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, 2024	Dec. 31, 2023	Dec. 31, 2022
Amounts recognized in Regulatory assets (liabilities)
Regulatory assets	$ 6,821	$ 6,317
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Accumulated benefit obligation, end of year	3,803	4,089
Change in projected benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	4,318	4,309
Service cost	58	57	$ 95
Interest cost	208	214	166
Actuarial (gain) loss	(254)	74
Benefits paid	(348)	(329)
Settlements	0	(7)
Projected/Accumulated postretirement benefit obligation, end of year	3,982	4,318	4,309
Change in plan assets
Plan assets at fair value, beginning of year	3,960	3,897
Actual return on plan assets	137	363
Company contributions	9	36
Benefits paid	(348)	(329)
Settlements	0	(7)
Plan assets at fair value, end of year	3,758	3,960	$ 3,897
Funded status	(224)	(358)
Amount recorded as:
Current liabilities	(10)	(8)
Noncurrent liabilities	(214)	(350)
Defined benefit plans liabilities	(224)	(358)
Amounts recognized in Accumulated other comprehensive income, pre-tax
Net actuarial loss	76	76
Amounts recognized in Accumulated other comprehensive income, pre-tax	76	76
Amounts recognized in Regulatory assets (liabilities)
Net actuarial (gain) loss	1,318	1,426
Prior service credit	(3)	(5)
Regulatory assets	$ 1,315	$ 1,421