Benefit Plans - Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain)/Loss	$ 79,309	$ 89,711
Net Prior Service Cost/(Credit)	2,900	3,245
Net Transition Obligation/(Asset)	0	0
Total at Year End	82,209	92,956	$ 83,298
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Net Actuarial (Gain)/Loss	(30,804)	(13,781)
Net Prior Service Cost/(Credit)	11,041	13,249
Net Transition Obligation/(Asset)	0	0
Total at Year End	$ (19,763)	$ (532)	$ (44,891)