Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 234,458	$ 63,846
Other comprehensive income (loss), net of tax:
Unrealized (losses) gains on debt securities	(99,453)	12,619
Unrealized (losses) gains on debt securities for which credit-related portion was recognized in earnings	(293)	85
Foreign currency translation adjustment	3,374	(33,556)
Pension benefit adjustment	1,002	399
Total other comprehensive loss, net of tax	(95,370)	(20,453)
Comprehensive income	139,088	43,393
Less: Comprehensive income attributable to noncontrolling interests	841	642
Comprehensive income attributable to the Company	$ 138,247	$ 42,751