Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 25	$ 24
Interest cost	50	54
Expected return on plan assets	(82)	(78)
Amortization of net actuarial loss	44	43
Amortization of prior service cost (credit)	0	0
Net periodic benefit cost (credit)	37	43
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	7
Interest cost	17	18
Expected return on plan assets	(36)	(33)
Amortization of net actuarial loss	3	3
Amortization of prior service cost (credit)	0	(3)
Net periodic benefit cost (credit)	(9)	(8)
Other Postretirement Benefits | DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5
Interest cost	13	14
Expected return on plan assets	(24)	(23)
Amortization of net actuarial loss	2	2
Amortization of prior service cost (credit)	0	(2)
Net periodic benefit cost (credit)	$ (4)	$ (4)