Note 4 - Employee Benefit Plans - Net Periodic Pension Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Abstract]
Service cost	$ 1,068	$ 914	$ 3,204	$ 2,744
Interest cost	2,094	2,076	6,282	6,227
Expected return on plan assets	(3,251)	(3,136)	(9,753)	(9,408)
Amortization of prior service cost	20	67	60	199
Amortization of net loss	326	15	978	46
Net periodic pension cost (benefit)	$ 257	$ (64)	$ 771	$ (192)