Long-Term and Short-Term Debt (Narrative) (Detail)		1 Months Ended	12 Months Ended
		Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Debt Instrument [Line Items]
Unfunded property additions			70.00%
Consecutive months for bond ratio			12 months
Months preceding issuance of bonds			18 months
Bonds Ratio			5
Commercial paper borrowing limit		$ 2,200,000,000
Affiliated and related party payables and other			$ 163,000,000	$ 115,000,000
Interest charges/expense from money pool transactions	[1]		250,000,000	220,000,000	$ 192,000,000
Maximum [Member]
Debt Instrument [Line Items]
Short term commercial paper maturity period		1 year
Dominion Energy
Debt Instrument [Line Items]
Inter company credit facility maximum capacity			900,000,000
Affiliated and related party payables and other			442,000,000	769,000,000
Interest charges/expense from money pool transactions			53,000,000	19,000,000
Dominion Energy | Maximum [Member]
Debt Instrument [Line Items]
Interest charges/expense from money pool transactions					1,000,000
Related Party | Maximum [Member]
Debt Instrument [Line Items]
Interest charges/expense from money pool transactions					1,000,000
Interest income from money pool transactions					$ 1,000,000
Joint Revolving Credit Facility
Debt Instrument [Line Items]
Facility limit	[2]		1,000,000,000	$ 1,000,000,000
Joint Revolving Credit Facility | Dominion Energy
Debt Instrument [Line Items]
Facility limit			6,000,000,000
Joint Revolving Credit Facility | Commercial Paper
Debt Instrument [Line Items]
Debt instrument, face amount			254,000,000
Industrial Revenue Bonds
Debt Instrument [Line Items]
Debt instrument, face amount			68,000,000
Intercompany Credit Facility
Debt Instrument [Line Items]
Line of credit, outstanding			135,000,000
Genco
Debt Instrument [Line Items]
Commercial paper borrowing limit		$ 200,000,000
Genco | Maximum [Member]
Debt Instrument [Line Items]
Short term commercial paper maturity period		1 year
Genco | Dominion Energy
Debt Instrument [Line Items]
Inter company credit facility maximum capacity			200,000,000
Genco | Intercompany Credit Facility
Debt Instrument [Line Items]
Line of credit, outstanding			34,000,000
Fuel company | Dominion Energy
Debt Instrument [Line Items]
Inter company credit facility maximum capacity			$ 400,000,000

[1] See Note 16 for amounts attributable to affiliates.

[2] A maximum of $1.0 billion of the facility is available to DESC, assuming adequate capacity is available after giving effect to uses by co-borrowers Dominion Energy, Virginia Power and Questar Gas. A sub-limit for DESC is set within the facility limit but can be changed at the option of the co-borrowers multiple times per year. At December 31, 2023, the sub-limit for DESC was $500 million. If DESC has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term borrowings from Dominion Energy. This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028. The credit facility can be used to support bank borrowings and the issuance of commercial paper, as well as to support up to $1.0 billion (or the sub-limit, whichever is less) of letters of credit.