Derivative Instruments and Hedging Activities - Schedule of Hedged Volume of Derivative Transactions (Details)	Mar. 31, 2026 MMBTU MWh MW gal
Electric Energy (MWh)
Derivatives, Fair Value [Line Items]
Notional amount | MWh	32,765,680
Capacity (MW)
Derivatives, Fair Value [Line Items]
Notional amount | MW	25,500
Natural Gas (Dt)
Derivatives, Fair Value [Line Items]
Notional amount | MMBTU	280,360,000
Refined Fuels (gallons)
Derivatives, Fair Value [Line Items]
Notional amount | gal	3,024,000
CECONY | Electric Energy (MWh) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | MWh	30,743,625
CECONY | Capacity (MW) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | MW	16,200
CECONY | Natural Gas (Dt) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | MMBTU	262,760,000
CECONY | Refined Fuels (gallons) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | gal	3,024,000