Employee Benefit Plans - Additional Information (Detail) - USD ($) |
12 Months Ended | ||
|---|---|---|---|
May 31, 2018 |
May 31, 2017 |
May 31, 2016 |
|
| Retirement Benefits [Abstract] | |||
| Participants contribution to compensation | 15.00% | ||
| Matching contributions in conjunction with employee contributions to plan | $ 51,550 | $ 62,622 | $ 57,178 |