Benefit Plans and Other Postretirement Benefits (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended		6 Months Ended
		Jan. 31, 2023	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Components of Net Periodic Benefit Cost [Abstract]
Operating and maintenance expenses			$ 57	$ 54	$ 115	$ 107
Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost			1	1	2	2
Interest cost (a)	[1]		2	1	3	2
Expected return on plan assets (a)	[1]		(2)	(2)	(4)	(4)
Amortization of net loss (a)	[1]		0	1	1	2
Net benefit cost recognized for financial reporting			$ 1	$ 1	$ 2	$ 2
Contributions to pension plans		$ 4
Pension Plan [Member] | Parent Company [Member]
Components of Net Periodic Benefit Cost [Abstract]
Contributions to pension plans		$ 50

[1] The components of net periodic cost other than the service cost component are included in the line item “Other income, net” in the consolidated statements of income or capitalized on the consolidated balance sheets as a regulatory asset.