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Asset Retirement Obligations (Rollforward) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Asset retirement obligations at January 1 $ 2,672 $ 2,469 $ 2,320
Accretion 157 149 140
Liabilities incurred 25 20 27
Liabilities settled (14) (17) (16)
Revision in estimated cash flows (1) 51 (2)
Asset retirement obligations at December 31 2,839 2,672 2,469
DTE Electric      
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]      
Asset retirement obligations at January 1 2,447 2,271 2,125
Accretion 145 138 129
Liabilities incurred 18 1 27
Liabilities settled (8) (14) (8)
Revision in estimated cash flows 5 51 (2)
Asset retirement obligations at December 31 $ 2,607 $ 2,447 $ 2,271