Condensed Consolidated Statement of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Series A Convertible Preferred Stock	Preferred Stock Series A Convertible Preferred Stock	Common Stock	Additional paid-in capital	Accumulated deficit
Balance, preferred stock (shares) at Dec. 31, 2017			8,000
Beginning balance at Dec. 31, 2017	$ 9,007		$ 0	$ 26	$ 187,784	$ (178,803)
Balance, common stock (shares) at Dec. 31, 2017				5,189,755
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Effect of the May 2018 reverse stock split on common stock and additional paid in capital, beginning balance				$ (20)	20
Stock-based compensation expense	129				129
Conversion of pre-funded warrants (shares)				483,221
Conversion of pre-funded warrants	24				24
Net loss	(2,901)					(2,901)
Balance, preferred stock (shares) at Mar. 31, 2018			8,000
Ending balance at Mar. 31, 2018	6,259		$ 0	$ 6	187,957	(181,704)
Balance, common stock (shares) at Mar. 31, 2018				5,672,976
Balance, preferred stock (shares) at Dec. 31, 2018		8,000	8,000
Beginning balance at Dec. 31, 2018	$ 9,557		$ 0	$ 10	198,627	(189,080)
Balance, common stock (shares) at Dec. 31, 2018	9,758,332			9,758,332
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation expense	$ 112				112
Net loss	(3,666)					(3,666)
Balance, preferred stock (shares) at Mar. 31, 2019		8,000	8,000
Ending balance at Mar. 31, 2019	$ 6,003		$ 0	$ 10	$ 198,739	$ (192,746)
Balance, common stock (shares) at Mar. 31, 2019	9,758,332			9,758,332