Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Condensed Consolidated Statements of Comprehensive Income [Abstract]
Net income	$ 18,172	$ 17,207
Other comprehensive income (loss), net of income tax:
Foreign currency translation adjustment	(1,634)	4,907
Total comprehensive income	16,538	22,114
Total comprehensive income attributable to:
Stockholders	16,542	22,033
Non-controlling interests	(4)	81
Total comprehensive income	$ 16,538	$ 22,114