Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Consolidated Statements of Comprehensive Income (Unaudited) [Abstract]
Net income	$ 53,146	$ 41,672	$ 139,646	$ 111,202
Other comprehensive income, net of tax:
Foreign currency translation adjustment, net of taxes of $(346) and $(3,054) for the three months ended September 30, 2018 and 2017, respectively, and $(51) and $(1,376) for the nine months ended September 30, 2018 and 2017, respectively	(7,095)	5,497	(16,095)	15,273
Net unrealized gains/(losses) on foreign currency cash flow hedges, net of taxes of zero and $15 for the three months ended September 30, 2018 and 2017, respectively, and $18 and $114 for the nine months ended September 30, 2018 and 2017, respectively	0	(27)	(160)	(207)
Reclassification adjustment for realized losses/(gains) in current earnings, net of taxes of zero and $(22) for the three months ended September 30, 2018 and 2017, respectively, and $(2) and $97 for the nine months ended September 30, 2018 and 2017, respectively	0	40	18	(177)
Total other comprehensive income (loss)	(7,095)	5,510	(16,237)	14,889
Comprehensive income	$ 46,051	$ 47,182	$ 123,409	$ 126,091