Note 9 - Employee Benefit Plans - Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest cost	$ 2,873	$ 2,313	$ 2,168
Pension Plan And Supplemental Plan [Member]
Interest cost	2,873	2,313	2,168
Expected return on plan assets	(2,111)	(3,006)	(2,174)
Amortization of net actuarial losses	(146)	63	145
Settlement/curtailment loss	(2,177)	0	0
Net periodic pension cost	$ (1,561)	$ (630)	$ 139