Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Statement Of Income And Comprehensive Income [Abstract]
Net Income (loss)	$ 23,083	$ (24,007)
Other comprehensive gain (loss) (net of tax):
Net change in net unrealized gain (loss) on investments	28	169
Net change in unrealized gain (loss) on hedging instruments	1,729	916
Other comprehensive income (loss)	1,757	1,085
Comprehensive income (loss)	$ 24,840	$ (22,922)