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, 2022	Jun. 30, 2022	Mar. 31, 2022	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2022	Sep. 30, 2021
Reclassification Adjustment Out of Accumulated Other Comprehensive Income (Loss)
Net realized gains (losses)	$ 573,170			$ 1,829			$ 591,562	$ 52,442
Earnings (loss) before income taxes	554,702			35,437			606,673	227,292
Income tax (expense) benefit	(114,809)			(6,194)			(121,096)	(43,222)
Net earnings (loss)	439,893	$ (2,239)	$ 47,923	29,243	$ 81,815	$ 73,012	485,577	184,070
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)	(1,912)			182			(2,684)	1,731
Credit gains presented within net realized gains	(34)			(22)			115	171
Earnings (loss) before income taxes	(1,946)			160			(2,569)	1,902
Income tax (expense) benefit	409			(34)			539	(399)
Net earnings (loss)	$ (1,537)			$ 126			$ (2,030)	$ 1,503