Note 11 - Retirement Plans - Changes in Supplemental Retirement Plans' Benefit Obligation (Details) - Supplemental Employee Retirement Plan [Member] - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| Change in Benefit Obligation | ||
| Obligation at beginning of year | $ 600 | $ 583 |
| Service cost | 19 | 15 |
| Interest cost | 24 | 19 |
| Actuarial loss | 111 | 19 |
| Benefit payments | (36) | (36) |
| Obligation at end of year | $ 718 | $ 600 |