Benefit Plans and Other Postretirement Benefits (Details) - USD ($) $ in Millions		1 Months Ended	3 Months Ended
		Jan. 31, 2025	Mar. 31, 2025	Mar. 31, 2024
Components of Net Periodic Benefit Cost [Abstract]
Operating and maintenance expenses			$ 63	$ 56
Pension Plan [Member]
Components of Net Periodic Benefit Cost [Abstract]
Service cost			1	1
Interest cost (a)	[1]		1	2
Expected return on plan assets (a)	[1]		(2)	(2)
Net periodic benefit cost			0	1
Net benefit cost recognized for financial reporting			$ 0	$ 1
Contributions to pension plans		$ 9
Pension Plan [Member] | Parent Company [Member]
Components of Net Periodic Benefit Cost [Abstract]
Contributions to pension plans		$ 125

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