Acquisitions and Dispositions - (Schedule of Results of Operations of Disposal Groups Reported As Discontinued Operations) (Parenthetical) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2025	Mar. 31, 2024
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)		$ (1)	$ 54
East Ohio, PSNC and Questar Gas
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)			(69)
East Ohio | Enbridge
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Income tax expense (benefit)	[1]		11
Employee benefit plans			45
Employee benefit plans after tax			$ 33

[1] Represents amounts attributable to Dominion Energy prior to the closing of the East Ohio Transaction which closed on March 6, 2024.