Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 25	$ 23	$ 50	$ 47
Interest cost	50	53	100	107
Expected return on plan assets	(83)	(77)	(165)	(155)
Amortization of net actuarial loss	45	43	89	86
Amortization of prior service credit	0	0	0	0
Net periodic benefit cost (credit)	37	42	74	85
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	6	14	13
Interest cost	17	19	34	37
Expected return on plan assets	(35)	(32)	(71)	(65)
Amortization of net actuarial loss	2	4	5	7
Amortization of prior service credit	0	(4)	0	(7)
Net periodic benefit cost (credit)	(9)	(7)	(18)	(15)
Other Postretirement Benefits | DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5	10	10
Interest cost	14	14	27	28
Expected return on plan assets	(25)	(22)	(49)	(45)
Amortization of net actuarial loss	2	2	4	4
Amortization of prior service credit	0	(3)	0	(5)
Net periodic benefit cost (credit)	$ (4)	$ (4)	$ (8)	$ (8)