Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 32,979	$ 49,581	$ 77,534	$ 130,081
Foreign currency translation adjustments, net of tax of $4,779, ($4,762), $3,010 and $12,371	(8,571)	8,171	(5,398)	(21,718)
Comprehensive income	$ 24,408	$ 57,752	$ 72,136	$ 108,363