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
	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)