Retirement Benefits and Trusteed Assets (Pension Plan - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Change in projected benefit obligation
Plan amendments	$ 0	$ 4
Amounts recognized in Regulatory assets
Regulatory assets	4,336	3,677
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Accumulated benefit obligation, end of year	4,078	5,448
Change in projected benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	5,857	6,304
Service cost	95	108	$ 99
Interest cost	166	158	186
Actuarial gain	(1,252)	(255)
Benefits paid	(278)	(414)
Settlements	(279)	(48)
Projected/Accumulated postretirement benefit obligation, end of year	4,309	5,857	6,304
Change in plan assets
Plan assets at fair value, beginning of year	5,507	5,497
Actual return on plan assets	(1,062)	460
Company contributions	9	12
Benefits paid	(278)	(414)
Settlements	(279)	(48)
Plan assets at fair value, end of year	3,897	5,507	$ 5,497
Funded status	(412)	(350)
Amount recorded as:
Current liabilities	(34)	(11)
Noncurrent liabilities	(378)	(339)
Defined benefit plans liabilities	(412)	(350)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	85	126
Prior service cost	0	1
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	85	127
Amounts recognized in Regulatory assets
Net actuarial loss	1,369	1,381
Prior service credit	(7)	(9)
Regulatory assets	$ 1,362	$ 1,372