v3.26.1
Fair Value Measurements - Schedule of Commodity Derivatives (Details)
$ in Millions
Jun. 30, 2026
USD ($)
$ / MWh
$ / kW-month
Dec. 31, 2025
USD ($)
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ 1,109 $ 956
CECONY | Subsidiaries    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives 1,060 913
Level 3    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives 10 5
Level 3 | CECONY | Subsidiaries    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives 7 $ 2
Level 3 | Electricity | Forward energy prices | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ 5  
Level 3 | Electricity | Forward energy prices | Minimum | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 40.10  
Level 3 | Electricity | Forward energy prices | Maximum | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 131.20  
Level 3 | Electricity | Forward energy prices | Average Market Price | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 67.02  
Level 3 | Electricity | Forward energy prices | CECONY | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ 5  
Level 3 | Electricity | Forward energy prices | CECONY | Minimum | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 40.10  
Level 3 | Electricity | Forward energy prices | CECONY | Maximum | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 131.20  
Level 3 | Electricity | Forward energy prices | CECONY | Average Market Price | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 67.02  
Level 3 | Electricity | Forward capacity prices | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ (2)  
Level 3 | Electricity | Forward capacity prices | Minimum | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 8.37  
Level 3 | Electricity | Forward capacity prices | Maximum | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 1.36  
Level 3 | Electricity | Forward capacity prices | Average Market Price | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 4.22  
Level 3 | Electricity | Forward capacity prices | CECONY | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ (2)  
Level 3 | Electricity | Forward capacity prices | CECONY | Minimum | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 1.36  
Level 3 | Electricity | Forward capacity prices | CECONY | Maximum | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 8.37  
Level 3 | Electricity | Forward capacity prices | CECONY | Average Market Price | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / kW-month 4.11  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ 1  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | Minimum | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 0.16  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | Maximum | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 4.88  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | Average Market Price | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 1.09  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | CECONY | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ 1  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | CECONY | Minimum | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 0.16  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | CECONY | Maximum | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 4.88  
Level 3 | Transmission Congestion Contracts | Inter-zonal forward price curves adjusted for historical zonal losses | CECONY | Average Market Price | Subsidiaries | Valuation Technique, Discounted Cash Flow    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Unobservable Inputs Range (dollar per unit) | $ / MWh 1.09  
Level 3 | Commodity    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ 4  
Level 3 | Commodity | CECONY | Subsidiaries    
Fair Value, Concentration of Risk, Financial Statement Captions [Line Items]    
Fair Value of commodity derivatives $ 4