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Fair Value (Fair Value of Financial Instruments) (Details) - USD ($)
$ in Millions
Sep. 30, 2021
Dec. 31, 2020
Carrying amount    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable $ 142 $ 141
Short-term borrowings 361 38
Notes payable 5 19
Long-term debt 17,222 19,439
Carrying amount | DTE Electric    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable 17 16
Short-term borrowings 159 0
Notes payable 4 17
Long-term debt 8,906 8,236
Carrying amount | DTE Electric | Affiliates    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term borrowings 32 101
Fair value | Level 1    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable 0 0
Short-term borrowings 0 0
Notes payable 0 0
Long-term debt 2,241 2,547
Fair value | Level 1 | DTE Electric    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable 0 0
Short-term borrowings 0 0
Notes payable 0 0
Long-term debt 0 0
Fair value | Level 1 | DTE Electric | Affiliates    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term borrowings 0 0
Fair value | Level 2    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable 0 0
Short-term borrowings 361 38
Notes payable 0 0
Long-term debt 15,486 18,230
Fair value | Level 2 | DTE Electric    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable 0 0
Short-term borrowings 159 0
Notes payable 0 0
Long-term debt 9,952 9,579
Fair value | Level 2 | DTE Electric | Affiliates    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term borrowings 0 0
Fair value | Level 3    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable 142 141
Short-term borrowings 0 0
Notes payable 5 19
Long-term debt 1,104 1,397
Fair value | Level 3 | DTE Electric    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Notes receivable 17 16
Short-term borrowings 0 0
Notes payable 4 17
Long-term debt 150 379
Fair value | Level 3 | DTE Electric | Affiliates    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Short-term borrowings $ 32 $ 101