Consolidated Statement of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 447,558	$ 546,847	$ 177,305
Foreign currency translation adjustments	(28,478)	25,462	10,331
Total comprehensive income	419,080	572,309	187,636
Total comprehensive income attributable to noncontrolling interests	(191)	(195)	(270)
Total comprehensive income attributable to common stockholders	$ 418,889	$ 572,114	$ 187,366