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Basis of Presentation and Summary of Significant Accounting Policies - Changes in the Balance of Each Component of Accumulated Other Comprehensive Earnings (Details) - USD ($) $ in Thousands | 3 Months Ended
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Mar. 31, 2026 | Mar. 31, 2025
Changes in the balance of each component of accumulated other comprehensive earnings (loss) |  |
Beginning balance | $ 1,778,196 | $ 1,521,967
Net current-period other comprehensive earnings (loss) | (25,366) | 30,030
Ending balance | 1,796,390 | 1,604,212
Balance of securities for which an allowance for credit losses has been recognized in net earnings | 1,710 | 1,692
Unrealized Gains and Losses on Available-for-Sale Securities |  |
Changes in the balance of each component of accumulated other comprehensive earnings (loss) |  |
Beginning balance | (88,074) | (173,723)
Other comprehensive earnings before reclassifications | (25,977) | 29,899
Amounts reclassified from accumulated other comprehensive earnings | 611 | 131
Net current-period other comprehensive earnings (loss) | (25,366) | 30,030
Ending balance | $ (113,440) | $ (143,693)

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