XML 37 R61.htm IDEA: XBRL DOCUMENT v2.4.1.9
Derivative Instruments and Hedging Activities - Hedged Volume of Derivative Transactions (Detail)
 3 Months Ended
Mar. 31, 2015
MWh
Electric Energy Derivative [Member]  
Derivatives, Fair Value [Line Items]  
MWHs 19,565,133ed_Mwhs
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_ElectricEnergyDerivativeMember
Electric Capacity Derivative [Member]  
Derivatives, Fair Value [Line Items]  
MWs 6,751ed_Mws
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_ElectricCapacityDerivativeMember
Natural Gas Derivative [Member]  
Derivatives, Fair Value [Line Items]  
Dths 54,964,831ed_Dths
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_NaturalGasDerivativeMember
Refined Fuels [Member]  
Derivatives, Fair Value [Line Items]  
Gallons 2,352,000us-gaap_DerivativeNonmonetaryNotionalAmountVolume
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_RefinedFuelsMember
CECONY [Member] | Electric Energy Derivative [Member]  
Derivatives, Fair Value [Line Items]  
MWHs 6,640,525ed_Mwhs
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_ElectricEnergyDerivativeMember
/ dei_LegalEntityAxis
= ed_CeconyMember
CECONY [Member] | Electric Capacity Derivative [Member]  
Derivatives, Fair Value [Line Items]  
MWs 2,100ed_Mws
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_ElectricCapacityDerivativeMember
/ dei_LegalEntityAxis
= ed_CeconyMember
CECONY [Member] | Natural Gas Derivative [Member]  
Derivatives, Fair Value [Line Items]  
Dths 53,860,000ed_Dths
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_NaturalGasDerivativeMember
/ dei_LegalEntityAxis
= ed_CeconyMember
CECONY [Member] | Refined Fuels [Member]  
Derivatives, Fair Value [Line Items]  
Gallons 2,352,000us-gaap_DerivativeNonmonetaryNotionalAmountVolume
/ us-gaap_DerivativeInstrumentRiskAxis
= ed_RefinedFuelsMember
/ dei_LegalEntityAxis
= ed_CeconyMember