CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (29,306)	$ (26,254)	$ (56,300)	$ (53,425)
Other comprehensive gain (loss), before tax:
Net change in unrealized gain (loss) on available-for-sale investments	13	(14)	132	116
Foreign currency translation gain	249	64	824	797
Net change in unrealized loss on derivative instruments	1,822	(2,886)	3,348	(277)
Other comprehensive gain (loss), before tax	2,084	(2,836)	4,304	636
Tax effect	(766)	(234)	(1,582)	(234)
Other comprehensive gain (loss), net of tax	1,318	(3,070)	2,722	402
Comprehensive loss	$ (27,988)	$ (29,324)	$ (53,578)	$ (53,023)