Benefit Plans - Components of Net Periodic Benefit Costs (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 Disclosure [Line Items]
Company Service Cost	$ 7,569	$ 7,342	$ 8,345
Interest Cost	11,276	13,036	15,705
Expected Return on Assets	(20,657)	(22,139)	(19,466)
Other Adjustments	0	0	0
Subtotal	(1,812)	(1,761)	4,584
Amortization of Net Transition Obligation/(Asset)	0	0	0
Amortization of Net Prior Service Cost/(Credit)	(239)	(247)	(281)
Amortization of Net Losses/(Gains)	5,490	6,578	8,412
Total Amortization	5,251	6,331	8,131
Net Periodic Benefit Cost	3,439	4,570	12,715
Cost of settlements	6,012	10,369	1,933
Total Expense for Year	9,451	14,939	14,648
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Company Service Cost	1,508	1,263	1,345
Interest Cost	648	832	1,130
Expected Return on Assets	(8,863)	(7,407)	(5,785)
Other Adjustments	0	0	0
Subtotal	(6,707)	(5,312)	(3,310)
Amortization of Net Transition Obligation/(Asset)	0	0	0
Amortization of Net Prior Service Cost/(Credit)	213	51	(34)
Amortization of Net Losses/(Gains)	(1,697)	(783)	0
Total Amortization	(1,484)	(732)	(34)
Net Periodic Benefit Cost	(8,191)	(6,044)	(3,344)
Cost of settlements	0	0	0
Total Expense for Year	$ (8,191)	$ (6,044)	$ (3,344)