Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 24	$ 22	$ 49	$ 43
Interest cost	53	52	106	105
Expected return on plan assets	(74)	(68)	(148)	(136)
Amortization of net actuarial loss	52	38	103	76
Amortization of prior service cost (credit)	0	0	0	0
Net periodic benefit cost (credit)	55	44	110	88
Pension Benefits | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	18	17	38	34
Interest cost	41	40	81	80
Expected return on plan assets	(52)	(49)	(105)	(97)
Amortization of net actuarial loss	36	26	74	53
Amortization of prior service cost (credit)	1	1	1	1
Net periodic benefit cost (credit)	44	35	89	71
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	8	9	17	18
Interest cost	21	22	41	45
Expected return on plan assets	(32)	(30)	(65)	(61)
Amortization of net actuarial loss	11	6	22	11
Amortization of prior service cost (credit)	(32)	(36)	(63)	(72)
Net periodic benefit cost (credit)	(24)	(29)	(48)	(59)
Other Postretirement Benefits | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	6	6	13	13
Interest cost	15	17	31	34
Expected return on plan assets	(22)	(21)	(45)	(42)
Amortization of net actuarial loss	8	5	16	8
Amortization of prior service cost (credit)	(23)	(28)	(47)	(55)
Net periodic benefit cost (credit)	$ (16)	$ (21)	$ (32)	$ (42)