Regulatory Assets and Liabilities (Schedule of Regulatory Assets) (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Jun. 30, 2020	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2019
Regulatory Assets [Line Items]
Regulatory assets-current				$ 663	$ 871	[1]
Regulatory assets-noncurrent				9,449	7,652	[1]
Total regulatory assets				$ 10,112	8,523
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				$ 218	433	[2]
Regulatory assets-noncurrent				3,610	1,863	[2]
Total regulatory assets				3,828	2,296
Excess deferred taxes adjusted in charge of operating revenue				29
Excess deferred taxes adjusted in charge of operating revenue net of tax				22
Write off of regulatory asset		$ 16	$ 17
Write off of regulatory asset, after tax		$ 15	$ 13
Regulatory reserve				$ 200
Virginia Electric and Power Company | Weighted Average
Regulatory Assets [Line Items]
Weighted average useful life				26 years
Regulatory assets not expect to earn return
Regulatory Assets [Line Items]
Regulatory assets-current	[3]			$ 0	48
Regulatory assets not expect to earn return | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[4]			0	48
Deferred project costs and DSM programs for gas utilities
Regulatory Assets [Line Items]
Regulatory assets-current	[5]			38	21
Unrecovered gas costs
Regulatory Assets [Line Items]
Regulatory assets-current	[6]			89	99
Deferred rate adjustment clause costs for Virginia electric utility
Regulatory Assets [Line Items]
Regulatory assets-current	[7],[8]			14	109
Regulatory assets-noncurrent	[7],[8],[9],[10]			390	235
Deferred nuclear refueling outage costs
Regulatory Assets [Line Items]
Regulatory assets-current	[11]			57	68
Deferred nuclear refueling outage costs | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[11]			57	68
PJM transmission rates
Regulatory Assets [Line Items]
Regulatory assets-current	[12]			95	121
Regulatory assets-noncurrent	[12]			46	85
PJM transmission rates | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[12]			95	121
Regulatory assets-noncurrent	[13]			46	85
Other
Regulatory Assets [Line Items]
Regulatory assets-current				232	267
Regulatory assets-noncurrent				502	579
Other | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current				52	87
Regulatory assets-noncurrent				119	123
NND Project Costs
Regulatory Assets [Line Items]
Regulatory assets-current	[14]			138	138
Regulatory assets-noncurrent	[14]			2,399	2,503
Pension and Other Postretirement Benefit Costs
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[15]			1,598	1,431
Deferred project costs for gas utilities
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[5]			588	521
Interest rate hedges
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[16]			1,207	709
Interest rate hedges | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[17]			895	404
AROs and related funding
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[18]			$ 311	311
Amortization period for deferred costs				105 years
Cost of reacquired debt
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[19]			$ 248	262
Amortization period for deferred costs				26 years
Ash pond and landfill closure costs
Regulatory Assets [Line Items]
Regulatory assets-noncurrent	[20]			$ 2,160	1,016
Regulatory assets expected collection period commencing year				2021
Ash pond and landfill closure costs | Maximum
Regulatory Assets [Line Items]
Regulatory assets amounts expected collection period				18 years
Ash pond and landfill closure costs | Minimum
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	[21]			$ 2,160	1,016
Regulatory assets expected collection period commencing year				2021
Ash pond and landfill closure costs | Virginia Electric and Power Company | Maximum
Regulatory Assets [Line Items]
Regulatory assets amounts expected collection period				18 years
Ash pond and landfill closure costs | Virginia Electric and Power Company | Minimum
Regulatory Assets [Line Items]
Regulatory assets amounts expected collection period				15 years
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
Transmission Rate Design For Allocation Of Costs Of Service | FERC-regulated
Regulatory Assets [Line Items]
Duration of payment under settlement agreement				10 years
Transmission Rate Design For Allocation Of Costs Of Service | Virginia Electric and Power Company | FERC-regulated
Regulatory Assets [Line Items]
Duration of payment under settlement agreement				10 years
Deferred rate adjustment clause costs | Virginia Electric and Power Company
Regulatory Assets [Line Items]
Regulatory assets-current	[7],[22]			$ 14	109
Regulatory assets-noncurrent	[7],[9],[22],[23]			$ 390	$ 235

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

[2] Virginia Power’s Consolidated Balance Sheet at December 31, 2019 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 or overrecovered gas costs at regulated gas operations, which are recovered or refunded through filings with the applicable regulatory authority.

[7] As a result of actions from the Virginia Commission in the first quarter of 2019 regarding the ratemaking treatment of excess deferred taxes from the adoption of the 2017 Tax Reform Act for all existing rate adjustment clauses, Virginia Power recorded a $29 million ($22 million after-tax) charge in operating revenue in the Consolidated Statements of Income for amounts which are probable of being returned to customers.

[8] Reflects deferrals under Virginia Power’s electric transmission FERC formula rate and the deferral of costs associated with certain current and prospective rider projects, net of excess deferred income taxes from the 2017 Tax Reform Act for Virginia Power.  See Note 13 for more information.

[9] During the first quarter of 2019, Virginia Power recorded a charge of $17 million ($13 million after-tax) in impairment of assets and other charges to write-off the balance of a regulatory asset for which it is no longer seeking recovery.

[10] During the second quarter of 2020, Virginia Power recorded a charge of $16 million ($15 million after-tax) in impairment of assets and other charges to write off the balance of a regulatory asset for which it is no longer seeking recovery. 

[11] 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.

[12] Reflects amounts to be recovered through retail rates in Virginia for payments Virginia Power will make to PJM over a ten-year period ending 2028 under the terms of a FERC settlement agreement in May 2018 resolving a PJM cost allocation matter.

[13] Reflects amounts to be recovered through retail rates in Virginia for payments Virginia Power will make to PJM over a ten-year period ending 2028 under the terms of a FERC settlement agreement in May 2018 resolving a PJM cost allocation matter.

[14] 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, 2019 for more information.

[15] 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.

[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 27 years as of September 30, 2020. 

[17] 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 September 30, 2020.

[18] 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.

[19] 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 September 30, 2020.

[20] Primarily reflects legislation enacted in Virginia in March 2019 which requires any CCR unit located at certain Virginia Power stations to be closed by removing the CCRs to an approved landfill or through recycling for beneficial reuse. Subject to approval by the Virginia Commission, amounts are expected to be collected over a period between 15 and 18 years commencing no earlier than 2021. Virginia Power is entitled to collect carrying costs once expenditures have been made. See Note 23 to the Consolidated Financial Statements in the Companies’ Annual Report on Form 10-K for the year ended December 31, 2019 for additional information. As a result of the March 2020 planned early retirement of certain facilities, amounts recoverable through riders were reclassified from property, plant and equipment.

[21] Primarily reflects legislation enacted in Virginia in March 2019 which requires any CCR unit located at certain Virginia Power stations to be closed by removing the CCR to an approved landfill or through recycling for beneficial reuse. Subject to approval by the Virginia Commission, amounts are expected to be collected over a period between 15 and 18 years commencing no earlier than 2021. Virginia Power is entitled to collect carrying costs once expenditures have been made. See Note 23 to the Consolidated Financial Statements in the Companies’ Annual Report on Form 10-K for the year ended December 31, 2019 for additional information. As a result of the March 2020 planned early retirement of certain facilities, amounts recoverable through riders were reclassified from property, plant and equipment.

[22] Reflects deferrals under Virginia Power’s electric transmission FERC formula rate and the deferral of costs associated with certain current and prospective rider projects, net of excess deferred income taxes from the 2017 Tax Reform Act for Virginia Power.  See Note 13 for more information.

[23] During the second quarter of 2020, Virginia Power recorded a charge of $16 million ($15 million after-tax) in impairment of assets and other charges to write off the balance of a regulatory asset for which it is no longer seeking recovery.