Environmental Matters - Environmental Remediation Costs (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 6	$ 5	$ 14	$ 13
CECONY \| Subsidiaries
Environmental Exit Cost [Line Items]
Remediation costs incurred	$ 6	$ 5	$ 13	$ 13

The charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
-SubTopic 30
-Section 55
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Reference 2: http://www.xbrl.org/2003/role/recommendedDisclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 410
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Reference 3: http://www.xbrl.org/2003/role/recommendedDisclosureRef
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-Name Accounting Standards Codification
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration