Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Foreign currency translation adjustments:
Change in unrealized foreign currency translation gains (losses) before income taxes	$ 4,736	$ (7,016)	$ (8,536)	$ 1,010
Change in unrealized foreign currency translation gains (losses), net of income taxes	4,736	(7,016)	(8,536)	1,010
Unrealized gain (losses) on available-for-sale securities:
Change in unrealized holding gains (losses) arising during period before income taxes	106,493	(55,060)	84,890	(39,694)
Income tax expense (benefit) on unrealized holding gains (losses) arising during period	22,769	(11,704)	18,053	(8,735)
Change in unrealized holding gains (losses) on available-for-sale securities arising during period, net of income taxes	83,724	(43,356)	66,837	(30,959)
Reclassification from accumulated OCI to net income for (gains) losses realized on available-for-sale securities	142	3	(429)	2,817
Income tax (expense) benefit on (gains) losses reclassified from accumulated OCI to net income	30	1	(90)	592
Reclassification from accumulated OCI to net income for (gains) losses realized on available-for-sale securities, net of income taxes	112	2	(339)	2,225
Change in unrealized gains (losses) on available-for-sale securities, net of income taxes and reclassification adjustment	83,836	(43,354)	66,498	(28,734)
Effect of change in discount rate assumptions on the LFPB:
Change in effect in discount rate assumptions on the LFPB before income taxes	(346,794)	410,460	(40,910)	314,487
Income tax (expense) benefit on the effect of change in discount rate assumptions on the LFPB from accumulated OCI to net income	(74,112)	88,209	(8,755)	67,268
Change in effect in discount rate assumptions on the LFPB, net of income taxes	$ (272,682)	$ 322,251	$ (32,155)	$ 247,219