Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Total
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, net of issue costs (in shares)	3,244,941
Issuance of common stock, net of issue costs	$ 33	9,611		9,644
Non-cash stock-based compensation		234		234
Net loss			(6,136)	(6,136)
Balance (in shares) at Mar. 31, 2019	11,885,524
Balance at Mar. 31, 2019	$ 119	527,872	(435,462)	92,529
Balance (in shares) at Dec. 31, 2019	14,083,232
Balance at Dec. 31, 2019	$ 141	530,349	(457,986)	72,504
Issuance of common stock, net of issue costs (in shares)	425,776
Issuance of common stock, net of issue costs	$ 4	902		906
Non-cash stock-based compensation		336		336
Issuance of common stock under stock plans, net of taxes (in shares)	105,882
Issuance of common stock under stock plans, net of taxes
Net loss			(9,253)	(9,253)
Balance (in shares) at Mar. 31, 2020	14,614,890
Balance at Mar. 31, 2020	$ 145	$ 531,587	$ (467,239)	$ 64,493