Significant Accounting Policies (Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value	$ 2,520	$ 938
Accumulated Amortization	(142)	(110)
Finite-lived intangible assets, net carrying value	2,378	828
Intangible assets, gross carrying value	2,535	959
Intangible assets, net carrying value	2,393	849
DTE Electric
Finite-Lived Intangible Assets [Line Items]
Intangible assets, net carrying value	15	21
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	15	21
DTE Electric renewable energy credits | DTE Electric
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	15	20
DTE Electric emission allowances | DTE Electric
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	0	1
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value	2,252	779
Accumulated Amortization	(66)	(44)
Finite-lived intangible assets, net carrying value	$ 2,186	735
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	25 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	40 years
Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value	$ 268	159
Accumulated Amortization	(76)	(66)
Finite-lived intangible assets, net carrying value	$ 192	$ 93
Contract intangibles | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	6 years
Contract intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	26 years