Summary of Significant Accounting Policies and Other Matters - Plant and Depreciation Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Public Utility, Property, Plant and Equipment [Line Items]
Annual aggregate depreciation allowance	$ 2,350
Software Licenses
Public Utility, Property, Plant and Equipment [Line Items]
Gross asset	52	$ 59
Estimated aggregate annual amortization expense	7
Accumulated amortization	$ 52	$ 45
CECONY
Public Utility, Property, Plant and Equipment [Line Items]
AFUDC rates (percent)	6.20%	5.90%	5.90%
Average depreciation rates (percent)	3.60%	3.60%	3.60%
Annual aggregate depreciation allowance	$ 2,225
CECONY | Software Licenses
Public Utility, Property, Plant and Equipment [Line Items]
Gross asset	49	$ 56
Estimated aggregate annual amortization expense	7
Accumulated amortization	$ 50	$ 43
CECONY | Electric | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
CECONY | Electric | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	80 years
CECONY | Gas | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
CECONY | Gas | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	80 years
CECONY | Steam | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
CECONY | Steam | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	55 years
CECONY | General Plant | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
CECONY | General Plant | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	50 years
O&R
Public Utility, Property, Plant and Equipment [Line Items]
AFUDC rates (percent)	6.00%	6.00%	6.20%
Average depreciation rates (percent)	3.30%	3.30%	3.10%
O&R | Electric | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
O&R | Electric | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	75 years
O&R | General Plant | Minimum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	5 years
O&R | General Plant | Maximum
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	50 years