CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Comprehensive Income (loss)
Net loss	$ (16,902)	$ (51,675)	$ (65,772)
Other comprehensive income (loss):
Net unrealized gain (loss) on short-term investments	1	6	(5)
Total other comprehensive income (loss)	1	6	(5)
Comprehensive loss	$ (16,901)	$ (51,669)	$ (65,777)