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v3.19.3.a.u2

Nature of Operations (Narrative) (Detail) | Dec. 31, 2019
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White Rive Hub [Member] |
Subsidiary, Sale of Stock [Line Items] |
Minority Interest Ownership Percentage By Parent | 50.00%

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- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
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
Name: | us-gaap_SubsidiarySaleOfStockLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
Name: | srt_OwnershipAxis=d_WhiteRiveHubMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |