Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement Of Income And Comprehensive Income [Abstract]
Consolidated net income (loss)	$ 49,990	$ 77,731	$ 147,421	$ 128,847
Other comprehensive income (loss), net of tax:
Foreign currency translation adjustments	(13,034)	4,571	(8,377)	11,052
Available for sale securities		978		691
Total other comprehensive income (loss), net of tax	(13,034)	5,549	(8,377)	11,743
Comprehensive income (loss)	36,956	83,280	139,044	140,590
Less: Comprehensive income (loss) attributable to noncontrolling interest in subsidiaries, net of tax	12,373	25,587	51,662	40,647
Comprehensive income (loss) attributable to common stockholders	$ 24,583	$ 57,693	$ 87,382	$ 99,943