Retirement Benefits and Trusteed Assets (Pension Plan - Fair Value Measurements) (Details) - Pension Plan - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	$ 3,832	$ 3,981	$ 3,720
Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	23	46
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	842	899
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	219	225
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	761	745
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	1,029	1,120
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	768	759
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	190	187
Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(154)	(239)
Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	154	239
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	1,819	1,929
Level 1 | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	23	46
Level 1 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	842	899
Level 1 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	219	225
Level 1 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	510	526
Level 1 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	5	7
Level 1 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	220	226
Level 1 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 1 | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(129)	(189)
Level 1 | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	129	189
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	1,371	1,427
Level 2 | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 2 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 2 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 2 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	251	219
Level 2 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	1,024	1,113
Level 2 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	96	95
Level 2 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 2 | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(25)	(50)
Level 2 | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	25	50
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	642	625	565
Level 3 | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 3 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 3 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 3 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 3 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 3 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	452	438	395
Level 3 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	190	187	170
Level 3 | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Level 3 | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	2,709	2,812	2,632
DTE Electric | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	16	33
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	599	638
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	157	162
DTE Electric | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	545	535
DTE Electric | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	703	763
DTE Electric | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	552	546
DTE Electric | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	137	135
DTE Electric | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(111)	(172)
DTE Electric | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	111	172
DTE Electric | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	1,301	1,379
DTE Electric | Level 1 | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	16	33
DTE Electric | Level 1 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	599	638
DTE Electric | Level 1 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	157	162
DTE Electric | Level 1 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	367	378
DTE Electric | Level 1 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	4	5
DTE Electric | Level 1 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	158	163
DTE Electric | Level 1 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 1 | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(93)	(136)
DTE Electric | Level 1 | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	93	136
DTE Electric | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	946	983
DTE Electric | Level 2 | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 2 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 2 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 2 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	178	157
DTE Electric | Level 2 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	699	758
DTE Electric | Level 2 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	69	68
DTE Electric | Level 2 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 2 | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(18)	(36)
DTE Electric | Level 2 | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	18	36
DTE Electric | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	462	450	407
DTE Electric | Level 3 | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 3 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 3 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 3 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 3 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 3 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	325	315	285
DTE Electric | Level 3 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	137	135	$ 122
DTE Electric | Level 3 | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Level 3 | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	$ 0	$ 0