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 Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 217,427	$ 180,778	$ 399,041	$ 348,351
Other comprehensive income (loss):
Change in unrealized currency translation adjustments	(14,492)	(104,455)	5,268	(91,656)
Change in unrealized investment gains (losses), net of taxes	118,649	(32,442)	244,424	(158,214)
Other comprehensive income (loss)	104,157	(136,897)	249,692	(249,870)
Comprehensive income	321,584	43,881	648,733	98,481
Noncontrolling interests	(748)	(666)	(1,592)	(1,853)
Comprehensive income to common stockholders	$ 320,836	$ 43,215	$ 647,141	$ 96,628