Environmental Matters - Accrued Liabilities and Regulatory Assets (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Site Contingency [Line Items]
Accrued liabilities	$ 1,112	$ 1,118
Regulatory assets	5,260	4,888
Manufactured gas plant sites
Site Contingency [Line Items]
Accrued liabilities	1,013	1,016
Other Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	99	102
Superfund Sites
Site Contingency [Line Items]
Accrued liabilities	1,112	1,118
Regulatory assets		1,105
CECONY
Site Contingency [Line Items]
Accrued liabilities	1,020	1,026
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	4,948	4,568
CECONY | Manufactured gas plant sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	922	924
CECONY | Other Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	98	102
CECONY | Superfund Sites | Subsidiaries
Site Contingency [Line Items]
Accrued liabilities	$ 1,020	1,026
Regulatory assets		$ 1,022