Benefit Plans and Other Postretirement Benefits (Details) - Pension Plan [Member] - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Jan. 31, 2024	Mar. 31, 2024	Mar. 31, 2023
Components of Net Periodic Benefit Cost [Abstract]
Service cost			$ 1	$ 1
Interest cost (a)	[1]		2	2
Expected return on plan assets (a)	[1]		(2)	(2)
Net periodic benefit cost			$ 1	$ 1
Contributions to pension plans		$ 7
Parent Company [Member]
Components of Net Periodic Benefit Cost [Abstract]
Contributions to pension plans		$ 100

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