Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 187,271	$ 155,091	$ 297,075	$ 231,263
Other comprehensive income (loss), net of tax:
Unrealized gains (losses) on debt securities	53,174	(12,475)	112,679	(59,271)
Foreign currency translation adjustment	3,444	(10,545)	10,332	(14,297)
Pension benefit adjustment	(75)	119	(151)	239
Total other comprehensive income (loss), net of tax	56,543	(22,901)	122,860	(73,329)
Comprehensive income	243,814	132,190	419,935	157,934
Less: Comprehensive income (loss) attributable to noncontrolling interests	616	(49)	844	(123)
Comprehensive income attributable to the Company	$ 243,198	$ 132,239	$ 419,091	$ 158,057

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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