	$	49,525		43	$	(2,007	)	$	57,609

Municipal securities	$	(104	)	$	2,468		6	$	(60	)	$	2,174		4	$	(164	)	$	4,642
Total held to maturity	$	(104	)	$	2,468		6	$	(60	)	$	2,174		4	$	(164	)	$	4,642

December 31, 2017
Government agency securities	$	—		$	—		—	$	(53	)	$	1,999		2	$	(53	)	$	1,999
SBA securities		(32	)		4,039		2		(67	)		1,778		2		(99	)		5,817
Mortgage-backed securities
Government sponsored agencies		(155	)		12,583		12		(169	)		9,909		10		(324	)		22,492
Collateralized mortgage obligations		(204	)		11,062		5		(80	)		1,977		3		(284	)		13,039
Corporate debt securities		(15	)		5,035		2		(33	)		1,972		2		(48	)		7,007
Total available for sale	$	(406	)	$	32,719		21	$	(402	)	$	17,635		19	$	(808	)	$	50,354

Municipal securities	$	(19	)	$	2,232		4	$	—		$	—		—	$	(19	)	$	2,232
Total held to maturity	$	(19	)	$	2,232		4	$	—		$	—		—	$	(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.

Loans

12 Months Ended

Dec. 31, 2018

Receivables [Abstract]

Loans

NOTE 5 - LOANS

The Company's loan portfolio consists primarily of loans to borrowers within the Los Angeles, California metropolitan area, the New York City metropolitan area, and Las Vegas, 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.

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

(dollars in thousands)	2018			2017			2016
Beginning balance	$	13,773		$	14,162		$	10,023
Additions (reductions) to the allowance charged to expense		4,469			(1,053	)		4,974
Recoveries on loans charged-off		36			747			—
		18,278			13,856			14,997
Less loans charged-off		(701	)		(83	)		(835	)
Ending balance	$	17,577		$	13,773		$	14,162

The following table presents the recorded investment in loans and impairment method as of December 31, 2018, 2017 and 2016 and the activity in the allowance for loan losses for the years then ended, by portfolio segment:

(dollars in thousands)
December 31, 2018	Real Estate		Commercial			Unallocated			Total
Allowance for loan losses:
Beginning of year	$	9,309	$	4,044		$	420		$	13,773
Provisions		4,128		761			(420	)		4,469
Charge-offs		—		(701	)		—			(701	)
Recoveries		—		36			—			36
	$	13,437	$	4,140		$	—		$	17,577
Reserves:
Specific	$	44	$	—		$	—		$	44
General		13,393		4,140			—			17,533
Loans acquired with deteriorated credit quality		—		—			—			—
	$	13,437	$	4,140		$	—		$	17,577
Loans evaluated for impairment:
Individually	$	2,309	$	972		$	—		$	3,281
Collectively		1,750,896		387,838			—			2,138,734
Loans acquired with deteriorated credit quality		—		—			—			—
	$	1,753,205	$	388,810		$	—		$	2,142,015

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

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 are considered impaired.

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

(dollars in thousands)			Special
December 31, 2018	Pass		Mention		Substandard		Impaired		Total
Real estate:
Construction and land development	$	112,959	$	—	$	—	$	276	$	113,235
Commercial real estate		743,123		7,069		6,496		2,033		758,721
Single-family residential mortgages		880,860		—		389		—		881,249
Commercial:
Other		295,226		6,286		2,798		—		304,310
SBA		79,057		—		4,471		972		84,500
	$	2,111,225	$	13,355	$	14,154	$	3,281	$	2,142,015

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 as of December 31, 2018 and 2017 by class of loans:

(dollars in thousands)	30-59		60-89		90 Days		Total		Loans Not				Non-Accrual
December 31, 2018	Days		Days		Or More		Past Due		Past Due		Total Loans		Loans ⁽¹⁾
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	113,235	$	113,235	$	—
Commercial real estate		—		678		—		678		758,043		758,721		—
Single-family residential mortgages		1,548		950		—		2,498		878,751		881,249		—
Commercial:
Other		—		—		—		—		304,310		304,310		—
SBA		957		—		914		1,871		82,629		84,500		914
	$	2,505	$	1,628	$	914	$	5,047	$	2,136,968	$	2,142,015	$	914
Real estate:
Single-family residential mortgages held for sale	$	—	$	458	$	—	$	458	$	434,064	$	434,522	$	—

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

Information relating to individually impaired loans presented by class of loans was as follows as of December 31, 2018, 2017 and 2016:

	Unpaid
(dollars in thousands)	Principal		Recorded		Average		Interest		Related
December 31, 2018	Balance		Investment		Balance		Income		Allowance
With no related allowance recorded
Construction and land development	$	276	$	276	$	283	$	23	$	—
Commercial real estate		2,033		2,033		2,126		134		—
Residential mortgage loans		—		—		—		—		—
Commercial - SBA		797		1,498		1,377		19		—
With related allowance recorded
Commercial-SBA		175		175		193		1		44
Total	$	3,281	$	3,982	$	3,979	$	177	$	44

December 31, 2017
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

No interest income was recognized on a cash basis as of December 31, 2018, 2017 and 2016.

The Company had four and four loans identified as troubled debt restructurings ("TDR's") at December 31, 2018 and 2017, respectively. There were no specific reserves allocated to the loans as of December 31, 2018 and 2017. There were no commitments to lend additional amounts as of December 31, 2018 and 2017, respectively, to customers with outstanding loans that are classified as TDR's.

During the year ended December 31, 2018, 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 2017.

The following table presents loans by class modified as TDR's that occurred during the year ended December 31, 2018:

Pre-

Post-

Modification

(dollars in thousands)

Number of

Recorded

December 31, 2018

Loans

Investment

Commercial real estate

1,029

There were no defaults of TDR’s in 2018 and 2017 where the loan was modified within the prior twelve months.

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 purchased credit-impaired loan fully paid off in September 2018. The outstanding balance and carrying amount of purchased credit-impaired loans as of December 31, 2018 and 2017 were as follows:

(dollars in thousands)	2018		2017
Outstanding balance	$	—	$	322
Carrying amount	$	—	$	315

For these purchased credit-impaired loans, the Company did not increase the allowance for loan losses during 2018 or 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 2018, 2017 and 2016:

(dollars in thousands)	2018			2017			2016
Beginning balance	$	7		$	142		$	349
Disposals		—			—			—
Restructuring as TDR		—			—			(22	)
Accretion of income		(7	)		(135	)		(185	)
Ending balance	$	—		$	7		$	142

- 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

12 Months Ended

Dec. 31, 2018

Loan Servicing [Abstract]

Loan Servicing

NOTE 6 - LOAN SERVICING

Mortgage and SBA loans serviced for others are not reported as assets. The principal balances as of December 31, 2018 and 2017 are as follows:

(dollars in thousands)	2018		2017
Loans serviced for others:
Mortgage loans	$	1,586,499	$	384,437
SBA loans	$	184,664	$	175,919

Activity for servicing assets follows:

	2018						2017						2016
	Mortgage			SBA			Mortgage			SBA			Mortgage			SBA
(dollars in thousands)	Loans			Loans			Loans			Loans			Loans			Loans
Servicing assets:
Beginning of year	$	1,540		$	4,417		$	1,002		$	2,702		$	298		$	1,807
Acquisitions		10,651			—			—			—			—			—
Additions		1,562			1,932			1,115			2,628			912			1,353
Disposals		(197	)		(1,177	)		(172	)		(367	)		—			—
Amortized to expense		(698	)		(660	)		(405	)		(546	)		(208	)		(458	)
End of year	$	12,858		$	4,512		$	1,540		$	4,417		$	1,002		$	2,702

The fair value of servicing assets for mortgage loans was $15.3 million and $2.5 million as of December 31, 2018 and 2017, respectively. Fair value at December 31, 2018 was determined using a discount rate of 10.59%, prepayment speeds ranging from 8.26% to 16.82%, depending on the stratification of the specific right, and a weighted-average default rate of 0.20%. 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%.

The fair value of servicing assets for SBA loans was $6.1 million and $5.9 million as of December 31, 2018 and 2017, respectively. Fair value at December 31, 2018 was determined using a discount rate of 8.50%, prepayment speeds ranging from 11.43% to 12.11%, depending on the stratification of the specific right, and a weighted-average default rate of 0.52%. Fair value at December 31, 2017 was determined using a discount rate of 8.50% and prepayment speeds ranging from 11.40% to 13.78%, depending on the stratification of the specific right.

Servicing fees net of servicing asset amortization totaled $850,000, $722,000, and $615,000 for the years ended December 31, 2018, 2017, and 2016, respectively.

Premises and Equipment

12 Months Ended

Dec. 31, 2018

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)	2018			2017
Land	$	5,020		$	2,956
Building and improvements		7,823			2,467
Furniture, fixtures, and equipment		4,833			3,222
Leasehold improvements		4,845			2,872
		22,521			11,517
Less accumulated depreciation and amortization		(6,312	)		(5,359	)
Construction in progress		1,098			425
	$	17,307		$	6,583

Depreciation and leasehold amortization expense was $989,000, $686,000, and $750,000 for 2018, 2017, and 2016, 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, 2018:

(dollars in thousands)
Year ending December 31:
2019	$	5,610
2020		5,081
2021		3,639
2022		3,470
2023		2,936
Thereafter		9,149
	$	29,885

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 $2.7 million, $1.5 million, and $1.6 million for 2018, 2017, and 2016, respectively.

The lease for the Company’s downtown headquarters expired in May 2018. In October 2018 the Company signed a lease for a new headquarters office at 1055 Wilshire Boulevard, Suite 1220, Los Angeles, California 90017, which the Company occupied in November 2018. In February 2018 the Company signed a lease for a new office in Irvine which the Company occupied in October 2018. In September 2017 the Company signed a lease to occupy a new location in Oxnard which the Company occupied in March 2018. In October 2018 the Company signed a lease to occupy a new location in Flushing, New York which the Company occupied in February 2019. The future payments for all of the new leases are included in the schedule above.

Deposits

12 Months Ended

Dec. 31, 2018

Maturities Of Time Deposits [Abstract]

Deposits

NOTE 8 - DEPOSITS

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

(dollars in thousands)
One year	$	967,811
Two to three years		152,567
Over three years		5,652
	$	1,126,030

Long-term Debt

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Long-term Debt

NOTE 9 - LONG-TERM DEBT

At December 31, 2018 and 2017, respectively, long-term debt was as follows:

(dollars in thousands)	2018		2017
Principal	$	105,000	$	50,000
Unamortized debt issuance costs	$	1,292	$	472

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.

In November 2018, the Company issued $55 million of 6.18% fixed to floating rate subordinated debentures, due December 1, 2028. The interest rate is fixed through December 1, 2023 and floats at 3 month LIBOR plus 315 basis points thereafter. The Company can redeem these subordinated debentures beginning December 1, 2023. The sub-debt is considered Tier-two capital at the Company. The Company allocated $25 million to the Bank as Tier-one capital.

Subordinated debentures

12 Months Ended

Dec. 31, 2018

Debt Instruments [Abstract]

Subordinated Debentures

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 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 have a variable rate of interest equal to the three month London Interbank Offered Rate (LIBOR) plus 1.65%, which was 4.45% at December 31, 2018.

In October 2018, the Company, through the acquisition of First American International Corp. acquired First American International Statutory Trust I (“Trust”), a Delaware statutory trust formed in December 2004. The Trust issued 7,000 units of thirty-year fixed to floating rate capital securities with an aggregate liquidation amount of $7,000,000 to an independent investor, and all of its common securities, amounting to $217,000, which is included in other assets. There was a $1.2 million 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 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 subordinated debenture have a variable rate of interest equal to the three-month LIBOR plus 2.25% through final maturity on December 15, 2034. The rate at December 31, 2018, was 5.04%.

The Company paid interest expenses of $263,000 in 2018, $144,000 in 2017 and $103,000 in 2016. The amount of amortization expense recognized in 2018 was $106,000, in 2017 was $90,000 and $79,000 in 2016.

For regulatory reporting purposes, the Federal Reserve Board has indicated that the capital securities qualify as Tier I capital of the Company subject to previously specified limitations, until further notice. If regulators make a determination that the capital securities can no longer be considered in regulatory capital, the securities become callable and the Company may redeem them.

In July 2017, British banking regulators announced plans 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

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Borrowing Arrangements

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, 2018 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, 2018 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 $17 million at December 31, 2018 is collateralized by loans pledged with a carrying value of $28.4 million.

FHLB Secured Line of Credit. The secured borrowing capacity of $823.1 million at December 31, 2018 is collateralized by loans pledged with a carrying value of $943.0 million.

At December 31, 2018, the Company had $319.5 million in short-term borrowings with the FHLB, with $35.0 million at 2.42% which matured and rolled over on January 15, 2019, and the remaining $284.5 million at 2.56% which matured and rolled over on January 2, 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. There were no amounts outstanding under any of the other borrowing arrangements above as of December 31, 2018 and 2017.

Income Taxes

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Income Taxes

NOTE 12 - 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.

Income tax expense consists of the following:

(dollars in thousands)	2018			2017		2016
Current:
Federal	$	6,616		$	12,097	$	9,345
State		3,451			3,773		2,841
		10,067			15,870		12,186
Deferred		(131	)		2,492		1,289
Deferred tax adjustment for enacted change in tax rate		(479	)		2,591		—
Affordable housing tax credits		644			316		14
	$	10,101		$	21,269	$	13,489

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

	2018						2017						2016
(dollars in thousands)	Amount			Rate			Amount			Rate			Amount			Rate
Statutory federal tax	$	9,703			21.0	%	$	16,379			35.0	%	$	11,399			35.0	%
State franchise tax, net of federal benefit		3,488			7.5	%		3,135			6.7	%		2,281			7.0	%
Tax-exempt income		(27	)		-0.1	%		(297	)		-0.6	%		(202	)		-0.6	%
Tax impact from enacted change in tax rate		(479	)		-1.0	%		2,591			5.5	%		—			0.0	%
Stock-based compensation		(2,643	)		-5.7	%		—			0.0	%		—			0.0	%
Other items, net		59			0.1	%		(539	)		-1.2	%		11			0.0	%
Actual tax expense	$	10,101			21.8	%	$	21,269			45.4	%	$	13,489			41.4	%

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)	2018			2017
Deferred tax assets:
Pre-opening expenses	$	154		$	173
Allowance for loan losses		5,545			4,072
Stock-based compensation		1,419			1,973
Off balance sheet reserve		217			83
Operating loss carryforwards		1,688			285
Other real estate owned		10			10
Unrealized loss on AFS securities		600			186
Mark to market on held for sale mortgage loans		2,451			676
Other		1,220			1,292
		13,304			8,750
Deferred tax liabilities:
Depreciation		(521	)		(511	)
Acquisition accounting fair value adjustments		(2,067	)		(145	)
Mortgage servicing rights		(3,586	)		(300	)
Other		(2,488	)		(1,708	)
		(8,662	)		(2,664	)
Net deferred tax assets	$	4,642		$	6,086

The Company has net operating loss carryforwards from acquisitions of approximately $34,000 for federal, $1.3 million for California, $12.0 million for New York State and $11.2 million for New York City income tax purposes. Net operating loss carry forwards, to the extent not used will begin to expire in 2028. 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, $11.4 million, $12.4 million and $11.7 million for federal, California, New York State and New York City income tax purposes, respectively. These operating loss carryforwards expire in 2028 through 2038.

The Company is subject to federal income tax and franchise tax of the state of California and New York. Income tax returns for the years ended after December 31, 2014 are open to audit by the federal and New York authorities and for the years ended after December 31, 2013 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, 2018, 2017, and 2016, respectively. The Company has determined that as of December 31, 2018 all tax positions taken to date are highly certain and, accordingly, no accounting adjustment has been made to the consolidated financial statements.

Commitments

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Commitments

NOTE 13 - COMMITMENTS

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.

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

	2018				2017
	Fixed		Variable		Fixed		Variable
(dollars in thousands)	Rate		Rate		Rate		Rate
Commitments to make loans	$	5,211	$	125,610	$	19,438	$	82,522
Unused lines of credit		61,191		75,908		58,291		40,926
Commercial and similar letters of credit		1,042		—		3,013		—
Standby letters of credit		2,701		673		1,225		350
	$	70,145	$	202,191	$	81,967	$	123,798

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 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

12 Months Ended

Dec. 31, 2018

Related Party Transactions

NOTE 14 - RELATED PARTY TRANSACTIONS

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

(dollars in thousands)	2018			2017
Beginning balance	$	2,300		$	3,445
New loans and advances		7,400			2,200
Repayments		(6,100	)		(3,345	)
Ending balance	$	3,600		$	2,300

Loan commitments outstanding to executive officers, directors and their related interests with whom they are associated totaled approximately $800,000 and $2.1 million as of December 31, 2018 and 2017, respectively.

Deposits from principal officers, directors, and their affiliates at year-end 2018 and 2017 were $52.1 million and $43.8 million.

Stock Option Plan

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Stock Option Plan

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, 2018, 1,330,545 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 $684,000, $779,000, and $894,000 in 2018, 2017, and 2016 and recognized income tax benefits on that expense of $202,000, $246,000, and $267,000, respectively.

The Company granted restricted stock units for 43,425 shares at a closing price of $29.38 in 2018. There were no restricted stock grants in prior years. These restricted stock units are scheduled to vest over a three year period from the August 15, 2018 grant date.

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. There were no stock options granted in 2018 and 2017.

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

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, 2018 and changes during the year then ended is presented below:

						Weighted-
				Weighted-		Average
				Average		Remaining	Aggregate
				Exercise		Contractual	Intrinsic
(dollars in thousands, except for share amounts)	Shares			Price		Term	Value
Outstanding at beginning of year		2,261,800		$	11.32
Granted		—		$	—
Exercised		(1,035,942	)	$	9.57
Forfeited or expired		(10,761	)	$	9.29
Outstanding at end of year		1,215,097		$	12.83	4.7 years	$	5,878
Options exercisable		1,153,089		$	12.54	4.5 years	$	5,878

As of December 31, 2018 there was approximately $113,000 of total unrecognized compensation cost related to outstanding stock options that will be recognized over a weighted-average period of 4 months. The intrinsic value of options exercised was $13.6 million, $2.8 million, and $216,000 in 2018, 2017, and 2016, respectively.

The total fair value of the shares vested was $734,000, $930,000, and $1,511,000 in 2018, 2017, and 2016, respectively. The number of nonvested stock options were 62,008 and 163,996 with a weighted average grant date fair value of $6.48 and $6.53 as of December 31, 2018 and 2017.

Cash received from the exercise of 1,035,942 share options was $9.6 million for the period ended December 31, 2018 with a related tax benefit of $3.9 million.

Regulatory Matters

12 Months Ended

Dec. 31, 2018

Regulated Operations [Abstract]

Regulatory Matters

NOTE 16 - 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 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 capital conservation buffer is being phased in for 0.0% for 2015 to 2.50% by 2019. The net unrealized gain or loss on available for sale securities is not included in computing regulatory capital. Management believes, as of December 31, 2018 and 2017, that the Bank meets all capital adequacy requirements to which it is subject.

As of December 31, 2018, 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, 2018:

						Amount of Capital Required
											To Be Well-
											Capitalized
						For Capital					Under Prompt
						Adequacy					Corrective
	Actual					Purposes					Provisions
(dollars in thousands)	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of December 31, 2018:
Tier 1 Leverage Ratio
Consolidated	$	321,407		11.80	%	NA		NA			NA		NA
Bank	$	370,304		13.66	%	$	108,445		4.0	%	$	135,556		5.0	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	311,901		15.28	%	NA		NA			NA		NA
Bank	$	370,304		18.17	%	$	91,722		4.5	%	$	132,487		6.5	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	321,407		15.74	%	NA		NA			NA		NA
Bank	$	370,304		18.17	%	$	122,296		6.0	%	$	163,061		8.0	%
Total Risk-Based Capital Ratio
Consolidated	$	443,379		21.71	%	NA		NA			NA		NA
Bank	$	388,569		19.07	%	$	163,061		8.0	%	$	203,826		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, 2017:

						Amount of Capital Required
											To Be Well-
											Capitalized
						For Capital					Under Prompt
						Adequacy					Corrective
	Actual					Purposes					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 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.

Fair Value Measurements

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value Measurements

NOTE 17 - 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 December 31, 2018.

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

(dollars in thousands)	Fair Value Measurements Using:
December 31, 2018	Level 1		Level 2		Level 3		Total
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	1,815			$	1,815
Collateralized mortgage obligations				12,066				12,066
Mortgage-backed securities
Government sponsored agencies				22,541				22,541
SBA agency securities				5,169				5,169
Corporate debt securities				32,171				32,171
	$	—	$	73,762	$	—	$	73,762
On a non-recurring basis:
Other real estate owned	$	—	$	—	$	1,101	$	1,101
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 2018 or 2017.

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

Weighted-

(dollars in thousands)

Fair Value

Valuation

Unobservable

Adjustment

Average

December 31, 2018

Amount

Technique

Input

Range

Adjustment

Other real estate owned

1,101

Third party

appraisals

Management adjustments to reflect

current conditions and selling costs

16%

December 31, 2017

Other real estate owned

293

Third party

appraisals

Management adjustments to reflect

current conditions and selling costs

21%

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2018

Fair Value Disclosures [Abstract]

Fair Value of Financial Instruments

NOTE 18 - 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.

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 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, 2018 and 2017 are summarized as follows:

		2018				2017
	Fair Value	Carrying		Fair		Carrying		Fair
(dollars in thousands)	Hierarchy	Value		Value		Value		Value
Financial Assets:
Cash and due from banks	Level 1	$	147,685	$	147,685	$	70,048	$	70,048
Federal funds sold and other cash equivalents	Level 1		—		—		80,000		80,000
Interest-earning deposits in other financial institutions	Level 1		600		600		600		600
Investment securities - AFS	Level 2		73,762		73,762		64,957		64,957
Investment securities - HTM	Level 2		9,961		9,940		10,009		10,250
Mortgage loans held for sale	Level 2		434,522		438,948		125,847		128,972
Loans, net	Level 3		2,124,438		2,114,341		1,235,301		1,236,289
Financial Liabilities:
Deposits	Level 2	$	2,144,041	$	2,143,196	$	1,337,281	$	1,336,353
FHLB advances	Level 2		319,500		319,500		25,000		25,000
Long-term debt	Level 2		103,708		79,756		49,528		44,319
Subordinated debentures	Level 3		9,506		10,356		3,424		3,348

- 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")

12 Months Ended

Dec. 31, 2018

Earnings Per Share [Abstract]

Earnings Per Share ("EPS")

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:

	2018					2017					2016
(dollars in thousands except per share amounts)	Income		Shares			Income		Shares			Income		Shares
Net income as reported	$	36,105				$	25,528				$	19,079
Shares outstanding				20,000,022					15,908,893					12,827,803
Impact of weighting shares				(2,848,800	)				(1,830,612	)				(26,813	)
Used in basic EPS		36,105		17,151,222			25,528		14,078,281			19,079		12,800,990
Dilutive effect of outstanding
Stock options				816,431					1,160,084					894,910
Used in dilutive EPS	$	36,105		17,967,653		$	25,528		15,238,365		$	19,079		13,695,900

Basic earnings per common share	$	2.11				$	1.81				$	1.49
Diluted earnings per common share	$	2.01				$	1.68				$	1.39

Stock options for 399,000 and 321,000 shares of common stock were not considered in computing diluted earnings per common share for 2018 and 2016, respectively, because they were anti-dilutive. There were no anti-dilutive stock options in 2017.

Qualified Affordable Housing Project Investments

12 Months Ended

Dec. 31, 2018

Text Block [Abstract]

Qualified Affordable Housing Project Investments

NOTE 20 – QUALIFIED AFFORDABLE HOUSING PROJECT INVESTMENTS

The Company began investing in qualified affordable housing projects in 2016. The balance of the investment for qualified affordable housing projects was $9.5 million at December 31, 2018 and $5.7 million at December 31, 2017. 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 $6.8 million at December 31, 2018. The Company expects to fulfill these commitments during the year ending 2027.

During the years ending December 31, 2018 and 2017, the Company recognized amortization expense of $644,000 and $316,000, respectively, which was included within income tax expense on the consolidated statements of income.

During the years ended December 31, 2018 and 2017, the Company recognized tax credits from its investment in affordable housing tax credits of $573,000 and $275,000, respectively. The Company had no impairment losses during the years ended December 31, 2018 and 2017

Parent Only Condensed Financial Information

12 Months Ended

Dec. 31, 2018

Condensed Financial Information Of Parent Company Only Disclosure [Abstract]

Parent Only Condensed Financial Information

NOTE 21 - PARENT ONLY CONDENSED FINANCIAL INFORMATION

(Dollars in Thousands)	2018			2017
ASSETS
Cash and cash equivalents	$	45,540		$	45,769
Investment in Bank		433,023			263,022
Investment in RAM		6,796			6,268
Other assets		2,820			3,538
Total assets	$	488,179		$	318,597

LIABILITIES AND SHAREHOLDERS' EQUITY
Long term debt		103,708			49,528
Subordinated debentures		9,506			3,424
Other liabilities		347			37
Total liabilities		113,561			52,989
Shareholders' equity:
Common stock		288,610			205,927
Additional paid-in capital		5,659			8,426
Retained earnings		81,615			51,697
Non-controlling interest		72			—
Accumulated other comprehensive income (loss)		(1,338	)		(442	)
Total shareholders' equity		374,618			265,608
Total liabilities and shareholders' equity	$	488,179		$	318,597

(Dollars in Thousands)	2018			2017			2016
Interest Income	$	15		$	—		$	—
Interest expense		4,083			3,629			2,728
Noninterest expense		1,690			704			123
Loss before equity in undistributed income of subsidiaries		(5,758	)		(4,333	)		(2,851	)
Equity in undistributed income of:
Bank		39,198			27,620			20,483
RAM		528			143			274
Income before income taxes		33,968			23,430			17,906
Income tax benefit		1,702			2,036			1,173
Net income		35,670			25,466			19,079
Other comprehensive income (loss)		(895	)		(104	)		(74	)
Total comprehensive income	$	34,775		$	25,362		$	19,005

(Dollars in Thousands)	2018			2017			2016
Cash flows from operating activities:
Net income	$	35,670		$	25,466		$	19,079
Net amortization of other		268			235			188
Provision for deferred income taxes		(1,905	)		1,807			(1,172	)
Undistributed income of subsidiaries		(39,726	)		(27,763	)		(20,757	)
Change in other assets and liabilities		3,927			(3,861	)		(159	)
		(1,766	)		(4,116	)		(2,821	)
Cash flows from investment activities:
Net cash acquired (outlay) in connection with acquisition		(41,358	)		—			(839	)
Investment in subsidiaries		(15,000	)		(25,000	)		(35,000	)
		(56,358	)		(25,000	)		(35,839	)
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs		54,018			—			49,274
Issuance of common stock, net of issuance costs		—			60,210			—
Dividends paid		(5,753	)		(5,118	)		(2,554	)
Stock options exercised		9,630			2,296			585
		57,895			57,388			47,305
Increase in cash and cash equivalents		(229	)		28,272			8,645
Cash and cash equivalents beginning of year		45,769			17,497			8,852
Cash and cash equivalents end of year	$	45,540		$	45,769		$	17,497

Subsequent Events

12 Months Ended

Dec. 31, 2018

Subsequent Events [Abstract]

Subsequent Events

NOTE 22 – SUBSEQUENT EVENTS

On January 17, 2019, the Company announced that the Board of Directors had declared a cash dividend of $0.10 per common share. The cash dividend is payable on February 15, 2019 to stockholders of record at the close of business on January 31, 2019 in the amount of $2.0 million.

On March 22, 2019, the Company closed its offer to exchange (the “Exchange Offer”) up to $55,000,000 aggregate principal amount of 6.180% fixed-to-floating rate subordinated notes due 2028, which were issued in a private placement to certain qualified institutional buyers and accredited investors, for a like principal amount of its new 6.180% fixed-to-floating rate subordinated notes due 2028 registered under the Securities Act of 1933, as amended.

According to information provided by the exchange agent, UMB Bank, N.A., $55,000,000 aggregate principal amount, or 100% of the privately-placed subordinated notes, were tendered for exchange in the Exchange Offer.

Quarterly Income Statements (Unaudited)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Quarterly Income Statements (Unaudited)

NOTE 23 – QUARTERLY INCOME STATEMENTS (Unaudited)

The following table presents the unaudited quarterly condensed income statements for the years 2018 and 2017.

	2018								2017
(dollars in thousands)	4th Quarter		3rd Quarter		2nd Quarter		1st Quarter		4th Quarter		3rd Quarter		2nd Quarter			1st Quarter
Interest income	$	35,181	$	24,473	$	22,284	$	20,177	$	21,478	$	18,346	$	17,521		$	16,759
Interest expense		9,599		5,857		4,457		3,732		3,588		3,618		3,487			3,245
Net interest income		25,582		18,616		17,827		16,445		17,890		14,728		14,034			13,514
Provision (recapture) for credit losses		1,890		1,695		700		184		2,435		700		(4,188	)		—
Net interest income after provision for credit losses		23,692		16,921		17,127		16,261		15,455		14,028		18,222			13,514
Noninterest income:		5,489		2,105		2,793		2,455		3,798		3,796		3,175			2,432
Noninterest expense:		15,503		8,654		8,191		8,289		6,885		7,200		6,960			6,578
Income before income taxes		13,678		10,372		11,729		10,427		12,368		10,624		14,437			9,368
Income tax expense		4,188		2,041		2,292		1,580		7,480		4,013		5,901			3,875
Net income	$	9,490	$	8,331	$	9,437	$	8,847	$	4,888	$	6,611	$	8,536		$	5,493

Net income per share
Basic	$	0.48	$	0.50	$	0.58	$	0.55	$	0.26	$	0.45	$	0.67		$	0.43
Diluted		0.47		0.48		0.54		0.52		0.24		0.42		0.62			0.40

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

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Basis of Presentation

Reclassifications

Principles of Consolidation and Nature of Operations

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

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

Transfer of Financial Assets

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:
2019	$	1,501
2020		1,285
2021		1,056
2022		879
2023		749
Thereafter		2,131
Total	$	7,601

Bank Owned Life Insurance

FHLB Stock and Other Equity Securities

Stock-Based Compensation

Income Taxes

Retirement Plans

The Company established a 401(k) plan in 2010. The Company contributed $341,000, $272,000, and $221,000 in 2018, 2017, and 2016, 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")

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

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

12 Months Ended

Dec. 31, 2018

Accounting Policies [Abstract]

Schedule of Future Estimated Amortization Expense

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

Year ending December 31:
2019	$	1,501
2020		1,285
2021		1,056
2022		879
2023		749
Thereafter		2,131
Total	$	7,601

Acquisitions (Tables) - First American International Bancorp

12 Months Ended

Dec. 31, 2018

Schedule of Assets Acquired and Liabilities Assumed and Fair Value Adjustments

	FAIC			Fair Value			Fair
(dollars in thousands)	Book Value			Adjustments			Value
Assets acquired
Cash and cash equivalents	$	55,891		$	—		$	55,891
Fed funds sold		218			—			218
Interest-bearing deposits in other financial Institutions		3,801			—			3,801
Investments - held to maturity		30,814			(611	)		30,203
Investments - available for sale		14,388			—			14,388
Mortgage loans held for sale		1,915			—			1,915
Loans, gross		721,732			(6,161	)		715,571
Allowance for loan losses		(9,583	)		9,583			—
Bank premises and equipment		5,785			3,439			9,224
Mortgage servicing rights		11,274			(660	)		10,614
Core deposit premium		—			6,738			6,738
Other assets		3,518			(2,119	)		1,399
Total assets acquired	$	839,753		$	10,209		$	849,962
Liabilities assumed
Deposits	$	629,609		$	94		$	629,703
FHLB advances		124,500			—			124,500
Subordinated debentures		7,217			(1,241	)		5,976
Other liabilities		14,940			(1,153	)		13,787
Total liabilities assumed		776,266			(2,300	)		773,966
Excess of assets acquired over liabilities assumed		63,487			12,509			75,996
	$	839,753		$	10,209
Stock consideration								69,602
Cash paid								34,837
Goodwill recognized							$	28,443

Schedule of Net Interest and Other Income, Net Income and Earnings Per Share

	Year Ended December 31,
	2018		2017		2016
Net interest and other income	$	122,640	$	120,778	$	103,966
Net income		37,084		31,559		23,665
Basic earnings per share		1.87		1.85		1.50
Diluted earnings per share		1.80		1.73		1.42

Investment Securities (Tables)

12 Months Ended

Dec. 31, 2018

Investments Debt And Equity Securities [Abstract]

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

			Gross		Gross
(dollars in thousands)	Amortized		Unrealized		Unrealized			Fair
December 31, 2018	Cost		Gains		Losses			Value
Available for sale
Government agency securities	$	1,873	$	—	$	(58	)	$	1,815
SBA agency securities		5,354		—		(185	)		5,169
Mortgage-backed securities
Government sponsored agencies		23,125		—		(584	)		22,541
Collateralized mortgage obligations		12,696		1		(631	)		12,066
Corporate debt securities		32,615		105		(549	)		32,171
	$	75,663	$	106	$	(2,007	)	$	73,762

Held to maturity
Municipal taxable securities	$	4,290	$	142	$	—		$	4,432
Municipal securities		5,671		1		(164	)		5,508
	$	9,961	$	143	$	(164	)	$	9,940

December 31, 2017
Available for sale
Government agency securities	$	2,052	$	—	$	(53	)	$	1,999
SBA agency securities		5,916		—		(99	)		5,817
Mortgage-backed securities
Government sponsored agencies		26,519		17		(324	)		26,212
Collateralized mortgage obligations		13,287		—		(284	)		13,003
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

Amortized Cost and Fair Value of Investment Securities Portfolio Expected Maturity

	Available for Sale				Held to Maturity
	Amortized		Fair		Amortized		Fair
(dollars in thousands)	Cost		Value		Cost		Value
Within one year	$	16,571	$	16,559	$	500	$	500
Due from one to five years		30,947		30,047		2,786		2,859
Due from five to ten years		24,116		23,538		1,870		1,940
Due from ten years and greater		4,029		3,618		4,805		4,641
	$	75,663	$	73,762	$	9,961	$	9,940

Summary of Securities With Unrealized Losses

	Less than Twelve Months							Twelve Months or More							Total
	Unrealized			Estimated		No. of		Unrealized			Estimated		No. of		Unrealized			Estimated
(dollars in thousands)	Losses			Fair Value		Issuances		Losses			Fair Value		Issuances		Losses			Fair Value
December 31, 2018
Government agency securities	$	—		$	—		—	$	(58	)	$	1,815		2	$	(58	)	$	1,815
SBA securities		—			—		—		(185	)		5,169		4		(185	)		5,169
Mortgage-backed securities
Government sponsored agencies		(11	)		3,484		2		(573	)		23,928		25		(584	)		27,412
Collateralized mortgage obligations		—			—		—		(631	)		12,065		8		(631	)		12,065
Corporate debt securities		(61	)		4,600		4		(488	)		6,548		4		(549	)		11,148
Total available for sale	$	(72	)	$	8,084		6	$	(1,935	)	$	49,525		43	$	(2,007	)	$	57,609

Municipal securities	$	(104	)	$	2,468		6	$	(60	)	$	2,174		4	$	(164	)	$	4,642
Total held to maturity	$	(104	)	$	2,468		6	$	(60	)	$	2,174		4	$	(164	)	$	4,642

December 31, 2017
Government agency securities	$	—		$	—		—	$	(53	)	$	1,999		2	$	(53	)	$	1,999
SBA securities		(32	)		4,039		2		(67	)		1,778		2		(99	)		5,817
Mortgage-backed securities
Government sponsored agencies		(155	)		12,583		12		(169	)		9,909		10		(324	)		22,492
Collateralized mortgage obligations		(204	)		11,062		5		(80	)		1,977		3		(284	)		13,039
Corporate debt securities		(15	)		5,035		2		(33	)		1,972		2		(48	)		7,007
Total available for sale	$	(406	)	$	32,719		21	$	(402	)	$	17,635		19	$	(808	)	$	50,354

Municipal securities	$	(19	)	$	2,232		4	$	—		$	—		—	$	(19	)	$	2,232
Total held to maturity	$	(19	)	$	2,232		4	$	—		$	—		—	$	(19	)	$	2,232

Loans (Tables)

12 Months Ended

Dec. 31, 2018

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

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

(dollars in thousands)	2018			2017			2016
Beginning balance	$	13,773		$	14,162		$	10,023
Additions (reductions) to the allowance charged to expense		4,469			(1,053	)		4,974
Recoveries on loans charged-off		36			747			—
		18,278			13,856			14,997
Less loans charged-off		(701	)		(83	)		(835	)
Ending balance	$	17,577		$	13,773		$	14,162

(dollars in thousands)
December 31, 2018	Real Estate		Commercial			Unallocated			Total
Allowance for loan losses:
Beginning of year	$	9,309	$	4,044		$	420		$	13,773
Provisions		4,128		761			(420	)		4,469
Charge-offs		—		(701	)		—			(701	)
Recoveries		—		36			—			36
	$	13,437	$	4,140		$	—		$	17,577
Reserves:
Specific	$	44	$	—		$	—		$	44
General		13,393		4,140			—			17,533
Loans acquired with deteriorated credit quality		—		—			—			—
	$	13,437	$	4,140		$	—		$	17,577
Loans evaluated for impairment:
Individually	$	2,309	$	972		$	—		$	3,281
Collectively		1,750,896		387,838			—			2,138,734
Loans acquired with deteriorated credit quality		—		—			—			—
	$	1,753,205	$	388,810		$	—		$	2,142,015

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

Summary of Risk Category of Loans by Class of Loans

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

(dollars in thousands)			Special
December 31, 2018	Pass		Mention		Substandard		Impaired		Total
Real estate:
Construction and land development	$	112,959	$	—	$	—	$	276	$	113,235
Commercial real estate		743,123		7,069		6,496		2,033		758,721
Single-family residential mortgages		880,860		—		389		—		881,249
Commercial:
Other		295,226		6,286		2,798		—		304,310
SBA		79,057		—		4,471		972		84,500
	$	2,111,225	$	13,355	$	14,154	$	3,281	$	2,142,015

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

Summary of Aging Recorded Investment Past-due Loans

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

(dollars in thousands)	30-59		60-89		90 Days		Total		Loans Not				Non-Accrual
December 31, 2018	Days		Days		Or More		Past Due		Past Due		Total Loans		Loans ⁽¹⁾
Real estate:
Construction and land development	$	—	$	—	$	—	$	—	$	113,235	$	113,235	$	—
Commercial real estate		—		678		—		678		758,043		758,721		—
Single-family residential mortgages		1,548		950		—		2,498		878,751		881,249		—
Commercial:
Other		—		—		—		—		304,310		304,310		—
SBA		957		—		914		1,871		82,629		84,500		914
	$	2,505	$	1,628	$	914	$	5,047	$	2,136,968	$	2,142,015	$	914
Real estate:
Single-family residential mortgages held for sale	$	—	$	458	$	—	$	458	$	434,064	$	434,522	$	—

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

Summary of Individually Impaired Loans Presented by Class of Loans

Information relating to individually impaired loans presented by class of loans was as follows as of December 31, 2018, 2017 and 2016:

	Unpaid
(dollars in thousands)	Principal		Recorded		Average		Interest		Related
December 31, 2018	Balance		Investment		Balance		Income		Allowance
With no related allowance recorded
Construction and land development	$	276	$	276	$	283	$	23	$	—
Commercial real estate		2,033		2,033		2,126		134		—
Residential mortgage loans		—		—		—		—		—
Commercial - SBA		797		1,498		1,377		19		—
With related allowance recorded
Commercial-SBA		175		175		193		1		44
Total	$	3,281	$	3,982	$	3,979	$	177	$	44

December 31, 2017
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

Summary of Loans Class Modified as TDRs

The following table presents loans by class modified as TDR's that occurred during the year ended December 31, 2018:

Pre-

Post-

Modification

(dollars in thousands)

Number of

Recorded

December 31, 2018

Loans

Investment

Commercial real estate

1,029

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

The purchased credit-impaired loan fully paid off in September 2018. The outstanding balance and carrying amount of purchased credit-impaired loans as of December 31, 2018 and 2017 were as follows:

(dollars in thousands)	2018		2017
Outstanding balance	$	—	$	322
Carrying amount	$	—	$	315

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 2018, 2017 and 2016:

(dollars in thousands)	2018			2017			2016
Beginning balance	$	7		$	142		$	349
Disposals		—			—			—
Restructuring as TDR		—			—			(22	)
Accretion of income		(7	)		(135	)		(185	)
Ending balance	$	—		$	7		$	142

Loan Servicing (Tables)

12 Months Ended

Dec. 31, 2018

Loan Servicing [Abstract]

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

Mortgage and SBA loans serviced for others are not reported as assets. The principal balances as of December 31, 2018 and 2017 are as follows:

(dollars in thousands)	2018		2017
Loans serviced for others:
Mortgage loans	$	1,586,499	$	384,437
SBA loans	$	184,664	$	175,919

Schedule of Activity for Servicing Assets

Activity for servicing assets follows:

	2018						2017						2016
	Mortgage			SBA			Mortgage			SBA			Mortgage			SBA
(dollars in thousands)	Loans			Loans			Loans			Loans			Loans			Loans
Servicing assets:
Beginning of year	$	1,540		$	4,417		$	1,002		$	2,702		$	298		$	1,807
Acquisitions		10,651			—			—			—			—			—
Additions		1,562			1,932			1,115			2,628			912			1,353
Disposals		(197	)		(1,177	)		(172	)		(367	)		—			—
Amortized to expense		(698	)		(660	)		(405	)		(546	)		(208	)		(458	)
End of year	$	12,858		$	4,512		$	1,540		$	4,417		$	1,002		$	2,702

Premises and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property Plant And Equipment [Abstract]

Summary of Premises and Equipment

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

(dollars in thousands)	2018			2017
Land	$	5,020		$	2,956
Building and improvements		7,823			2,467
Furniture, fixtures, and equipment		4,833			3,222
Leasehold improvements		4,845			2,872
		22,521			11,517
Less accumulated depreciation and amortization		(6,312	)		(5,359	)
Construction in progress		1,098			425
	$	17,307		$	6,583

Schedule of Future Minimum Rent Payments on Company's Leases

Future minimum rent payments on the Company's leases were as follows as of December 31, 2018:

(dollars in thousands)
Year ending December 31:
2019	$	5,610
2020		5,081
2021		3,639
2022		3,470
2023		2,936
Thereafter		9,149
	$	29,885

Deposits (Tables)

12 Months Ended

Dec. 31, 2018

Maturities Of Time Deposits [Abstract]

Schedule of Maturities of Time Deposits

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

(dollars in thousands)
One year	$	967,811
Two to three years		152,567
Over three years		5,652
	$	1,126,030

Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2018

Debt Disclosure [Abstract]

Schedule of Long-term Debt

At December 31, 2018 and 2017, respectively, long-term debt was as follows:

(dollars in thousands)	2018		2017
Principal	$	105,000	$	50,000
Unamortized debt issuance costs	$	1,292	$	472

- 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://fasb.org/us-gaap/role/ref/legacyRef
-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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-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://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-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 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2018

Income Tax Disclosure [Abstract]

Components of Income Tax Expense

Income tax expense consists of the following:

(dollars in thousands)	2018			2017		2016
Current:
Federal	$	6,616		$	12,097	$	9,345
State		3,451			3,773		2,841
		10,067			15,870		12,186
Deferred		(131	)		2,492		1,289
Deferred tax adjustment for enacted change in tax rate		(479	)		2,591		—
Affordable housing tax credits		644			316		14
	$	10,101		$	21,269	$	13,489

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:

	2018						2017						2016
(dollars in thousands)	Amount			Rate			Amount			Rate			Amount			Rate
Statutory federal tax	$	9,703			21.0	%	$	16,379			35.0	%	$	11,399			35.0	%
State franchise tax, net of federal benefit		3,488			7.5	%		3,135			6.7	%		2,281			7.0	%
Tax-exempt income		(27	)		-0.1	%		(297	)		-0.6	%		(202	)		-0.6	%
Tax impact from enacted change in tax rate		(479	)		-1.0	%		2,591			5.5	%		—			0.0	%
Stock-based compensation		(2,643	)		-5.7	%		—			0.0	%		—			0.0	%
Other items, net		59			0.1	%		(539	)		-1.2	%		11			0.0	%
Actual tax expense	$	10,101			21.8	%	$	21,269			45.4	%	$	13,489			41.4	%

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)	2018			2017
Deferred tax assets:
Pre-opening expenses	$	154		$	173
Allowance for loan losses		5,545			4,072
Stock-based compensation		1,419			1,973
Off balance sheet reserve		217			83
Operating loss carryforwards		1,688			285
Other real estate owned		10			10
Unrealized loss on AFS securities		600			186
Mark to market on held for sale mortgage loans		2,451			676
Other		1,220			1,292
		13,304			8,750
Deferred tax liabilities:
Depreciation		(521	)		(511	)
Acquisition accounting fair value adjustments		(2,067	)		(145	)
Mortgage servicing rights		(3,586	)		(300	)
Other		(2,488	)		(1,708	)
		(8,662	)		(2,664	)
Net deferred tax assets	$	4,642		$	6,086

Commitments (Tables)

12 Months Ended

Dec. 31, 2018

Commitments And Contingencies Disclosure [Abstract]

Schedule of Financial Commitments whose Contractual Amount Represents Credit Risk

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

	2018				2017
	Fixed		Variable		Fixed		Variable
(dollars in thousands)	Rate		Rate		Rate		Rate
Commitments to make loans	$	5,211	$	125,610	$	19,438	$	82,522
Unused lines of credit		61,191		75,908		58,291		40,926
Commercial and similar letters of credit		1,042		—		3,013		—
Standby letters of credit		2,701		673		1,225		350
	$	70,145	$	202,191	$	81,967	$	123,798

Related Party Transactions (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Related Party Transactions

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

(dollars in thousands)	2018			2017
Beginning balance	$	2,300		$	3,445
New loans and advances		7,400			2,200
Repayments		(6,100	)		(3,345	)
Ending balance	$	3,600		$	2,300

Stock Option Plan (Tables)

12 Months Ended

Dec. 31, 2018

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

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

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

Summary of Stock Option Plan

A summary of the status of the Company's stock option plan as of December 31, 2018 and changes during the year then ended is presented below:

						Weighted-
				Weighted-		Average
				Average		Remaining	Aggregate
				Exercise		Contractual	Intrinsic
(dollars in thousands, except for share amounts)	Shares			Price		Term	Value
Outstanding at beginning of year		2,261,800		$	11.32
Granted		—		$	—
Exercised		(1,035,942	)	$	9.57
Forfeited or expired		(10,761	)	$	9.29
Outstanding at end of year		1,215,097		$	12.83	4.7 years	$	5,878
Options exercisable		1,153,089		$	12.54	4.5 years	$	5,878

Regulatory Matters (Tables)

12 Months Ended

Dec. 31, 2018

Regulated Operations [Abstract]

Summary of Actual Capital Amounts and Ratios and Related Regulatory Requirements

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, 2018:

						Amount of Capital Required
											To Be Well-
											Capitalized
						For Capital					Under Prompt
						Adequacy					Corrective
	Actual					Purposes					Provisions
(dollars in thousands)	Amount		Ratio			Amount		Ratio			Amount		Ratio
As of December 31, 2018:
Tier 1 Leverage Ratio
Consolidated	$	321,407		11.80	%	NA		NA			NA		NA
Bank	$	370,304		13.66	%	$	108,445		4.0	%	$	135,556		5.0	%
Common Equity Tier 1 Risk-Based Capital Ratio
Consolidated	$	311,901		15.28	%	NA		NA			NA		NA
Bank	$	370,304		18.17	%	$	91,722		4.5	%	$	132,487		6.5	%
Tier 1 Risk-Based Capital Ratio
Consolidated	$	321,407		15.74	%	NA		NA			NA		NA
Bank	$	370,304		18.17	%	$	122,296		6.0	%	$	163,061		8.0	%
Total Risk-Based Capital Ratio
Consolidated	$	443,379		21.71	%	NA		NA			NA		NA
Bank	$	388,569		19.07	%	$	163,061		8.0	%	$	203,826		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, 2017:

						Amount of Capital Required
											To Be Well-
											Capitalized
						For Capital					Under Prompt
						Adequacy					Corrective
	Actual					Purposes					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	%

Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2018

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 December 31, 2018 and 2017:

(dollars in thousands)	Fair Value Measurements Using:
December 31, 2018	Level 1		Level 2		Level 3		Total
Assets measured at fair value:
On a recurring basis:
Securities available for sale
Government agency securities			$	1,815			$	1,815
Collateralized mortgage obligations				12,066				12,066
Mortgage-backed securities
Government sponsored agencies				22,541				22,541
SBA agency securities				5,169				5,169
Corporate debt securities				32,171				32,171
	$	—	$	73,762	$	—	$	73,762
On a non-recurring basis:
Other real estate owned	$	—	$	—	$	1,101	$	1,101
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

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 as of December 31, 2018 and 2017 is as follows:

Weighted-

(dollars in thousands)

Fair Value

Valuation

Unobservable

Adjustment

Average

December 31, 2018

Amount

Technique

Input

Range

Adjustment

Other real estate owned

1,101

Third party

appraisals

Management adjustments to reflect

current conditions and selling costs

16%

December 31, 2017

Other real estate owned

293

Third party

appraisals

Management adjustments to reflect

current conditions and selling costs

21%

- 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)

12 Months Ended

Dec. 31, 2018

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 December 31, 2018 and 2017 are summarized as follows:

		2018				2017
	Fair Value	Carrying		Fair		Carrying		Fair
(dollars in thousands)	Hierarchy	Value		Value		Value		Value
Financial Assets:
Cash and due from banks	Level 1	$	147,685	$	147,685	$	70,048	$	70,048
Federal funds sold and other cash equivalents	Level 1		—		—		80,000		80,000
Interest-earning deposits in other financial institutions	Level 1		600		600		600		600
Investment securities - AFS	Level 2		73,762		73,762		64,957		64,957
Investment securities - HTM	Level 2		9,961		9,940		10,009		10,250
Mortgage loans held for sale	Level 2		434,522		438,948		125,847		128,972
Loans, net	Level 3		2,124,438		2,114,341		1,235,301		1,236,289
Financial Liabilities:
Deposits	Level 2	$	2,144,041	$	2,143,196	$	1,337,281	$	1,336,353
FHLB advances	Level 2		319,500		319,500		25,000		25,000
Long-term debt	Level 2		103,708		79,756		49,528		44,319
Subordinated debentures	Level 3		9,506		10,356		3,424		3,348

Earnings Per Share ("EPS") (Tables)

12 Months Ended

Dec. 31, 2018

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:

	2018					2017					2016
(dollars in thousands except per share amounts)	Income		Shares			Income		Shares			Income		Shares
Net income as reported	$	36,105				$	25,528				$	19,079
Shares outstanding				20,000,022					15,908,893					12,827,803
Impact of weighting shares				(2,848,800	)				(1,830,612	)				(26,813	)
Used in basic EPS		36,105		17,151,222			25,528		14,078,281			19,079		12,800,990
Dilutive effect of outstanding
Stock options				816,431					1,160,084					894,910
Used in dilutive EPS	$	36,105		17,967,653		$	25,528		15,238,365		$	19,079		13,695,900

Basic earnings per common share	$	2.11				$	1.81				$	1.49
Diluted earnings per common share	$	2.01				$	1.68				$	1.39

Parent Only Condensed Financial Information (Tables) - RBB Bancorp

12 Months Ended

Dec. 31, 2018

Condensed Financial Information Of Parent Company Only Disclosure [Line Items]

Schedule of Parent Only Condensed Balance Sheets

(Dollars in Thousands)	2018			2017
ASSETS
Cash and cash equivalents	$	45,540		$	45,769
Investment in Bank		433,023			263,022
Investment in RAM		6,796			6,268
Other assets		2,820			3,538
Total assets	$	488,179		$	318,597

LIABILITIES AND SHAREHOLDERS' EQUITY
Long term debt		103,708			49,528
Subordinated debentures		9,506			3,424
Other liabilities		347			37
Total liabilities		113,561			52,989
Shareholders' equity:
Common stock		288,610			205,927
Additional paid-in capital		5,659			8,426
Retained earnings		81,615			51,697
Non-controlling interest		72			—
Accumulated other comprehensive income (loss)		(1,338	)		(442	)
Total shareholders' equity		374,618			265,608
Total liabilities and shareholders' equity	$	488,179		$	318,597

Schedule of Parent Only Condensed Statements of Income

(Dollars in Thousands)	2018			2017			2016
Interest Income	$	15		$	—		$	—
Interest expense		4,083			3,629			2,728
Noninterest expense		1,690			704			123
Loss before equity in undistributed income of subsidiaries		(5,758	)		(4,333	)		(2,851	)
Equity in undistributed income of:
Bank		39,198			27,620			20,483
RAM		528			143			274
Income before income taxes		33,968			23,430			17,906
Income tax benefit		1,702			2,036			1,173
Net income		35,670			25,466			19,079
Other comprehensive income (loss)		(895	)		(104	)		(74	)
Total comprehensive income	$	34,775		$	25,362		$	19,005

Schedule of Parent Only Condensed Statements of Cash Flows

(Dollars in Thousands)	2018			2017			2016
Cash flows from operating activities:
Net income	$	35,670		$	25,466		$	19,079
Net amortization of other		268			235			188
Provision for deferred income taxes		(1,905	)		1,807			(1,172	)
Undistributed income of subsidiaries		(39,726	)		(27,763	)		(20,757	)
Change in other assets and liabilities		3,927			(3,861	)		(159	)
		(1,766	)		(4,116	)		(2,821	)
Cash flows from investment activities:
Net cash acquired (outlay) in connection with acquisition		(41,358	)		—			(839	)
Investment in subsidiaries		(15,000	)		(25,000	)		(35,000	)
		(56,358	)		(25,000	)		(35,839	)
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs		54,018			—			49,274
Issuance of common stock, net of issuance costs		—			60,210			—
Dividends paid		(5,753	)		(5,118	)		(2,554	)
Stock options exercised		9,630			2,296			585
		57,895			57,388			47,305
Increase in cash and cash equivalents		(229	)		28,272			8,645
Cash and cash equivalents beginning of year		45,769			17,497			8,852
Cash and cash equivalents end of year	$	45,540		$	45,769		$	17,497

Quarterly Income Statements (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2018

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Condensed Income Statements

The following table presents the unaudited quarterly condensed income statements for the years 2018 and 2017.

	2018								2017
(dollars in thousands)	4th Quarter		3rd Quarter		2nd Quarter		1st Quarter		4th Quarter		3rd Quarter		2nd Quarter			1st Quarter
Interest income	$	35,181	$	24,473	$	22,284	$	20,177	$	21,478	$	18,346	$	17,521		$	16,759
Interest expense		9,599		5,857		4,457		3,732		3,588		3,618		3,487			3,245
Net interest income		25,582		18,616		17,827		16,445		17,890		14,728		14,034			13,514
Provision (recapture) for credit losses		1,890		1,695		700		184		2,435		700		(4,188	)		—
Net interest income after provision for credit losses		23,692		16,921		17,127		16,261		15,455		14,028		18,222			13,514
Noninterest income:		5,489		2,105		2,793		2,455		3,798		3,796		3,175			2,432
Noninterest expense:		15,503		8,654		8,191		8,289		6,885		7,200		6,960			6,578
Income before income taxes		13,678		10,372		11,729		10,427		12,368		10,624		14,437			9,368
Income tax expense		4,188		2,041		2,292		1,580		7,480		4,013		5,901			3,875
Net income	$	9,490	$	8,331	$	9,437	$	8,847	$	4,888	$	6,611	$	8,536		$	5,493

Net income per share
Basic	$	0.48	$	0.50	$	0.58	$	0.55	$	0.26	$	0.45	$	0.67		$	0.43
Diluted		0.47		0.48		0.54		0.52		0.24		0.42		0.62			0.40

Business Description - Additional Information (Details) $ / shares in Units, $ in Thousands		87 Months Ended
	Jul. 31, 2017 $ / shares shares	Oct. 15, 2018 Acquisition	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Description Of Business [Line Items]
Total assets			$ 2,974,002	$ 1,691,059
Gross loans			2,142,015	1,249,074
Total deposits			2,144,041	1,337,281
Total stockholders' Equity			$ 374,621	$ 265,176	$ 181,585	$ 163,645
Number of acquisitions \| Acquisition		5
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 (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2019 USD ($)	Sep. 30, 2018	Dec. 31, 2018 USD ($) Subsidiary Trust	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Number of inactive subsidiaries acquired \| Subsidiary			4
Number of statutory business trusts acquired \| Trust			2
Cash and due from banks, reserves required to be held			$ 24,500,000	$ 19,700,000
Securities evaluation for other-than-temporary impairment, measurement basis			quarterly
Threshold period past due principal or interest, to discontinue accrual of interest on loans			90 days
Gain on sale of loans			$ 7,126,000	9,318,000	$ 5,847,000
Gains on sale of mortgage loans, total			4,300,000	3,700,000	3,400,000
Gains on sale of SBA loans, total			2,800,000	5,600,000	2,400,000
Goodwill			58,383,000	29,940,000
Impairment losses recognized on goodwill			0	0
Amortization of intangibles			575,000	$ 355,000	$ 372,000
Reclassification of income tax effects of tax reform act from AOCI to retained earnings			$ 72,000
Corporate income tax rate			21.00%	35.00%	35.00%
Out-of-Scope Topic 606
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of non interest income		80.00%
ASU 2014-09
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Percentage of non interest income		20.00%
401(k) Plan
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Contributions to plan			$ 341,000	$ 272,000	$ 221,000
Pacific Coast Bankers' Bank
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Carrying amount of equity securities without readily determinable fair values			217,000
Pacific Coast Bankers' Bank \| Scenario, Forecast
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated gain on equity securities	$ 107,000
Atlantic Community Bankers’ Bank
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Carrying amount of equity securities without readily determinable fair values			60,000
Atlantic Community Bankers’ Bank \| Scenario, Forecast
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Estimated gain on equity securities	$ 40,000
Core Deposit Intangible
Basis Of Presentation And Summary Of Significant Accounting Policies [Line Items]
Unamortized balance of intangible assets			7,600,000	1,400,000
Amortization of intangibles			$ 575,000	355,000	372,000
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			$ 7,100,000	$ 9,300,000	$ 5,800,000
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
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
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

Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Future Estimated Amortization Expense (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Goodwill And Intangible Assets Disclosure [Abstract]
2019	$ 1,501
2020	1,285
2021	1,056
2022	879
2023	749
Thereafter	2,131
Total	$ 7,601

Acquisitions - Additional Information (Details)		12 Months Ended
Acquisitions - Additional Information (Details)	Oct. 15, 2018 USD ($) Branch $ / shares shares	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill		$ 58,383,000	$ 29,940,000
Non-impaired Loans and Customer Receivables
Business Acquisition [Line Items]
Receivables acquired not subject to requirements with fair value on the date of acquisition	$ 715,600,000
Receivables acquired not subject to requirements with gross contractual amounts receivable on the date of acquisition	721,700,000
First American International Bancorp
Business Acquisition [Line Items]
Cash consideration	34,800,000
Business acquisition, stock value of acquirer	$ 69,600,000
Business acquisition, common shares issued \| shares	3,011,762
Business acquisition, share price \| $ / shares	$ 23.11
Goodwill	$ 28,400,000
Merger effective date		Jan. 01, 2018
First American International Bancorp \| New York
Business Acquisition [Line Items]
Number of branches operated \| Branch	9
First American International Bancorp Acquistion [Member]
Business Acquisition [Line Items]
Loans acquired for deterioration of credit quality	$ 0

Acquisitions - Schedule of Assets Acquired and Liabilities Assumed and Fair Value Adjustments (Details) - USD ($) $ in Thousands	Oct. 15, 2018	Dec. 31, 2018	Dec. 31, 2017
Business Acquisition [Line Items]
Goodwill recognized		$ 58,383	$ 29,940
First American International Bancorp \| Book Value
Business Acquisition [Line Items]
Cash and cash equivalents	$ 55,891
Fed funds sold	218
Interest-bearing deposits in other financial Institutions	3,801
Investments - held to maturity	30,814
Investments - available for sale	14,388
Mortgage loans held for sale	1,915
Loans, gross	721,732
Allowance for loan losses	(9,583)
Bank premises and equipment	5,785
Mortgage servicing rights	11,274
Other assets	3,518
Total assets acquired	839,753
Deposits	629,609
FHLB advances	124,500
Subordinated debentures	7,217
Other liabilities	14,940
Total liabilities assumed	776,266
Excess of assets acquired over liabilities assumed	63,487
Business combination, Recognized identifiable assets acquired and liabilities assumed, net	839,753
First American International Bancorp \| Fair Value Adjustments
Business Acquisition [Line Items]
Investments - held to maturity	(611)
Loans, gross	(6,161)
Allowance for loan losses	9,583
Bank premises and equipment	3,439
Mortgage servicing rights	(660)
Core deposit premium	6,738
Other assets	(2,119)
Total assets acquired	10,209
Deposits	94
Subordinated debentures	(1,241)
Other liabilities	(1,153)
Total liabilities assumed	(2,300)
Excess of assets acquired over liabilities assumed	12,509
Business combination, Recognized identifiable assets acquired and liabilities assumed, net	10,209
First American International Bancorp \| Fair Value
Business Acquisition [Line Items]
Cash and cash equivalents	55,891
Fed funds sold	218
Interest-bearing deposits in other financial Institutions	3,801
Investments - held to maturity	30,203
Investments - available for sale	14,388
Mortgage loans held for sale	1,915
Loans, gross	715,571
Bank premises and equipment	9,224
Mortgage servicing rights	10,614
Core deposit premium	6,738
Other assets	1,399
Total assets acquired	849,962
Deposits	629,703
FHLB advances	124,500
Subordinated debentures	5,976
Other liabilities	13,787
Total liabilities assumed	773,966
Excess of assets acquired over liabilities assumed	75,996
Stock consideration	69,602
Cash paid	34,837
Goodwill recognized	$ 28,443

Acquisitions - Schedule of Net Interest and Other Income, Net Income and Earnings Per Share (Details) - First American International Bancorp - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Net interest and other income	$ 122,640	$ 120,778	$ 103,966
Net income	$ 37,084	$ 31,559	$ 23,665
Basic earnings per share	$ 1.87	$ 1.85	$ 1.50
Diluted earnings per share	$ 1.80	$ 1.73	$ 1.42

Investment Securities - Summary of Amortized Cost and Fair Value of Securities Available for Sale and Held to Maturity - (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available for sale, Amortized Cost	$ 75,663	$ 65,587
Available for sale, Gross Unrealized Gains	106	178
Available for sale, Gross Unrealized Losses	(2,007)	(808)
Available for sale, Fair Value	73,762	64,957
Held to maturity, Amortized Cost	9,961	10,009
Held to maturity, Gross Unrealized Gains	143	260
Held to maturity, Gross Unrealized Losses	(164)	(19)
Securities held to maturity, fair value	9,940	10,250
Government Agency Securities
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available for sale, Amortized Cost	1,873	2,052
Available for sale, Gross Unrealized Losses	(58)	(53)
Available for sale, Fair Value	1,815	1,999
SBA Agency Securities
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available for sale, Amortized Cost	5,354	5,916
Available for sale, Gross Unrealized Losses	(185)	(99)
Available for sale, Fair Value	5,169	5,817
Government Sponsored Agencies
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available for sale, Amortized Cost	23,125	26,519
Available for sale, Gross Unrealized Gains		17
Available for sale, Gross Unrealized Losses	(584)	(324)
Available for sale, Fair Value	22,541	26,212
Corporate Debt Securities
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available for sale, Amortized Cost	32,615	17,813
Available for sale, Gross Unrealized Gains	105	161
Available for sale, Gross Unrealized Losses	(549)	(48)
Available for sale, Fair Value	32,171	17,926
Collateralized Mortgage Obligations
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Available for sale, Amortized Cost	12,696	13,287
Available for sale, Gross Unrealized Gains	1
Available for sale, Gross Unrealized Losses	(631)	(284)
Available for sale, Fair Value	12,066	13,003
Municipal Taxable Securities
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Held to maturity, Amortized Cost	4,290	4,295
Held to maturity, Gross Unrealized Gains	142	228
Securities held to maturity, fair value	4,432	4,523
Municipal Securities
Schedule Of Available For Sale And Held To Maturity Securities [Line Items]
Held to maturity, Amortized Cost	5,671	5,714
Held to maturity, Gross Unrealized Gains	1	32
Held to maturity, Gross Unrealized Losses	(164)	(19)
Securities held to maturity, fair value	$ 5,508	$ 5,727

Investment Securities - Additional Information (Details)	12 Months Ended
	Dec. 31, 2018 USD ($) Security	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Investments in Debt Securities [Line Items]
Securities sold	$ 44,591,000	$ 0	$ 5,083,000
Securities held to maturity and available for sale, sold	44,600,000
Securities, recognizing gross gains	$ 5,000		$ 19,000
Number of investment securities pledged as collateral \| Security	1
Fair value of securities pledged to secure local agency deposit	$ 697,000	$ 796,000
First American International Bancorp
Investments in Debt Securities [Line Items]
Securities sold	$ 30,200,000

Investment Securities - Amortized Cost and Fair Value of Investment Securities Portfolio Expected Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Fiscal Year Maturity [Abstract]
Within one year, Available for sale, Amortized Cost	$ 16,571
Due from one to five years, Available for sale, Amortized Cost	30,947
Due from five to ten years, Available for sale, Amortized Cost	24,116
Due from ten years and greater, Available for sale, Amortized Cost	4,029
Available for sale, Amortized Cost	75,663	$ 65,587
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Within one year, Available for sale, Fair Value	16,559
Due from one to five years, Available for sale, Fair Value	30,047
Due from five to ten years, Available for sale, Fair Value	23,538
Due from ten years and greater, Available for sale, Fair Value	3,618
Available for sale, Fair value	73,762	64,957
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount [Abstract]
Within one year, Held to Maturity, Amortized Cost	500
Due from one to five years, Held to Maturity, Amortized Cost	2,786
Due from five to ten years, Held to Maturity, Amortized Cost	1,870
Due from ten years and greater, Held to Maturity, Amortized Cost	4,805
Held to maturity, Amortized Cost	9,961	10,009
Held-to-maturity Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Within one year, Held to Maturity, Fair Value	500
Due from one to five years, Held to Maturity, Fair Value	2,859
Due from five to ten years, Held to Maturity, Fair Value	1,940
Due from ten years and greater, Held to Maturity, Fair Value	4,641
Held to Maturity, Fair Value	$ 9,940	$ 10,250

Investment Securities - Summary of Securities With Unrealized Losses (Details) $ in Thousands	Dec. 31, 2018 USD ($) Security	Dec. 31, 2017 USD ($) Security
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses	$ (72)	$ (406)
Less than Twelve Months Estimated Fair Value	$ 8,084	$ 32,719
Less than Twelve Months No. of Issuances \| Security	6	21
Twelve Months or More Unrealized Losses	$ (1,935)	$ (402)
Twelve Months or More Estimated Fair Value	$ 49,525	$ 17,635
Twelve Months or More No. of Issuances \| Security	43	19
Total Unrealized Losses	$ (2,007)	$ (808)
Total Estimated Fair Value	57,609	50,354
Held to maturity, Less than Twelve Months Unrealized Losses	(104)	(19)
Held to maturity, Less than Twelve Months Estimated Fair Value	$ 2,468	$ 2,232
Held to maturity, Less than Twelve Months, No. of Issuances \| Security	6	4
Held to maturity, Twelve Months or More Unrealized Losses	$ (60)
Held to maturity, Twelve Months or More Estimated Fair Value	$ 2,174
Twelve Months or More \| Security	4
Held to maturity, Total Unrealized Losses	$ (164)	$ (19)
Held to maturity, Total Estimated Fair Value	4,642	2,232
Government Agency Securities
Schedule Of Available For Sale Securities [Line Items]
Twelve Months or More Unrealized Losses	(58)	(53)
Twelve Months or More Estimated Fair Value	$ 1,815	$ 1,999
Twelve Months or More No. of Issuances \| Security	2	2
Total Unrealized Losses	$ (58)	$ (53)
Total Estimated Fair Value	1,815	1,999
Government Sponsored Agencies
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses	(11)	(155)
Less than Twelve Months Estimated Fair Value	$ 3,484	$ 12,583
Less than Twelve Months No. of Issuances \| Security	2	12
Twelve Months or More Unrealized Losses	$ (573)	$ (169)
Twelve Months or More Estimated Fair Value	$ 23,928	$ 9,909
Twelve Months or More No. of Issuances \| Security	25	10
Total Unrealized Losses	$ (584)	$ (324)
Total Estimated Fair Value	27,412	22,492
Collateralized Mortgage Obligations
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses		(204)
Less than Twelve Months Estimated Fair Value		$ 11,062
Less than Twelve Months No. of Issuances \| Security		5
Twelve Months or More Unrealized Losses	(631)	$ (80)
Twelve Months or More Estimated Fair Value	$ 12,065	$ 1,977
Twelve Months or More No. of Issuances \| Security	8	3
Total Unrealized Losses	$ (631)	$ (284)
Total Estimated Fair Value	12,065	13,039
Corporate Debt Securities
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses	(61)	(15)
Less than Twelve Months Estimated Fair Value	$ 4,600	$ 5,035
Less than Twelve Months No. of Issuances \| Security	4	2
Twelve Months or More Unrealized Losses	$ (488)	$ (33)
Twelve Months or More Estimated Fair Value	$ 6,548	$ 1,972
Twelve Months or More No. of Issuances \| Security	4	2
Total Unrealized Losses	$ (549)	$ (48)
Total Estimated Fair Value	11,148	7,007
SBA Securities
Schedule Of Available For Sale Securities [Line Items]
Less than Twelve Months Unrealized Losses		(32)
Less than Twelve Months Estimated Fair Value		$ 4,039
Less than Twelve Months No. of Issuances \| Security		2
Twelve Months or More Unrealized Losses	(185)	$ (67)
Twelve Months or More Estimated Fair Value	$ 5,169	$ 1,778
Twelve Months or More No. of Issuances \| Security	4	2
Total Unrealized Losses	$ (185)	$ (99)
Total Estimated Fair Value	5,169	5,817
Municipal Securities
Schedule Of Available For Sale Securities [Line Items]
Held to maturity, Less than Twelve Months Unrealized Losses	(104)	(19)
Held to maturity, Less than Twelve Months Estimated Fair Value	$ 2,468	$ 2,232
Held to maturity, Less than Twelve Months, No. of Issuances \| Security	6	4
Held to maturity, Twelve Months or More Unrealized Losses	$ (60)
Held to maturity, Twelve Months or More Estimated Fair Value	$ 2,174
Twelve Months or More \| Security	4
Held to maturity, Total Unrealized Losses	$ (164)	$ (19)
Held to maturity, Total Estimated Fair Value	$ 4,642	$ 2,232

Loans - Summary of Changes in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Allowance for loan losses, Beginning balance	$ 13,773	$ 14,162	$ 10,023
Additions (reductions) to the allowance charged to expense	4,469	(1,053)	4,974
Recoveries on loans charged-off	36	747
Allowance for loan losses before charged off	18,278	13,856	14,997
Less loans charged-off	(701)	(83)	(835)
Allowance for loan losses, Ending balance	$ 17,577	$ 13,773	$ 14,162

Loans - Summary of Recorded Investment in Loans Impairment Method and Activity in Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for loan losses:
Allowance for loan losses, Beginning balance	$ 13,773	$ 14,162	$ 10,023
Allowance for loan losses, Provisions	4,469	(1,053)	4,974
Allowance for loan losses, Charge-offs	(701)	(83)	(835)
Allowance for loan losses, Recoveries	36	747
Allowance for loan losses, Ending balance	17,577	13,773	14,162
Reserves:
Loan losses, Reserves	17,577	13,773	14,162
Loans evaluated for impairment:
Loans, Individually evaluated for impairment	3,281	2,575	6,133
Loans, Collectively evaluated for impairment	2,138,734	1,246,184	1,103,583
Total loans, gross	2,142,015	1,249,074	1,110,446
Loans Acquired with Deteriorated Credit Quality
Loans evaluated for impairment:
Loans acquired		315	730
Specific Reserves
Reserves:
Loan losses, Reserves	44		1,782
General Reserves
Reserves:
Loan losses, Reserves	17,533	13,773	12,380
Real Estate
Allowance for loan losses:
Allowance for loan losses, Beginning balance	9,309	8,111	5,788
Allowance for loan losses, Provisions	4,128	1,198	2,323
Allowance for loan losses, Ending balance	13,437	9,309	8,111
Reserves:
Loan losses, Reserves	13,437	9,309	8,111
Loans evaluated for impairment:
Loans, Individually evaluated for impairment	2,309	2,420	2,556
Loans, Collectively evaluated for impairment	1,750,896	834,152	744,349
Total loans, gross	1,753,205	836,887	747,635
Real Estate \| Loans Acquired with Deteriorated Credit Quality
Loans evaluated for impairment:
Loans acquired		315	730
Real Estate \| Specific Reserves
Reserves:
Loan losses, Reserves	44
Real Estate \| General Reserves
Reserves:
Loan losses, Reserves	13,393	9,309	8,111
Commercial
Allowance for loan losses:
Allowance for loan losses, Beginning balance	4,044	6,051	4,235
Allowance for loan losses, Provisions	761	(2,671)	2,651
Allowance for loan losses, Charge-offs	(701)	(83)	(835)
Allowance for loan losses, Recoveries	36	747
Allowance for loan losses, Ending balance	4,140	4,044	6,051
Reserves:
Loan losses, Reserves	4,140	4,044	6,051
Loans evaluated for impairment:
Loans, Individually evaluated for impairment	972	155	3,577
Loans, Collectively evaluated for impairment	387,838	412,032	359,234
Total loans, gross	388,810	412,187	362,811
Commercial \| Specific Reserves
Reserves:
Loan losses, Reserves			1,782
Commercial \| General Reserves
Reserves:
Loan losses, Reserves	4,140	4,044	$ 4,269
Unallocated
Allowance for loan losses:
Allowance for loan losses, Beginning balance	420
Allowance for loan losses, Provisions	$ (420)	420
Allowance for loan losses, Ending balance		420
Reserves:
Loan losses, Reserves		420
Unallocated \| General Reserves
Reserves:
Loan losses, Reserves		$ 420

Loans - Summary of Risk Category of Loans by Class of Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 2,142,015	$ 1,249,074
Real Estate \| Construction and Land Development
Accounts Notes And Loans Receivable [Line Items]
Total loans	113,235	91,908
Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	758,721	496,039
Real Estate \| Single-family Residential Mortgages
Accounts Notes And Loans Receivable [Line Items]
Total loans	881,249	248,940
Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	304,310	280,766
Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	84,500	131,421
Pass
Accounts Notes And Loans Receivable [Line Items]
Total loans	2,111,225	1,214,258
Pass \| Real Estate \| Construction and Land Development
Accounts Notes And Loans Receivable [Line Items]
Total loans	112,959	91,619
Pass \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	743,123	469,422
Pass \| Real Estate \| Single-family Residential Mortgages
Accounts Notes And Loans Receivable [Line Items]
Total loans	880,860	248,940
Pass \| Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	295,226	277,518
Pass \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	79,057	126,759
Special Mention
Accounts Notes And Loans Receivable [Line Items]
Total loans	13,355	23,208
Special Mention \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	7,069	19,070
Special Mention \| Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	6,286	2,360
Special Mention \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans		1,778
Substandard
Accounts Notes And Loans Receivable [Line Items]
Total loans	14,154	9,033
Substandard \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	6,496	5,416
Substandard \| Real Estate \| Single-family Residential Mortgages
Accounts Notes And Loans Receivable [Line Items]
Total loans	389
Substandard \| Commercial \| Other
Accounts Notes And Loans Receivable [Line Items]
Total loans	2,798	888
Substandard \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	4,471	2,729
Impaired
Accounts Notes And Loans Receivable [Line Items]
Total loans	3,281	2,575
Impaired \| Real Estate \| Construction and Land Development
Accounts Notes And Loans Receivable [Line Items]
Total loans	276	289
Impaired \| Real Estate \| Commercial Real Estate
Accounts Notes And Loans Receivable [Line Items]
Total loans	2,033	2,131
Impaired \| Commercial \| SBA
Accounts Notes And Loans Receivable [Line Items]
Total loans	$ 972	$ 155

Loans - Summary of Aging Recorded Investment Past-due Loans (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	$ 5,047	$ 3,023
Loans Not Past Due	2,136,968	1,246,051
Total Loans	2,142,015	1,249,074
Non-Accrual Loans	914	155
30-59 Days
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,505	1,175
60-89 Days
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,628	1,764
90 Days Or More
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	914	84
Real Estate \| Construction and Land Development
Financing Receivable Recorded Investment Past Due [Line Items]
Loans Not Past Due	113,235	91,908
Total Loans	113,235	91,908
Real Estate \| Commercial Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	678
Loans Not Past Due	758,043	496,039
Total Loans	758,721	496,039
Real Estate \| Single-family Residential Mortgages
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	2,498	1,513
Loans Not Past Due	878,751	247,427
Total Loans	881,249	248,940
Real Estate \| Single-family residential mortgages held for sale
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	458	697
Loans Not Past Due	434,064	125,150
Total Loans	434,522	125,847
Real Estate \| 30-59 Days \| Single-family Residential Mortgages
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,548	1,175
Real Estate \| 30-59 Days \| Single-family residential mortgages held for sale
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due		697
Real Estate \| 60-89 Days \| Commercial Real Estate
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	678
Real Estate \| 60-89 Days \| Single-family Residential Mortgages
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	950	338
Real Estate \| 60-89 Days \| Single-family residential mortgages held for sale
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	458
Commercial \| Other
Financing Receivable Recorded Investment Past Due [Line Items]
Loans Not Past Due	304,310	280,766
Total Loans	304,310	280,766
Commercial \| SBA
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	1,871	1,510
Loans Not Past Due	82,629	129,911
Total Loans	84,500	131,421
Non-Accrual Loans	914	155
Commercial \| 30-59 Days \| SBA
Financing Receivable Recorded Investment Past Due [Line Items]
Total Past Due	957
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	$ 914	$ 84

Loans - Summary of Individually Impaired Loans Presented by Class of Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded		$ 2,575	$ 2,574
Recorded Investment, With no related allowance recorded		2,575	2,574
Average Balance, With no related allowance recorded		2,566	2,112
Interest Income, With no related allowance recorded		328	301
Unpaid Principal Balance	$ 3,281		6,133
Recorded Investment	3,982		6,133
Average Balance	3,979		5,671
Interest Income	177		301
Related Allowance	44		1,782
Construction and Land Development
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded	276	289	303
Recorded Investment, With no related allowance recorded	276	289	303
Average Balance, With no related allowance recorded	283	296	309
Interest Income, With no related allowance recorded	23	16	21
Commercial Real Estate
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded	2,033	2,131	2,253
Recorded Investment, With no related allowance recorded	2,033	2,131	2,253
Average Balance, With no related allowance recorded	2,126	2,192	1,710
Interest Income, With no related allowance recorded	134	297	280
Commercial \| SBA
Financing Receivable Impaired [Line Items]
Unpaid Principal Balance, With no related allowance recorded	797	155	18
Recorded Investment, With no related allowance recorded	1,498	155	18
Average Balance, With no related allowance recorded	1,377	78	93
Interest Income, With no related allowance recorded	19	$ 15
Unpaid Principal Balance, With related allowance recorded	175		3,559
Recorded Investment, With related allowance recorded	175		3,559
Average Balance, With related allowance recorded	193		3,559
Interest Income, With related allowance recorded	1
Related Allowance, With related allowance recorded	$ 44		$ 1,782

Loans - Additional Information (Details)	12 Months Ended
Loans - Additional Information (Details)	Dec. 31, 2018 USD ($) Loan	Dec. 31, 2017 USD ($) Loan	Dec. 31, 2016 USD ($)
Financing Receivable Recorded Investment [Line Items]
Interest income recognized on cash basis	$ 0	$ 0	$ 0
Number of loans identified as troubled debt restructurings \| Loan	4	4
Specific reserve	$ 17,577,000	$ 13,773,000	$ 14,162,000
Commitments to lend an additional amounts of outstanding loans are classified as TDR's	$ 0	$ 0
Description of loans modified as troubled debt restructuring	During the year ended December 31, 2018, 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 2017.
Number of loans defaulted \| Loan	0	0
Increase in allowance for loan losses under purchased credit-impaired loans	$ 0	$ 0
Significant reductions in allowance for loan losses under purchased credit-impaired loans	$ 0	0
Minimum
Financing Receivable Recorded Investment [Line Items]
Moratorium on loan payments period granted	3 months
Maximum
Financing Receivable Recorded Investment [Line Items]
Moratorium on loan payments period granted	6 months
One Loan
Financing Receivable Recorded Investment [Line Items]
Specific reserve	$ 0	$ 0

Loans - Summary of Loans Class Modified as TDRs (Details) - Commercial Real Estate $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Loan
Financing Receivable Recorded Investment [Line Items]
Number of Loans \| Loan	1
Pre-Modification Recorded Investment	$ 1,029
Post-Modification Recorded Investment	$ 1,029

Loans - Summary of Outstanding Balance and Carrying Amount of Purchased Credit-impaired Loans (Details) $ in Thousands	Dec. 31, 2017 USD ($)
Receivables [Abstract]
Outstanding balance	$ 322
Carrying amount	$ 315

Loans - Summary of Activity in Accretable Yield on Purchased Credit-impaired Loans (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Receivables [Abstract]
Beginning balance	$ 7	$ 142	$ 349
Restructuring as TDR			(22)
Accretion of income	$ (7)	(135)	(185)
Ending balance		$ 7	$ 142

Loan Servicing - Schedule of Principal Balances of Mortgage and SBA Loans Serviced for Others (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Mortgage Loans
Schedule Of Mortgage And Small Business Administration Loans Serviced [Line Items]
Loans serviced for others	$ 1,586,499	$ 384,437
SBA Loans
Schedule Of Mortgage And Small Business Administration Loans Serviced [Line Items]
Loans serviced for others	$ 184,664	$ 175,919

Loan Servicing - Schedule of Activity for Servicing Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Mortgage Loans
Servicing assets:
Beginning of year	$ 1,540	$ 1,002	$ 298
Acquisitions	10,651
Additions	1,562	1,115	912
Disposals	(197)	(172)
Amortized to expense	(698)	(405)	(208)
End of year	12,858	1,540	1,002
SBA Loans
Servicing assets:
Beginning of year	4,417	2,702	1,807
Additions	1,932	2,628	1,353
Disposals	(1,177)	(367)
Amortized to expense	(660)	(546)	(458)
End of year	$ 4,512	$ 4,417	$ 2,702

Loan Servicing - Additional Information (Details)	12 Months Ended
Loan Servicing - Additional Information (Details)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	$ 17,370,000	$ 5,957,000
Servicing fees net of servicing asset amortization	850,000	722,000	$ 615,000
Mortgage Loans
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	$ 15,300,000	$ 2,500,000
Mortgage Loans \| Fair Value Discount Rate
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	10.59	12.50
Mortgage Loans \| Fair Value Prepayment Rate \| Minimum
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	8.26	20.00
Mortgage Loans \| Fair Value Prepayment Rate \| Maximum
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	16.82	21.79
Mortgage Loans \| Fair Value Weighted Average Default Rate
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	0.20	0.25
SBA
Loan Sales And Mortgage Servicing Rights [Line Items]
Servicing assets	$ 6,100,000	$ 5,900,000
SBA \| Fair Value Discount Rate
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	8.50	8.50
SBA \| Fair Value Prepayment Rate \| Minimum
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	11.43	11.40
SBA \| Fair Value Prepayment Rate \| Maximum
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	12.11	13.78
SBA \| Fair Value Weighted Average Default Rate
Loan Sales And Mortgage Servicing Rights [Line Items]
Fair value of servicing assets percentage	0.52

Premises and Equipment - Summary of Premises and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Property Plant And Equipment [Line Items]
Premises and equipment, gross	$ 22,521	$ 11,517
Less accumulated depreciation and amortization	(6,312)	(5,359)
Construction in progress	1,098	425
Premises and equipment	17,307	6,583
Land
Property Plant And Equipment [Line Items]
Premises and equipment, gross	5,020	2,956
Building and Improvements
Property Plant And Equipment [Line Items]
Premises and equipment, gross	7,823	2,467
Leasehold Improvements
Property Plant And Equipment [Line Items]
Premises and equipment, gross	4,845	2,872
Furnitures, Fixtures and Equipment
Property Plant And Equipment [Line Items]
Premises and equipment, gross	$ 4,833	$ 3,222

Premises and Equipment - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property Plant And Equipment [Abstract]
Depreciation and leasehold amortization expense	$ 989,000	$ 686,000	$ 750,000
Operating leases expire at various dates through year	2028
Total rental expense, recognized on straight-line basis	$ 2,700,000	$ 1,500,000	$ 1,600,000
Operating lease expiration date	2018-05

Premises and Equipment - Schedule of Future Minimum Rent Payments on Company's Leases (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Commitments And Contingencies Disclosure [Abstract]
2019	$ 5,610
2020	5,081
2021	3,639
2022	3,470
2023	2,936
Thereafter	9,149
Total	$ 29,885

Deposits - Schedule of Maturities of Time Deposits (Details) $ in Thousands	Dec. 31, 2018 USD ($)
Maturities Of Time Deposits [Abstract]
One year	$ 967,811
Two to three years	152,567
Over three years	5,652
Total	$ 1,126,030

Long-term Debt - Schedule of Long-term Debt (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Debt Instruments [Abstract]
Principal	$ 105,000,000	$ 50,000,000
Unamortized debt issuance costs	$ 1,292,000	$ 472,000

Long-term Debt - Additional Information (Details) - USD ($)	1 Months Ended		12 Months Ended
	Nov. 30, 2018	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Debt instrument, face amount			$ 105,000,000	$ 50,000,000
6.5% Fixed to Floating Rate Subordinated Debentures, Due March 31, 2026
Debt Instrument [Line Items]
Debt instrument, face amount		$ 50,000,000
Debt instrument, due date		Mar. 31, 2026
Long-term debt, fixed interest rate		6.50%
Debt instrument, fixed to floating interest rate conversion date		Mar. 31, 2021
Debt instrument, floating rate description			3 month LIBOR plus 516 basis points
Debt instrument, basis points		5.16%
Tier-1 capital			$ 35,000,000
Debt instrument, redemption period, start date			Mar. 31, 2021
6.18% Fixed to Floating Rate Subordinated Debentures, Due December 1, 2028
Debt Instrument [Line Items]
Debt instrument, face amount	$ 55,000,000
Debt instrument, due date	Dec. 01, 2028
Long-term debt, fixed interest rate	6.18%
Debt instrument, fixed to floating interest rate conversion date	Dec. 01, 2023
Debt instrument, floating rate description			3 month LIBOR plus 315 basis points
Debt instrument, basis points	3.15%
Tier-1 capital			$ 25,000,000
Debt instrument, redemption period, start date			Dec. 01, 2023

Subordinated Debentures - Additional Information (Details) - USD ($)			1 Months Ended	12 Months Ended
	Feb. 19, 2016	Mar. 15, 2012	Oct. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt instrument, face amount				$ 105,000,000	$ 50,000,000
Interest expenses, paid				263,000	144,000	$ 103,000
Debt amortization expense				$ 106,000	$ 90,000	$ 79,000
Subordinated Debentures
Debt Instrument [Line Items]
Percentage of principal amount redeemed		100.00%
Debt instrument redemption period				Mar. 15, 2012
Debt instrument maturity period				Mar. 15, 2037
Defer interest payments maximum period				5 years
Debt instrument interest rate description				three month London Interbank Offered Rate (LIBOR) plus 1.65%, which was 4.45% at December 31, 2018.
Debt instrument interest percentage				4.45%
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
TFC Statutory Trust \| Fair Value, Inputs, Level 1
Debt Instrument [Line Items]
Subordinated debenture liability	$ 3,255,000
First American International Statutory Trust I
Debt Instrument [Line Items]
Number of units issued			7,000
Aggregate liquidation amount of units issued			$ 7,000,000
Floating rate maturity period			30 years
First American International Statutory Trust I \| Subordinated Debentures
Debt Instrument [Line Items]
Debt valuation reserve				$ 1,200,000
Debt instrument maturity period				Dec. 15, 2034
Defer interest payments maximum period				5 years
Debt instrument interest rate description				the three-month LIBOR plus 2.25% through final maturity on December 15, 2034. The rate at December 31, 2018, was 5.04%
Debt instrument interest percentage				5.04%
Other Assets
Debt Instrument [Line Items]
Investment in common stock				$ 155,000
Other Assets \| First American International Statutory Trust I
Debt Instrument [Line Items]
Investment in common stock				$ 217,000
London Interbank Offered Rate \| Subordinated Debentures
Debt Instrument [Line Items]
Debt instrument, basis points				1.65%
London Interbank Offered Rate \| First American International Statutory Trust I \| Subordinated Debentures
Debt Instrument [Line Items]
Debt instrument, basis points				2.25%

Borrowing Arrangements - Additional Information (Details) - USD ($)			12 Months Ended
	Jan. 15, 2019	Jan. 02, 2018	Dec. 31, 2017	Dec. 31, 2018
Debt Instrument [Line Items]
Line of credit amount outstanding			$ 0	$ 0
FRB Secured Line of Credit
Debt Instrument [Line Items]
Borrowing capacity				17,000,000
Carrying value of collateral loan pledged				28,400,000
FHLB Secured Line of Credit
Debt Instrument [Line Items]
Borrowing capacity				823,100,000
Carrying value of collateral loan pledged				943,000,000
FHLB
Debt Instrument [Line Items]
Short-term borrowings			$ 25,000,000	319,500,000
Amount of short-term borrowings matured and rolled over		$ 284,500,000
Short-term borrowings interest percentage		2.56%	1.41%
Short-term borrowings, rolled over date		Jan. 02, 2018
Short-term borrowings repayment date			Jan. 02, 2018
FHLB \| Subsequent Event
Debt Instrument [Line Items]
Amount of short-term borrowings matured and rolled over	$ 35,000,000
Short-term borrowings interest percentage	2.42%
Short-term borrowings, rolled over date	Jan. 15, 2019
Zions Bank
Debt Instrument [Line Items]
Borrowing capacity				20,000,000
Wells Fargo Bank
Debt Instrument [Line Items]
Borrowing capacity				10,000,000
Wells Fargo Bank \| Letter of Credit
Debt Instrument [Line Items]
Borrowing capacity				2,000,000
First Tennessee National Bank
Debt Instrument [Line Items]
Borrowing capacity				12,000,000
Pacific Coast Bankers' Bank
Debt Instrument [Line Items]
Borrowing capacity				$ 5,000,000

Income Taxes - Components of Income Tax Expense (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current:
Federal									$ 6,616	$ 12,097	$ 9,345
State									3,451	3,773	2,841
Current									10,067	15,870	12,186
Deferred									(131)	2,492	1,289
Deferred tax adjustment for enacted change in tax rate									(479)	2,591
Affordable housing tax credits									644	316	14
Income tax expense	$ 4,188	$ 2,041	$ 2,292	$ 1,580	$ 7,480	$ 4,013	$ 5,901	$ 3,875	$ 10,101	$ 21,269	$ 13,489

Income Taxes - Comparison of Federal Statutory Income Tax Rates to Effective Income Tax Rates (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amount
Statutory federal tax									$ 9,703	$ 16,379	$ 11,399
State franchise tax, net of federal benefit									3,488	3,135	2,281
Tax-exempt income									(27)	(297)	(202)
Tax impact from enacted change in tax rate									(479)	2,591
Stock-based compensation									(2,643)
Other items, net									59	(539)	11
Income tax expense	$ 4,188	$ 2,041	$ 2,292	$ 1,580	$ 7,480	$ 4,013	$ 5,901	$ 3,875	$ 10,101	$ 21,269	$ 13,489
Rate
Statutory federal tax									21.00%	35.00%	35.00%
State franchise tax, net of federal benefit									7.50%	6.70%	7.00%
Tax-exempt income									(0.10%)	(0.60%)	(0.60%)
Tax impact from enacted change in tax rate									(1.00%)	5.50%	0.00%
Stock-based compensation									(5.70%)	0.00%	0.00%
Other items, net									0.10%	(1.20%)	0.00%
Actual tax expense									21.80%	45.40%	41.40%

Income Taxes - Components of Net Deferred Tax Asset (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax assets:
Pre-opening expenses	$ 154	$ 173
Allowance for loan losses	5,545	4,072
Stock-based compensation	1,419	1,973
Off balance sheet reserve	217	83
Operating loss carryforwards	1,688	285
Other real estate owned	10	10
Unrealized loss on AFS securities	600	186
Mark to market on held for sale mortgage loans	2,451	676
Other	1,220	1,292
Deferred tax assets	13,304	8,750
Deferred tax liabilities:
Depreciation	(521)	(511)
Acquisition accounting fair value adjustments	(2,067)	(145)
Mortgage servicing rights	(3,586)	(300)
Other	(2,488)	(1,708)
Deferred tax liabilities	(8,662)	(2,664)
Net deferred tax assets	$ 4,642	$ 6,086

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax [Line Items]
Net operating loss carry forwards expiration, description	begin to expire in 2028
Net operating loss carry forwards expiration year start	2028
Net operating loss carryforwards utilized expiration, description	expire in 2028 through 2038
Net operating loss carryforwards utilized expiration year start	2028
Net operating loss carryforwards utilized expiration year end	2038
Income tax return examination, description	Income tax returns for the years ended after December 31, 2014 are open to audit by the federal and New York authorities and for the years ended after December 31, 2013 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
California Tax
Income Tax [Line Items]
Net operating loss carryforwards	1,300,000
Net operating loss carryforwards utilized	11,400,000
New York State Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	12,000,000
Net operating loss carryforwards utilized	12,400,000
New York City Income Tax
Income Tax [Line Items]
Net operating loss carryforwards	11,200,000
Net operating loss carryforwards utilized	11,700,000
Federal
Income Tax [Line Items]
Net operating loss carryforwards	34,000
Net operating loss carryforwards utilized	$ 3,800,000

Commitments - Schedule of Financial Commitments whose Contractual Amount Represents Credit Risk (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	$ 70,145	$ 81,967
Financial commitments, contractual amount, Variable Rate	202,191	123,798
Commitments to Make Loans
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	5,211	19,438
Financial commitments, contractual amount, Variable Rate	125,610	82,522
Unused Lines of Credit
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	61,191	58,291
Financial commitments, contractual amount, Variable Rate	75,908	40,926
Commercial and Similar Letters of Credit
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	1,042	3,013
Standby Letters of Credit
Loss Contingencies [Line Items]
Financial commitments, contractual amount, Fixed Rate	2,701	1,225
Financial commitments, contractual amount, Variable Rate	$ 673	$ 350

Related Party Transactions - Schedule of Related Party Transactions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Related Party Transactions [Abstract]
Beginning balance	$ 2,300	$ 3,445
New loans and advances	7,400	2,200
Repayments	(6,100)	(3,345)
Ending balance	$ 3,600	$ 2,300

Related Party Transactions - Additional Information (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Executive Officers, Directors and their Related Interests
Related Party Transaction [Line Items]
Loan commitments outstanding to related parties	$ 800,000	$ 2,100,000
Principal Officers, Directors and their Affiliates
Related Party Transaction [Line Items]
Deposits from related parties	$ 52,100,000	$ 43,800,000

Stock Option Plan - Additional Information (Details) - USD ($)		12 Months Ended
	Aug. 15, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock-based compensation expense		$ 684,000	$ 779,000	$ 894,000
Income tax benefits recognized		$ 202,000	$ 246,000	267,000
Stock options granted		0	0
Total unrecognized compensation cost		$ 113,000
Unrecognized compensation costs, weighted-average recognition period		4 months
Option exercised of intrinsic value		$ 13,600,000	$ 2,800,000	216,000
Total fair of share vested		$ 734,000	$ 930,000	1,511,000
Number of nonvested stock options		62,008	163,996
Weighted average grant date fair value, nonvested stock options		$ 6.48	$ 6.53
Stock options exercised, shares		1,035,942
Stock options exercised		$ 9,629,000	$ 2,296,000	$ 595,000
Excess tax benefit		$ 3,900,000
Restricted Stock Units
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Vesting period	3 years
Number of units granted	43,425		0
Closing price of units granted	$ 29.38
2017 Omnibus Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option expiration period from date of grant		10 years
Vesting period		3 years
Number of shares available for future grant		1,330,545
Maximum \| 2017 Omnibus Stock Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of option to purchase number of outstanding common stock		30.00%
Percentage of fair market value stock on date of the grant		100.00%

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

Stock Option Plan - Summary of Stock Option Plan (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Beginning Balance, Shares	2,261,800
Granted, Shares	0	0
Exercised, Shares	(1,035,942)
Forfeited or expired, Shares	(10,761)
Ending Balance, Shares	1,215,097	2,261,800
Options exercisable, Shares	1,153,089
Beginning Balance, Weighted Average Exercise Price	$ 11.32
Exercised, Weighted Average Exercise Price	9.57
Forfeited or expired, Weighted Average Exercise Price	9.29
Ending Balance, Weighted Average Exercise Price	12.83	$ 11.32
Options exercisable, Weighted Average Exercise Price	$ 12.54
Ending Balance, Weighted Average Remaining Contractual Term	4 years 8 months 12 days
Options exercisable, Weighted Average Remaining Contractual Term	4 years 6 months
Ending Balance, Aggregate Intrinsic Value	$ 5,878
Options exercisable, Aggregate Intrinsic Value	$ 5,878

Regulatory Matters - Additional Information (Details) - USD ($)			12 Months Ended
	Jan. 02, 2016	Jan. 01, 2015	Dec. 31, 2019	Dec. 31, 2015	Dec. 31, 2018	Jan. 01, 2018
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		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		6.00%
Increased Tier 1 capital to risk-weighted assets ratio with minimum for prompt corrective action purposes		8.00%
Capital conservation buffer		2.50%
Capital conservation buffer phased-in on pro rata basis period	4 years
Capital conservation buffer phased				0.00%
Scenario, Forecast
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Capital conservation buffer phased			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%

Regulatory Matters - Summary of Actual Capital Amounts and Ratios and Related Regulatory Requirements (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2015
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 Risk-Based Capital Ratio, For Capital Adequacy Purposes Ratio			4.00%
Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio			6.00%
RBB Bancorp
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 Leverage Ratio, Amount	$ 321,407	$ 238,219
Tier 1 Leverage Ratio, Ratio	11.80%	14.35%
Common Equity Tier 1 Risk-Based Capital Ratio, Amount	$ 311,901	$ 234,794
Common Equity Tier 1 Risk-Based Capital Ratio, Ratio	15.28%	17.54%
Tier 1 Risk-Based Capital Ratio, Amount	$ 321,407	$ 238,219
Tier 1 Risk-Based Capital Ratio, Ratio	15.74%	17.80%
Total Risk-Based Capital Ratio, Amount	$ 443,379	$ 301,802
Total Risk-Based Capital Ratio, Ratio	21.71%	22.55%
Royal Business Bank
Compliance With Regulatory Capital Requirements Under Banking Regulations [Line Items]
Tier 1 Leverage Ratio, Amount	$ 370,304	$ 232,765
Tier 1 Leverage Ratio, Ratio	13.66%	14.50%
Tier 1 Leverage Ratio, For Capital Adequacy Purposes Amount	$ 108,445	$ 64,214
Tier 1 Leverage Ratio, For Capital Adequacy Purposes Ratio	4.00%	4.00%
Tier 1 Leverage Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 135,556	$ 80,267
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	$ 370,304	$ 232,765
Common Equity Tier 1 Risk-Based Capital Ratio, Ratio	18.17%	17.42%
Common Equity Tier 1 Risk-Based Capital Ratio, For Capital Adequacy Purposes Amount	$ 91,722	$ 60,122
Common Equity Tier 1 Risk-Based Capital Ratio, 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	$ 132,487	$ 86,843
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	$ 370,304	$ 232,765
Tier 1 Risk-Based Capital Ratio, Ratio	18.17%	17.42%
Tier 1 Risk-Based Capital Ratio, For Capital Adequacy Purposes Amount	$ 122,296	$ 80,163
Tier 1 Risk-Based Capital Ratio, For Capital Adequacy Purposes Ratio	6.00%	6.00%
Tier 1 Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 163,061	$ 106,884
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	$ 388,569	$ 246,820
Total Risk-Based Capital Ratio, Ratio	19.07%	18.47%
Total Risk-Based Capital Ratio, For Capital Adequacy Purposes Amount	$ 163,061	$ 106,884
Total Risk-Based Capital Ratio, For Capital Adequacy Purposes Ratio	8.00%	8.00%
Total Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Amount	$ 203,826	$ 133,605
Total Risk-Based Capital Ratio, To Be Well-Capitalized Under Prompt Corrective Provisions Ratio	10.00%	10.00%

Fair Value Measurements - Schedule of Hierarchy and Fair Value for Each Major Category of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Fair Value Measurements, Recurring Basis
Assets measured at fair value:
Assets measured at fair value	$ 73,762	$ 64,957
Fair Value Measurements, Recurring Basis \| Government Agency Securities
Assets measured at fair value:
Assets measured at fair value	1,815	7,816
Fair Value Measurements, Recurring Basis \| Collateralized Mortgage Obligations
Assets measured at fair value:
Assets measured at fair value	12,066
Fair Value Measurements, Recurring Basis \| Mortgage-Backed Securities Government Sponsored Agencies
Assets measured at fair value:
Assets measured at fair value	22,541	39,215
Fair Value Measurements, Recurring Basis \| Corporate Debt Securities
Assets measured at fair value:
Assets measured at fair value	32,171	17,926
Fair Value Measurements, Recurring Basis \| SBA Agency Securities
Assets measured at fair value:
Assets measured at fair value	5,169
Fair Value Measurements, Nonrecurring Basis \| Other Real Estate Owned
Assets measured at fair value:
Assets measured at fair value	1,101	293
Fair Value Measurements Using Level 2 \| Fair Value Measurements, Recurring Basis
Assets measured at fair value:
Assets measured at fair value	73,762	64,957
Fair Value Measurements Using Level 2 \| Fair Value Measurements, Recurring Basis \| Government Agency Securities
Assets measured at fair value:
Assets measured at fair value	1,815	7,816
Fair Value Measurements Using Level 2 \| Fair Value Measurements, Recurring Basis \| Collateralized Mortgage Obligations
Assets measured at fair value:
Assets measured at fair value	12,066
Fair Value Measurements Using Level 2 \| Fair Value Measurements, Recurring Basis \| Mortgage-Backed Securities Government Sponsored Agencies
Assets measured at fair value:
Assets measured at fair value	22,541	39,215
Fair Value Measurements Using Level 2 \| Fair Value Measurements, Recurring Basis \| Corporate Debt Securities
Assets measured at fair value:
Assets measured at fair value	32,171	17,926
Fair Value Measurements Using Level 2 \| Fair Value Measurements, Recurring Basis \| SBA Agency Securities
Assets measured at fair value:
Assets measured at fair value	5,169
Fair Value Measurements Using Level 3 \| Fair Value Measurements, Nonrecurring Basis \| Other Real Estate Owned
Assets measured at fair value:
Assets measured at fair value	$ 1,101	$ 293

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

Fair Value Measurements - Summary of Quantitative Information About Non-recurring Level 3 Fair Value Measurements (Details) - Other Real Estate Owned $ in Thousands	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Fair Value Measurements, Nonrecurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 1,101	$ 293
Level 3 \| Fair Value Measurements, Nonrecurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 1,101	$ 293
Level 3 \| Third Party Appraisals \| Measurement Input, Comparability Adjustment
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value Adjustment	16	21
Level 3 \| Third Party Appraisals \| Measurement Input, Comparability Adjustment \| Weighted Average
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Fair Value Adjustment	16	21
Level 3 \| Third Party Appraisals \| Fair Value Measurements, Nonrecurring Basis
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Assets measured at fair value	$ 1,101	$ 293

Fair Value of Financial Instruments - Schedule of Fair Value Hierarchy Level and Estimated Fair Value of Significant Financial Instruments (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financial Assets:
Investment securities - AFS	$ 73,762	$ 64,957
Investment securities - HTM	9,940	10,250
Carrying Value
Financial Assets:
Cash and due from banks	147,685	70,048
Federal funds sold and other cash equivalents		80,000
Interest-earning deposits in other financial institutions	600	600
Investment securities - AFS	73,762	64,957
Investment securities - HTM	9,961	10,009
Mortgage loans held for sale	434,522	125,847
Loans, net	2,124,438	1,235,301
Financial Liabilities:
Deposits	2,144,041	1,337,281
FHLB advances	319,500	25,000
Long-term debt	103,708	49,528
Subordinated debenture liability	9,506	3,424
Fair Value \| Fair Value, Inputs, Level 1
Financial Assets:
Cash and due from banks	147,685	70,048
Federal funds sold and other cash equivalents		80,000
Interest-earning deposits in other financial institutions	600	600
Fair Value \| Fair Value Measurements Using Level 2
Financial Assets:
Investment securities - AFS	73,762	64,957
Investment securities - HTM	9,940	10,250
Mortgage loans held for sale	438,948	128,972
Financial Liabilities:
Deposits	2,143,196	1,336,353
FHLB advances	319,500	25,000
Long-term debt	79,756	44,319
Fair Value \| Fair Value Measurements Using Level 3
Financial Assets:
Loans, net	2,114,341	1,236,289
Financial Liabilities:
Subordinated debenture liability	$ 10,356	$ 3,348

Earnings Per Share ("EPS") - Computation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Earnings Per Share [Abstract]
Net income as reported	$ 9,490	$ 8,331	$ 9,437	$ 8,847	$ 4,888	$ 6,611	$ 8,536	$ 5,493	$ 36,105	$ 25,528	$ 19,079
Shares outstanding									20,000,022	15,908,893	12,827,803
Impact of weighting shares									(2,848,800)	(1,830,612)	(26,813)
Used in basic EPS, Income									$ 36,105	$ 25,528	$ 19,079
Used in basic EPS, Shares									17,151,222	14,078,281	12,800,990
Dilutive effect of outstanding
Stock options, Shares									816,431	1,160,084	894,910
Used in dilutive EPS, Income									$ 36,105	$ 25,528	$ 19,079
Used in dilutive EPS, Shares									17,967,653	15,238,365	13,695,900
Basic earnings per common share	$ 0.48	$ 0.50	$ 0.58	$ 0.55	$ 0.26	$ 0.45	$ 0.67	$ 0.43	$ 2.11	$ 1.81	$ 1.49
Diluted earnings per common share	$ 0.47	$ 0.48	$ 0.54	$ 0.52	$ 0.24	$ 0.42	$ 0.62	$ 0.40	$ 2.01	$ 1.68	$ 1.39

Earnings Per Share ("EPS") - Additional Information (Details) - shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
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	399,000	0	321,000

Qualified Affordable Housing Project Investments - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Equity Method Investments And Joint Ventures [Abstract]
Investment for qualified affordable housing projects	$ 9,500,000	$ 5,700,000
Unfunded commitments related to the investments in qualified affordable housing projects	$ 6,800,000
Expected year in which commitments are fulfilled	2027
Amortization expense	$ 644,000	316,000
Recognized tax credits from its investment in affordable housing tax credits	573,000	275,000
Impairment losses	$ 0	$ 0

Parent Only Condensed Financial Information - Schedule of Parent Only Condensed Balance Sheets (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Assets
Cash and cash equivalents	$ 147,685	$ 70,048
Total assets	2,974,002	1,691,059
Liabilities and Shareholders’ Equity
Reserve for unfunded commitments	688	282
Long term debt	103,708	49,528
Subordinated debentures	9,506	3,424
Accrued interest and other liabilities	21,938	10,368
Total liabilities	2,599,381	1,425,883
Shareholders' equity:
Common stock	288,610	205,927
Additional paid-in capital	5,659	8,426
Retained earnings	81,618	51,266
Non-controlling interest	72
Accumulated other comprehensive income (loss)	(1,338)	(443)
Total shareholders’ equity	374,621	265,176	$ 181,585	$ 163,645
Total liabilities and shareholders’ equity	2,974,002	1,691,059
RBB Bancorp
Assets
Cash and cash equivalents	45,540	45,769
Other assets	2,820	3,538
Total assets	488,179	318,597
Liabilities and Shareholders’ Equity
Long term debt	103,708	49,528
Subordinated debentures	9,506	3,424
Other liabilities	347	37
Total liabilities	113,561	52,989
Shareholders' equity:
Common stock	288,610	205,927
Additional paid-in capital	5,659	8,426
Retained earnings	81,615	51,697
Non-controlling interest	72
Accumulated other comprehensive income (loss)	(1,338)	(442)
Total shareholders’ equity	374,618	265,608
Total liabilities and shareholders’ equity	488,179	318,597
RBB Bancorp \| Royal Business Bank
Assets
Investment	433,023	263,022
RBB Bancorp \| Royal Asset Management
Assets
Investment	$ 6,796	$ 6,268

Parent Only Condensed Financial Information - Schedule of Parent Only Condensed Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Consolidated Statements of Income and Comprehensive Income
Interest Income	$ 35,181	$ 24,473	$ 22,284	$ 20,177	$ 21,478	$ 18,346	$ 17,521	$ 16,759	$ 102,115	$ 74,104	$ 68,189
Interest expense	9,599	5,857	4,457	3,732	3,588	3,618	3,487	3,245	23,645	13,938	11,707
Noninterest expense	15,503	8,654	8,191	8,289	6,885	7,200	6,960	6,578	40,637	27,623	27,906
Income before income taxes	13,678	10,372	11,729	10,427	12,368	10,624	14,437	9,368	46,206	46,797	32,568
Income tax benefit	(4,188)	(2,041)	(2,292)	(1,580)	(7,480)	(4,013)	(5,901)	(3,875)	(10,101)	(21,269)	(13,489)
Net income	$ 9,490	$ 8,331	$ 9,437	$ 8,847	$ 4,888	$ 6,611	$ 8,536	$ 5,493	36,105	25,528	19,079
Other comprehensive income (loss)									(895)	(104)	(74)
Total comprehensive income									35,210	25,424	19,005
RBB Bancorp
Consolidated Statements of Income and Comprehensive Income
Interest Income									15
Interest expense									4,083	3,629	2,728
Noninterest expense									1,690	704	123
Loss before equity in undistributed income of subsidiaries									(5,758)	(4,333)	(2,851)
Income before income taxes									33,968	23,430	17,906
Income tax benefit									1,702	2,036	1,173
Net income									35,670	25,466	19,079
Other comprehensive income (loss)									(895)	(104)	(74)
Total comprehensive income									34,775	25,362	19,005
RBB Bancorp \| Royal Business Bank
Consolidated Statements of Income and Comprehensive Income
Equity in undistributed income									39,198	27,620	20,483
RBB Bancorp \| Royal Asset Management
Consolidated Statements of Income and Comprehensive Income
Equity in undistributed income									$ 528	$ 143	$ 274

Parent Only Condensed Financial Information - Schedule of Parent Only Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities:
Net income	$ 36,105	$ 25,528	$ 19,079
Net cash from operating activities	(84,648)	28,783	56,219
Cash flows from investment activities:
Net cash acquired (outlay) in connection with acquisition	25,073		(35,051)
Net cash from investing activities	(322,390)	(264,446)	7,202
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs	54,018		49,274
Issuance of common stock, net of issuance costs		60,210
Cash dividends paid	(5,753)	(5,118)	(2,554)
Stock options exercised	9,629	2,296	595
Net cash from financing activities	404,675	266,998	(58,599)
Net (decrease) increase in cash and cash equivalents	(2,363)	31,335	4,822
RBB Bancorp
Cash flows from operating activities:
Net income	35,670	25,466	19,079
Net amortization of other	268	235	188
Provision for deferred income taxes	(1,905)	1,807	(1,172)
Undistributed income of subsidiaries	(39,726)	(27,763)	(20,757)
Change in other assets and liabilities	3,927	(3,861)	(159)
Net cash from operating activities	(1,766)	(4,116)	(2,821)
Cash flows from investment activities:
Net cash acquired (outlay) in connection with acquisition	(41,358)		(839)
Investment in subsidiaries	(15,000)	(25,000)	(35,000)
Net cash from investing activities	(56,358)	(25,000)	(35,839)
Cash flows from financing activities:
Issuance of subordinated debentures, net of issuance costs	54,018		49,274
Issuance of common stock, net of issuance costs		60,210
Cash dividends paid	(5,753)	(5,118)	(2,554)
Stock options exercised	9,630	2,296	585
Net cash from financing activities	57,895	57,388	47,305
Net (decrease) increase in cash and cash equivalents	(229)	28,272	8,645
Cash and cash equivalents beginning of year	45,769	17,497	8,852
Cash and cash equivalents end of year	$ 45,540	$ 45,769	$ 17,497

Subsequent Events - Additional Information (Details) - USD ($)				12 Months Ended
	Mar. 22, 2019	Mar. 21, 2019	Jan. 17, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 31, 2019
Subsequent Event [Line Items]
Cash dividends declared per common share				$ 0.35	$ 0.38	$ 0.20
Debt instrument, face amount				$ 105,000,000	$ 50,000,000
Subsequent Event
Subsequent Event [Line Items]
Cash dividends declared per common share			$ 0.10
Cash dividend declared date			Jan. 17, 2019
Cash dividend payable date			Feb. 15, 2019
Cash dividend declared, record date			Jan. 31, 2019
Cash dividend payable amount							$ 2,000,000
Subsequent Event \| Private Placement \| UMB Bank, N.A.
Subsequent Event [Line Items]
Debt instrument, face amount	$ 55,000,000
Percentage of aggregate principal amount of subordinated notes	100.00%
Subsequent Event \| 6.180% Fixed-to-Floating Rate Subordinated Notes Due 2028
Subsequent Event [Line Items]
Long-term debt, fixed interest rate	6.18%
Debt instrument, due date	Dec. 01, 2028
Subsequent Event \| 6.180% Fixed-to-Floating Rate Subordinated Notes Due 2028 \| Private Placement
Subsequent Event [Line Items]
Exchange offer closed date	Mar. 22, 2019
Debt instrument, face amount		$ 55,000,000
Long-term debt, fixed interest rate		6.18%
Debt instrument, due date		Dec. 01, 2028

Quarterly Income Statements (Unaudited) - Schedule of Quarterly Condensed Income Statements (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Interest Income	$ 35,181	$ 24,473	$ 22,284	$ 20,177	$ 21,478	$ 18,346	$ 17,521	$ 16,759	$ 102,115	$ 74,104	$ 68,189
Interest expense	9,599	5,857	4,457	3,732	3,588	3,618	3,487	3,245	23,645	13,938	11,707
Net interest income	25,582	18,616	17,827	16,445	17,890	14,728	14,034	13,514	78,470	60,166	56,482
Provision (recapture) for credit losses	1,890	1,695	700	184	2,435	700	(4,188)		4,469	(1,053)	4,974
Net interest income after provision (recapture) for credit losses	23,692	16,921	17,127	16,261	15,455	14,028	18,222	13,514	74,001	61,219	51,508
Noninterest income:	5,489	2,105	2,793	2,455	3,798	3,796	3,175	2,432	12,842	13,201	8,966
Noninterest expense	15,503	8,654	8,191	8,289	6,885	7,200	6,960	6,578	40,637	27,623	27,906
Income before income taxes	13,678	10,372	11,729	10,427	12,368	10,624	14,437	9,368	46,206	46,797	32,568
Income tax expense	4,188	2,041	2,292	1,580	7,480	4,013	5,901	3,875	10,101	21,269	13,489
Net income	$ 9,490	$ 8,331	$ 9,437	$ 8,847	$ 4,888	$ 6,611	$ 8,536	$ 5,493	$ 36,105	$ 25,528	$ 19,079
Net income per share
Basic	$ 0.48	$ 0.50	$ 0.58	$ 0.55	$ 0.26	$ 0.45	$ 0.67	$ 0.43	$ 2.11	$ 1.81	$ 1.49
Diluted	$ 0.47	$ 0.48	$ 0.54	$ 0.52	$ 0.24	$ 0.42	$ 0.62	$ 0.40	$ 2.01	$ 1.68	$ 1.39