Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Site Contingency [Line Items]
Accrued liabilities	$ 934	$ 940
Regulatory assets	3,969	3,845
Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	843	850
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	840	845
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	94	95
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	934	940
Regulatory assets	933	938
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	3,620	3,504
CECONY | Manufactured gas plant sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	750	755
CECONY | Other Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	93	95
CECONY | Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	843	850
Regulatory assets	$ 854	$ 860