Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
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, 2019
Dec. 31, 2018
Options Outstanding, Number of Shares Outstanding    
Outstanding, beginning balance (in shares) 3,004,000  
Granted (in shares) 95,000  
Canceled or expired (in shares) (1,356,000)  
Outstanding, ending balance (in shares) 1,743,000 3,004,000
Exercisable (in shares) 1,149,000  
Options Outstanding, Weighted-Average Exercise Price    
Outstanding, beginning balance (usd per share) $ 5.77  
Granted (usd per share) 0.44  
Cancelled or expired (usd per share) 5.55  
Outstanding, ending balance (usd per share) 5.66 $ 5.77
Exercisable (usd per share) $ 7.92  
Weighted-Average Remaining Contractual Term and Aggregate Intrinsic Value    
Weighted- Average Remaining Contractual Term, Outstanding (in years) 6 years 10 months 28 days 5 years 8 months 13 days
Weighted- Average Remaining Contractual Term, Exercisable (in years) 5 years 11 months 5 days  
Aggregate Intrinsic Value, Outstanding $ 0 $ 0
Aggregate Intrinsic Value, Exercisable $ 0