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Financial and Other Derivative Instruments (Cumulative Gross Volume of Derivative Contracts Outstanding) (Details) (CAD)
Mar. 31, 2015
MMBTU
Natural Gas  
Derivative [Line Items]  
Number of units 935,928,277us-gaap_DerivativeNumberOfInstrumentsHeld
/ us-gaap_DerivativeInstrumentRiskAxis
= dte_NaturalGasCommodityContractMember
Electricity  
Derivative [Line Items]  
Number of units 13,667,643us-gaap_DerivativeNumberOfInstrumentsHeld
/ us-gaap_DerivativeInstrumentRiskAxis
= dte_ElectricityCommodityContractMember
Oil  
Derivative [Line Items]  
Number of units 27,048,000us-gaap_DerivativeNumberOfInstrumentsHeld
/ us-gaap_DerivativeInstrumentRiskAxis
= dte_OilCommodityContractMember
Foreign currency exchange contracts  
Derivative [Line Items]  
Derivative fair value 80,737,962us-gaap_DerivativeAssetsLiabilitiesAtFairValueNet
/ us-gaap_DerivativeInstrumentRiskAxis
= us-gaap_ForeignExchangeContractMember