Summary of Significant Accounting Policies - Effects of Reclassifications out of Accumulated Other Comprehensive Earnings (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss)
Net realized gains (losses) - Available-for-sale	$ (5,276)	$ (3,641)	$ (2,997)
Earnings before income taxes	427,551	377,265	720,678
Income tax (expense) benefit	(81,772)	(72,654)	(137,267)
Net earnings	345,779	304,611	583,411
Unrealized Gains and Losses on Available-for-Sale Securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss)
Net realized gains (losses) - Available-for-sale	(5,276)	(3,641)	(2,997)
Credit gains (losses) presented within net realized gains	110	32	102
Earnings before income taxes	(5,166)	(3,609)	(2,895)
Income tax (expense) benefit	1,085	758	608
Net earnings	$ (4,081)	$ (2,851)	$ (2,287)