Retirement Benefits and Trusteed Assets (OPEB - Other Changes in Plan Assets and APBO Recognized in Regulatory Assets and OCI) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (68)	$ (68)
Amortization of net actuarial loss	(30)	(43)
Amortization of prior service credit	119	126
Total recognized in Regulatory assets and Other comprehensive income (loss)	21	15
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(90)	(84)
Net actuarial loss	16	32
Prior service credit	(14)	(118)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	(59)	(57)
Amortization of net actuarial loss	(21)	(31)
Amortization of prior service credit	89	95
Total recognized in Regulatory assets and Other comprehensive income (loss)	9	7
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(68)	(60)
Net actuarial loss	10	22
Prior service credit	$ (10)	$ (89)