Other Income (Expense), Net (Components of Other Income (Expense), Net) (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Income Statement [Abstract]
Other income		$ 2	$ 1	$ 7	$ 3
Gains on sales of assets		1	1	1	2
Other expense		(1)	(4)	(3)	(9)
Allowance for equity funds used during construction		1	3	1	6
Other income (expense), net	[1]	$ 3	$ 1	$ 6	$ 2

[1] Items designated are other segment items for each reportable segment.