Description of Business	12 Months Ended
Dec. 31, 2023
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Description of Business	1. DESCRIPTION OF BUSINESS First US Bancshares, Inc., a Delaware corporation (“Bancshares” and, together with its subsidiary, the “Company”), is a bank holding company formed in 1983 registered under the Bank Holding Company Act of 1956, as amended (the “BHCA”). Bancshares operates one banking subsidiary, First US Bank, an Alabama banking corporation (the “Bank”). Prior to its name change on October 11, 2016, Bancshares was known as United Security Bancshares, Inc. Bancshares and the Bank are headquartered in Birmingham, Alabama. The Bank conducts a general commercial banking business and offers banking services such as demand, savings, individual retirement account and time deposits, personal and commercial loans, safe deposit box services and remote deposit capture. The Bank operates and serves its customers through 15 full-service banking offices located in Birmingham, Butler, Calera, Centreville, Gilbertown, Grove Hill, Harpersville, Jackson, Thomasville, Tuscaloosa and Woodstock, Alabama; Knoxville and Powell, Tennessee; and Rose Hill, Virginia; as well as loan production offices in Mobile, Alabama and the Chattanooga, Tennessee area. The Bank provides a wide range of commercial banking services to small- and medium-sized businesses, property managers, business executives, professionals and other individuals. The Bank also performs indirect lending through third-party retailers and currently conducts this lending in 17 states, including Alabama, Arkansas, Florida, Georgia, Indiana, Iowa, Kansas, Kentucky, Mississippi, Missouri, Nebraska, North Carolina, Oklahoma, South Carolina, Tennessee, Texas and Virginia. Previously, the Bank had two wholly owned subsidiaries: Acceptance Loan Company, Inc., an Alabama corporation (“ALC”), and FUSB Reinsurance, Inc., an Arizona corporation (“FUSB Reinsurance”). Both ALC and FUSB Reinsurance were dissolved in 2023, after all remaining assets and liabilities of these entities were transferred to the Bank. As used herein, unless the context suggests otherwise, references to the “Company,” “we,” “us” and “our” refer to Bancshares and the Bank, as well as ALC and FUSB Reinsurance (for periods prior to their dissolution), collectively. ALC was a finance company headquartered in Mobile, Alabama. The Bank will continue to manage the remaining loans from ALC’s portfolio, which totaled $10.5 million as of December 31, 2023, through final resolution. FUSB Reinsurance was designed to reinsure certain insurance policies sold to the Bank's and ALC's consumer loan customers.

Description of Business

12 Months Ended

Dec. 31, 2023

Organization, Consolidation and Presentation of Financial Statements [Abstract]

DESCRIPTION OF BUSINESS

First US Bancshares, Inc., a Delaware corporation (“Bancshares” and, together with its subsidiary, the “Company”), is a bank holding company formed in 1983 registered under the Bank Holding Company Act of 1956, as amended (the “BHCA”). Bancshares operates one banking subsidiary, First US Bank, an Alabama banking corporation (the “Bank”). Prior to its name change on October 11, 2016, Bancshares was known as United Security Bancshares, Inc. Bancshares and the Bank are headquartered in Birmingham, Alabama.

The Bank conducts a general commercial banking business and offers banking services such as demand, savings, individual retirement account and time deposits, personal and commercial loans, safe deposit box services and remote deposit capture. The Bank operates and serves its customers through 15 full-service banking offices located in Birmingham, Butler, Calera, Centreville, Gilbertown, Grove Hill, Harpersville, Jackson, Thomasville, Tuscaloosa and Woodstock, Alabama; Knoxville and Powell, Tennessee; and Rose Hill, Virginia; as well as loan production offices in Mobile, Alabama and the Chattanooga, Tennessee area. The Bank provides a wide range of commercial banking services to small- and medium-sized businesses, property managers, business executives, professionals and other individuals. The Bank also performs indirect lending through third-party retailers and currently conducts this lending in 17 states, including Alabama, Arkansas, Florida, Georgia, Indiana, Iowa, Kansas, Kentucky, Mississippi, Missouri, Nebraska, North Carolina, Oklahoma, South Carolina, Tennessee, Texas and Virginia.

Previously, the Bank had two wholly owned subsidiaries: Acceptance Loan Company, Inc., an Alabama corporation (“ALC”), and FUSB Reinsurance, Inc., an Arizona corporation (“FUSB Reinsurance”). Both ALC and FUSB Reinsurance were dissolved in 2023, after all remaining assets and liabilities of these entities were transferred to the Bank. As used herein, unless the context suggests otherwise, references to the “Company,” “we,” “us” and “our” refer to Bancshares and the Bank, as well as ALC and FUSB Reinsurance (for periods prior to their dissolution), collectively.

ALC was a finance company headquartered in Mobile, Alabama. The Bank will continue to manage the remaining loans from ALC’s portfolio, which totaled $10.5 million as of December 31, 2023, through final resolution. FUSB Reinsurance was designed to reinsure certain insurance policies sold to the Bank's and ALC's consumer loan customers.