CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
Net loss	$ (15,992)	$ (12,894)	$ (69,392)	$ (44,352)
Unrealized gains (losses) on available-for-sale securities:
Unrealized (loss) gain on available-for-sale securities, net of tax	(5)	(12)	12	23
Comprehensive loss	$ (15,997)	$ (12,906)	$ (69,380)	$ (44,329)