Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income before noncontrolling interests	$ 181,614	$ 167,573
Other comprehensive income (losses):
Change in unrealized currency translation adjustments	19,760	12,799
Change in unrealized investment gains (losses), net of taxes	125,774	(125,772)
Other comprehensive income (loss)	145,534	(112,973)
Comprehensive income	327,148	54,600
Noncontrolling interests	(845)	(1,188)
Comprehensive income to common stockholders	$ 326,303	$ 53,412