Long-Term and Short-Term Debt (Narrative) (Detail)		1 Months Ended	12 Months Ended
		Mar. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
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			7
Redemption of remaining principal outstanding plus accrued interest			$ 0	$ 34,000,000	$ 0
Commercial paper borrowing limit		$ 2,200,000,000
Short-term borrowings outstanding			871,000,000	458,000,000
Interest charges	[1]		220,000,000	192,000,000	229,000,000
Interest income from money pool transactions					2,000,000
Interest expense from money pool transactions					2,000,000
Maximum [Member]
Debt Instrument [Line Items]
Short term commercial paper maturity period		1 year
Interest income from money pool transactions				1,000,000
Interest expense from money pool transactions				1,000,000
Dominion Energy [Member]
Debt Instrument [Line Items]
Short-term borrowings outstanding, maximum			900,000,000
Short-term borrowings outstanding			769,000,000	415,000,000
Interest charges			19,000,000		$ 7,000,000
Dominion Energy [Member] | Maximum [Member]
Debt Instrument [Line Items]
Interest charges				1,000,000
Joint Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Facility limit	[2]		1,000,000,000	$ 1,000,000,000
Joint Revolving Credit Facility [Member] | Dominion Energy [Member]
Debt Instrument [Line Items]
Facility limit			6,000,000,000.0
Industrial Revenue Bonds [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 68,000,000
Commercial Paper
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage			4.76%
Letter of Credit
Debt Instrument [Line Items]
Debt instrument, face amount			$ 68,000,000
Facility limit			$ 1,000,000,000.0
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

[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, 2022, 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 DESC's parent or 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.