XML 141 R144.htm IDEA: XBRL DOCUMENT v2.4.1.9
Variable Interest Entities - Summary of VIEs (Parenthetical) (Detail)
 12 Months Ended
Dec. 31, 2014
Variable Interest Entity, Primary Beneficiary [Member] | Texas Solar 4 [Member]  
Variable Interest Entity [Line Items]  
Percentage of variable interests 80.00%us-gaap_VariableInterestEntityOwnershipPercentage
/ us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis
= ed_OCISolarSanAntonioMember
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Variable Interest Entity, Not Primary Beneficiary, Aggregated Disclosure [Member]  
Variable Interest Entity [Line Items]  
Percentage of variable interests 50.00%us-gaap_VariableInterestEntityOwnershipPercentage
/ us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis
= us-gaap_VariableInterestEntityNotPrimaryBeneficiaryAggregatedDisclosureMember
Minimum [Member] | Solar Renewable Energy Credit Hedge [Member] | Pilesgrove [Member]  
Variable Interest Entity [Line Items]  
Renewable Energy Credit 3 years
Maximum [Member] | Solar Renewable Energy Credit Hedge [Member] | Pilesgrove [Member]  
Variable Interest Entity [Line Items]  
Renewable Energy Credit 5 years