Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 38,023	$ 33,126	$ 80,486	$ 62,089
Net cumulative translation adjustment and foreign currency exchange hedge, net of tax of $(1,106), $2,089, $(1,634) and $4,101, respectively	1,325	(1,804)	960	(4,041)
Net unrealized (loss) gain on securities available-for-sale, net of tax of $(20), $21, $(6) and $136, respectively	(33)	34	(10)	221
Comprehensive Income	$ 39,315	$ 31,356	$ 81,436	$ 58,269