Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Foreign currency translation adjustments:
Change in unrealized foreign currency translation gains (losses)	$ 10,044	$ (20,826)	$ 6,969
Change in unrealized foreign currency translation gains (losses), net of income taxes	10,044	(20,826)	6,969
Unrealized gain (losses) on available-for-sale securities:
Change in unrealized holding gains (losses) arising during period before income taxes	87,390	(385,735)	(78,348)
Income tax expense (benefit) on unrealized holding gains (losses) arising during period	18,751	(82,185)	(17,038)
Change in unrealized holding gains (losses) on available-for-sale securities arising during period, net of income taxes	68,639	(303,550)	(61,310)
Reclassification adjustment for investment (gains) losses included in net income	2,811	(1,387)	(3,849)
Income tax (expense) benefit on (gains) losses reclassified from accumulated OCI to net income	590	(292)	(808)
Reclassification from accumulated OCI to net income for (gains) losses realized on available-for-sale securities, net of income taxes	2,221	(1,095)	(3,041)
Change in unrealized gains (losses) on available-for-sale securities, net of income taxes and reclassification adjustment	70,860	(304,645)	(64,351)
Effect of change in discount rate assumptions on the LFPB:
Change in effect in discount rate assumptions on the LFPB before income taxes	(216,301)	1,739,762	347,041
Income tax (expense) benefit on the effect of change in discount rate assumptions on the LFPB from accumulated OCI to net income	(46,799)	371,166	74,599
Change in effect in discount rate assumptions on the LFPB, net of income taxes	$ (169,502)	$ 1,368,596	$ 272,442