Significant Accounting Policies (Details Textuals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Significant Accounting Policies [Line Items]
Other income	$ 55	$ 55	$ 155	$ 136
Deferred tax expense					$ 8
Unrecognized tax benefits that would impact effective tax rate	2		2
Decrease in unrecognized tax benefits	6
Power and Industrial Projects
Significant Accounting Policies [Line Items]
Other income	24	25	$ 64	57
Minimum
Significant Accounting Policies [Line Items]
Finite-lived intangible asset, useful life			1 year
Maximum
Significant Accounting Policies [Line Items]
Finite-lived intangible asset, useful life			26 years
DTE Electric
Significant Accounting Policies [Line Items]
Other income	14	$ 15	$ 42	$ 45
DTE Electric | DTE Energy
Significant Accounting Policies [Line Items]
Income tax receivable	$ 68		$ 68		$ 29