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Property, Plant, and Equipment (Capitalized Software) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Property, Plant, and Equipment [Line Items]      
Amortization expense of capitalized software $ 101 $ 89 $ 98
Gross carrying value of capitalized software 890 715  
Accumulated amortization of capitalized software 500 435  
DTE Electric      
Property, Plant, and Equipment [Line Items]      
Amortization expense of capitalized software 93 83 $ 80
Gross carrying value of capitalized software 774 610  
Accumulated amortization of capitalized software $ 423 $ 365