Application date of public utilities transmission.

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Approval date of public utilities regulatory filing.

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Asset impairment benefit.

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Asset impairment benefit after tax.

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Asset Impairment Charges After Tax

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Increase decrease in annual base fuel component recoveries.

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Percentage of pipeline system replaced.

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Power generation, targeted capacity provided by legislation.

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- Definition

Public utilities actual earned return on equity percentage.

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- Definition

Public utilities annual transportation cost rate adjustment approval request to recover amount.

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Public utilities, approved rate, amount.

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Amount of public utility's approved rate increase (decrease) by regulatory agency.

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Public utilities authorized return on equity percentage.

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Public utilities cumulative property plant and equipment amount of construction work in process included in rate base.

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Public utilities operating expense estimated fuel expenses recovery.

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Public utilities property plant and equipment requested cost of construction.

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Public utilities requested authorized return on equity percentage.

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- Definition

Public utilities requested rate increase decrease amount in connection with federal and state income tax reductions.

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Public utilities, start date of proposed rate in month and year.

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- Definition

Amount of write-down of assets recognized in the income statement. Includes, but is not limited to, losses from tangible assets, intangible assets and goodwill.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Topic 230
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The increase (decrease) during the period in the costs deferred for rate-making purposes.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of public utility's interim rate increase (decrease) allowed while waiting final decision of regulatory agency.

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Discloses the amount of construction work in process that is included in the rate making process at period end.

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Amount of public utility's requested rate increase (decrease) with regulatory agency.

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Percentage of public utility's requested return on equity.

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Regulatory Matters (Narrative) (Detail) $ in Millions	1 Months Ended							3 Months Ended				12 Months Ended
Regulatory Matters (Narrative) (Detail) $ in Millions	Apr. 30, 2021 USD ($)	Mar. 31, 2021 USD ($)	Feb. 28, 2021 USD ($)	Jan. 31, 2021 USD ($)	Jul. 31, 2020 USD ($) MW	Jun. 30, 2020 USD ($)	Apr. 30, 2020	Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Sep. 30, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2008	Dec. 31, 2019 USD ($)
Public Utilities General Disclosures [Line Items]
Asset net impairment charge								$ 95			$ 768
Virginia Electric and Power Company \| Impairment of Assets and Other Charges
Public Utilities General Disclosures [Line Items]
Asset net impairment charge								76	$ 127		754
Impairment of assets and other charges after tax								56			$ 561
Virginia Electric and Power Company \| GTSA \| Impairment of Assets and Other Charges
Public Utilities General Disclosures [Line Items]
Asset net impairment charge									130	$ 130
Benefit in impairment of assets and other charges								130
Benefit in impairment of assets and other charges after tax								$ 97
Virginia Electric and Power Company \| Grassfields Solar Norge Solar And Sycamore Solar
Public Utilities General Disclosures [Line Items]
Proposed cost of project					$ 170
Targeted capacity provided by legislation \| MW					82
Virginia Electric and Power Company \| Grassfields Solar Norge Solar And Sycamore Solar \| Subsequent Event
Public Utilities General Disclosures [Line Items]
Approved annual revenue required	$ 10
Questar Gas Company \| Utah Regulation \| Subsequent Event
Public Utilities General Disclosures [Line Items]
Increase in gas cost	$ 43
Base Rate Case \| Virginia Electric and Power Company
Public Utilities General Disclosures [Line Items]
Return of equity percentage		10.85%
CVOWP project investment elected for CCRO to offset available revenues		$ 26
Authorized return percentage		9.20%
Requested authorized return on equity percentage		10.80%
Base Rate Case \| PSNC \| Subsequent Event
Public Utilities General Disclosures [Line Items]
Authorized return percentage	9.70%
Increase (decrease) in revenue requirement	$ 53
Increase (decrease) in revenue requirement in connection with federal and state income tax reductions	$ 42
Percentage of earned return	10.25%
Rider U \| Virginia Electric and Power Company \| Virginia Regulation
Public Utilities General Disclosures [Line Items]
Projected capital investment						$ 80
Increase (decrease) in revenue requirement						28
Rider U \| Virginia Electric and Power Company \| Virginia Regulation \| Fifth Phase
Public Utilities General Disclosures [Line Items]
Projected capital investment						36
Rider U \| Virginia Electric and Power Company \| Virginia Regulation \| Previous Phase
Public Utilities General Disclosures [Line Items]
Projected capital investment						$ 44
Rider CCR \| Virginia Electric and Power Company \| Virginia Regulation
Public Utilities General Disclosures [Line Items]
Increase (decrease) in revenue requirement			$ 216
Rider DSM
Public Utilities General Disclosures [Line Items]
Application date				2021-01
Approval date							2021-04
Rider DSM \| Dominion Energy South Carolina Inc \| South Carolina Regulation
Public Utilities General Disclosures [Line Items]
Annual transportation cost rate adjustment, approval amount requested to recover amount				$ 48
Cost of Fuel
Public Utilities General Disclosures [Line Items]
Application date			2021-02
Approval date							2021-04
Rate year beginning			2021-05
Cost of Fuel \| Dominion Energy South Carolina Inc \| South Carolina Regulation
Public Utilities General Disclosures [Line Items]
Increase decrease in annual base fuel component recoveries			$ 36
PIR Program
Public Utilities General Disclosures [Line Items]
Percentage of pipeline system replaced													25.00%
PIR Program \| Ohio Regulation
Public Utilities General Disclosures [Line Items]
Approved annual revenue required			243
Total estimated cost									178			$ 178
Total cumulative estimated cost			$ 2,000
C E P Program \| Ohio Regulation
Public Utilities General Disclosures [Line Items]
Total estimated cost									99			99		$ 137
Total cumulative estimated cost									$ 957			957
Proposed revenue requirement												$ 119