Retirement Benefits (Changes In Fair Value Of Plan Assets) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Pension Benefits [Member]
Change in fair value of plan assets
Beginning balance	$ 2,026	$ 1,818
Actual return on plan assets	290	329
Employer contributions	7	4
Plan participant contributions	0	0
Settlements	(80)	(35)
Benefits paid	(57)	(90)
Ending balance	2,186	2,026
Other Benefits [Member]
Change in fair value of plan assets
Beginning balance	367	336
Actual return on plan assets	33	55
Employer contributions	11	5
Plan participant contributions	18	17
Settlements	0	0
Benefits paid	(38)	(46)
Ending balance	$ 391	$ 367

Defined Benefit Plan Benefits Paid Fair Value

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- Definition

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of contribution received by defined benefit plan from employer which increases plan assets.

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- Definition

Amount of asset segregated and restricted to provide benefit under defined benefit plan. Asset includes, but is not limited to, stock, bond, other investment, earning from investment, and contribution by employer and employee.

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Amount of contributions received by defined benefit plan from participant which increases plan assets.

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Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract.

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