Short-Term Debt and Credit Agreements (Narrative) (Detail) - USD ($)		1 Months Ended				12 Months Ended
		Oct. 31, 2023	Jul. 31, 2023	Mar. 31, 2023	Jan. 31, 2023	Dec. 31, 2023		Dec. 31, 2021	Nov. 30, 2023	Oct. 01, 2023	Aug. 01, 2023	Feb. 28, 2023	Feb. 27, 2023	Dec. 31, 2022		Nov. 30, 2022	Jun. 30, 2021	Oct. 31, 2020	Nov. 30, 2017
Debt Instrument [Line Items]
Facility Limit			$ 600,000,000			$ 6,000,000,000	[1]							$ 6,000,000,000	[1]
Line of credit issued						5,725,000,000		$ 1,265,000,000
Securities due within one year						6,589,000,000								3,337,000,000
Short-term debt						$ 3,956,000,000								$ 3,423,000,000
Weighted-average percentage interest rates						5.69%								4.73%
Letters of credit outstanding, amount	[1]					$ 16,000,000								$ 202,000,000
Floating Rate Demand Notes
Debt Instrument [Line Items]
Short-term debt						$ 409,000,000								$ 347,000,000
Weighted-average percentage interest rates						5.50%								4.24%
Floating Rate Demand Notes | Shelf Registration for Sale of Demand Notes
Debt Instrument [Line Items]
Facility Limit																			$ 3,000,000,000
Debt instrument, maximum principal outstanding amount																		$ 1,000,000,000
Dominion Energy South Carolina Inc
Debt Instrument [Line Items]
Facility Limit						$ 500,000,000
Short-term indebtedness outstanding				$ 2,200,000,000
Debt, maturity month and year				2025-03
Questar Gas
Debt Instrument [Line Items]
Facility Limit						250,000,000
GENCO
Debt Instrument [Line Items]
Short-term indebtedness outstanding				$ 200,000,000
Debt, maturity month and year				2025-03
Virginia Electric and Power Company
Debt Instrument [Line Items]
Facility Limit	[2]					6,000,000,000								$ 6,000,000,000
Securities due within one year						381,000,000								1,164,000,000
Short-term debt						$ 455,000,000								$ 941,000,000
Weighted-average percentage interest rates						5.65%								4.68%
Letters of credit outstanding, amount	[2]					$ 10,000,000								$ 140,000,000
Revolving Credit Facility
Debt Instrument [Line Items]
Facility Limit																	$ 6,000,000,000
Revolving Credit Facility | Virginia Electric and Power Company
Debt Instrument [Line Items]
Facility Limit																$ 3,000,000,000
Letter of Credit
Debt Instrument [Line Items]
Facility Limit				$ 100,000,000		54,000,000
Credit facility, outstanding amount						54,000,000							$ 0
Letter of Credit | Maximum
Debt Instrument [Line Items]
Letters of credit issued and outstanding												$ 1,000,000
Letter of Credit | Credit Facility, Maturing in June 2022
Debt Instrument [Line Items]
Credit facility, outstanding amount						25,000,000								25,000,000
Letter of Credit | Credit Facility Maturing In June 2024
Debt Instrument [Line Items]
Facility Limit				$ 30,000,000
Credit facility, maturity date				Jun. 30, 2024
Letter of Credit | Virginia Electric and Power Company
Debt Instrument [Line Items]
Facility Limit				$ 200,000,000										2,000,000,000
Line of credit issued						124,000,000
Letter of Credit | Virginia Electric and Power Company | Credit Facility, Maturing in January 2026
Debt Instrument [Line Items]
Facility Limit					$ 125,000,000
Credit facility, maturity date					Jan. 31, 2026
Credit Facilities Maturing in December 2021 with 1 Year Automatic Renewals Through 2024 | DECP Holdings
Debt Instrument [Line Items]
Facility Limit						$ 110,000,000
Automatic renewal period						1 year
Letters of credit outstanding, amount						$ 110,000,000								110,000,000
Letters of credit borrowed, amount						0								$ 0
364 Term loan facility
Debt Instrument [Line Items]
Facility Limit		$ 500,000,000			$ 2,500,000,000
Credit facility, outstanding amount				$ 1,000,000,000	$ 1,000,000,000					$ 225,000,000	$ 750,000,000	$ 500,000,000
Securities due within one year						2,500,000,000
Line of credit facility remaining borrowing and terminated		225,000,000
Credit facility, maturity date					Jan. 31, 2024
364 Term loan facility | Term Loan Facility, Maturing in July 2024
Debt Instrument [Line Items]
Facility Limit			$ 600,000,000
Credit facility, maturity date			Jul. 31, 2024
364 Term loan facility | Term Loan Facility, Maturing in Oct 2024
Debt Instrument [Line Items]
Facility Limit		$ 2,250,000,000
Securities due within one year						2,250,000,000
Credit facility, maturity date		Oct. 31, 2024
364 Term loan facility | General Corporate
Debt Instrument [Line Items]
Credit facility, outstanding amount		$ 1,000,000,000				$ 750,000,000			$ 500,000,000
364 Term loan facility | Cove Point
Debt Instrument [Line Items]
Credit facility, outstanding amount			$ 750,000,000

[1] This credit facility matures in June 2026, with the potential to be extended by the borrowers to June 2028, and can be used by the borrowers under the credit facility to support bank borrowings and the issuance of commercial paper, as well as to support up to a combined $2.0 billion of letters of credit.

[2] The full amount of the facility is available to Virginia Power, less any amounts outstanding to co-borrowers Dominion Energy, Questar Gas and DESC. The sub-limit for Virginia Power is set pursuant to the terms of the facility but can be changed at the option of the borrowers multiple times per year. At December 31, 2023, the sub-limit for Virginia Power was $1.75 billion. If Virginia Power has liquidity needs in excess of its sub-limit, the sub-limit may be changed or such needs may be satisfied through short-term intercompany 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 $2.0 billion (or the sub-limit, whichever is less) of letters of credit.