Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Site Contingency [Line Items]
Accrued liabilities	$ 1,101	$ 1,118
Regulatory assets	5,541	4,888
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	996	1,016
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	105	102
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	1,101	1,118
Regulatory assets	1,093	1,105
CECONY
Site Contingency [Line Items]
Accrued liabilities	1,009	1,026
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	5,164	4,568
CECONY | Manufactured gas plant sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	904	924
CECONY | Other Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	105	102
CECONY | Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	1,009	1,026
Regulatory assets	$ 1,010	$ 1,022