Environmental Matters - Accrued Liability (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Site Contingency [Line Items]
Regulatory assets	$ 4,514	$ 4,279
Asbestos Suits
Site Contingency [Line Items]
Accrued liability	8	8
Regulatory assets	8	8
Workers’ Compensation
Site Contingency [Line Items]
Accrued liability	57	61
Regulatory assets	12	11
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	4,220	3,955
CECONY | Asbestos Suits | Subsidiaries
Site Contingency [Line Items]
Accrued liability	7	7
Regulatory assets	7	7
CECONY | Workers’ Compensation | Subsidiaries
Site Contingency [Line Items]
Accrued liability	55	59
Regulatory assets	$ 15	$ 11