Commitments and Contingencies - Additional Information (Detail) - USD ($) |
12 Months Ended | |||
|---|---|---|---|---|
May 31, 2018 |
May 31, 2017 |
May 31, 2016 |
May 31, 2014 |
|
| Commitments and Contingencies Disclosure [Abstract] | ||||
| Capital lease obligation period | 5 years | |||
| Lease payments | $ 38,890 | $ 38,890 | ||
| Total lease expense | $ 47,829 | 47,695 | $ 73,688 | |
| Royalty pool interest | 5.00% | |||
| Interest payable date | Mar. 31, 1995 | |||
| Royalty expense | $ 1,527 | $ 15,407 | $ 14,825 | |