Benefit Plans - Development of Funded Status (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	$ 390,747	$ 423,305
Projected Benefit Obligation	(391,698)	(423,713)	$ (413,350)
Plan Assets at Fair Value	391,555	411,245	402,691
Funded Status - Overfunded/(Underfunded)	(143)	(12,468)
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated Benefit Obligation	25,635	28,714
Projected Benefit Obligation	(25,635)	(28,714)	(27,496)
Plan Assets at Fair Value	140,839	119,024	$ 99,590
Funded Status - Overfunded/(Underfunded)	$ 115,204	$ 90,310