Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands	4 Months Ended	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Sep. 16, 2014
Class of Stock [Line Items]
Amortization of offering costs		$ 87,000	$ 89,000
Common Stock
Class of Stock [Line Items]
Sale of common stock under sales agreement (shares)		17	326
Common Stock | MLV & Co. LLC | At Market Issuance Sales Agreement
Class of Stock [Line Items]
Stock offering, maximum sales value				$ 8,000,000
Stock offering costs, commissions (percent)	3.00%	3.00%
Sale of common stock under sales agreement (shares)		17	325
Sale of common stock, weighted-average (in dollars per share)	$ 1.28	$ 1.11	$ 1.28
Proceeds from sale of common stock		$ 19,000	$ 416,000
Proceeds from sale of common stock, net of offering costs		18,000	377,000
Deferred offering costs		125,000
Amortization of offering costs		$ 100,000	$ 25,000