Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 162,818	$ 220,663	$ 397,065	$ 449,816
Other comprehensive income (loss):
Change in unrealized currency translation adjustments	28,592	(19,470)	71,574	(77,389)
Change in unrealized investment gains (losses), net of taxes	(8,168)	(47,676)	26,598	134,213
Other comprehensive income (loss)	20,424	(67,146)	98,172	56,824
Comprehensive income	183,242	153,517	495,237	506,640
Noncontrolling interests	(731)	44	(2,541)	(623)
Comprehensive income to common stockholders	$ 182,511	$ 153,561	$ 492,696	$ 506,017