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Leases - Additional Information (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Lessee, Lease, Description [Line Items] |  |
Lease, renewal term | 5 years |
Assets under finance leases | $ 3 | $ 1
Finance leases, accumulated amortization | 3 | 5
Right-of-use asset obtained in exchange for operating lease liability | 23 | 39
CECONY |  |
Lessee, Lease, Description [Line Items] |  |
Assets under finance leases | 2 |
Finance leases, accumulated amortization | 1 | 3
Right-of-use asset obtained in exchange for operating lease liability | $ 11 | $ 4
Minimum |  |
Lessee, Lease, Description [Line Items] |  |
Lease, term | 1 year |
Maximum |  |
Lessee, Lease, Description [Line Items] |  |
Lease, term | 40 years |

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- Definition Direct Financing Lease, Accumulated Amortization + References No definition available. + Details
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- Definition Amount of residual asset covered by residual value guarantee under direct financing lease. Excludes guarantee considered to be lease payments for lessor. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 3 -Subparagraph (b)(3) -URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919359-209981 + Details
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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 Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980 + Details
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- Definition Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918673-209980 + Details
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- Definition Amount of increase in right-of-use asset obtained in exchange for operating lease liability. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 55 -Paragraph 53 -URI http://asc.fasb.org/extlink&oid=121568110&loc=SL77918982-209971 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 20 -Section 50 -Paragraph 4 -Subparagraph (g)(2) -URI http://asc.fasb.org/extlink&oid=121609121&loc=SL77918686-209980 + Details
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