XML 105 R45.htm IDEA: XBRL DOCUMENT v3.19.3
Significant Accounting Policies (Intangible Assets) (Details) - USD ($)
$ in Millions
9 Months Ended
Sep. 30, 2019
Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]    
Finite-lived intangible assets, gross carrying value $ 1,049 $ 938
Accumulated Amortization (130) (110)
Finite-lived intangible assets, net carrying value 919 828
Intangible assets, gross carrying value 1,070 959
Intangible assets, net carrying value 940 849
Indefinite-lived Intangible Assets [Line Items]    
Indefinite-lived intangible assets 21 21
DTE Electric    
Finite-Lived Intangible Assets [Line Items]    
Accumulated Amortization 0 0
Intangible assets, gross carrying value 21 21
Intangible assets, net carrying value 21 21
DTE Electric renewable energy credits | DTE Electric    
Indefinite-lived Intangible Assets [Line Items]    
Indefinite-lived intangible assets 20 20
DTE Electric emission allowances | DTE Electric    
Indefinite-lived Intangible Assets [Line Items]    
Indefinite-lived intangible assets 1 1
Customer relationships    
Finite-Lived Intangible Assets [Line Items]    
Finite-lived intangible assets, gross carrying value 779 779
Accumulated Amortization (58) (44)
Finite-lived intangible assets, net carrying value 721 735
Contract intangibles    
Finite-Lived Intangible Assets [Line Items]    
Finite-lived intangible assets, gross carrying value 270 159
Accumulated Amortization (72) (66)
Finite-lived intangible assets, net carrying value $ 198 $ 93
Minimum | Customer relationships    
Finite-Lived Intangible Assets [Line Items]    
Useful Lives 25 years  
Minimum | Contract intangibles    
Finite-Lived Intangible Assets [Line Items]    
Useful Lives 6 years  
Maximum | Customer relationships    
Finite-Lived Intangible Assets [Line Items]    
Useful Lives 40 years  
Maximum | Contract intangibles    
Finite-Lived Intangible Assets [Line Items]    
Useful Lives 26 years