Retirement Benefits and Trusteed Assets (OPEB - Fair Value Measurements) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1,758	$ 1,617	$ 1,528
Assets valued at NAV	587	539
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	870	803
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	301	275
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	40	7
Short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	39	7
Short-term investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	0
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	284	264
U.S. Large Capitalization (Cap) Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	284	264
U.S. Large Capitalization (Cap) Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	156	138
U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	156	138
U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	324	317
Assets valued at NAV	61	55
Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	262	262
Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	0
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	439	413
Assets valued at NAV	125	115
Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	15	23
Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	299	275
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	338	325
Assets valued at NAV	224	216
Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	114	109
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	177	153
Assets valued at NAV	177	153
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
Securities lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(31)	(128)
Securities lending | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(28)	(122)
Securities lending | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(3)	(6)
Securities lending collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	31	128
Securities lending collateral | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	28	122
Securities lending collateral | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3	6
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,218	1,131	$ 1,038
Assets valued at NAV	409	380
DTE Electric | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	604	562
DTE Electric | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	205	189
DTE Electric | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	29	5
DTE Electric | Short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	28	5
DTE Electric | Short-term investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	0
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	195	183
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	195	183
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	109	97
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	109	97
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	224	221
Assets valued at NAV	41	37
DTE Electric | Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	182	184
DTE Electric | Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	0
DTE Electric | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	303	289
Assets valued at NAV	90	83
DTE Electric | Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	10	17
DTE Electric | Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	203	189
DTE Electric | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	234	227
Assets valued at NAV	154	151
DTE Electric | Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	80	76
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	124	109
Assets valued at NAV	124	109
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
DTE Electric | Securities lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(21)	(91)
DTE Electric | Securities lending | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(20)	(87)
DTE Electric | Securities lending | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(1)	(4)
DTE Electric | Securities lending collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	21	91
DTE Electric | Securities lending collateral | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	20	87
DTE Electric | Securities lending collateral | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1	$ 4