Note 6 - Accrued Retirement Benefits - Net Periodic Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Pension and other benefits:
Interest cost	$ 783	$ 1,034
Expected return on plan assets	(657)	(1,226)
Recognized net actuarial loss	310	585
Settlement expense	0	7,492
Pension expense	436	7,885
Other changes in plan assets and benefit obligations recognized in comprehensive income:
Net loss (gain)	(1,060)	696
Amortization of recognized loss	(310)	(8,077)
Total recognized gain in comprehensive income	$ (1,370)	$ (7,381)