Other Material Contingencies - Con Edison Transmission (Details) - Payment Guarantee by CET Electric of Contributions to New York Transco LLC	3 Months Ended
Mar. 31, 2021
Guarantor Obligations [Line Items]
Estimated project cost percentage	175.00%
NY Transco
Guarantor Obligations [Line Items]
Ownership interest, percentage	45.70%

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.

No definition available.

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