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Parent Company Condensed Financial Information - Statements of Net Income (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Condensed Income Statements, Captions [Line Items] |  |  |
Total Interest and Dividend Income | $ 477,901 | $ 340,751 | $ 289,262
Interest expense on long-term debt | 1,332 | 411 | 458
Income tax benefit | 34,023 | 33,410 | 25,325
Equity in undistributed net income (distribution in excess of net income) of: |  |  |
Net Income | 144,781 | 135,520 | 110,343
S&T |  |  |
Condensed Income Statements, Captions [Line Items] |  |  |
Dividends from subsidiaries | 86,950 | 61,426 | 62,333
Investment income | 0 | 0 | 0
Total Interest and Dividend Income | 86,950 | 61,426 | 62,333
Interest expense on long-term debt | 2,372 | 1,545 | 1,400
Other expenses | 4,764 | 4,112 | 3,947
Tax expense | 7,136 | 5,657 | 5,347
Income before income tax and undistributed net income of subsidiaries | 79,814 | 55,769 | 56,986
Income tax benefit | (1,478) | (1,208) | (1,140)
Income before undistributed net income of subsidiaries | 81,292 | 56,977 | 58,126
Equity in undistributed net income (distribution in excess of net income) of: |  |  |
Bank subsidiary | 63,337 | 79,566 | 57,025
Nonbank subsidiaries | 152 | (1,023) | (4,808)
Net Income | $ 144,781 | $ 135,520 | $ 110,343

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