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Commitments and Contingencies (Nuclear Insurance) (Parenthetical) (Detail) $ in Millions | Dec. 31, 2020 USD ($)
--- | ---
Maximum | Surry and North Anna |
Guarantee Obligations [Line Items] |
Blanket Property Limit | $ 200

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- Definition Property And Casualty Insurance Coverage Amount + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition 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. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_GuaranteeObligationsByNatureAxis=d_SurryAndNorthAnnaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |