Pension and Other Postretirement Benefits (Details) - USD ($)	1 Months Ended		3 Months Ended		6 Months Ended
	Feb. 28, 2023	Jul. 31, 2022	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Pension and other postretirement benefits expenses
Increase in stockholders equity	$ 11,324
Pensions
Pension and other postretirement benefits expenses
Service cost			$ 577,000	$ 1,328,000	$ 1,350,000	$ 2,883,000
Interest cost			4,801,000	3,434,000	9,696,000	6,868,000
Expected return on plan assets			(7,449,000)	(7,257,000)	(14,983,000)	(14,538,000)
Amortization of prior service cost			83,000	99,000	170,000	207,000
Amortization of actuarial losses			420,000	3,518,000	838,000	6,657,000
Curtailment gain		$ (668,000)		0	(668,000)	0
Settlement gain		$ 476,000	731,000	0	731,000	0
Special termination benefits			0	0	0	136,000
Net periodic benefit (income) cost			(2,967,000)	1,122,000	(4,328,000)	2,213,000
Other Postretirement Benefits
Pension and other postretirement benefits expenses
Service cost			6,000	15,000	19,000	39,000
Interest cost			274,000	203,000	560,000	409,000
Amortization of prior service cost			2,000	9,000	5,000	18,000
Amortization of actuarial losses			(47,000)	(1,000)	(73,000)	(1,000)
Net periodic benefit (income) cost			$ 235,000	$ 226,000	$ 511,000	$ 465,000