Note 4 - Employee Benefit Plans - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Service cost	$ 1,068	$ 915
Interest cost	2,094	2,076
Expected return on plan assets	(3,251)	(3,136)
Amortization of prior service cost	20	66
Amortization of net loss	326	15
Net periodic pension cost (benefit)	$ 257	$ (64)