Short-Term Borrowings (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Short-term Debt [Line Items]
Amount outstanding at period end	$ 220	$ 220	$ 145
Money Pool
Short-term Debt [Line Items]
Borrowing limit	100	100	100	$ 100
Amount outstanding at period end	62	62	7	27
Average amount outstanding	45	31	24	46
Maximum amount outstanding	$ 100	$ 100	$ 100	$ 100
Weighted average interest rate, computed on a daily basis (percentage)	3.95%	4.19%	5.29%	5.04%
Line of Credit Facility, Interest Rate at Period End	3.88%	3.88%	4.58%	5.34%
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	$ 600	$ 600	$ 500	$ 500
Amount outstanding at period end	220	220	145	75
Average amount outstanding	68	97	35	50
Maximum amount outstanding	$ 235	$ 314	$ 160	$ 119
Weighted average interest rate, computed on a daily basis (percentage)	4.00%	4.51%	5.47%	5.12%
Weighted average interest rate at period end (percentage)	3.93%	3.93%	4.66%	5.56%