CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 33,325	$ 28,274	$ 105,131	$ 76,158
Other comprehensive income:
Currency translation adjustment	16,698	(4,981)	13,907	31,361
Comprehensive income	$ 50,023	$ 23,293	$ 119,038	$ 107,519