Long-Term Debt (Total Long Term Debt) (Detail) - USD ($) $ in Millions		Dec. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Weighted-average percentage interest rates		0.31%	0.29%
Total principal	[1]	$ 37,694	$ 35,496
Securities due within one year	[2]	(805)	(1,905)
Unamortized discount, premium and debt issuances costs, net		(315)	(293)
Derivative restructuring		738	773
Finance lease liabilities	[3]	112	108
Total long-term debt		37,426	33,957
Supplemental 364-Day credit facility, variable rate, due 2021			225
Fair value hedge valuation	[4]	$ 2	3
Long term debt due within one year
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[2],[5]	2.79%
Supplemental 364-Day credit facility, variable rate, due 2021
Debt Instrument [Line Items]
Supplemental 364-Day credit facility, variable rate, due 2021			225
4.82%, due 2042
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[6]	4.82%
Total principal	[6]	$ 314	331
Term loans, variable rates, due 2023 and 2024
Debt Instrument [Line Items]
Total principal	[7]		476
Senior Notes | Variable rates, due 2023
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	0.73%
Total principal		$ 1,000	1,000
Senior Notes | 1.45% to 7.0%, due 2021 to 2049
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[8]	3.78%
Total principal	[8]	$ 11,238	9,938
Tax-Exempt Financings | Variable Rate Due 2038
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[9]	0.14%
Total principal	[9]	$ 35	35
Tax-Exempt Financings | GENCO variable rate due 2038 [Member]
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[9]	0.14%
Total principal	[9]	$ 33	33
Tax-Exempt Financings | 3.625% and 4.00%, due 2028 and 2033
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[9]	3.90%
Total principal	[9]	$ 54	54
Tax-Exempt Financings | Other
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[9]	3.65%
Total principal	[9]	$ 1	1
Tax-Exempt Financings | Tax-Exempt Financing, 1.7% due 2033
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	1.70%
Total principal		$ 27	27
Junior Subordinated Debt | 8.4% due 2031
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	8.40%
Total principal		$ 10	10
Junior Subordinated Debt | 2.715% to 4.104%, Due 2021 and 2024
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	3.07%
Total principal		$ 700	1,950
Enhanced Junior Subordinated Notes | 5.25% and 5.75%, due 2054 and 2076
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[10]	5.75%
Total principal	[10]	$ 685	1,485
Questar Gas | 2.21% to 7.20%, due 2024 to 2051
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	3.85%
Total principal		$ 1,000	750
DECP Holdings | Term Loan, Variable Rate, Due 2024
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[11]	1.50%
Total principal	[11]	$ 2,500
East Ohio | 1.30% to 3.00%, due 2025 to 2050
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	2.25%
Total principal		$ 1,800	1,800
PSNC | 3.10% to 7.45%, due 2021 to 2051
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	4.34%
Total principal		$ 800	800
DESC | First mortgage bonds, 2.30% to 6.625%, due 2021 to 2065
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	5.09%
Total principal		$ 3,634	$ 3,267
Virginia Electric and Power Company
Debt Instrument [Line Items]
Weighted-average percentage interest rates		0.26%	0.30%
Total principal		$ 13,863	$ 13,314
Securities due within one year		(300)
Unamortized discount, premium and debt issuances costs, net		(110)	(107)
Derivative restructuring		446	444
Finance lease liabilities	[3]	57	36
Total long-term debt		$ 13,956	13,687
Virginia Electric and Power Company | Long term debt due within one year
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	3.45%
Virginia Electric and Power Company | Senior Notes | 2.30% to 8.875%, due 2022 to 2051
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5]	4.07%
Total principal		$ 13,238	12,689
Virginia Electric and Power Company | Tax-Exempt Financings | 0.45% to 1.90%, due 2032 to 2041
Debt Instrument [Line Items]
Weighted-average percentage interest rates	[5],[12]	1.14%
Total principal	[12]	$ 625	$ 625

[1] Excludes amounts classified as held for sale at December 31, 2020. See Note 3.

[2] At December 31, 2020, includes $22 million of estimated mandatory prepayments due within one year based on estimated cash flows in excess of debt service at SBL Holdco and Dominion Solar Projects III, Inc.

[3] Included in other long-term debt in the Companies’ Consolidated Balance Sheets.

[4] Represents the valuation of certain fair value hedges associated with Dominion Energy’s fixed rate debt.

[5] Represents weighted-average coupon rates for debt outstanding as of December 31, 2021.

[6] Represents debt associated with Eagle Solar. The debt is nonrecourse to Dominion Energy and is secured by Eagle Solar’s interest in certain solar facilities.

[7] Represents debt associated with SBL Holdco and Dominion Solar Projects III, Inc. The debt was nonrecourse to Dominion Energy and was secured by SBL Holdco’s and Dominion Solar Projects III, Inc’s interest in certain solar facilities. In connection with the sales of certain non-wholly owned nonregulated solar facilities discussed in Note 10, the outstanding debt of SBL Holdco was assumed by Terra Nova Renewable Partners and Dominion Energy utilized proceeds from Clearway to repay the outstanding balance of the Dominion Solar Projects III, Inc. term loan.

[8] Includes debt assumed by Dominion Energy from the merger of its former CNG subsidiary.

[9] Industrial revenue bonds totaling $68 million are secured by letters of credit that expire, subject to renewal, in the fourth quarter of 2022.

[10] In August 2021, Dominion Energy redeemed the remaining principal outstanding of $800 million of its July 2016 hybrids, which would have otherwise matured in 2076.

[11] The term loan amortizes over a 17-year period and matures in December 2024 with the potential to be extended to December 2026. The debt is secured by DECP Holdings’ noncontrolling interest in Cove Point.

[12] These financings relate to certain pollution control equipment at Virginia Power’s generating facilities.