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Property, Plant, and Equipment (Capitalized Software) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Property, Plant, and Equipment [Line Items]      
Amortization expense of capitalized software $ 98 $ 77 $ 71
Gross carrying value of capitalized software 770 668  
Accumulated amortization of capitalized software 439 335  
DTE Electric      
Property, Plant, and Equipment [Line Items]      
Amortization expense of capitalized software 80 71 $ 64
Gross carrying value of capitalized software 664 590  
Accumulated amortization of capitalized software $ 369 $ 293