Benefit Plans - Change in Project Benefit/Accumulated Benefit Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	$ 274,975	$ 391,698
Company Service Cost	0	7,153	$ 7,569
Interest Cost	13,787	12,461	11,276
Plan Participants' Contributions	0	0
Net Actuarial (Gain)/Loss	16,995	(83,240)
Benefit Payments from Fund	(13,549)	(13,165)
Benefit and Settlement Payments Paid Directly by Company	(384)	(114)
Plan Amendments	0	3,247
Curtailments	0	(352)
Settlement Payments from Fund (1)	(30,494)	(42,713)
Other Adjustment	0	0
Benefit Obligation at End of Year	261,330	274,975	391,698
Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	29,580	25,635
Company Service Cost	1,497	1,307	1,508
Interest Cost	1,633	694	648
Plan Participants' Contributions	311	463
Net Actuarial (Gain)/Loss	1,294	(8,123)
Benefit Payments from Fund	(3,439)	(1,504)
Benefit and Settlement Payments Paid Directly by Company	0	0
Plan Amendments	(346)	11,278
Curtailments	0	0
Settlement Payments from Fund (1)	0	0
Other Adjustment	(292)	(170)
Benefit Obligation at End of Year	$ 30,238	$ 29,580	$ 25,635