Commercial Paper (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	$ 60	$ 60	$ 47
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	7	6	25	16
Maximum amount outstanding	$ 43	$ 43	$ 81	$ 78
Line of Credit Facility, Interest Rate During Period	5.34%	4.98%	1.10%	0.05%
Commercial Paper [Member]
Short-term Debt [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 150	$ 150	$ 150	$ 150
Amount outstanding at period end	60	60	47	83
Average amount outstanding	10	15	18	3
Maximum amount outstanding	$ 74	$ 93	$ 123	$ 83
Line of Credit Facility, Interest Rate During Period	5.48%	4.85%	1.03%	0.18%
Weighted average interest rate at period end (percentage)	5.50%	5.50%	4.55%	0.21%