Organization and Basis of Presentation (Details) - USD ($) $ in Thousands	Nov. 14, 2017	Nov. 01, 2017	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Cash and cash equivalents			$ 11,338	$ 25,342	$ 30,716	$ 36,079
Net working capital			7,700
Accumulated deficit			$ 145,784	$ 123,311
Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Number of shares sold (in shares)	5,525,000	5,525,000
Net proceeds from sale of stock	$ 7,000
Pre-Funded Warrant | Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Number of warrant sold (in shares)	4,475,000	4,475,000
Common Warrants | Subsequent Event
Subsidiary, Sale of Stock [Line Items]
Number of warrant sold (in shares)	10,000,000