Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Detail) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2021	Dec. 31, 2020
Regulatory Assets [Line Items]
Regulatory assets-current		$ 650	$ 699	[1]
Regulatory assets-noncurrent		8,793	9,133	[1]
Total regulatory assets		$ 9,443	9,832
Weighted Average
Regulatory Assets [Line Items]
Weighted average useful life		27 years
SCANA
Regulatory Assets [Line Items]
Electric service customers over period		20 years
Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current		$ 292	295	[2]
Regulatory assets-noncurrent		3,235	3,509	[2]
Total regulatory assets		$ 3,527	3,804
Virginia Electric and Power Company | Weighted Average
Regulatory Assets [Line Items]
Weighted average useful life		26 years
Deferred project costs and DSM programs for gas utilities
Regulatory Assets [Line Items]
Regulatory assets-current	[3]	$ 17	35
Unrecovered gas costs
Regulatory Assets [Line Items]
Regulatory assets-current	[4]	63	78
Deferred rider costs for Virginia electric utility
Regulatory Assets [Line Items]
Regulatory assets-current	[5]	123	98
Regulatory assets-noncurrent	[5]	347	311
Deferred nuclear refueling outage costs
Regulatory Assets [Line Items]
Regulatory assets-current	[6]	54	53
Deferred nuclear refueling outage costs | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[6]	54	53
PJM transmission rates
Regulatory Assets [Line Items]
Regulatory assets-current	[7]	48	71
PJM transmission rates | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[7]	48	71
Other
Regulatory Assets [Line Items]
Regulatory assets-current		207	226
Regulatory assets-noncurrent		549	544
Other | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current		67	73
Regulatory assets-noncurrent		162	164
NND Project Costs
Regulatory Assets [Line Items]
Regulatory assets-current	[8]	138	138
Regulatory assets-noncurrent	[8]	2,330	2,364
Pension and Other Postretirement Benefit Costs
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[9]	1,304	1,363
Deferred project costs for gas utilities
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[3]	658	632
Interest rate hedges
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[10]	624	1,042
Interest rate hedges | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[11]	327	733
AROs and related funding
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[12]	$ 340	331
Amortization period for deferred costs		105 years
Cost of reacquired debt
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[13]	$ 242	245
Amortization period for deferred costs		26 years
Ash pond and landfill closure costs
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[14]	$ 2,317	2,301
Ash pond and landfill closure costs | Rider CCR
Regulatory Assets [Line Items]
Regulatory assets expected collection period commencing month and year		2021-12
Ash pond and landfill closure costs | Maximum | Rider CCR
Regulatory Assets [Line Items]
Regulatory assets amounts expected collection period		18 years
Ash pond and landfill closure costs | Minimum | Rider CCR
Regulatory Assets [Line Items]
Regulatory assets amounts expected collection period		15 years
Ash pond and landfill closure costs | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[14]	$ 2,317	2,301
Ash pond and landfill closure costs | Virginia Electric and Power Company | Rider CCR
Regulatory Assets [Line Items]
Regulatory assets expected collection period commencing month and year		2021-12
Ash pond and landfill closure costs | Virginia Electric and Power Company | Maximum | Rider CCR
Regulatory Assets [Line Items]
Regulatory assets amounts expected collection period		18 years
Ash pond and landfill closure costs | Virginia Electric and Power Company | Minimum | Rider CCR
Regulatory Assets [Line Items]
Regulatory assets amounts expected collection period		15 years
Deferred cost of fuel used in electric generation
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[15]	$ 82
Deferred cost of fuel used in electric generation | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[16]	82
Deferred rider costs | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[17]	123	98
Regulatory assets-noncurrent	[17]	$ 347	$ 311
Deferred Project Costs | Maximum
Regulatory Assets [Line Items]
Amortization period for deferred costs		18 months
Deferred Project Costs | Virginia Electric and Power Company | Maximum
Regulatory Assets [Line Items]
Amortization period for deferred costs		18 months

[1] Dominion Energy’s Consolidated Balance Sheet at December 31, 2020 has been derived from the audited Consolidated Balance Sheet at that date.

[2] Virginia Power’s Consolidated Balance Sheet at December 31, 2020 has been derived from the audited Consolidated Balance Sheet at that date.

[3] Primarily reflects amounts expected to be collected from or owed to gas customers in Dominion Energy’s service territories associated with current and prospective rider projects, including CEP, PIR and pipeline integrity management. See Note 13 for more information.

[4] Reflects unrecovered or overrecovered gas costs at regulated gas operations, which are recovered or refunded through filings with the applicable regulatory authority.

[5] Reflects deferrals under Virginia Power’s electric transmission FERC formula rate and the deferral of costs associated with certain current and prospective rider projects. See Note 13 to the Consolidated Financial Statements in the Companies’ Annual Report on Form 10-K for the year ended December 31, 2020 for more information.

[6] Legislation enacted in Virginia in April 2014 requires Virginia Power to defer operation and maintenance costs incurred in connection with the refueling of any nuclear-powered generating plant. These deferred costs will be amortized over the refueling cycle, not to exceed 18 months.

[7] Reflects current portion of amounts to be recovered through retail rates in Virginia for payments Virginia Power expects to make to PJM through 2026 under the terms of a FERC settlement agreement in May 2018 resolving a PJM cost allocation matter.

[8] Reflects expenditures by DESC associated with the NND Project, which pursuant to the SCANA Merger Approval Order, will be recovered from DESC electric service customers over a 20-year period ending in 2039. See Note 3 to the Consolidated Financial Statements in the Companies’ Annual Report on Form 10-K for the year ended December 31, 2020 for more information.

[9] Represents unrecognized pension and other postretirement employee benefit costs expected to be recovered or refunded through future rates generally over the expected remaining service period of plan participants by certain of Dominion Energy's rate-regulated subsidiaries.

[10] Reflects interest rate hedges recoverable from or refundable to customers. Certain of these instruments are settled and any related payments are being amortized into interest expense over the life of the related debt, which has a weighted-average useful life of approximately 27 years as of March 31, 2021. 

[11] Reflects interest rate hedges recoverable from or refundable to customers. Certain of these instruments are settled and any related payments are being amortized into interest expense over the life of the related debt, which has a weighted-average useful life of approximately 26 years as of March 31, 2021.

[12] Represents deferred depreciation and accretion expense related to legal obligations associated with the future retirement of generation, transmission and distribution properties. The AROs primarily relate to DESC’s electric generating facilities, including Summer, and are expected to be recovered over the related property lives and periods of decommissioning which may range up to approximately 105 years.

[13] Costs of the reacquisition of debt are deferred and amortized as interest expense over the would-be remaining life of the reacquired debt.  The reacquired debt costs had a weighted-average life of approximately 26 years as of March 31, 2021.

[14] Primarily reflects legislation enacted in Virginia in 2019, which requires any CCR asset located at certain Virginia Power stations to be closed by removing the CCR to an approved landfill or through beneficial reuse. These deferred costs are expected to be collected over a period between 15 and 18 years commencing December 2021 through Rider CCR. Virginia Power is entitled to collect carrying costs once expenditures have been made. See Note 13 for additional information.

[15] Reflects deferred fuel expenses for the Virginia, North Carolina and South Carolina jurisdictions of Dominion Energy’s electric generation operations.

[16]   Reflects deferred fuel expenses for the Virginia and North Carolina jurisdictions of Virginia Power’s generation operations.

[17] Reflects deferrals under Virginia Power’s electric transmission FERC formula rate and the deferral of costs associated with certain current and prospective rider projects. See Note 13 to the Consolidated Financial Statements in the Companies’ Annual Report on Form 10-K for the year ended December 31, 2020 for more information.