Note 8 - Employee Post-employment Benefits - Weighted-average Assumptions Used to Determine the Benefit Obligation (Details) |
Jun. 06, 2017 |
May 31, 2016 |
|---|---|---|
| Pension Plan [Member] | ||
| Rate of compensation increase | 2.00% | 2.00% |
| Discount rate | 3.90% | 4.00% |
| Postretirement Medical and Life Benefits [Member] | ||
| Rate of compensation increase | 2.00% | 2.00% |
| Discount rate | 3.50% | 3.50% |