Stock Options and Stock Based Compensation - Schedule of Options Granted, Exercised, and Forfeited or Canceled (Detail) - $ / shares |
12 Months Ended | ||
|---|---|---|---|
May 31, 2018 |
May 31, 2017 |
May 31, 2016 |
|
| Disclosure of Compensation Related Costs, Share-based Payments [Abstract] | |||
| Number of Shares, Options outstanding - beginning of period | 360,000 | 147,500 | 332,500 |
| Number of Shares, Options granted | 0 | 212,500 | 0 |
| Number of Shares, Options exercised | 0 | 0 | 0 |
| Number of Shares, Options forfeited/canceled | (41,668) | 0 | (185,000) |
| Number of Shares, Options outstanding - end of period | 318,332 | 360,000 | 147,500 |
| Weighted Average Exercise Price, Options outstanding - beginning of period | $ 2.28 | $ 3.11 | $ 3.68 |
| Weighted Average Exercise Price, Options granted | 0.00 | 1.70 | 0.00 |
| Weighted Average Exercise Price, Options exercised | 0.00 | 0.00 | 0.00 |
| Weighted Average Exercise Price, Options forfeited/canceled | 1.70 | 0.00 | 4.13 |
| Weighted Average Exercise Price, Options outstanding - end of period | $ 2.36 | $ 2.28 | $ 3.11 |