Regulatory Matters (Narrative) (Detail) $ in Millions		1 Months Ended												3 Months Ended		6 Months Ended		12 Months Ended
	Nov. 01, 2020 USD ($)	Jun. 30, 2020 USD ($)	May 31, 2020 USD ($) kV	Apr. 30, 2020 USD ($) MW GW	Mar. 31, 2020 USD ($)	Feb. 29, 2020 USD ($) kV mi	Jan. 31, 2020 USD ($)	Dec. 31, 2019 USD ($) a kV	Nov. 30, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jul. 31, 2019 USD ($)	Mar. 31, 2019 USD ($)	Jul. 31, 2018 USD ($)	Jun. 30, 2020 USD ($) GW	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2008	Jan. 31, 2019 USD ($)
Public Utilities General Disclosures [Line Items]
Number of new demand response programs | a								1
Impairment of assets and other charges														$ 531	$ 312	$ 1,299	$ 1,147
Pipeline Integrity and Safety Program
Public Utilities General Disclosures [Line Items]
Rate year beginning					2020-03
Rider DSM
Public Utilities General Disclosures [Line Items]
Approval date				2020-04
Application date							2020-01
Cost of Fuel
Public Utilities General Disclosures [Line Items]
Rate year beginning						2020-05
Approval date				2020-04
Application date						2020-02
PIR Program
Public Utilities General Disclosures [Line Items]
Percentage of pipeline system replaced																					25.00%
PREP
Public Utilities General Disclosures [Line Items]
Rate year beginning			2020-11
Application date			2020-05
Target to Reach by End of 2025
Public Utilities General Disclosures [Line Items]
Energy efficiency target percentage. based on energy savings from 2019 baseline				5.00%
Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Impairment of assets and other charges														$ 44	197	808	743
Virginia Electric and Power Company | Rider US-4
Public Utilities General Disclosures [Line Items]
Total revenue requirement																$ 12
Rate year beginning																2021-06
Increase (decrease) in revenue requirement																$ 4
Application date																2020-07
Virginia Electric and Power Company | Riders C1A C2A and C3A
Public Utilities General Disclosures [Line Items]
Increase (decrease) in revenue requirement								$ 11
Amount of cost recovery								186
Virginia Power | Grassfield Solar, Norge Solar and Sycamore Solar
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | GW														82
Proposed cost of project														$ 170
Dominion Energy South Carolina Inc | Transmission Lines in Aiken County South Carolina
Public Utilities General Disclosures [Line Items]
Estimated cost of project						$ 30
DETI
Public Utilities General Disclosures [Line Items]
Impairment of assets and other charges																$ 482
Ohio Regulation
Public Utilities General Disclosures [Line Items]
Contract with customer credits tax reform																				$ 600
Tax Reform Act's impact on its equity return																				19
Ohio Regulation | PIR Program
Public Utilities General Disclosures [Line Items]
Approved annual revenue required				$ 218
Total estimated cost								209												209
Total cumulative estimated cost				$ 1,800
Virginia Regulation
Public Utilities General Disclosures [Line Items]
Percentage of electric energy excluding existing nuclear generation and certain new carbon resources				100.00%
Cap on revenue reductions in the first triennial				$ 50
Virginia Regulation | Virginia Electric and Power Company | Annual Fuel Factor
Public Utilities General Disclosures [Line Items]
Total revenue requirement						$ 1,200
Rate year beginning					2020-05	2020-07
Proposed revenue requirement recovered balance		$ 103				$ 81
Increase (decrease) in revenue requirement					$ (393)
Approval date		2020-06
Virginia Regulation | Virginia Electric and Power Company | Rider T1 | Operating Segments
Public Utilities General Disclosures [Line Items]
Approved annual revenue required			$ 73
Total revenue requirement			$ 529
Approval date			2020-07
Application date			2020-05
Beginning date of total revenue requirement			Sep. 01, 2020
Virginia Regulation | Virginia Electric and Power Company | Riders C1A C2A and C3A | Operating Segments | Energy Efficiency Program
Public Utilities General Disclosures [Line Items]
Approved annual revenue required								$ 60
Number of new energy efficiency programs | a								10
Period for cost cap								5 years
Virginia Regulation | Virginia Electric and Power Company | Rider U
Public Utilities General Disclosures [Line Items]
Increase (decrease) in revenue requirement		$ 28
Projected capital investment		80
Virginia Regulation | Virginia Electric and Power Company | GTSA
Public Utilities General Disclosures [Line Items]
Proposed cost of project										$ 503
Estimated cost of project													$ 816									$ 68
Operations and maintenance expenses										78			$ 102
Increase (decrease) in revenue requirement					212
Virginia Regulation | Virginia Electric and Power Company | Transmission Component of Virginia Power's | Rider T1 | Operating Segments
Public Utilities General Disclosures [Line Items]
Total revenue requirement			$ 474
Virginia Regulation | Virginia Electric and Power Company | Fifth Phase | Rider U
Public Utilities General Disclosures [Line Items]
Projected capital investment		36
Virginia Regulation | Virginia Electric and Power Company | Previous Phase | Rider U
Public Utilities General Disclosures [Line Items]
Projected capital investment		44
Virginia Regulation | Virginia Electric and Power Company | Solar and Onshore Wind | Target to Reach by End of 2035
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | GW				16.1
Virginia Regulation | Virginia Electric and Power Company | Utility-scale Solar | Target to Reach by End of 2035 | Maximum
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | GW				15.0
Virginia Regulation | Virginia Electric and Power Company | Utility-scale Solar | Target to Reach by End of 2024
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | GW				3.0
Virginia Regulation | Virginia Electric and Power Company | Small-scale Solar | Target to Reach by End of 2035
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | GW				1.1
Virginia Regulation | Virginia Electric and Power Company | Energy Storage | Target to Reach by End of 2035
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | MW				2,700
Virginia Regulation | Virginia Electric and Power Company | Offshore Wind Facility | Target to Reach by End of 2035 | Maximum
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | MW				5,200
Constructed by utility capacity | MW				3,000
Virginia Regulation | Virginia Electric and Power Company | Offshore Wind Facility | Target to Reach by End of 2035 | Minimum
Public Utilities General Disclosures [Line Items]
Constructed by utility capacity | MW				2,500
Virginia Regulation | Virginia Electric and Power Company | Pumped Storage | Target to Reach by End of 2035 | Maximum
Public Utilities General Disclosures [Line Items]
Targeted capacity provided by legislation | MW				800
Virginia Regulation | Virginia Electric and Power Company | Solar Development Project | Rider US-4
Public Utilities General Disclosures [Line Items]
Estimated cost of project											$ 146
Proposed revenue requirement											$ 9
Solar capacity factor when normalized for force majeure events							22.00%
Approved annual revenue required					7
Virginia Regulation | Virginia Electric and Power Company | Electric Transmission Projects | Brambleton-Yardley Ridge line and Brambleton-Poland Road line in Loudoun County, Virginia
Public Utilities General Disclosures [Line Items]
Estimated cost of project								$ 30												30
Capacity of transmission line (kV) | kV								230
Virginia Regulation | Virginia Electric and Power Company | Electric Transmission Projects | Brambleton-Yardley Ridge line
Public Utilities General Disclosures [Line Items]
Estimated cost of project			$ 25
Capacity of transmission line (kV) | kV			230
Federal Energy Regulatory Commission | General Rate Case
Public Utilities General Disclosures [Line Items]
Annual cost-of-service, amount							$ 182
Federal Energy Regulatory Commission | Electric Power Cost Adjustment | Atlantic Coast Pipeline
Public Utilities General Disclosures [Line Items]
Total revenue requirement					$ 28
Federal Energy Regulatory Commission | Virginia Electric and Power Company | Operating Segments
Public Utilities General Disclosures [Line Items]
Total revenue requirement			$ 1,000
Federal Energy Regulatory Commission | Overthrust
Public Utilities General Disclosures [Line Items]
Expected cost of project			$ 10
Federal Energy Regulatory Commission | DETI
Public Utilities General Disclosures [Line Items]
Impairment of assets and other charges															13
Asset impairment after tax charge															$ 10		$ 10
North Carolina Regulation | Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Approved return on equity percentage							9.75%
North Carolina Regulation | Virginia Electric and Power Company | Base Rate Case
Public Utilities General Disclosures [Line Items]
Increase (decrease) in revenue requirement										$ 24		$ 27
Percentage of earned return												7.52%
Authorized return percentage												9.90%
Return of equity percentage												10.75%
North Carolina Regulation | PSNC | Pipeline Integrity and Safety Program
Public Utilities General Disclosures [Line Items]
Total revenue requirement						28
Increase (decrease) in revenue requirement						7
South Carolina Regulation | Gas Rate Case
Public Utilities General Disclosures [Line Items]
Total revenue requirement		$ 409
Increase (decrease) in revenue requirement																9
South Carolina Regulation | Dominion Energy South Carolina Inc | Rider DSM
Public Utilities General Disclosures [Line Items]
Annual transportation cost rate adjustment, approval amount requested to recover amount							$ 40
South Carolina Regulation | Dominion Energy South Carolina Inc | Cost of Fuel
Public Utilities General Disclosures [Line Items]
Increase decrease in annual base fuel component recoveries						$ 44
South Carolina Regulation | Dominion Energy South Carolina Inc | Transmission Lines in Aiken County South Carolina
Public Utilities General Disclosures [Line Items]
Capacity of transmission line (kV) | kV						230
Length of kV line (miles | mi						28
South Carolina Regulation | Dominion Energy South Carolina Inc | Scenario Forecast
Public Utilities General Disclosures [Line Items]
Estimated cost of project																			$ 75
West Virginia Regulation | Hope Gas, Inc. | PREP
Public Utilities General Disclosures [Line Items]
Amount of cost recovery																				$ 27
West Virginia Regulation | Hope Gas, Inc. | Scenario Forecast | PREP
Public Utilities General Disclosures [Line Items]
Amount of cost recovery	$ 13
Projected capital investment																		$ 54	$ 39
Wyoming Base Rate Case | Questar Gas
Public Utilities General Disclosures [Line Items]
Increase (decrease) in revenue requirement																$ 2
Return of equity percentage									10.50%
Approved return on equity percentage																9.35%
Base fuel cost									$ 4
Percentage of earned return									7.46%
Authorized return percentage									9.50%