Stockholders' Equity - September 2017 Financing (Details) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended		3 Months Ended	9 Months Ended
	Sep. 10, 2017	Mar. 31, 2016	Jan. 31, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Class of Stock [Line Items]
Net proceeds from sale of common stock and warrants after transaction costs				$ 9,600
Shares issuable upon exercise (in shares)					7,270,070
Aggregate gross proceeds from sale of common stock and warrants		$ 7,800	$ 2,200
Transaction costs					$ 1,235	$ 641
September 2017 Warrants
Class of Stock [Line Items]
Shares issuable upon exercise (in shares)					1,068,307
Warrant exercise price (in usd per share)					$ 1.67
September 2017 Placement Agent Warrants
Class of Stock [Line Items]
Shares issuable upon exercise (in shares)					106,831
Warrant exercise price (in usd per share)					$ 2.16
Common Stock
Class of Stock [Line Items]
Issuance of common stock (in shares)			252,842
September 2017 Financing
Class of Stock [Line Items]
Net proceeds from sale of common stock and warrants after transaction costs	$ 3,100
September 2017 Financing | September 2017 Financing Warrants
Class of Stock [Line Items]
Expected term	2 years 6 months
Volatility rate (as a percent)	110.40%
Dividend yield (as a percent)	0.00%
Risk-free interest rate (as a percent)	1.38%
September 2017 Financing | September 2017 Financing Warrants | Warrants Not Settleable in Cash
Class of Stock [Line Items]
Aggregate gross proceeds from sale of common stock and warrants	$ 900
September 2017 Financing | September 2017 Warrants
Class of Stock [Line Items]
Shares issuable upon exercise (in shares)	1,068,307
Date from which warrants are exercisable	Sep. 13, 2017
Warrant exercise price (in usd per share)	$ 1.67
Warrant expiration period	2 years 6 months
September 2017 Financing | September 2017 Placement Agent Warrants
Class of Stock [Line Items]
Warrant exercise price (in usd per share)	$ 2.16
Warrant expiration period	2 years 6 months
September 2017 Financing | Common Stock
Class of Stock [Line Items]
Issuance of common stock (in shares)	2,136,614
Shares issued, price per share (in usd per share)	$ 1.73
Aggregate gross proceeds from sale of common stock and warrants	$ 2,800
Transaction costs	$ 600
H.C. Wainwright | September 2017 Financing | September 2017 Placement Agent Warrants
Class of Stock [Line Items]
Shares issuable upon exercise (in shares)	106,831