Condensed Consolidated Statements of Stockholders' Equity (Deficit) (unaudited) - 6 months ended Jun. 30, 2017 - 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 at Dec. 31, 2016	$ 7,861		$ 0	$ 15	$ 170,409	$ (162,563)
Balance, preferred stock (shares) at Dec. 31, 2016		0	0
Balance, common stock (shares) at Dec. 31, 2016	14,688,135			14,688,135
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of Series A convertible preferred stock with detachable warrants, net of issuance costs of $377	$ 7,623				7,623
Issuance of Series A convertible preferred stock with detachable warrants, net of issuance costs of $377 (shares)			8,000
Stock-based compensation expense	63				63
Exercise of liability-classified warrants	41				41
Exercise of liability-classified warrants (shares)				6,941
Conversion of promissory notes	2				2
Conversion of promissory notes (shares)				14,895
Net loss	(19,025)					(19,025)
Balance at Jun. 30, 2017	$ (3,435)		$ 0	$ 15	$ 178,138	$ (181,588)
Balance, preferred stock (shares) at Jun. 30, 2017		8,000	8,000
Balance, common stock (shares) at Jun. 30, 2017	14,709,971			14,709,971