CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 51,367	$ 27,616	$ 142,061	$ 95,143
Net change in currency translation adjustment	(76)	114	(143)	(95)
Change in unrealized gains (losses) on available-for-sale securities, net of tax	(437)	98	1,038	260
Other comprehensive income (loss)	(513)	212	895	165
Comprehensive income	$ 50,854	$ 27,828	$ 142,956	$ 95,308