Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
COMPREHENSIVE INCOME:
Net income	$ 434,288	$ 290,584	$ 343,389
Foreign currency translation adjustments, net of tax	(19,616)	24,009	(10,208)
Total comprehensive income	$ 414,672	$ 314,593	$ 333,181