Retirement Benefits and Trusteed Assets (OPEB - Fair Value Measurements) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1,819	$ 1,689	$ 1,848
Assets valued at NAV	1,105	681
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	458	656
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	256	352
Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	80	16
Short-term Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	80	14
Short-term Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	2
Equity Securities, Domestic
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	324	300
Assets valued at NAV	273	0
Equity Securities, Domestic | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	51	300
Equity Securities, Domestic | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Equity Securities, International
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	271	301
Assets valued at NAV	89	67
Equity Securities, International | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	182	234
Equity Securities, International | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Fixed Income Securities, Governmental
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	74	85
Assets valued at NAV	0	0
Fixed Income Securities, Governmental | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	74	0
Fixed Income Securities, Governmental | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	85
Fixed Income Securities, Corporate
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	507	406
Assets valued at NAV	251	130
Fixed Income Securities, Corporate | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	11
Fixed Income Securities, Corporate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	256	265
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	253	300
Assets valued at NAV	182	203
Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	71	97
Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	310	281
Assets valued at NAV	310	281
Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,236	1,158	$ 1,272
Assets valued at NAV	758	471
DTE Electric | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	310	454
DTE Electric | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	168	233
DTE Electric | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	55	11
DTE Electric | Short-term Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	55	10
DTE Electric | Short-term Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	1
DTE Electric | Equity Securities, Domestic
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	219	206
Assets valued at NAV	185	0
DTE Electric | Equity Securities, Domestic | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	34	206
DTE Electric | Equity Securities, Domestic | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Equity Securities, International
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	184	208
Assets valued at NAV	60	45
DTE Electric | Equity Securities, International | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	124	163
DTE Electric | Equity Securities, International | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Fixed Income Securities, Governmental
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	48	53
Assets valued at NAV	0	0
DTE Electric | Fixed Income Securities, Governmental | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	48	0
DTE Electric | Fixed Income Securities, Governmental | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	53
DTE Electric | Fixed Income Securities, Corporate
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	344	278
Assets valued at NAV	176	92
DTE Electric | Fixed Income Securities, Corporate | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	7
DTE Electric | Fixed Income Securities, Corporate | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	168	179
DTE Electric | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	172	207
Assets valued at NAV	123	139
DTE Electric | Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	49	68
DTE Electric | Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	214	195
Assets valued at NAV	214	195
DTE Electric | Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 0	$ 0