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Other Material Contingencies - Con Edison Transmission (Details) - Payment Guarantee by CET Electric of Contributions to New York Transco LLC | 3 Months Ended
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Mar. 31, 2020
Guarantor Obligations [Line Items] |
Estimated project cost percentage | 175.00%
NY Transco |
Guarantor Obligations [Line Items] |
Ownership interest, percentage | 45.70%

X
- Definition Percentage of estimated costs on projects. + References No definition available. + Details
Name: | ed_PercentageOfEstimatedCostsOnProjects
Namespace Prefix: | ed_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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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_GuaranteeObligationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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

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

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