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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 trusts - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Debt Securities, Available-for-sale [Line Items]      
Realized gains $ 65 $ 83 $ 74
Realized losses (42) (29) (63)
Proceeds from sale of securities $ 1,203 $ 1,240 $ 1,457