Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2017	1,090,553
Balance at Dec. 31, 2017	$ 11	$ 464,870	$ (401,350)	$ 63,531
Shares issued upon reverse stock split (in shares)	12,261
Issuance of common stock under stock plans, net of taxes (in shares)	119
Issuance of common stock under stock plans, net of taxes
Issuance of common stock, net of issue costs & warrants (in shares)	6,936,930
Issuance of common stock, net of issue costs & warrants	$ 69	38,877		38,946
Non-cash stock-based compensation		571		$ 571
Issuance of common stock upon exercise of warrants (in shares)	300,911			300,911
Issuance of common stock upon exercise of warrants	$ 3	6,165		$ 6,168
Issuance of common stock upon exchange of debt (in shares)	299,809
Issuance of common stock upon exchange of debt	$ 3	7,544		7,547
Net loss			(27,976)	(27,976)
Balance (in shares) at Dec. 31, 2018	8,640,583
Balance at Dec. 31, 2018	$ 86	518,027	(429,326)	88,787
Issuance of common stock under stock plans, net of taxes (in shares)	1,476,961
Issuance of common stock under stock plans, net of taxes	$ 15	(216)		(201)
Issuance of common stock, net of issue costs & warrants (in shares)	3,965,688
Issuance of common stock, net of issue costs & warrants	$ 40	11,317		11,357
Non-cash stock-based compensation		1,221		1,221
Net loss			(28,660)	(28,660)
Balance (in shares) at Dec. 31, 2019	14,083,232
Balance at Dec. 31, 2019	$ 141	$ 530,349	$ (457,986)	$ 72,504