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	$ (66,837)	$ (85,516)	$ (64,899)
Other comprehensive income, net of tax:
Foreign currency translation adjustment	3,748	686	308
Net change in unrealized gains (losses) on investments	88	(247)	(187)
Other comprehensive income, net of tax	3,836	439	121
Total comprehensive loss	$ (63,001)	$ (85,077)	$ (64,778)