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Note 12 - Retirement Plans (Details Textual) | 12 Months Ended
--- | ---
Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($)
Retirement Plan Expense | $ 1,200,000 | $ 900,000 | $ 900,000
Defined Contribution Plan [Member] |  |  |
Company Matching Percentage on First Six Percent of Employee Contributions | 50.00% |  |
Employee Contribution Percentage for Which Company Will Match at Fifty Percent | 6.00% |  |
Defined Contribution Plan Number of Investment Options | 23 |  |
Pension Plan [Member] |  |  |
Number of Non-contributory Defined Benefit Plans | 2 |  |
Liability, Defined Benefit Plan, Total | $ 1,700,000 | 1,700,000 |
Accumulated Other Comprehensive Income (Loss), Unrecognized Net Actuarial Losses, Net of Tax | 1,800,000 | 1,600,000 |
Defined Benefit Plan, Accumulated Benefit Obligation | 6,400,000 | 6,100,000 |
Defined Benefit Plan, Plan Assets, Amount, Ending Balance | 4,800,000 | 4,400,000 |
Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Total | $ 0 | $ 0 | $ 0
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate | 2.83% | 3.98% |
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets | 7.50% | 7.50% |
Non-qualified Retirement Savings Plan [Member] |  |  |
Company Matching Percentage on First Ten Thousand Dollar Employee Contributions | 50.00% |  |
Officer Contribution for Which Company Will Match at Fifty Percent | $ 10,000 |  |
Select Employee Contribution for Which Company Will Match at Fifty Percent | 5,000 |  |
Deferred Compensation Liability, Current and Noncurrent, Total | $ 5,200,000 | $ 4,700,000 |

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