Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Summary of Employee and Nonemployee Stock Option Activity (Details)

v3.10.0.1
Stock-Based Compensation - Summary of Employee and Nonemployee Stock Option Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
9 Months Ended 12 Months Ended
Sep. 30, 2018
Dec. 31, 2017
Options Outstanding, Number of Shares Outstanding    
Outstanding, beginning balance (in shares) 2,844,000  
Granted (in shares) 757,000  
Canceled or expired (in shares) (560,000)  
Outstanding, ending balance (in shares) 3,041,000 2,844,000
Exercisable March 31, 2018 (in shares) 1,838,000  
Options Outstanding, Weighted-Average Exercise Price    
Outstanding, beginning balance (usd per share) $ 7.00  
Granted (usd per share) 0.91  
Cancelled or expired (usd per share) 5.14  
Outstanding, ending balance (usd per share) 5.83 $ 7.00
Exercisable March 31, 2018 (usd per share) $ 8.50  
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value    
Weighted- Average Remaining Contractual Term, Outstanding (in years) 5 years 11 months 19 days 6 years 11 months 16 days
Weighted- Average Remaining Contractual Term, Exercisable (in years) 3 years 10 months 28 days  
Aggregate Intrinsic Value, Outstanding $ 92 $ 4
Aggregate Intrinsic Value, Exercisable $ 0