Business Description	9 Months Ended
Sep. 30, 2017
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. Our principal business is to serve as the holding company for our wholly-owned banking subsidiaries, Royal Business Bank ("Bank") and RBB Asset Management Company ("RAM"), collectively referred to herein as "the Company". At September 30, 2017, the Company had total assets of $1.6 billion, gross loans of $1.2 billion, total deposits of $1.3 billion and total stockholders' equity of $260.3 million. On July 31, 2017, the Company completed its initial public offering of 3,750,000 shares at a price to the public of $23.00 per share. The Company’s stock trades on the Nasdaq Global Select Market under the symbol “RBB”. Royal Business Bank provides business banking services to the Chinese-American communities in Los Angeles County, Orange County, Ventura County and in Las Vegas, including remote deposit, E-banking, mobile banking, commercial and investor real estate loans, business loans and lines of credit, SBA 7A and 504 loans, mortgage loans, trade finance and a full range of depository accounts. RAM was formed to hold and manage problem assets acquired in business combinations. The Company operates full-service banking offices in Arcadia, Cerritos, Diamond Bar, Los Angeles, Monterey Park, Oxnard, Rowland Heights, San Gabriel, Silver Lake, Torrance, West LA, and Westlake Village, California and Las Vegas, Nevada and a loan production office in the City of Industry, California. The Company's primary source of revenue is providing loans to customers, who are predominately small and middle-market businesses and individuals. We generate our revenue primarily from interest received on loans and leases and, to a lesser extent, from interest received on investment securities. We have also derived income from noninterest sources, such as fees received in connection with various lending and deposit services, residential mortgage loan originations, loan servicing and gain on sales of loans. Our 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. We have completed four acquisitions from July 8, 2011 through February 19, 2016, including the acquisition of TFC Holding Company on February 19, 2016. Our acquisitions have been accounted for using the acquisition method of accounting and, accordingly, the operating results of the acquired entities have been included in the consolidated financial statements from their respective acquisition dates. See Note 3. Acquisitions, for more information about the TFC acquisition.

NOTE 1 - BUSINESS DESCRIPTION

RBB Bancorp is a bank holding company registered under the Bank Holding Company Act of 1956, as amended. Our principal business is to serve as the holding company for our wholly-owned banking subsidiaries, Royal Business Bank ("Bank") and RBB Asset Management Company ("RAM"), collectively referred to herein as "the Company". At September 30, 2017, the Company had total assets of $1.6 billion, gross loans of $1.2 billion, total deposits of $1.3 billion and total stockholders' equity of $260.3 million. On July 31, 2017, the Company completed its initial public offering of 3,750,000 shares at a price to the public of $23.00 per share. The Company’s stock trades on the Nasdaq Global Select Market under the symbol “RBB”.

Royal Business Bank provides business banking services to the Chinese-American communities in Los Angeles County, Orange County, Ventura County and in Las Vegas, including remote deposit, E-banking, mobile banking, commercial and investor real estate loans, business loans and lines of credit, SBA 7A and 504 loans, mortgage loans, trade finance and a full range of depository accounts. RAM was formed to hold and manage problem assets acquired in business combinations.

The Company operates full-service banking offices in Arcadia, Cerritos, Diamond Bar, Los Angeles, Monterey Park, Oxnard, Rowland Heights, San Gabriel, Silver Lake, Torrance, West LA, and Westlake Village, California and Las Vegas, Nevada and a loan production office in the City of Industry, California. The Company's primary source of revenue is providing loans to customers, who are predominately small and middle-market businesses and individuals.

We generate our revenue primarily from interest received on loans and leases and, to a lesser extent, from interest received on investment securities. We have also derived income from noninterest sources, such as fees received in connection with various lending and deposit services, residential mortgage loan originations, loan servicing and gain on sales of loans. Our 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.

We have completed four acquisitions from July 8, 2011 through February 19, 2016, including the acquisition of TFC Holding Company on February 19, 2016. Our acquisitions have been accounted for using the acquisition method of accounting and, accordingly, the operating results of the acquired entities have been included in the consolidated financial statements from their respective acquisition dates. See Note 3. Acquisitions, for more information about the TFC acquisition.