Note 6 - Other Assets (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Liability, Defined Benefit Plan, Noncurrent, Total	$ 23,909	$ 24,620
Cash Surrender Value, Fair Value Disclosure	16,100	14,700
Increase (Decrease) in Cash Surrender Value	1,300	1,400
Investments Held in Rabbi Trust [Member]
Debt Securities, Available-for-sale, Amortized Cost, Total	300	700
Debt Securities, Available-for-sale, Total	300	700
Supplemental Employee Retirement Plan [Member]
Liability, Defined Benefit Plan, Noncurrent, Total	23,600	24,300
Investments, Fair Value Disclosure, Total	$ 16,400	$ 15,400