Significant Accounting Policies (Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 963	$ 912
Accumulated Amortization	(96)	(70)
Intangible assets, net carrying value	$ 867	842
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Lives	40 years
DTE Electric
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 25	31
Intangible assets, gross	25	31
Accumulated Amortization	0	0
Intangible assets, net carrying value	25	31
DTE Electric | DTE Electric renewable energy credits
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	24	30
DTE Electric | DTE Electric emission allowances
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	1	1
DTE Energy
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	938	881
Accumulated Amortization	(96)	(70)
Finite-lived intangible assets, net carrying value	842	811
DTE Energy | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	770	770
Accumulated Amortization	(24)	(5)
Finite-lived intangible assets, net carrying value	746	765
DTE Energy | Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	168	111
Accumulated Amortization	(72)	(65)
Finite-lived intangible assets, net carrying value	$ 96	$ 46
Minimum | Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Useful Lives	6 years
Maximum | Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Useful Lives	26 years