Retirement Benefits - Assumptions (Details)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Pension Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	3.00%	2.70%	3.35%
Rate of compensation increase	4.50%	4.50%	4.50%
Benefit Cost Assumptions
Discount rate	2.70%	3.35%	4.40%
Return on plan assets	7.00%	7.00%	7.00%
Rate of compensation increase	4.50%	4.50%	4.50%
Nonqualified Plan | Pension Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	3.00%	2.70%	3.35%
Rate of compensation increase	4.50%	4.50%	4.50%
Benefit Cost Assumptions
Discount rate	2.70%	3.35%	4.40%
Return on plan assets	0.00%	0.00%	0.00%
Rate of compensation increase	4.50%	4.50%	4.50%
Qualified Plan | Pension Plan [Member]
Defined Benefit Plan, Weighted Average Assumptions Used in Calculating Benefit Obligation [Abstract]
Discount rate	3.00%	2.70%	3.35%
Rate of compensation increase	4.50%	4.50%	4.50%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate	4.00%	4.00%	4.00%
Benefit Cost Assumptions
Discount rate	2.70%	3.35%	4.40%
Return on plan assets	6.50%	7.15%	7.50%
Rate of compensation increase	4.50%	4.50%	4.50%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate	4.00%	4.00%	4.00%