Consolidated Statements of Stockholders Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Accumulated Other Comprehensive Income (Loss)	Accumulated Deficit
Beginning balance (in shares) at Dec. 31, 2017		28,406,026
Beginning balance at Dec. 31, 2017	$ (79,588)	$ 28	$ 220,117	$ 115	$ (299,848)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(21,558)				(21,558)
Share-based compensation	13,494		13,494
Common stock sales (in shares)		5,893,428
Common stock sales	13,568	$ 6	13,562
Equity instrument exercises (in shares)		4,753,858
Equity instrument exercises	60,892	$ 5	60,887
Reclassification of liability-classified stock-based compensation	(12)		(12)
Other	$ (113)		(30)	(83)
Ending balance (in shares) at Dec. 31, 2018	39,053,312	39,053,312
Ending balance at Dec. 31, 2018	$ (13,124)	$ 39	308,018	32	(321,213)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(25,614)
Share-based compensation	425		425
Common stock sales (in shares)		11,999,597
Common stock sales	10,840	$ 12	10,828
Equity instrument exercises (in shares)		2,250
Equity instrument exercises	4		4
Other	$ (259)		0	(259)
Ending balance (in shares) at Dec. 31, 2019	51,055,159	51,055,159
Ending balance at Dec. 31, 2019	$ (27,728)	$ 51	$ 319,275	$ (227)	$ (346,827)