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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, 2022 | Sep. 30, 2022 | Jun. 30, 2022 | Mar. 31, 2022 | Dec. 31, 2021 | Sep. 30, 2021 | Jun. 30, 2021 | Mar. 31, 2021 | Dec. 31, 2022 | Dec. 31, 2021
Cash flows from operating activities: |  |  |  |  |  |  |  |  |  |
Net income | $ 2,228 | $ 1,860 | $ 1,415 | $ 1,361 | $ 1,711 | $ 837 | $ 953 | $ 950 | $ 6,864 | $ 4,451
Adjustments to reconcile net income to net cash provided by operating activities: |  |  |  |  |  |  |  |  |  |
Net cash provided by operating activities |  |  |  |  |  |  |  |  | 12,529 | 9,825
Cash flows from investing activities: |  |  |  |  |  |  |  |  |  |
Net cash used in investing activities |  |  |  |  |  |  |  |  | (80,199) | (108,315)
Cash flows from financing activities: |  |  |  |  |  |  |  |  |  |
Net proceeds from long-term borrowings |  |  |  |  |  |  |  |  |  | 10,653
Net share-based compensation transactions |  |  |  |  |  |  |  |  |  | (7)
Dividends paid |  |  |  |  |  |  |  |  | (832) | (745)
Treasury stock repurchases |  |  |  |  |  |  |  |  | (4,481) | (525)
Net cash provided by financing activities |  |  |  |  |  |  |  |  | 36,578 | 65,319
Net decrease in cash and cash equivalents |  |  |  |  |  |  |  |  | (31,092) | (33,171)
Cash and cash equivalents, beginning of period |  |  |  | 61,244 |  |  |  | 94,415 | 61,244 | 94,415
Cash and cash equivalents, end of period | 30,152 |  |  |  | 61,244 |  |  |  | 30,152 | 61,244
FUSB [Member] |  |  |  |  |  |  |  |  |  |
Cash flows from operating activities: |  |  |  |  |  |  |  |  |  |
Net income |  |  |  |  |  |  |  |  | 6,864 | 4,451
Adjustments to reconcile net income to net cash provided by operating activities: |  |  |  |  |  |  |  |  |  |
Distributions in excess of undistributed income of subsidiaries |  |  |  |  |  |  |  |  | (4,721) | (3,936)
Change in other assets and liabilities |  |  |  |  |  |  |  |  | 135 | 580
Net cash provided by operating activities |  |  |  |  |  |  |  |  | 2,278 | 1,095
Cash flows from investing activities: |  |  |  |  |  |  |  |  |  |
Investment in subsidiaries |  |  |  |  |  |  |  |  |  | (5,000)
Net cash used in investing activities |  |  |  |  |  |  |  |  |  | (5,000)
Cash flows from financing activities: |  |  |  |  |  |  |  |  |  |
Net proceeds from long-term borrowings |  |  |  |  |  |  |  |  |  | 10,653
Net share-based compensation transactions |  |  |  |  |  |  |  |  |  | (7)
Dividends paid |  |  |  |  |  |  |  |  | (832) | (745)
Treasury stock repurchases |  |  |  |  |  |  |  |  | (4,481) | (525)
Net cash provided by financing activities |  |  |  |  |  |  |  |  | (5,313) | 9,376
Net decrease in cash and cash equivalents |  |  |  |  |  |  |  |  | (3,035) | 5,471
Cash and cash equivalents, beginning of period |  |  |  | $ 5,890 |  |  |  | $ 419 | 5,890 | 419
Cash and cash equivalents, end of period | $ 2,855 |  |  |  | $ 5,890 |  |  |  | $ 2,855 | $ 5,890

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