CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net loss	$ (103,799)	$ (84,052)	$ (67,415)
Other comprehensive loss, net of tax
Net change in unrealized loss on available-for-sale investments	(213)	(44)	(71)
Foreign currency translation loss	(488)	(942)	(467)
Net change in unrealized loss on derivative instruments	(2,271)	(711)	0
Comprehensive loss	$ (106,771)	$ (85,749)	$ (67,953)