Other Material Contingencies (Narrative) (Details) (USD $) In Millions	9 Months Ended
Sep. 30, 2011	Dec. 31, 2010
Guarantor Obligations [Line Items]
Lease in lease out total investment	$ 259
Lease in lease out total financed by equity	93
Lease in lease out total financed by long-term debt	166
The company's investment in leverage leases	(52)	(41)
Gross investment in leverage leases	234	235
Deferred tax liabilities	286	276
Tax savings from lease in lease out transactions	232
Total guarantees, by type and term	862	859
Maximum exposure	5
Tax Deficiency Paid In December 2005 [Member]
Guarantor Obligations [Line Items]
Tax deficiency paid to IRS	0.3
Interest In April 2006 [Member]
Guarantor Obligations [Line Items]
Interest paid related to tax deficiency	0.2
Interest Up To March 2011 [Member]
Guarantor Obligations [Line Items]
Interest paid related to tax deficiency	86.0
Disallowance Of Tax 1998-2007 [Member]
Guarantor Obligations [Line Items]
Disallowed deduction	416
Disallowance Of Tax 2010 [Member]
Guarantor Obligations [Line Items]
Disallowed deduction	40
Disallowance Of Tax 2009 [Member]
Guarantor Obligations [Line Items]
Disallowed deduction	41
Disallowance Of Tax 2008 [Member]
Guarantor Obligations [Line Items]
Disallowed deduction	$ 42

Guarantees Obligations Maximum Exposure

Name:	ed_GuaranteesObligationsMaximumExposure
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Income Tax Paid Upon IRS Examination

+ Details

Name:	ed_IncomeTaxPaidUponIrsExamination
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

IRS Disallowed Deduction

+ Details

Name:	ed_IrsDisallowedDeduction
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Lease in lease out total financed by equity

+ Details

Name:	ed_LeaseInLeaseOutTotalFinancedByEquity
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Lease In Lease Out Total Financed By Non Recourse Long Term Debt

+ Details

Name:	ed_LeaseInLeaseOutTotalFinancedByNonRecourseLongTermDebt
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Lease in lease out total investment

+ Details

Name:	ed_LeaseInLeaseOutTotalInvestment
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Leveraged Lease Gross Investment In Leveraged Leases Disclosure Investment In Leveraged Leases Gross

+ Details

Name:	ed_LeveragedLeaseGrossInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesGross
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Tax Savings From Lease In Lease Out Transactions

+ Details

Name:	ed_TaxSavingsFromLeaseInLeaseOutTransactions
Namespace Prefix:	ed
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The amount as of the balance sheet date of the estimated future tax effects attributable to differences between the methods used to account for leasing arrangements for tax purposes and under generally accepted accounting principles which will increase future taxable income when such differences reverse.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 25

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=6969291&loc=d3e28680-109314

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 109

-Paragraph 11

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 8

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319

+ Details

Name:	us-gaap_DeferredTaxLiabilitiesLeasingArrangements
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.

+ Details

Name:	us-gaap_GuaranteeObligationsLineItems
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 45

-Paragraph 13

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 460

-SubTopic 10

-Section 50

-Paragraph 4

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6851643&loc=d3e12069-110248

+ Details

Name:	us-gaap_GuaranteeObligationsMaximumExposure
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The amount of interest expense recorded in the period based upon the specified tax examination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

+ Details

Name:	us-gaap_IncomeTaxExaminationInterestFromExamination
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The net investment in arrangements meeting the criteria for classification as leveraged leases including deferred taxes.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 13

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 35

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=6792017&loc=d3e43930-112732

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 840

-SubTopic 30

-Section 30

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=6791857&loc=d3e42840-112730

+ Details

Name:	us-gaap_LeveragedLeasesNetInvestmentInLeveragedLeasesDisclosureInvestmentInLeveragedLeasesNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant