Commercial Paper (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Short-term Debt [Line Items]
Amount outstanding at period end	$ 35	$ 35	$ 60
money pool
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	150	150	150	$ 150
Amount outstanding at period end	0	0	0	0
Average amount outstanding	0	4	6	25
Maximum amount outstanding	0	$ 54	$ 43	$ 81
Line of Credit Facility, Interest Rate During Period		5.34%	4.98%	1.10%
Commercial Paper [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	150	$ 150	$ 150	$ 150
Amount outstanding at period end	35	35	60	47
Average amount outstanding	3	11	15	18
Maximum amount outstanding	$ 35	$ 99	$ 93	$ 123
Line of Credit Facility, Interest Rate During Period	4.59%	5.42%	4.85%	1.03%
Weighted average interest rate at period end (percentage)	4.59%	4.59%	5.50%	4.55%