Consolidated Statements of Comprehensive Income Statement - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 148,551	$ 132,884	$ 129,671
Other comprehensive (loss) income:
Net foreign currency translation adjustment	(3,936)	4,237	(1,798)
Derivative instrument adjustment	(1,108)	0	0
Total comprehensive income	$ 143,507	$ 137,121	$ 127,873