Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 188,167	$ 151,461	$ 485,242	$ 382,724
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on debt securities	13,493	(14,662)	126,172	(73,933)
Foreign currency translation adjustment	(7,373)	3,001	2,959	(11,296)
Pension benefit adjustment	(76)	118	(227)	357
Total other comprehensive income (loss), net of tax	6,044	(11,543)	128,904	(84,872)
Comprehensive income	194,211	139,918	614,146	297,852
Less: Comprehensive income (loss) attributable to noncontrolling interests	985	(19)	1,829	(142)
Comprehensive income attributable to the Company	$ 193,226	$ 139,937	$ 612,317	$ 297,994

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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