Retirement Benefits - Schedule of Assumptions Used to Determine Benefit Obligations (Details)	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Medical and Life Insurance Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (percentage)	2.77%	2.28%
Ultimate healthcare trend rate (percentage)	4.50%	4.50%
Initial healthcare trend rate (pre 65/post 65) (percentage)	6.25%	6.50%
Qualified Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (percentage)	2.90%	2.52%	3.28%
Nonqualified Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Discount rate (percentage)	2.89%	2.51%