Savings Plans, Pension Plans and Other Postretirement Employee Benefits (Amounts Recorded in AOCI on Consolidated Balance Sheets, Not Recognized as Components of Net Periodic Benefit Costs) (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Pension Plans [Member]
Net (loss) income	$ (27,307)	$ (33,043)
Prior service cost	(15)	(49)
Total amount unrecognized	(27,322)	(33,092)
OPEB [Member]
Net (loss) income	8,397	4,598
Prior service cost	0	0
Total amount unrecognized	$ 8,397	$ 4,598