Environmental Matters - Environmental Remediation Costs (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 1	$ 3	$ 8	$ 17
CECONY \| Subsidiaries
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 1	$ 3	$ 8	$ 16

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

Name:	us-gaap_EnvironmentalRemediationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration