Note 13 - Postretirement Medical Benefits - Amounts Recognized in Accumulated Other Comprehensive Income (Details) - Postretirement Health Coverage [Member] - USD ($) $ in Thousands |
Dec. 31, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Unrecognized net actuarial (gain) loss | $ (93) | $ 566 |
| Unrecognized prior service cost | 75 | 125 |
| Total | $ (18) | $ 691 |