Capitalization - Additional Information (Details)	1 Months Ended	3 Months Ended
Mar. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)
Level 2
Schedule of Capitalization [Line Items]
Long-term debt, fair value	$ 15,570,000,000	$ 15,570,000,000
Level 3
Schedule of Capitalization [Line Items]
Long-term debt, fair value	636,000,000	636,000,000
CECONY \| Level 2
Schedule of Capitalization [Line Items]
Long-term debt, fair value	12,652,000,000	12,652,000,000
CECONY \| Level 3
Schedule of Capitalization [Line Items]
Long-term debt, fair value	636,000,000	636,000,000
Tax-exempt debt		636,000,000
Variable Rate Term Loan Due 2018 \| Term Loan
Schedule of Capitalization [Line Items]
Amount of debt prepaid	400,000,000
Debentures \| 2.00% Debentures Due 2020
Schedule of Capitalization [Line Items]
Debt Instrument, face amount	$ 400,000,000	$ 400,000,000
Debt instrument, interest rate	2.00%	2.00%
Senior Notes \| 4.45% Senior Notes Due 2042 \| Con Edison Development
Schedule of Capitalization [Line Items]
Debt Instrument, face amount	$ 97,000,000	$ 97,000,000
Debt instrument, interest rate	4.45%	4.45%

Tax-Exempt Debt, Total

No definition available.

Name:	ed_TaxExemptDebt
Namespace Prefix:	ed_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Face (par) amount of debt instrument at time of issuance.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

+ Details

Name:	us-gaap_DebtInstrumentFaceAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Gross amount of debt extinguished.

+ References

No definition available.

+ Details

Name:	us-gaap_ExtinguishmentOfDebtAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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- Details

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- Details

Name:	dei_LegalEntityAxis=ed_CeconyMember
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_DebtInstrumentAxis=ed_VariableRateTermLoanDue2018Member
Namespace Prefix:
Data Type:	na
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- Details

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- Details

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- Details

Name:	us-gaap_DebtInstrumentAxis=ed_A2DebenturesDue2020Member
Namespace Prefix:
Data Type:	na
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- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
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- Details

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Namespace Prefix:
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- Details

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