Quarterly report pursuant to Section 13 or 15(d)

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

v3.7.0.1
Stock-Based Compensation - Summary of Employee and Nonemployee Stock Option Activity (Details) - USD ($)
$ / shares in Units, $ in Thousands
6 Months Ended 12 Months Ended
Jun. 30, 2017
Dec. 31, 2016
Options Outstanding, Number of Shares Outstanding    
Outstanding, beginning balance (in shares) 2,198,000  
Granted (in shares) 602,000  
Exercised (in shares) (2,000)  
Canceled or expired (in shares) (220,000)  
Outstanding, ending balance (in shares) 2,578,000 2,198,000
Exercisable June 30, 2017 (in shares) 1,435,000  
Options Outstanding, Weighted-Average Exercise Price    
Outstanding, beginning balance (usd per share) $ 9.09  
Granted (usd per share) 2.85  
Exercised (usd per share) 2.27  
Cancelled or expired (usd per share) 11.12  
Outstanding, ending balance (usd per share) 7.46 $ 9.09
Exercisable June 30, 2017 (usd per share) $ 9.77  
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value    
Weighted- Average Remaining Contractual Term, Outstanding (in years) 7 years 1 month 21 days 7 years 15 days
Weighted- Average Remaining Contractual Term, Exercisable (in years) 5 years 8 months 19 days  
Aggregate Intrinsic Value, Outstanding $ 1,407 $ 0
Aggregate Intrinsic Value, Exercisable $ 196