Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Site Contingency [Line Items]
Accrued liabilities	$ 996	$ 997
Regulatory assets	4,514	4,279
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	874	876
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	122	121
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	996	997
Regulatory assets	983	991
CECONY
Site Contingency [Line Items]
Accrued liabilities	902	903
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	4,220	3,955
CECONY | Manufactured gas plant sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	780	782
CECONY | Other Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	121	121
CECONY | Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	901	903
Regulatory assets	$ 899	$ 906