Long-Term and Short-Term Debt (Schedule of Line of Credit Facilities) (Parenthetical) (Detail) - USD ($)		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022
Minimum [Member]
Debt Instrument [Line Items]
Line of credit facility maturity date		2026-06
Maximum [Member]
Debt Instrument [Line Items]
Line of credit facility maturity date		2028-06
Joint Revolving Credit Facility
Debt Instrument [Line Items]
Facility limit	[1]	$ 1,000,000,000	$ 1,000,000,000
Line of Credit Facility
Debt Instrument [Line Items]
Facility limit		$ 500,000,000
Commercial Paper
Debt Instrument [Line Items]
Line of credit facility, commitment fee percentage		5.70%	4.76%
Letter of Credit
Debt Instrument [Line Items]
Facility limit		$ 1,000,000,000

[1] 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.