Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 27	$ 19	$ 76	$ 62
Interest cost	52	54	158	159
Expected return on plan assets	(74)	(69)	(222)	(205)
Amortization of net actuarial loss	51	42	154	118
Amortization of prior service credit	0	0	0	0
Net periodic benefit cost (credit)	56	46	166	134
Pension Benefits | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	21	14	59	48
Interest cost	39	41	120	121
Expected return on plan assets	(53)	(48)	(158)	(145)
Amortization of net actuarial loss	36	30	110	83
Amortization of prior service credit	0	0	1	1
Net periodic benefit cost (credit)	43	37	132	108
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	8	8	25	26
Interest cost	20	22	61	67
Expected return on plan assets	(33)	(31)	(98)	(92)
Amortization of net actuarial loss	10	4	32	15
Amortization of prior service credit	(31)	(36)	(94)	(108)
Net periodic benefit cost (credit)	(26)	(33)	(74)	(92)
Other Postretirement Benefits | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	6	6	19	19
Interest cost	15	17	46	51
Expected return on plan assets	(23)	(21)	(68)	(63)
Amortization of net actuarial loss	8	3	24	11
Amortization of prior service credit	(24)	(27)	(71)	(82)
Net periodic benefit cost (credit)	$ (18)	$ (22)	$ (50)	$ (64)