Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Site Contingency [Line Items]
Accrued liabilities	$ 923	$ 940
Regulatory assets	3,987	3,845
Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	833	850
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	833	845
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	90	95
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	923	940
Regulatory assets	919	938
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	3,667	3,504
CECONY | Manufactured gas plant sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	744	755
CECONY | Other Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	89	95
CECONY | Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	833	850
Regulatory assets	$ 840	$ 860