Significant Financing Transactions (Narrative) (Detail)			1 Months Ended											3 Months Ended		9 Months Ended
		Jun. 14, 2019 USD ($) $ / shares shares	Jun. 30, 2022 shares	Nov. 30, 2020 USD ($)	Sep. 30, 2020 USD ($) Bond agreement shares	Aug. 31, 2020 USD ($) shares	Jun. 30, 2020 USD ($) Bond	May 31, 2020 USD ($)	Apr. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) $ / shares shares		Jan. 31, 2019 USD ($) shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 shares	Sep. 30, 2020 USD ($) $ / shares shares	Sep. 30, 2019 USD ($) shares	Dec. 15, 2024 $ / shares	Jul. 31, 2020 USD ($)	Feb. 29, 2020 USD ($)	Nov. 30, 2017 USD ($)
Debt Instrument [Line Items]
Facility Limit	[1],[2]				$ 6,000,000,000									$ 6,000,000,000		$ 6,000,000,000
Short-term debt					2,328,000,000						$ 849,000,000	[3]		2,328,000,000		2,328,000,000
Other long-term debt					882,000,000						100,000,000	[3]		882,000,000		882,000,000
Shares of common stock issued in acquisition, value																	$ 6,818,000,000
Amount of income taxes recognized in equity primarily attributable to establishing additional regulatory liabilities																	$ (40,000,000)
Total Preferred Stock					$ 2,387,000,000						$ 2,387,000,000	[3]		2,387,000,000		2,387,000,000
Preferred stock, redemption price per share | $ / shares											$ 1,020
Stock repurchased, value														2,385,000,000		2,385,000,000
Number of prepaid accelerated share repurchase agreements | agreement					2
Accelerated share repurchase, payments					$ 1,500,000,000									$ 1,500,000,000		$ 1,500,000,000
Accelerated share repurchase, cash paid for number of shares exchange | shares					17,200,000									17,200,000		17,200,000
Decrease in common stock														$ 1,500,000,000
Common stock worth based on closing Price					$ 1,500,000,000									$ 1,500,000,000		$ 1,500,000,000
Scenario Forecast
Debt Instrument [Line Items]
Preferred stock, redemption price per share | $ / shares																		$ 1,000
Common Stock
Debt Instrument [Line Items]
Shares of common stock issued in acquisition | shares																	96,000,000
Shares of common stock issued in acquisition, value																	$ 6,818,000,000
Amount of income taxes recognized in equity primarily attributable to establishing additional regulatory liabilities																	$ 1,181,000,000
Issuance of common stock (in shares) | shares														4,000,000	20,000,000	6,000,000	24,000,000
Stock repurchase program, authorized amount																			$ 3,000,000,000.0
Stock repurchased, shares | shares					4,100,000									28,000,000		28,000,000
Stock repurchased, value					$ 323,000,000									$ 2,385,000,000		$ 2,385,000,000
Common Stock | Open Market Agreement
Debt Instrument [Line Items]
Stock repurchased, shares | shares														7,200,000
Stock repurchased, value														$ 562,000,000
Common Stock | Settlement Agreement
Debt Instrument [Line Items]
Issuance of common stock (in shares) | shares					4,100,000
Common Stock | Scenario Forecast
Debt Instrument [Line Items]
Stock repurchased, value				$ 1,000,000,000.0
2019 Corporate Units
Debt Instrument [Line Items]
Total Long-term Debt		$ 1,600,000,000
Percentage of interest in undivided beneficial ownership		10.00%
Total Preferred Stock	[4]	$ 1,610,000,000
Dividend rate percentage		1.75%
Issuance of common stock (in shares) | shares		16,000,000
2019 Corporate Units | Scenario Forecast | Maximum
Debt Instrument [Line Items]
Shares to be issued under purchase contracts | shares			21,800,000
2019 Corporate Units | Common Stock
Debt Instrument [Line Items]
Purchase price to be paid under stock purchase contracts | $ / shares		$ 100
Interest Rate Swap
Debt Instrument [Line Items]
Derivative notional value							$ 2,000,000,000.0
Derivative maturity month and year							2024-12
Other long-term debt							$ 326,000,000
Derivative imputed interest rate							1.19%
SCANA
Debt Instrument [Line Items]
Debt instrument, maturity date, description																In March 2020, SCANA redeemed the remaining principal outstanding of $183 million of its 4.75% medium-term notes and $155 million of its 4.125% medium-term notes plus accrued interest and make-whole premiums. The notes would have otherwise matured in May 2021 and February 2022, respectively.
Shares of common stock issued in acquisition | shares													95,600,000
Shares of common stock issued in acquisition, value													$ 6,800,000,000
June 2006 Hybrids
Debt Instrument [Line Items]
Debt, amount redeemed																				$ 111,000,000
September 2006 Hybrids
Debt Instrument [Line Items]
Debt, amount redeemed																				$ 286,000,000
June 2006 and September 2006 Hybrids | Interest and Related Charges
Debt Instrument [Line Items]
Expenses related to early redemption of hybrids																$ 10,000,000
Shelf Registration for Sale of Common Stock through At-the-market Program
Debt Instrument [Line Items]
Issuance of common stock (in shares) | shares						0										0
Shelf Registration for Sale of Common Stock through At-the-market Program | Maximum
Debt Instrument [Line Items]
Sale of stock authorized amount						$ 1,000,000,000.0				$ 500,000,000
DESC
Debt Instrument [Line Items]
Facility Limit					$ 500,000,000									500,000,000		$ 500,000,000
Short-term indebtedness outstanding																$ 2,200,000,000
Debt maturity month and year																2021-03
Questar Gas
Debt Instrument [Line Items]
Facility Limit					250,000,000									250,000,000		$ 250,000,000
GESC
Debt Instrument [Line Items]
Short-term indebtedness outstanding																$ 200,000,000
Debt maturity month and year																2021-03
Virginia Electric and Power Company
Debt Instrument [Line Items]
Facility Limit	[1],[5]				6,000,000,000									6,000,000,000		$ 6,000,000,000
Short-term debt					422,000,000						$ 243,000,000	[6]		422,000,000		422,000,000
Other long-term debt					$ 477,000,000						$ 16,000,000	[6]		$ 477,000,000		$ 477,000,000
Issuance of common stock (in shares) | shares														0	0	0	0
Virginia Electric and Power Company | Tax Exempt Bonds
Debt Instrument [Line Items]
Number of series of tax exempt bonds | Bond					3		1
Long-term debt					$ 322,000,000		$ 105,000,000							$ 322,000,000		$ 322,000,000
Virginia Power | Interest Rate Swap
Debt Instrument [Line Items]
Derivative notional value						$ 900,000,000
Derivative maturity month and year						2023-12
Other long-term debt						$ 443,000,000
Derivative imputed interest rate						0.34%
Dominion Energy Midstream Partners, LP
Debt Instrument [Line Items]
Shares of common stock issued in acquisition | shares													22,500,000
Shares of common stock issued in acquisition, value													$ 1,600,000,000
Common units conversion ratio													0.2492
Gain or loss recognized in equity transaction													$ 0
Amount of income taxes recognized in equity primarily attributable to establishing additional regulatory liabilities													$ 40,000,000
Dominion Energy
Debt Instrument [Line Items]
Dividend rate percentage											2.993%
Dominion Energy | Series B Preferred Stock
Debt Instrument [Line Items]
Preferred stock shares authorized | shares											800,000
Total Preferred Stock											$ 791,000,000
Issuance of costs											9,000,000
Preferred stock liquidation value											$ 1,000
Dividend rate percentage											4.65%
Dividend stock														$ 9,000,000		$ 27,000,000
Recorded dividends per share | $ / shares														$ 11.625		$ 34.875
Credit Facilities, Maturing in December 2017 with 1 year Automatic Renewals through 2023 | SBL Holdco
Debt Instrument [Line Items]
Facility Limit					30,000,000									$ 30,000,000		$ 30,000,000
Automatic renewal period																1 year
Short-term debt					0									0		$ 0
Credit Facilities, Maturing in May 2018 with 1 year Automatic Renewals through 2024 | Dominion Solar Projects III, Inc
Debt Instrument [Line Items]
Facility Limit					25,000,000									25,000,000		$ 25,000,000
Automatic renewal period																1 year
Short-term debt					0									0		$ 0
Term Loan Credit Agreement
Debt Instrument [Line Items]
Credit facility, outstanding amount									$ 625,000,000	$ 500,000,000
Debt Instrument, Term									364 days	364 days
Floating Rate Demand Notes
Debt Instrument [Line Items]
Short-term debt					215,000,000						$ 75,000,000			215,000,000		215,000,000
Floating Rate Demand Notes | Shelf Registration for Sale of Demand Notes
Debt Instrument [Line Items]
Facility Limit																					$ 3,000,000,000.0
Debt instrument, maximum principal outstanding amount																					$ 1,000,000,000.0
Floating rate senior notes
Debt Instrument [Line Items]
Total Long-term Debt					$ 1,000,000,000.0									$ 1,000,000,000.0		$ 1,000,000,000.0
Debt maturity year					2023
Floating rate senior notes | SCANA
Debt Instrument [Line Items]
Debt, amount redeemed										$ 66,000,000
Debt instrument, maturity date, description																In March 2020, SCANA redeemed its floating rate senior notes at the remaining principal balance of $66 million plus accrued interest. The notes would have otherwise matured in June 2034.
Floating rate senior notes | Interest and Related Charges | SCANA
Debt Instrument [Line Items]
Expenses related to early redemption of hybrids																$ 7,000,000
4.75% Medium Term Notes | SCANA
Debt Instrument [Line Items]
Debt, amount redeemed										$ 183,000,000
Interest Rate										4.75%
4.125% Medium Term Notes | SCANA
Debt Instrument [Line Items]
Debt, amount redeemed										$ 155,000,000
Interest Rate										4.125%
4.75% and 4.125% Medium Term Notes | Interest and Related Charges | SCANA
Debt Instrument [Line Items]
Expenses related to early redemption of hybrids																$ 14,000,000
Senior Notes Due in 2025 | Senior Notes
Debt Instrument [Line Items]
Interest Rate							1.30%			3.30%
Total Long-term Debt							$ 500,000,000			$ 400,000,000
Debt maturity year							2025			2025
Senior Notes Due in 2027 | Senior Notes
Debt Instrument [Line Items]
Interest Rate										3.60%
Total Long-term Debt										$ 350,000,000
Debt maturity year										2027
Senior Notes Due in 2030 | Senior Notes
Debt Instrument [Line Items]
Interest Rate							2.00%		3.375%
Total Long-term Debt							$ 500,000,000		$ 1,500,000,000
Debt maturity year							2030		2030
Senior Notes Due in 2030 | PSNC
Debt Instrument [Line Items]
Interest Rate										4.05%
Total Long-term Debt										$ 200,000,000
Debt maturity year										2030
2.579% Junior Subordinated Notes | Unsecured Junior Subordinated Notes
Debt Instrument [Line Items]
Debt maturity month and year									2020-07
Interest Rate									2.579%
Debt instrument repurchased and canceled amount							$ 993,000,000		$ 7,000,000
Senior Notes Due in 2050 | Senior Notes
Debt Instrument [Line Items]
Interest Rate							3.00%
Total Long-term Debt							$ 800,000,000
Debt maturity year							2050
1.20% Tax-Exempt Bond | Virginia Electric and Power Company | Tax Exempt Bonds
Debt Instrument [Line Items]
Interest Rate							1.20%
0.45% Tax Exempt Bond | Virginia Electric and Power Company | Tax Exempt Bonds
Debt Instrument [Line Items]
Interest Rate					0.45%									0.45%		0.45%
Number of series of tax exempt bonds | Bond					1
0.75% Tax Exempt Bond | Virginia Electric and Power Company | Tax Exempt Bonds
Debt Instrument [Line Items]
Interest Rate					0.75%									0.75%		0.75%
Number of series of tax exempt bonds | Bond					2
Letter of Credit
Debt Instrument [Line Items]
Facility Limit					$ 2,000,000,000.0									$ 2,000,000,000.0		$ 2,000,000,000.0
Letter of Credit | Virginia Electric and Power Company
Debt Instrument [Line Items]
Facility Limit					2,000,000,000.0									2,000,000,000.0		2,000,000,000.0
Letter of Credit | Credit Facility, Maturing in June 2020
Debt Instrument [Line Items]
Facility Limit								$ 30,000,000	$ 21,000,000
Credit facility, outstanding amount					28,000,000									28,000,000		$ 28,000,000
Credit facility, maturity date								Jun. 30, 2022								Jun. 30, 2020
364-Day Revolving Credit Facility
Debt Instrument [Line Items]
Facility Limit										$ 900,000,000
Credit facility, outstanding amount					$ 225,000,000									$ 225,000,000		$ 225,000,000
Debt Instrument, Term										364 days

[1] In October 2020, the joint revolving credit facility was amended to remove Dominion Energy Gas as a co-borrower.

[2] This credit facility matures in March 2023 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.

[3] Dominion Energy’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.

[4] Dominion Energy recorded dividends of $7 million ($4.375 per share) and $21 million ($13.125 per share) for the three and nine months ended September 30, 2020, respectively.

[5] 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 within the facility limit but can be changed at the option of the borrowers under the credit facility multiple times per year. At September 30, 2020, the sub-limit for Virginia Power was $1.5 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 March 2023 and 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.

[6] Virginia Power’s Consolidated Balance Sheet at December 31, 2019 has been derived from the audited Consolidated Balance Sheet at that date.