Retirement Benefits and Trusteed Assets (OPEB - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Amounts recognized in Regulatory assets (see Note 8 - Regulatory Matters)
Regulatory Assets	$ 3,724	$ 3,727
Other Postretirement Benefit Plan
Change in accumulated postretirement benefit obligation
Projected benefit obligation, beginning of year	2,044	1,878
Service cost	34	34	$ 47
Interest cost	81	89	88
Actuarial (gain) loss	(224)	131
Benefits paid	(89)	(88)
Projected benefit obligation, end of year	1,846	2,044	1,878
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value plan asset	1,617	1,528	1,527
Actual return on plan assets	(25)	62
Company contributions	199	24
Benefits paid	(85)	(85)
Funded status of the plans	(229)	(516)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent assets	0	0
Current liabilities	(1)	(1)
Noncurrent liabilities	(228)	(515)
Defined benefit plans liabilities	(229)	(516)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	24	34
Prior service credit	(2)	(5)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	22	29
Amounts recognized in Regulatory assets (see Note 8 - Regulatory Matters)
Net actuarial loss	387	488
Prior service credit	(131)	(254)
Regulatory Assets	256	234
DTE Electric
Amounts recognized in Regulatory assets (see Note 8 - Regulatory Matters)
Regulatory Assets	2,986	2,959
DTE Electric | Other Postretirement Benefit Plan
Change in accumulated postretirement benefit obligation
Projected benefit obligation, beginning of year	1,558	1,430
Service cost	25	26	35
Interest cost	62	68	67
Actuarial (gain) loss	(166)	100
Benefits paid	(65)	(66)
Projected benefit obligation, end of year	1,414	1,558	1,430
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Fair value plan asset	1,131	1,038	$ 1,061
Actual return on plan assets	(19)	41
Company contributions	175	0
Benefits paid	(63)	(64)
Funded status of the plans	(283)	(520)
Defined Benefit Plan, Amounts Recognized in Balance Sheet [Abstract]
Noncurrent assets	24	0
Current liabilities	0	0
Noncurrent liabilities	(307)	(520)
Defined benefit plans liabilities	(283)	(520)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	0	0
Prior service credit	0	0
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	0	0
Amounts recognized in Regulatory assets (see Note 8 - Regulatory Matters)
Net actuarial loss	297	385
Prior service credit	(99)	(194)
Regulatory Assets	$ 198	$ 191