CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 252,521	$ 254,690	$ 245,327
Other comprehensive loss:
Foreign currency translation adjustments	(20,410)	(29,110)	(11,295)
Comprehensive income	$ 232,111	$ 225,580	$ 234,032