Quarterly report pursuant to Section 13 or 15(d)

Stock-based compensation - Summary of Status of Company's Stock Option Activity (Details)

v3.8.0.1
Stock-based compensation - Summary of Status of Company's Stock Option Activity (Details)
 3 Months Ended 9 Months Ended
Sep. 30, 2017
USD ($)
$ / shares
shares
Sep. 30, 2017
USD ($)
$ / shares
shares
Number of Shares    
Beginning balance (in shares) | shares   1,857,012
Granted (in shares) | shares 0 960,000
Cancelled, expired, or forfeited (in shares) | shares   674,977
Ending balance (in shares) | shares 2,142,035 2,142,035
Exercisable at end of period (in shares) | shares 986,211 986,211
Weighted Average Exercise Price    
Beginning balance (in dollars per share) | $ / shares   $ 4.28
Granted (in dollars per share) | $ / shares   2.13
Cancelled, expired, or forfeited (in dollars per share) | $ / shares   3.24
Ending balance (in dollars per share) | $ / shares $ 3.65 3.65
Exercisable at end of period (in dollars per share) | $ / shares $ 4.63 $ 4.63
Weighted Average Remaining Contractual Life (Years)    
Outstanding ending balance   7 years 2 months 23 days
Exercisable at end of period   5 years 4 months 10 days
Intrinsic Value    
Outstanding ending balance | $ $ 0 $ 0
Exercisable at end of period | $ $ 0 $ 0