Benefit Plans - Change in Project Benefit/Accumulated Benefit Obligations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Pension and Supplemental Executive Retirement Plans
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	$ 423,713	$ 413,350
Company Service Cost	7,569	7,342	$ 8,345
Interest Cost	11,276	13,036	15,705
Plan Participants' Contributions	0	0
Net Actuarial (Gain)/Loss	(10,018)	36,196
Benefit Payments from the Fund	(40,482)	(40,260)
Benefit Payments Directly by Company	(362)	(5,953)
Plan Amendments	2	2
Other Adjustment	0	0
Settlement (Gain)Loss	0	0
Benefit Obligation at End of Year	391,698	423,713	413,350
Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Benefit Obligation [Roll Forward]
Benefit Obligation at Beginning of Year	28,714	27,496
Company Service Cost	1,508	1,263	1,345
Interest Cost	648	832	1,130
Plan Participants' Contributions	456	425
Net Actuarial (Gain)/Loss	(3,574)	660
Benefit Payments from the Fund	(1,963)	(1,975)
Benefit Payments Directly by Company	0	0
Plan Amendments	0	0
Other Adjustment	(154)	13
Settlement (Gain)Loss	0	0
Benefit Obligation at End of Year	$ 25,635	$ 28,714	$ 27,496