Basis of Presentation and Summary of Significant Accounting Policies - Schedule of Effects of Reclassifications out of Accumulated Other Comprehensive Earnings (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2023	Sep. 30, 2022
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss)
Earnings before income taxes	$ 15,019			$ 554,702			$ 233,841	$ 606,673
Income tax (expense) benefit	(1,483)			(114,809)			(43,842)	(121,096)
Net earnings	13,536	$ 77,652	$ 98,811	439,893	$ (2,239)	$ 47,923	189,999	485,577
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	(271)			(1,912)			(2,808)	(2,684)
Credit gains (losses) presented within net realized gains	(270)			(34)			(365)	115
Earnings before income taxes	(541)			(1,946)			(3,173)	(2,569)
Income tax (expense) benefit	114			409			666	539
Net earnings	$ (427)			$ (1,537)			$ (2,507)	$ (2,030)