Note 16 - Pension and Postretirement Benefit Plans - Actuarial Assumptions Used to Determine Benefit Obligations (Details) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
|
| QDBP [Member] | ||
| Discount rate | ||
| Rate of increase for future compensation | ||
| Expected long-term rate of return on plan assets | ||
| SERP I and SERP II [Member] | ||
| Discount rate | 3.75% | 3.90% |
| Rate of increase for future compensation | ||
| Expected long-term rate of return on plan assets | ||
| PRBP [Member] | ||
| Discount rate | 2.80% | 3.90% |
| Rate of increase for future compensation | ||
| Expected long-term rate of return on plan assets | ||