Retirement Benefits and Trusteed Assets (OPEB - Postretirement Cost Inclusions) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 27	$ 34	$ 34
Interest cost	80	81	89
Expected return on plan assets	(129)	(131)	(122)
Net actuarial loss	30	43	20
Prior service cost	(118)	(126)	(144)
Other	(1)	0	0
Net pension cost	(111)	(99)	(123)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	25	26
Interest cost	61	62	68
Expected return on plan assets	(90)	(90)	(85)
Net actuarial loss	21	31	14
Prior service cost	(89)	(95)	(109)
Net pension cost	$ (77)	$ (67)	$ (86)