Note 4 - Employee Benefit Plans - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Service cost	$ 1,068	$ 915	$ 2,136	$ 1,830
Interest cost	2,094	2,075	4,188	4,151
Expected return on plan assets	(3,251)	(3,136)	(6,502)	(6,272)
Amortization of prior service cost	20	66	40	132
Amortization of net loss	326	16	652	31
Net periodic pension cost (benefit)	$ 257	$ (64)	$ 514	$ (128)