Note 4 - Employee Benefit Plans - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Defined Benefit Plan, Service Cost	$ 1,566	$ 1,455	$ 4,697	$ 4,365
Defined Benefit Plan, Interest Cost	1,369	1,248	4,107	3,744
Expected return on plan assets	(3,363)	(2,313)	(10,089)	(6,939)
Defined Benefit Plan, Amortization of Prior Service Cost (Credit)	128	99	384	297
Amortization of net loss	512	1,125	1,537	3,375
Net periodic pension cost	$ 212	$ 1,614	$ 636	$ 4,842