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Income Taxes (Income Tax Expense Differences from the Amount Computed by Applying the U.S. Federal Income Tax Rate) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Income Taxes |  |  |
U.S. Federal income tax rate (as a percent) | 21.00% | 21.00% | 21.00%
Reasons for the difference of income tax expense |  |  |
Computed expected tax expense | $ 107,134 | $ 110,065 | $ 80,893
Change in taxes resulting from: |  |  |
Tax-exempt interest income | (3,233) | (3,663) | (2,433)
State tax, net of federal income taxes and tax credit and refunds | 4,636 | 4,808 | 4,094
Other investment income | (2,626) | (2,761) | (1,391)
Net investment expense, low-income housing investment | (2,531) | 1,974 | 1,906
Other | (3,827) | 1,321 | (662)
Total income taxes | $ 99,553 | $ 111,744 | $ 82,407

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