Retirement Plans, Components of Net Periodic Benefit Cost, Other Postretirement Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Recognition of actuarial gain	$ (22,438)	$ (58,147)	$ (44,491)
Other Postretirement Benefits [Member]
Components of net periodic benefit cost [Abstract]
Interest cost	22	17	17
Amortization of actuarial gain	(344)	(394)	(451)
Net periodic benefit cost	(322)	(377)	(434)
Defined Benefit Plan, Amounts Recognized in Other Comprehensive Income (Loss) [Abstract]
Current year actuarial loss (gain)	65	(58)	104
Recognition of actuarial gain	344	394	451
Total recognized in other comprehensive income	409	336	555
Total recognized in net periodic benefit cost and other comprehensive income	$ 87	$ (41)	$ 121