Annual report pursuant to Section 13 and 15(d)

Stock-based compensation - Summary of status of company's stock option activity (Details)

v3.7.0.1
Stock-based compensation - Summary of status of company's stock option activity (Details) - Employee Stock Option - USD ($)
 12 Months Ended
Sep. 19, 2016
Sep. 06, 2016
Apr. 08, 2016
Apr. 01, 2016
Dec. 31, 2016
Dec. 31, 2015
Shares            
Beginning balance outstanding (in shares)         1,672,578  
Granted (in shares) 30,000 30,000 1,000,000 250,000 560,000 0
Exercised (in shares)         0  
Cancelled, expired, or forfeited (in shares)         (375,566)  
Ending balance outstanding (in shares)         1,857,012 1,672,578
Exercisable (in shares)         832,442  
Weighted Average Exercise Price            
Beginning balance outstanding (in dollars per share)         $ 5.05  
Granted (in dollars per share) $ 2.39 $ 2.61 $ 2.73 $ 2.83 2.72  
Exercised (in dollars per share)         0.00  
Cancelled, expired, or forfeited (in dollars per share)         5.01  
Ending balance outstanding (in dollars per share)         4.28 $ 5.05
Exercisable (in dollars per share)         $ 4.71  
Weighted Average Remaining Contractual Life (Years)            
Outstanding         7 years 9 months 18 days  
Exercisable         7 years 4 months 6 days  
Intrinsic Value            
Outstanding         $ 0  
Exercisable         $ 0