Condensed Consolidated Statements of Stockholders' Equity (unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Accumulated Deficit [Member]
Balances at beginning at Dec. 31, 2018	$ 30,413	$ 32	$ 157,413	$ (127,032)
Balances at beginning (shares) at Dec. 31, 2018		31,755,169
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	202		202
Issuance of restricted stock units under equity incentive plans	46		46
Issuance of restricted stock units under equity incentive plans (shares)		21,415
Net loss	(7,030)			(7,030)
Balances at ending at Mar. 31, 2019	23,631	$ 32	157,661	(134,062)
Balances at end (shares) at Mar. 31, 2019		31,776,584
Balances at beginning at Dec. 31, 2019	14,947	$ 45	172,708	(157,806)
Balances at beginning (shares) at Dec. 31, 2019		44,658,054
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	296		296
Issuance of restricted stock units under equity incentive plans	96		96
Issuance of restricted stock units under equity incentive plans (shares)		28,757
Net loss	(5,858)			(5,858)
Balances at ending at Mar. 31, 2020	$ 9,481	$ 45	$ 173,100	$ (163,664)
Balances at end (shares) at Mar. 31, 2020		44,686,811