Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 75,759	$ 80,937	$ 207,135	$ 153,477
Other comprehensive income (loss), net of tax:
Unrealized (losses) gains on securities	(10,942)	(14,735)	(19,374)	11,504
Foreign currency translation adjustment	(15,416)	(12,557)	(29,210)	(6,985)
Pension benefit adjustment	4,058	907	13,260	8,690
Other comprehensive (loss) income, net of tax	(22,300)	(26,385)	(35,324)	13,209
Comprehensive income	53,459	54,552	171,811	166,686
Less: Comprehensive income attributable to noncontrolling interests	206	235	598	464
Comprehensive income attributable to the Company	$ 53,253	$ 54,317	$ 171,213	$ 166,222