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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, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Debt Securities, Available-for-sale [Line Items]        
Realized gains $ 17 $ 19 $ 28 $ 42
Realized losses (10) (6) (17) (15)
Proceeds from sale of securities $ 220 $ 280 $ 396 $ 616