Derivative Instruments and Hedging Activities - Hedged Volume of Derivative Transactions (Details)	Sep. 30, 2025 MWh MW gal MMBTU
Electric Energy (MWh)
Derivatives, Fair Value [Line Items]
Notional amount | MWh	31,734,340
Capacity (MW)
Derivatives, Fair Value [Line Items]
Notional amount | MW	25,200
Natural Gas (Dt)
Derivatives, Fair Value [Line Items]
Notional amount | MMBTU	340,270,000
Refined Fuels (gallons)
Derivatives, Fair Value [Line Items]
Notional amount | gal	3,528,000
CECONY | Electric Energy (MWh) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | MWh	29,204,950
CECONY | Capacity (MW) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | MW	14,100
CECONY | Natural Gas (Dt) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | MMBTU	319,960,000
CECONY | Refined Fuels (gallons) | Subsidiaries
Derivatives, Fair Value [Line Items]
Notional amount | gal	3,528,000