CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income	$ 255,697	$ 249,104	$ 61,102
Other comprehensive income (loss):
Unrealized gain (loss) on available for sale securities, net of tax	3,136	(202)	316
Cumulative translation adjustment, net of tax	(1,239)	(1,581)	416
Comprehensive income	$ 257,594	$ 247,321	$ 61,834