Unaudited Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net loss	$ (15,046)	$ (11,663)
Other comprehensive income (loss):
Unrealized loss on short-term investments	(8)
Unrealized income (loss) on derivative instruments	(2,101)	2,124
Total other comprehensive income (loss)	(2,109)	2,124
Comprehensive loss	$ (17,155)	$ (9,539)