Retirement Benefits and Trusteed Assets (Pension Plan - Other Changes in Plan Assets and Benefit Obligations recognized in Reg Assets and OCI) (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial loss	$ 19	$ 805
Amortization of net actuarial loss	(205)	(157)
Prior service credit	0	(7)
Total recognized in Regulatory assets and Other comprehensive income (loss)	(186)	641
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	35	820
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	162	206
DTE Electric
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial loss	(13)	614
Amortization of net actuarial loss	(147)	(110)
Prior service credit	0	(2)
Amortization of prior service cost	(1)	(2)
Total recognized in Regulatory assets and Other comprehensive income (loss)	(161)	500
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	15	644
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	115	149
Future amortization of prior service cost into net periodic benefit cost	$ 1	$ 1