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Fair Value (Fair Value and Unrealized Gains and Losses for the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - USD ($)
$ in Millions
Dec. 31, 2021
Dec. 31, 2020
Debt Securities, Available-for-sale [Line Items]    
Fair Value $ 2,071 $ 1,855
Unrealized Gains 628 501
Unrealized Losses (25) (7)
Cash equivalents    
Debt Securities, Available-for-sale [Line Items]    
Fair Value 39 27
Private Equity and Other    
Debt Securities, Available-for-sale [Line Items]    
Fair Value 205 104
Unrealized Gains 58 11
Unrealized Losses (8) 0
Hedge Funds and Similar Investments    
Debt Securities, Available-for-sale [Line Items]    
Fair Value 76 0
Unrealized Gains 1 0
Unrealized Losses (2) 0
Equity securities    
Debt Securities, Available-for-sale [Line Items]    
Fair Value 1,107 1,169
Unrealized Gains 546 468
Unrealized Losses (9) (6)
Fixed Income Securities    
Debt Securities, Available-for-sale [Line Items]    
Fair Value 644 555
Unrealized Gains 23 22
Unrealized Losses $ (6) $ (1)