Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	AOCI Attributable to Parent [Member]	Total
Balance	$ 86	$ 518,027	$ (429,326)	$ 88,787
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	$ 86	518,027	(429,326)	88,787
Balance (in shares) at Dec. 31, 2018	8,640,583
Balance at Dec. 31, 2018	$ 86	518,027	(429,326)	88,787
Net loss				(13,226)
Balance (in shares) at Jun. 30, 2019	11,885,524
Balance	$ 86	518,027	(429,326)	88,787
Balance	$ 119	527,872	(435,462)	92,529
Balance (in shares) at Mar. 31, 2019	11,885,524
Balance at Mar. 31, 2019	$ 119	527,872	(435,462)	92,529
Issuance of common stock, net of issue costs (in shares)
Issuance of common stock, net of issue costs		(14)		(14)
Non-cash stock-based compensation		172		172
Net loss			(7,090)	(7,090)
Balance (in shares) at Jun. 30, 2019	11,885,524
Balance	$ 119	527,872	(435,462)	92,529
Balance	119	528,030	(442,552)	85,597
Balance	$ 141	530,349	(457,986)	72,504
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	$ 141	530,349	(457,986)	72,504
Balance (in shares) at Dec. 31, 2019	14,083,232
Balance at Dec. 31, 2019	$ 141	530,349	(457,986)	72,504
Net loss				(15,296)
Balance (in shares) at Jun. 30, 2020	15,514,098
Balance	$ 141	530,349	(457,986)	72,504
Balance	$ 145	531,587	(467,239)	64,493
Balance (in shares) at Mar. 31, 2020	14,614,890
Balance at Mar. 31, 2020	$ 145	531,587	(467,239)	64,493
Issuance of common stock, net of issue costs (in shares)	917,345
Issuance of common stock, net of issue costs	$ 9	1,238		1,247
Non-cash stock-based compensation		497		497
Issuance of common stock under stock plans, net of taxes (in shares)	(18,137)
Issuance of common stock under stock plans, net of taxes		(307)		(307)
Net loss			(6,043)	(6,043)
Balance (in shares) at Jun. 30, 2020	15,514,098
Balance	$ 145	531,587	(467,239)	64,493
Balance	$ 154	$ 533,015	$ (473,282)	$ 59,887