Consolidated Statements of Comprehensive Income (Unaudited) Statement - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 109,573	$ 108,906	$ 234,247	$ 229,153
Other comprehensive income:
Change in unrealized currency translation adjustments	20,247	(55,870)	42,982	(57,917)
Change in unrealized investment gains, net of taxes	43,597	105,033	34,766	181,888
Other comprehensive income	63,844	49,163	77,748	123,971
Comprehensive income	173,417	158,069	311,995	353,124
Noncontrolling interests	(602)	56	(1,810)	(667)
Comprehensive income to common stockholders	$ 172,815	$ 158,125	$ 310,185	$ 352,457