Pension and Other Postretirement Benefits (Details) - USD ($)	1 Months Ended		3 Months Ended		9 Months Ended
	Feb. 28, 2023	Jul. 31, 2022	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Pension and other postretirement benefits expenses
Increase in stockholders equity	$ 11,324
Pensions
Pension and other postretirement benefits expenses
Service cost			$ 622,000	$ 1,462,000	$ 1,972,000	$ 4,345,000
Interest cost			4,796,000	3,643,000	14,492,000	10,511,000
Expected return on plan assets			(7,453,000)	(7,264,000)	(22,436,000)	(21,801,000)
Amortization of prior service cost			88,000	97,000	258,000	304,000
Amortization of actuarial losses			402,000	3,098,000	1,240,000	9,755,000
Curtailment loss (gain)		$ 0		1,158,000	(668,000)	1,158,000
Settlement gain		$ 476,000	0	0	731,000	0
Special termination benefits			0	259,000	0	395,000
Net periodic benefit (income) cost			(1,545,000)	2,453,000	(5,873,000)	4,667,000
Other Postretirement Benefits
Pension and other postretirement benefits expenses
Service cost			10,000	19,000	29,000	58,000
Interest cost			282,000	197,000	842,000	606,000
Amortization of prior service cost			3,000	9,000	8,000	27,000
Amortization of actuarial losses			(37,000)	(1,000)	(110,000)	(2,000)
Net periodic benefit (income) cost			$ 258,000	$ 224,000	$ 769,000	$ 689,000