Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement Of Income And Comprehensive Income [Abstract]
Net income	$ 47,940	$ 42,463
Net cumulative translation adjustment and foreign currency exchange hedge, net of tax of $(823)and $(527), respectively	268	(365)
Net unrealized (loss) gain on securities available-for-sale, net of tax of $(107) and $14, respectively	(334)	23
Comprehensive income	$ 47,874	$ 42,121