CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 265,636	$ 252,521	$ 254,690
Other comprehensive loss:
Foreign currency translation adjustments	(5,488)	(20,410)	(29,110)
Comprehensive income	$ 260,148	$ 232,111	$ 225,580