Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Site Contingency [Line Items]
Accrued Liabilities	$ 940	$ 857
Regulatory assets	3,845	6,461
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued Liabilities	845	752
Other Superfund Sites
Site Contingency [Line Items]
Accrued Liabilities	95	105
Superfund Sites
Site Contingency [Line Items]
Accrued Liabilities	940	857
Regulatory assets	938	865
CECONY
Site Contingency [Line Items]
Accrued Liabilities	850	780
Regulatory assets	3,504	5,989
CECONY | Manufactured gas plant sites
Site Contingency [Line Items]
Accrued Liabilities	755	676
CECONY | Other Superfund Sites
Site Contingency [Line Items]
Accrued Liabilities	95	104
CECONY | Superfund Sites
Site Contingency [Line Items]
Accrued Liabilities	850	780
Regulatory assets	$ 860	$ 791