Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 24	$ 22	$ 74	$ 69
Interest cost	51	53	151	160
Expected return on plan assets	(82)	(78)	(247)	(233)
Amortization of net actuarial loss	43	46	132	132
Amortization of prior service cost (credit)	0	1	0	1
Net periodic benefit cost (credit)	36	44	110	129
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	6	7	20	20
Interest cost	18	18	52	55
Expected return on plan assets	(36)	(33)	(107)	(98)
Amortization of net actuarial loss	3	3	8	10
Amortization of prior service cost (credit)	0	(3)	0	(10)
Net periodic benefit cost (credit)	(9)	(8)	(27)	(23)
Other Postretirement Benefits | DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5	15	15
Interest cost	13	14	40	42
Expected return on plan assets	(25)	(23)	(74)	(68)
Amortization of net actuarial loss	3	2	7	6
Amortization of prior service cost (credit)	0	(2)	0	(7)
Net periodic benefit cost (credit)	$ (4)	$ (4)	$ (12)	$ (12)