Summary of Significant Accounting Policies and Other Matters - Plant and Depreciation Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Public Utility, Property, Plant and Equipment [Line Items]
Annual aggregate depreciation allowance	$ 2,030
Software Licenses
Public Utility, Property, Plant and Equipment [Line Items]
Gross asset	65	$ 72
Estimated aggregate annual amortization expense	7
Accumulated amortization	$ 38	$ 31
Non-Utility Plant | Maximum | Wind Power Generating Assets
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	30 years
Non-Utility Plant | Maximum | Solar Powered Generating Assets
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	35 years
Non-Utility Plant | Maximum | Land And Conduit
Public Utility, Property, Plant and Equipment [Line Items]
Estimated useful lives (years)	10 years
CECONY
Public Utility, Property, Plant and Equipment [Line Items]
AFUDC rates (percent)	5.90%	5.20%	4.50%
Average depreciation rates (percent)	3.60%	3.50%	3.50%
Annual aggregate depreciation allowance	$ 1,925
CECONY | Software Licenses
Public Utility, Property, Plant and Equipment [Line Items]
Gross asset	62	$ 69
Estimated aggregate annual amortization expense	7
Accumulated amortization	$ 36	$ 31
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)	90 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)	80 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)	55 years
O&R
Public Utility, Property, Plant and Equipment [Line Items]
AFUDC rates (percent)	6.20%	5.00%	4.80%
Average depreciation rates (percent)	3.10%	3.00%	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