Note 8 - Employee Post-employment Benefits - Allocation of Retirement Plan's Assets Held in Trust (Details)
|
Jun. 06, 2017 |
May 31, 2016 |
| Actual Allocation |
100.00%
|
100.00%
|
| Equity Securities [Member] |
|
|
| Target Allocation |
56.00%
|
|
| Actual Allocation |
63.00%
|
61.00%
|
| Equity Securities [Member] | Minimum [Member] |
|
|
| Target Allocation |
41.00%
|
41.00%
|
| Equity Securities [Member] | Maximum [Member] |
|
|
| Target Allocation |
71.00%
|
71.00%
|
| Fixed Income Securities [Member] |
|
|
| Target Allocation |
28.00%
|
|
| Actual Allocation |
25.00%
|
20.00%
|
| Fixed Income Securities [Member] | Minimum [Member] |
|
|
| Target Allocation |
13.00%
|
13.00%
|
| Fixed Income Securities [Member] | Maximum [Member] |
|
|
| Target Allocation |
43.00%
|
43.00%
|
| Public Real Estate Investment Trusts [Member] |
|
|
| Actual Allocation |
0.00%
|
5.00%
|
| Public Real Estate Investment Trusts [Member] | Minimum [Member] |
|
|
| Target Allocation |
0.00%
|
0.00%
|
| Public Real Estate Investment Trusts [Member] | Maximum [Member] |
|
|
| Target Allocation |
10.00%
|
10.00%
|
| Cash and Cash Equivalents [Member] |
|
|
| Actual Allocation |
1.00%
|
4.00%
|
| Cash and Cash Equivalents [Member] | Minimum [Member] |
|
|
| Target Allocation |
0.00%
|
0.00%
|
| Cash and Cash Equivalents [Member] | Maximum [Member] |
|
|
| Target Allocation |
20.00%
|
20.00%
|
| Other Retirement Plan Assets [Member] |
|
|
| Actual Allocation |
11.00%
|
10.00%
|
| Other Retirement Plan Assets [Member] | Minimum [Member] |
|
|
| Target Allocation |
0.00%
|
0.00%
|
| Other Retirement Plan Assets [Member] | Maximum [Member] |
|
|
| Target Allocation |
21.00%
|
21.00%
|