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Note 6 - Other Assets (Details Textual) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021
Liability, Defined Benefit Plan, Noncurrent, Total | $ 18,522 | $ 23,909
Liability, Defined Benefit Plan, Noncurrent, Total | 18,522 | 23,909
Cash Surrender Value, Fair Value Disclosure | 13,900 | 16,100
Increase (Decrease) in Cash Surrender Value | (2,200) | 1,300
Investments Held in Rabbi Trust [Member] |  |
Debt Securities, Available-for-Sale, Amortized Cost, Total | 100 | 300
Debt Securities, Available-for-Sale, Total | 100 | 300
Supplemental Employee Retirement Plan [Member] |  |
Liability, Defined Benefit Plan, Noncurrent, Total | 18,200 | 23,600
Liability, Defined Benefit Plan, Noncurrent, Total | 18,200 | 23,600
Investments, Fair Value Disclosure, Total | $ 14,000 | $ 16,400

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