Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 450,465	$ 183,591	$ 988,331	$ 419,131
Other comprehensive income (loss), net of tax:
Unrealized (losses) gains on debt securities	(42,715)	1,991	(104,578)	73,077
Unrealized gains (losses) on debt securities for which credit-related portion was recognized in earnings	1	(7)	(276)	140
Foreign currency translation adjustment	(12,619)	10,074	(3,835)	(9,109)
Pension benefit adjustment	1,002	399	3,006	1,197
Total other comprehensive (loss) income, net of tax	(54,331)	12,457	(105,683)	65,305
Comprehensive income	396,134	196,048	882,648	484,436
Less: Comprehensive income attributable to noncontrolling interests	5,215	1,312	7,165	2,993
Comprehensive income attributable to the Company	$ 390,919	$ 194,736	$ 875,483	$ 481,443