Note 9 - Retirement Plans and Postretirement Benefit Plans - Projected Payments (Details) |
Dec. 31, 2016
USD ($)
|
|---|---|
| Postretirement Life Insurance [Member] | |
| 2017 | $ 286,000 |
| 2018 | 298,000 |
| 2019 | 309,000 |
| 2020 | 319,000 |
| 2021 | 340,000 |
| 2022-2026 | 1,816,000 |
| Postretirement Health Coverage [Member] | |
| 2017 | 141,000 |
| 2018 | 160,000 |
| 2019 | 170,000 |
| 2020 | 177,000 |
| 2021 | 183,000 |
| 2022-2026 | $ 998,000 |