Retirement Benefits and Trusteed Assets (Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Amounts recognized in Regulatory assets
Regulatory assets	$ 7,550	$ 6,821
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Accumulated benefit obligation, end of year	3,851	3,803
Change in projected benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	3,982	4,318
Service cost	49	58	$ 57
Interest cost	216	208	214
Actuarial (gain) loss	111	(254)
Benefits paid	(315)	(348)
Projected/Accumulated postretirement benefit obligation, end of year	4,043	3,982	4,318
Change in plan assets
Plan assets at fair value, beginning of year	3,758	3,960
Actual return on plan assets	343	137
Company contributions	9	9
Benefits paid	(315)	(348)
Plan assets at fair value, end of year	3,795	3,758	$ 3,960
Funded status	(248)	(224)
Amount recorded as:
Current liabilities	(13)	(10)
Noncurrent liabilities	(235)	(214)
Defined benefit plans liabilities	(248)	(224)
Amounts recognized in Accumulated other comprehensive income, pre-tax
Net actuarial loss	82	76
Amounts recognized in Accumulated other comprehensive income, pre-tax	82	76
Amounts recognized in Regulatory assets
Net actuarial loss	1,283	1,318
Prior service credit	(2)	(3)
Regulatory assets	$ 1,281	$ 1,315