CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Aspire Capital Fund, LLC	Aspire Capital Fund, LLC Common Stock	Aspire Capital Fund, LLC Additional Paid-in Capital
Beginning balance (shares) at Dec. 31, 2018		33,159,253.2
Beginning balance at Dec. 31, 2018	$ (4,496)	$ 332	$ 980,012	$ (984,840)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of restricted stock awards	651		651
Cancellation of restricted stock awards (shares)		(8,473)
Cancellation of restricted stock awards	0
Net loss	(9,884)			(9,884)
Ending balance (shares) at Mar. 31, 2019		33,150,780.2
Ending balance at Mar. 31, 2019	$ (13,729)	$ 332	980,663	(994,724)
Beginning balance (shares) at Dec. 31, 2019	33,241,793	33,241,793
Beginning balance at Dec. 31, 2019	$ (33,911)	$ 332	982,738	(1,016,981)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cancellation of restricted stock awards	625		625
Issuance of shares in connection with Aspire Capital agreement (shares)						3,340,516
Issuance of shares in connection with Aspire Capital agreement					$ 2,726	$ 34	$ 2,692
Net loss	$ (9,709)			(9,709)
Ending balance (shares) at Mar. 31, 2020	36,582,309	36,582,309
Ending balance at Mar. 31, 2020	$ (40,269)	$ 366	$ 986,055	$ (1,026,690)