Retirement Benefits and Trusteed Assets (OPEB - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amounts recognized in Regulatory assets
Regulatory assets	$ 4,721	$ 3,778
Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,910	1,795
Service cost	27	27	$ 27
Interest cost	69	73	80
Plan amendments	(44)	0
Actuarial (gain) loss	(227)	101
Benefits paid	(90)	(86)
Projected/Accumulated postretirement benefit obligation, end of year	1,645	1,910	1,795
Change in plan assets
Plan assets at fair value, beginning of year	1,848	1,758
Actual return on plan assets	(75)	252
Benefits paid	(84)	(162)
Plan assets at fair value, end of year	1,689	1,848	1,758
Funded status	44	(62)
Amount recorded as:
Noncurrent assets	45	0
Current liabilities	(1)	(1)
Noncurrent liabilities	0	(61)
Defined benefit plans assets (liabilities)	44	(62)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial (gain) loss	1	(1)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	1	(1)
Amounts recognized in Regulatory assets
Net actuarial loss	257	279
Prior service credit	(44)	(1)
Regulatory assets	213	278
DTE Electric
Amounts recognized in Regulatory assets
Regulatory assets	3,977	3,055
DTE Electric | Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,470	1,373
Service cost	20	20	20
Interest cost	53	56	61
Plan amendments	(35)	0
Actuarial (gain) loss	(196)	84
Benefits paid	(65)	(63)
Projected/Accumulated postretirement benefit obligation, end of year	1,247	1,470	1,373
Change in plan assets
Plan assets at fair value, beginning of year	1,272	1,218
Actual return on plan assets	(52)	172
Benefits paid	(62)	(118)
Plan assets at fair value, end of year	1,158	1,272	$ 1,218
Funded status	(89)	(198)
Amount recorded as:
Noncurrent assets	189	113
Current liabilities	0	0
Noncurrent liabilities	(278)	(311)
Defined benefit plans assets (liabilities)	(89)	(198)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial (gain) loss	0	0
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	0	0
Amounts recognized in Regulatory assets
Net actuarial loss	156	211
Prior service credit	(35)	0
Regulatory assets	$ 121	$ 211