CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 442,776	$ 400,235	$ 231,418
Net change in foreign currency translation adjustment	1,787	(3,631)	1,741
Change in unrealized gains (losses) on investments, net of tax	299	286	(232)
Other comprehensive income (loss)	2,086	(3,345)	1,509
Comprehensive income	$ 444,862	$ 396,890	$ 232,927