Revenue Recognition - Additional information (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2020
Disaggregation of Revenue [Line Items]
Late fee and other fees not collected	$ 22	$ 46
CECONY
Disaggregation of Revenue [Line Items]
Late fee and other fees not collected	$ 21	$ 44

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.

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