Leases - Additional Information (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Lessee, Lease, Description [Line Items]
Assets under finance leases	$ 1	$ 1
Finance leases, accumulated amortization	3	5
CECONY
Lessee, Lease, Description [Line Items]
Finance leases, accumulated amortization	$ 1	$ 3

Amount of residual asset covered by residual value guarantee under direct financing lease. Excludes guarantee considered to be lease payments for lessor.

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=119202524&loc=SL77919359-209981

Name:	us-gaap_DirectFinancingLeaseResidualValueOfLeasedAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant