Quarterly report pursuant to Section 13 or 15(d)

Stock Option and Incentive Plans - Summary of Stock Option Activity (Detail)

v3.19.1
Stock Option and Incentive Plans - Summary of Stock Option Activity (Detail)
3 Months Ended
Mar. 31, 2019
USD ($)
$ / shares
shares
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]  
Number of Options, Options outstanding, Beginning balance | shares 7,187,885
Number of Options, Granted | shares 2,160,000
Number of Options, Exercised | shares 0
Number of Options, Expired | shares (150,016)
Number of Options, Forfeited | shares (113,125)
Number of Options, Options outstanding, Ending balance | shares 9,084,744
Number of Options, Vested and exercisable, Ending Balance | shares 5,191,031
Weighted Average Exercise Price, Options outstanding, Beginning balance | $ / shares $ 3.17
Weighted Average Exercise Price, Granted | $ / shares 0.40
Weighted Average Exercise Price, Exercised | $ / shares 0
Weighted Average Exercise Price, Expired | $ / shares 3.03
Weighted Average Exercise Price, Forfeited | $ / shares 1.46
Weighted Average Exercise Price, Options outstanding, Ending balance | $ / shares 2.53
Weighted Average Exercise Price, Vested and exercisable, Ending balance | $ / shares $ 3.63
Weighted Average Remaining Contractual Life (in years), Options outstanding 7 years 2 months 12 days
Weighted Average Remaining Contractual Life (in years), Vested and exercisable 5 years 9 months 3 days
Aggregate Intrinsic value, Options outstanding | $ $ 0
Aggregate Intrinsic value, Vested and exercisable | $ $ 0