Environmental Matters - Accrued Liability (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Site Contingency [Line Items]
Regulatory assets	$ 5,672	$ 5,664
Regulatory liabilities	5,069	5,546
Asbestos Suits
Site Contingency [Line Items]
Accrued liability	8	8
Regulatory assets	8	8
Workers’ Compensation
Site Contingency [Line Items]
Accrued liability	52	53
Regulatory liabilities	21	20
CECONY | Subsidiaries
Site Contingency [Line Items]
Regulatory assets	5,307	5,264
Regulatory liabilities	4,539	4,980
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	49	51
Regulatory liabilities	$ 21	$ 20