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Fair Value (Gains and Losses and Proceeds from the Sale of Securities by the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - Nuclear decommissioning trust fund - USD ($)
$ in Millions
3 Months Ended 6 Months Ended
Jun. 30, 2017
Jun. 30, 2016
Jun. 30, 2017
Jun. 30, 2016
Schedule of Available-for-sale Securities [Line Items]        
Realized gains $ 26 $ 37 $ 49 $ 46
Realized losses (8) (25) (16) (40)
Proceeds from sale of securities $ 311 $ 481 $ 705 $ 741