Fair Value Measurements - Schedule of Commodity Derivatives (Details) $ in Millions	Mar. 31, 2023 USD ($) $ / kW-month $ / MWh	Dec. 31, 2022 USD ($)
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ 740	$ 874
CECONY | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	711	663
Level 3
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	0	33
Level 3 | CECONY | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	0	$ 2
Level 3 | Electricity | Forward capacity prices
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (11)
Level 3 | Electricity | Forward capacity prices | Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / kW-month	2.25
Level 3 | Electricity | Forward capacity prices | Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / kW-month	7.26
Level 3 | Electricity | Forward capacity prices | CECONY | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (5)
Level 3 | Electricity | Forward capacity prices | CECONY | Minimum | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / kW-month	2.25
Level 3 | Electricity | Forward capacity prices | CECONY | Maximum | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / kW-month	7.26
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ 0
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | Minimum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / MWh	0.38
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | Maximum
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / MWh	1.38
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | CECONY | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ 0
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | CECONY | Minimum | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / MWh	0.38
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | CECONY | Maximum | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Unobservable Inputs Range (dollar per unit) | $ / MWh	1.38
Level 3 | Commodity
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (11)
Level 3 | Commodity | CECONY | Subsidiaries
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]
Fair Value of commodity derivatives	$ (5)