CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 144,020	$ 145,832	$ 64,295
Net change in cumulative translation adjustment	(154)	(196)	62
Change in unrealized gains (losses) on available-for sale securities, net of tax	(686)	(238)	29
Other comprehensive income (loss)	(840)	(434)	91
Comprehensive income (loss)	$ 143,180	$ 145,398	$ 64,386