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Variable Interest Entities - Additional Information (Details) - Variable Interest Entity, Primary Beneficiary - Tax Equity Projects - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020
Variable Interest Entity [Line Items] |  |
Income (loss) before tax | $ 3 |
Net income (loss) | $ 2 |
Con Edison Development |  |
Variable Interest Entity [Line Items] |  |
Percentage of variable interests (less than) | 100.00% |
Income (loss) before tax |  | $ (14)
Net income (loss) |  | (10)
Tax Equity Investors |  |
Variable Interest Entity [Line Items] |  |
Income (loss) before tax | $ 2 | 17
Net income (loss) | $ 1 | $ 13

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- Definition Variable Interest Entity, Measure Of Activity, Net Income (Loss) + References No definition available. + Details
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Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Description of the amount of pre-tax income (loss) derived by the reporting entity from the Variable Interest Entity (VIE). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph d -URI http://asc.fasb.org/extlink&oid=121559654&loc=d3e5747-111685 + Details
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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
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- Definition Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 5A -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121559654&loc=SL6759159-111685 + Details
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- Details
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- Details
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- Details
Name: | dei_LegalEntityAxis=ed_ConsolidatedEdisonDevelopmentMember
Namespace Prefix: |
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Balance Type: |
Period Type: |

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- Details
Name: | dei_LegalEntityAxis=ed_TaxEquityInvestorsMember
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Period Type: |