Note 13 - Postretirement Medical Benefits - Plans Benefit Obligation (Details) - Postretirement Health Coverage [Member] - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Obligation at beginning of year | $ 16,204 | $ 14,792 |
| Service cost | 637 | 739 |
| Interest cost | 683 | 649 |
| Actuarial (gain) loss | (660) | 313 |
| Participant contributions | 153 | 129 |
| Benefit payments | (462) | (418) |
| Obligation at end of year | $ 16,555 | $ 16,204 |