Acquisitions and Dispositions (Sale of Kewaunee) (Narrative) (Detail) - Dominion Energy Kewaunee, Inc - USD ($) $ in Millions	3 Months Ended
Sep. 30, 2021	May 31, 2021
Business Acquisition And Dispositions [Line Items]
Percentage of equity interests expected to be sold		100.00%
Disposal group, expected to recognized a gain	$ (710)
Disposal group, expected to recognized a gain after tax	$ 565

Disposal group including discontinued operation gain (loss) on disposal after tax.

No definition available.

Name:	d_DisposalGroupIncludingDiscontinuedOperationGainLossOnDisposalAfterTax
Namespace Prefix:	d_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration