Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 121,506	$ 75,306	$ 93,512
Other comprehensive income (loss), net of income tax:
Foreign currency translation adjustment	(13,792)	24,670	(9,847)
Total comprehensive income	107,714	99,976	83,665
Total comprehensive income attributable to:
Stockholders	107,716	99,639	81,839
Non-controlling interests	(2)	337	1,826
Total comprehensive income	$ 107,714	$ 99,976	$ 83,665