Short-Term Borrowings (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Short-term Debt [Line Items]
Amount outstanding at period end	$ 75	$ 75	$ 34
Money Pool
Short-term Debt [Line Items]
Borrowing limit	100	100	100	$ 100
Amount outstanding at period end	27	27	0	91
Average amount outstanding	14	46	35	51
Maximum amount outstanding	$ 44	$ 100	$ 100	$ 100
Weighted average interest rate, computed on a daily basis (percentage)	5.34%	5.04%	0.44%	0.05%
Line of Credit Facility, Interest Rate at Period End	5.34%	5.34%		0.05%
Commercial Paper
Short-term Debt [Line Items]
Borrowing limit	$ 500	$ 500	$ 500	$ 500
Amount outstanding at period end	75	75	34	137
Average amount outstanding	18	50	100	63
Maximum amount outstanding	$ 95	$ 119	$ 324	$ 342
Weighted average interest rate, computed on a daily basis (percentage)	5.54%	5.12%	0.79%	0.21%
Weighted average interest rate at period end (percentage)	5.56%	5.56%	4.55%	0.26%