Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2021	Dec. 31, 2020
Regulatory Assets [Line Items]
Regulatory assets-current		$ 1,193		$ 1,193	$ 699	[1]
Regulatory assets-noncurrent		9,213		9,213	9,133	[1]
Total regulatory assets		10,406		10,406	9,832
Asset retirement obligations increase (decrease)				$ (252)
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		690		$ 690	295	[2]
Regulatory assets-noncurrent		3,941		3,941	3,509	[2]
Total regulatory assets		4,631		$ 4,631	3,804
Virginia Electric and Power Company | Weighted Average
Regulatory Assets [Line Items]
Weighted average useful life				25 years
DESC
Regulatory Assets [Line Items]
Write off of regulatory asset			$ 237
Write off of regulatory asset, after tax			$ 178
Deferred cost of fuel used in electric generation
Regulatory Assets [Line Items]
Regulatory assets-current	[3]	147		$ 147
Regulatory assets-noncurrent	[3]	139		139
Deferred cost of fuel used in electric generation | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[4]	147		147
Regulatory assets-noncurrent	[4]	139		139
Deferred project costs and DSM programs for gas utilities
Regulatory Assets [Line Items]
Regulatory assets-current	[5]	37		37	35
Unrecovered gas costs
Regulatory Assets [Line Items]
Regulatory assets-current	[6]	161		161	78
Deferred rider costs for Virginia electric utility
Regulatory Assets [Line Items]
Regulatory assets-current	[7]	49		49	98
Regulatory assets-noncurrent	[7]	442		442	311
Deferred nuclear refueling outage costs
Regulatory Assets [Line Items]
Regulatory assets-current	[8]	70		$ 70	53
Deferred nuclear refueling outage costs | Maximum
Regulatory Assets [Line Items]
Amortization period for deferred costs				18 months
Deferred nuclear refueling outage costs | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[8]	70		$ 70	53
Deferred nuclear refueling outage costs | Virginia Electric and Power Company | Maximum
Regulatory Assets [Line Items]
Amortization period for deferred costs				18 months
PJM transmission rates
Regulatory Assets [Line Items]
Regulatory assets-current	[9]	9		$ 9	71
PJM transmission rates | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[9]	9		9	71
Other
Regulatory Assets [Line Items]
Regulatory assets-current		195		195	193
Regulatory assets-noncurrent		605		605	544
Other | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current		36		36	33
Regulatory assets-noncurrent		177		177	164
Deferred early plant retirement charges
Regulatory Assets [Line Items]
Regulatory assets-current	[10]	226		226
Regulatory assets-noncurrent	[10]	282		282
Deferred early plant retirement charges | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[11]	226		226
Regulatory assets-noncurrent	[11]	282		282
Derivatives
Regulatory Assets [Line Items]
Regulatory assets-current	[12]	161		161	33
Derivatives | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[12]	153		153	40
NND Project Costs
Regulatory Assets [Line Items]
Regulatory assets-current	[13]	138		138	138
Regulatory assets-noncurrent	[13]	2,261		2,261	2,364
Pension and Other Postretirement Benefit Costs
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[14]	1,274		1,274	1,363
Deferred project costs for gas utilities
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[5]	668		668	632
Interest rate hedges
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[15]	838		838	1,042
Interest rate hedges | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[16]	540		540	733
AROs and related funding
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[17]	332		$ 332	331
Amortization period for deferred costs				105 years
Cost of reacquired debt
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[18]	11		$ 11	245
Ash pond and landfill closure costs
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[19]	2,361		$ 2,361	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	[19]	2,361		$ 2,361	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
Revision of Certain Gas Distribution Pipeline
Regulatory Assets [Line Items]
Asset retirement obligations increase (decrease)		66
Deferred rider costs | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[20]	49		$ 49	98
Regulatory assets-noncurrent	[20]	$ 442		$ 442	$ 311

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

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

[5] 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.

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

[7] 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 for more information.

[8] 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.

[9] 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.

[10] Reflects amounts from the early retirements of certain coal- and oil-fired generating units to be amortized through 2023 in accordance with the proposed settlement of the 2021 Triennial Review. See Note 13 for additional information.

[11] Reflects amounts from the early retirements of certain coal- and oil-fired generating units to be amortized through 2023 in accordance with the proposed settlement of the 2021 Triennial Review.  See Note 13 for additional information.

[12] For jurisdictions subject to cost-based rate regulation, changes in the fair value of derivative instruments result in the recognition of regulatory assets or regulatory liabilities as they are expected to be recovered from or refunded to customers.

[13] 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.

[14] 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.

[15] 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 September 30, 2021. 

[16] 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 25 years as of September 30, 2021.

[17] 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.

[18] During the second quarter of 2021, DESC recorded a charge of $237 million ($178 million after-tax) in impairment of assets and other charges to write-off the balance of a regulatory asset that is no longer probable of recovery under the settlement agreement approved in DESC’s retail electric base rate case.  See Note 13 for more information.

[19] 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.

[20] 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 for more information.