Environmental Matters - Environmental Remediation Costs (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 3	$ 6	$ 7	$ 14
CECONY \| Subsidiaries
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 3	$ 6	$ 6	$ 13

Amount, before recovery, of expense for known and estimated future costs arising from requirement to perform environmental remediation.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 410
-SubTopic 30
-Name Accounting Standards Codification
-Section 55
-Paragraph 11
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481899/410-30-55-11

Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 410
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 4
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481960/410-30-45-4

Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Topic 410
-SubTopic 30
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147481931/410-30-50-12

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration