Regulatory Assets and Liabilities (Schedule of Regulatory Liabilities) (Detail) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Oct. 31, 2017
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		$ 809	$ 455
Regulatory liabilities-noncurrent		10,187	10,204
Total regulatory liabilities		10,996	10,659
Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		425	167
Regulatory liabilities-noncurrent		5,338	5,074
Total regulatory liabilities		$ 5,763	5,241
SCANA
Regulatory Liabilities [Line Items]
Regulatory liabilities-current				$ 67
Total regulatory liabilities				$ 1,100
Estimation period of collection to be credited		11 years
Electric service customers over period		20 years
Deferred cost of fuel used in electric generation
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[1]	$ 58
Deferred cost of fuel used in electric generation | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[2]	58
Regulatory liabilities-noncurrent	[2]	54	30
Provision for future cost of removal and AROs
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[3]	183	124
Regulatory liabilities-noncurrent	[3]	2,150	2,208
Provision for future cost of removal and AROs | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[4]	152	103
Reserve for refunds and rate credits to electric utility customers
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[5]	128	143
Regulatory liabilities-noncurrent	[5]	540	656
Cost-of-service impact of 2017 Tax Reform Act
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[6]	12	4
Income taxes refundable through future rates
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[7]	124	71
Regulatory liabilities-noncurrent	[7]	4,376	4,529
Income taxes refundable through future rates | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[8]	54	54
Regulatory liabilities-noncurrent	[8]	2,404	2,438
Monetization of guarantee settlement
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[9]	67	67
Regulatory liabilities-noncurrent	[9]	$ 903	970
Electric service customers over period		20 years
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		$ 117	46
Regulatory liabilities-noncurrent		388	316
Other | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current		41	10
Regulatory liabilities-noncurrent		181	81
Nuclear decommissioning trust
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[10]	1,719	1,471
Nuclear decommissioning trust | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[11]	1,719	1,471
Reserve for future credits to Virginia electric customers
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[12]	120
Reserve for future credits to Virginia electric customers | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-current	[12]	120
Overrecovered Other Postretirement Benefit Costs
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[13]	111	54
Provision For Future Cost Of Removal | Virginia Electric and Power Company
Regulatory Liabilities [Line Items]
Regulatory liabilities-noncurrent	[4]	$ 980	$ 1,054

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

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

[3] Rates charged to customers by Dominion Energy’s regulated businesses include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement

[4] Rates charged to customers by Virginia Power's regulated businesses include a provision for the cost of future activities to remove assets that are expected to be incurred at the time of retirement

[5] Reflects amounts previously collected from retail electric customers of DESC for the NND Project to be credited over an estimated 11-year period effective February 2019, in connection with the SCANA Merger Approval Order. See Notes 3 and 13 for more information

[6] Balance refundable to customers related to the decrease in revenue requirements for recovery of income taxes at the Companies’ regulated electric generation and electric and natural gas distribution operations. See Notes 3 and 13 for more information

[7] Amounts recorded to pass the effect of reduced income taxes from the 2017 Tax Reform Act to customers in future periods, which will primarily reverse at the weighted average tax rate that was used to build the reserves over the remaining book life of the property, net of amounts to be recovered through future rates to pay income taxes that become payable when rate revenue is provided to recover AFUDC equity

[8] Amounts recorded to pass the effect of reduced income taxes from the 2017 Tax Reform Act to customers in future periods, which will reverse at the weighted average tax rate that was used to build the reserves over the remaining book life of the property, net of amounts to be recovered through future rates to pay income taxes that become payable when rate revenue is provided to recover AFUDC equity

[9] Reflects amounts to be refunded to DESC electric service customers over a 20-year period ending in 2039 associated with the monetization of a bankruptcy settlement agreement. See Note 3 for more information

[10] Primarily reflects a regulatory liability representing amounts collected from Virginia jurisdictional customers and placed in external trusts (including income, losses and changes in fair value thereon, as applicable) for the future decommissioning of Dominion Energy’s utility nuclear generation stations, in excess of the related AROs

[11] Primarily reflects a regulatory liability representing amounts collected from Virginia jurisdictional customers and placed in external trusts (including income, losses and changes in fair value thereon) for the future decommissioning of Virginia Power’s utility nuclear generation stations, in excess of the related AROs

[12] Represents a reserve for benefits expected to be provided through the use of a CCRO in accordance with the GTSA to jurisdictional retail electric customers in Virginia in connection with the 2021 Triennial Review.  See Note 13 for additional information.

[13] Reflects a regulatory liability for the collection of postretirement benefit costs allowed in rates in excess of expense incurred