Retirement Benefits (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Settlement loss	$ 28	$ 26	$ 29
Net amount of assets (liabilities) of cash, investment income receivable and amounts due to/from brokers, excluded from fair values of pension benefit assets and other benefit assets	36	48
Claims settlements to be paid from other benefit assets	17	29
Contributions made to 401k retirement benefit plans	275	241	221
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation for the defined benefit pension plans	1,413	1,857
Projected benefit obligation	44
Accumulated benefit obligation	0
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation	44
Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets	0
Settlement loss	28	26	29
Payment for Pension and Other Postretirement Benefits	$ 4	7	$ 7
Pre-Medicare [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate to be used for next year to measure expected cost of other benefits	8.00%
Ultimate health care cost trend rate	4.50%
Year in which ultimate trend rate reached	2035
Post-Medicare [Member] | Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Assumed health care cost trend rate to be used for next year to measure expected cost of other benefits	6.50%
Ultimate health care cost trend rate	4.50%
Year in which ultimate trend rate reached	2035
Equity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average target allocation for plan assets	37.00%
Fixed Maturity Securities [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average target allocation for plan assets	58.00%
All Other Investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Weighted-average target allocation for plan assets	5.00%
Partnership investments [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Unfunded Commitment	$ 2	$ 3