v3.25.4
First US Bancshares, Inc. (Parent Company Only) Financial Information - Statements of Cash Flow (Detail) - USD ($)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2025
Sep. 30, 2025
Jun. 30, 2025
Mar. 31, 2025
Dec. 31, 2024
Sep. 30, 2024
Jun. 30, 2024
Mar. 31, 2024
Dec. 31, 2025
Dec. 31, 2024
Cash flows from operating activities:                    
Net income $ 2,129 $ 1,936 $ 155 $ 1,772 $ 1,714 $ 2,222 $ 2,127 $ 2,107 $ 5,992 $ 8,170
Adjustments to reconcile net income to net cash provided by operating activities:                    
Net cash provided by operating activities                 12,325 7,761
Cash flows from financing activities:                    
Net share-based compensation transactions                 93 64
Dividends paid                 (1,608) (1,264)
Treasury stock repurchases                 (1,761) (1,643)
Net cash provided by financing activities                 42,129 19,523
Net increase (decrease) in cash and cash equivalents                 26,331 (3,063)
Cash and cash equivalents, beginning of period       47,216       50,279 47,216 50,279
Cash and cash equivalents, end of period 73,547       47,216       73,547 47,216
FUSB [Member]                    
Cash flows from operating activities:                    
Net income                 5,992 8,170
Adjustments to reconcile net income to net cash provided by operating activities:                    
Distributions in excess of undistributed income of subsidiary                 868 (4,079)
Change in other assets and liabilities                 413 (388)
Net cash provided by operating activities                 7,273 3,703
Cash flows from financing activities:                    
Net share-based compensation transactions                 93 64
Dividends paid                 (1,608) (1,264)
Treasury stock repurchases                 (1,761) (1,643)
Net cash provided by financing activities                 (3,276) (2,843)
Net increase (decrease) in cash and cash equivalents                 3,997 860
Cash and cash equivalents, beginning of period       $ 2,716       $ 1,856 2,716 1,856
Cash and cash equivalents, end of period $ 6,713       $ 2,716       $ 6,713 $ 2,716