Note 13 - Postretirement Medical Benefits - Incremental Effects From a One Percent Change in Assumed Health Care Cost (Details) - Postretirement Health Coverage [Member] $ in Thousands |
12 Months Ended |
|---|---|
|
Dec. 31, 2016
USD ($)
| |
| Effect on total of service and interest cost components of net periodic postretirement health care benefit cost, 1% Increase | $ 335 |
| Effect on total of service and interest cost components of net periodic postretirement health care benefit cost, 1% Decrease | (250) |
| Effect on accumulated postretirement benefit obligation, 1% Increase | 3,366 |
| Effect on accumulated postretirement benefit obligation, 1% Decrease | $ (2,612) |