DTE Electric 10-K 10 Feb 16 2015 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Jan. 29, 2016	Jun. 30, 2015
Entity Information [Line Items]
Entity Registrant Name	DTE ENERGY CO
Entity Central Index Key	936,340
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		179,476,008
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 12,900,000,000
DTE Electric
Entity Information [Line Items]
Entity Registrant Name	DTE ELECTRIC CO
Entity Central Index Key	28,385
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		138,632,324
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Revenues
Utility operations	$ 6,238	$ 6,884	$ 6,643
Non-utility operations	4,099	5,417	3,018
Operating Revenues	10,337	12,301	9,661
Operating Expenses
Fuel, purchased power, and gas — utility	2,081	2,407	2,281
Fuel, purchased power, and gas — non-utility	3,481	4,615	2,544
Operation and maintenance	2,214	2,204	2,208
Depreciation and amortization	852	1,145	1,094
Taxes other than income	364	352	340
Asset (gains) losses and impairments, net	106	(12)	(9)
Total operating expenses	9,098	10,711	8,458
Operating Income	1,239	1,590	1,203
Other (Income) and Deductions
Interest expense	450	429	436
Interest income	(13)	(10)	(9)
Other income	(209)	(196)	(201)
Other expenses	61	92	55
Total Other (Income) and Deductions	289	315	281
Income Before Income Taxes	950	1,275	922
Income Tax Expense (Benefit)	230	364	254
Net Income	720	911	668
Less: Net Income (Loss) Attributable to Noncontrolling Interests	(7)	6	7
Net Income	$ 727	$ 905	$ 661
Basic Earnings per Common Share
Net Income Attributable to DTE Energy Company (in dollars per share)	$ 4.05	$ 5.11	$ 3.76
Diluted Earnings per Common Share
Net Income Attributable to DTE Energy Company (in dollars per share)	$ 4.05	$ 5.10	$ 3.76
Weighted Average Common Shares Outstanding
Basic (in shares)	179	177	175
Diluted (in shares)	179	177	175
Dividends Declared per Common Share	$ 2.84	$ 2.69	$ 2.59
DTE Electric
Operating Revenues
Operating Revenues	$ 4,900	$ 5,282	$ 5,197
Operating Expenses
Fuel, purchased power, and gas — utility	1,574	1,706	1,668
Operation and maintenance	1,342	1,331	1,376
Depreciation and amortization	633	927	896
Taxes other than income	277	267	260
Asset (gains) losses and impairments, net	0	(1)	(3)
Total operating expenses	3,826	4,230	4,197
Operating Income	1,074	1,052	1,000
Other (Income) and Deductions
Interest expense	258	250	268
Interest income	0	(1)	0
Other income	(60)	(62)	(54)
Other expenses	40	35	45
Total Other (Income) and Deductions	238	222	259
Income Before Income Taxes	836	830	741
Income Tax Expense (Benefit)	292	298	254
Net Income	$ 544	$ 532	$ 487

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net Income	$ 265	$ 727	$ 905	$ 661
Net Income		720	911	668
Other comprehensive income (loss), net of tax:
Benefit obligations, net of taxes of $8, $(9), and $13, respectively DTE Electric $(4), $4 for 2014 and 2013 respectively		13	(18)	22
Net unrealized gains on investments during the period, net of taxes of $—, $1, and $1, respectively DTE Electric $--, $--, and $--, respectively		1	1	2
Foreign currency translation		(4)	(2)	(2)
Net current-period Other comprehensive income (loss)		10	(19)	22
Comprehensive income		730	892	690
Less comprehensive income (loss) attributable to noncontrolling interests		(7)	6	7
Comprehensive income attributable to DTE Energy Company		737	886	683
DTE Electric
Net Income	$ 216	544	532	487
Other comprehensive income (loss), net of tax:
Transfer of benefit obligations, net of taxes of $18 in 2015		27	0	0
Benefit obligations, net of taxes of $8, $(9), and $13, respectively DTE Electric $(4), $4 for 2014 and 2013 respectively		0	(10)	5
Net unrealized gains on investments during the period, net of taxes of $—, $1, and $1, respectively DTE Electric $--, $--, and $--, respectively		1	0	1
Net current-period Other comprehensive income (loss)		28	(10)	6
Comprehensive income attributable to DTE Energy Company		$ 572	$ 522	$ 493

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Tax effect on benefit obligation	$ 8	$ (9)	$ 13
Tax effect on net unrealized gains (losses) on investments during the period	0	1	1
DTE Electric
Benefit obligations	18	0	0
Tax effect on benefit obligation	0	(4)	4
Tax effect on net unrealized gains (losses) on investments during the period	$ 0	$ 0	$ 0

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets
Cash and cash equivalents	$ 37	$ 48
Restricted cash	23	120
Accounts receivable (less allowance for doubtful accounts of $49 and $54, respectively DTE Electric $28 and $29, respectively)
Customer	1,276	1,504
Other	72	94
Inventories
Fuel and gas	480	512
Materials and supplies	323	292
Derivative assets	129	128
Notes receivable
Regulatory assets	32	76
Other	203	238
Total Current Assets	2,575	3,012
Investments
Nuclear decommissioning trust funds	1,236	1,241
Investments in equity method investees	514	434
Other	186	194
Total Investments	1,936	1,869
Property
Property, plant, and equipment	28,121	26,538
Less accumulated depreciation and amortization	(10,087)	(9,718)
Property, plant and equipment, net	18,034	16,820
Other Assets
Goodwill	2,018	2,018
Regulatory assets	3,692	3,651
Securitized regulatory assets	0	34
Intangible assets	89	102
Notes receivable	85	90
Derivative assets	54	44
Other	254	259
Total Noncurrent Assets	6,192	6,198
Total Assets	28,737	27,899
Current Liabilities
Accounts payable	809	973
Accrued interest	89	86
Dividends payable	131	122
Short-term borrowings	499	398
Current portion long-term debt, including capital leases	473	274
Derivative liabilities	57	77
Regulatory liabilities	41	153
Other	429	494
Total Current Liabilities	2,528	2,577
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	8,340	7,860
Junior subordinated debentures	480	480
Capital lease obligations	15	3
Total Long-Term Debt (net of current portion)	8,835	8,343
Other Liabilities
Deferred income taxes	3,923	3,701
Regulatory liabilities	569	667
Asset retirement obligations	2,194	1,962
Unamortized investment tax credit	62	41
Derivative liabilities	86	8
Accrued pension liability	1,133	1,280
Accrued postretirement liability	228	515
Nuclear decommissioning	177	182
Other	207	281
Total Noncurrent Liabilities	$ 8,579	$ 8,637
Commitments and Contingencies (Notes 8 and 17)
Equity
Common stock, without par value, 400,000,000 shares authorized, and 179,470,213 and 176,991,231 shares issued and outstanding, respectively	$ 4,123	$ 3,904
Retained earnings	4,794	4,578
Accumulated other comprehensive loss	(145)	(155)
Total DTE Energy Company Equity	8,772	8,327
Noncontrolling interests	23	15
Total Equity	8,795	8,342
Total Liabilities and Equity	28,737	27,899
DTE Electric
Current Assets
Cash and cash equivalents	15	14
Restricted cash	0	96
Accounts receivable (less allowance for doubtful accounts of $49 and $54, respectively DTE Electric $28 and $29, respectively)
Customer	657	688
Affiliates	14	31
Other	40	15
Inventories
Fuel and gas	271	269
Materials and supplies	251	231
Notes receivable
Affiliates	0	8
Other	0	8
Regulatory assets	17	46
Other	66	73
Total Current Assets	1,331	1,479
Investments
Nuclear decommissioning trust funds	1,236	1,241
Other	35	172
Total Investments	1,271	1,413
Property
Property, plant, and equipment	21,391	19,805
Less accumulated depreciation and amortization	(7,646)	(7,216)
Property, plant and equipment, net	13,745	12,589
Other Assets
Regulatory assets	2,969	2,913
Securitized regulatory assets	0	34
Intangible assets	34	37
Prepaid postretirement costs — affiliates	24	0
Other	180	182
Total Noncurrent Assets	3,207	3,166
Total Assets	19,554	18,647
Current Liabilities
Affiliates	40	60
Other	329	366
Accrued interest	62	58
Current portion long-term debt, including capital leases	157	118
Regulatory liabilities	19	150
Affiliates	75	84
Other	272	50
Other	138	151
Total Current Liabilities	1,092	1,037
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	5,473	5,144
Capital lease obligations	15	0
Total Long-Term Debt (net of current portion)	5,488	5,144
Other Liabilities
Deferred income taxes	3,498	3,186
Regulatory liabilities	199	245
Asset retirement obligations	2,020	1,796
Unamortized investment tax credit	58	36
Nuclear decommissioning	177	182
Accrued pension liability — affiliates	976	1,200
Accrued postretirement liability — affiliates	307	520
Other	66	105
Total Noncurrent Liabilities	7,301	7,270
Commitments and Contingencies (Notes 8 and 17)	0	0
Equity
Common stock, without par value, 400,000,000 shares authorized, and 179,470,213 and 176,991,231 shares issued and outstanding, respectively	4,086	3,786
Retained earnings	1,585	1,436
Accumulated other comprehensive loss	2	(26)
Total DTE Energy Company Equity	5,673	5,196
Total Liabilities and Equity	$ 19,554	$ 18,647

Consolidated Statements of Fin6

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Allowance for doubtful accounts	$ 49	$ 54
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	179,470,213	176,991,231
Common stock, shares outstanding (in shares)	179,470,213	176,991,231
DTE Electric
Current Assets:
Allowance for doubtful accounts	$ 28	$ 29
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 10	$ 10
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	138,632,324	138,632,324
Common stock, shares outstanding (in shares)	138,632,324	138,632,324

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities
Net Income	$ 727	$ 905	$ 661
Net Income	720	911	668
Adjustments to reconcile Net Income to net cash from operating activities:
Depreciation and amortization	852	1,145	1,094
Nuclear fuel amortization	46	48	38
Allowance for equity funds used during construction	(21)	(21)	(15)
Deferred income taxes	237	356	164
Equity earnings of equity method investees	(66)	(48)	(59)
Dividends from equity method investees	64	55	61
Asset (gains) losses and impairments, net	107	(4)	(8)
Changes in assets and liabilities:
Accounts receivable, net	259	48	(154)
Inventories	1	(177)	123
Accounts payable	(158)	128	14
Accrued pension liability	(147)	627	(644)
Accrued postretirement liability	(287)	165	(526)
Derivative assets and liabilities	47	(199)	107
Regulatory assets and liabilities	85	(1,177)	1,269
Other current and noncurrent assets and liabilities	172	(18)	22
Net cash from operating activities	1,911	1,839	2,154
Investing Activities
Plant and equipment expenditures — utility	(1,817)	(1,784)	(1,534)
Plant and equipment expenditures — non-utility	(203)	(265)	(342)
Acquisition	(241)	0	0
Proceeds from sale of assets	16	45	36
Restricted cash for debt redemption, principally Securitization, net	97	3	(1)
Proceeds from sale of nuclear decommissioning trust fund assets	885	1,146	1,118
Investment in nuclear decommissioning trust funds	(898)	(1,156)	(1,134)
Distributions from equity method investees	19	13	8
Contributions to equity method investees	(98)	(42)	(21)
Other	36	(20)	(36)
Net cash used for investing activities	(2,204)	(2,060)	(1,906)
Financing Activities
Issuance of long-term debt, net of issuance costs	956	1,736	1,234
Redemption of long-term debt	(286)	(1,237)	(961)
Short-term borrowings, net	101	267	(109)
Issuance of common stock	9	0	39
Repurchase of common stock	0	(52)	0
Dividends on common stock	(501)	(470)	(445)
Other	3	(27)	(19)
Net cash from (used for) financing activities	282	217	(261)
Net Decrease in Cash and Cash Equivalents	(11)	(4)	(13)
Cash and Cash Equivalents at Beginning of Period	48	52	65
Cash and Cash Equivalents at End of Period	37	48	52
Supplemental disclosure of cash information
Cash paid (received) for: Interest (net of interest capitalized)	428	415	418
Cash paid (received) for: Income taxes	14	(35)	121
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Plant and equipment expenditures in accounts payable	207	212	329
DTE Electric
Operating Activities
Net Income	544	532	487
Adjustments to reconcile Net Income to net cash from operating activities:
Depreciation and amortization	633	927	896
Nuclear fuel amortization	46	48	38
Allowance for equity funds used during construction	(20)	(21)	(14)
Deferred income taxes	320	297	108
Asset (gains) losses and impairments, net	0	(1)	(3)
Changes in assets and liabilities:
Accounts receivable, net	33	33	(30)
Inventories	(22)	(97)	36
Prepaid postretirement benefit costs — affiliates	(24)	0	0
Accounts payable	(46)	11	(23)
Regulatory assets and liabilities	65	(926)	1,029
Accrued pension liability — affiliates	(224)	495	(663)
Accrued postretirement liability — affiliates	(213)	151	(417)
Other current and noncurrent assets and liabilities	58	(65)	44
Net cash from operating activities	1,150	1,384	1,488
Investing Activities
Restricted cash for debt redemption, principally Securitization, net	96	4	2
Proceeds from sale of nuclear decommissioning trust fund assets	885	1,146	1,118
Investment in nuclear decommissioning trust funds	(898)	(1,156)	(1,134)
Other	6	(14)	(33)
Plant and equipment expenditures	(1,545)	(1,561)	(1,325)
Acquisitions	(310)	0	0
Notes receivable — affiliate	8	192	(200)
Transfer of Rabbi Trust assets to affiliate	137	0	0
Net cash used for investing activities	(1,621)	(1,389)	(1,572)
Financing Activities
Issuance of long-term debt, net of issuance costs	495	942	768
Redemption of long-term debt	(135)	(837)	(590)
Dividends on common stock	(395)	(370)	(342)
Other	(7)	(9)	(3)
Capital contribution by parent company	300	190	400
Short-term borrowings, net — other	222	50	(130)
Short-term borrowings, net — affiliate	(8)	26	(22)
Net cash from (used for) financing activities	472	(8)	81
Net Decrease in Cash and Cash Equivalents	1	(13)	(3)
Cash and Cash Equivalents at Beginning of Period	14	27	30
Cash and Cash Equivalents at End of Period	15	14	27
Supplemental disclosure of cash information
Cash paid (received) for: Interest (net of interest capitalized)	244	240	256
Cash paid (received) for: Income taxes	(53)	4	183
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Plant and equipment expenditures in accounts payable	$ 150	$ 162	$ 231

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Non-Controlling Interest	DTE Electric	DTE ElectricCommon Stock	DTE ElectricRetained Earnings	DTE ElectricAccumulated Other Comprehensive Loss	DTE ElectricAdditional Paid-in Capital
Beginning Balance (in shares) at Dec. 31, 2012		172,352,000					138,632,000
Beginning Balance at Dec. 31, 2012						$ 4,303	$ 1,386	$ 1,129	$ (22)	$ 1,810
Beginning Balance at Dec. 31, 2012	$ 7,411	$ 3,587	$ 3,944	$ (158)	$ 38
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	668		661		7
Net Income	661					487		487
Dividends declared on common stock	(454)		(454)			(342)		(342)
Transfer of benefit obligations, net of taxes of $18 in 2015						0
Issuance of common stock (in shares)		589,000
Issuance of common stock	39	$ 39
Contribution of common stock to pension plan (in shares)		3,026,000
Contribution of common stock to pension plan	200	$ 200
Benefit obligations, net of tax	22			22		5			5
Net change in unrealized gains on investments, net of tax	2			2		1			1
Adjustments to Additional Paid in Capital, Contributions from Parent						400				400
Foreign currency translation	(2)			(2)
Stock-based compensation, distributions to noncontrolling interests and other (in shares)		1,120,000
Stock-based compensation, distributions to noncontrolling interests, and other	68	$ 81	(1)		(12)
Ending Balance (in shares) at Dec. 31, 2013		177,087,000					138,632,000
Ending Balance at Dec. 31, 2013						4,854	$ 1,386	1,274	(16)	2,210
Ending Balance at Dec. 31, 2013	7,954	$ 3,907	4,150	(136)	33
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	911		905		6
Net Income	905					532		532
Dividends declared on common stock	(476)		(476)			(370)		(370)
Transfer of benefit obligations, net of taxes of $18 in 2015						0
Repurchase of common stock (in shares)		713,000
Repurchase of common stock	(52)	$ (52)
Benefit obligations, net of tax	(18)			(18)		(10)			(10)
Net change in unrealized gains on investments, net of tax	1			1		0
Adjustments to Additional Paid in Capital, Contributions from Parent						$ 190				190
Foreign currency translation	(2)			(2)
Stock-based compensation, distributions to noncontrolling interests and other (in shares)		617,000
Stock-based compensation, distributions to noncontrolling interests, and other	$ 24	$ 49	(1)		(24)
Ending Balance (in shares) at Dec. 31, 2014	176,991,231	176,991,000				138,632,324	138,632,000
Ending Balance at Dec. 31, 2014	$ 8,327					$ 5,196	$ 1,386	1,436	(26)	2,400
Ending Balance at Dec. 31, 2014	8,342	$ 3,904	4,578	(155)	15
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	720		727		(7)
Net Income	727					544		544
Dividends declared on common stock	(510)		(510)			(395)		(395)
Transfer of benefit obligations, net of taxes of $18 in 2015						27			27
Issuance of common stock (in shares)		105,000
Issuance of common stock	9	$ 9
Contribution of common stock to pension plan (in shares)		1,428,000
Contribution of common stock to VEBA Trust	117	$ 117
Benefit obligations, net of tax	13			13		0
Net change in unrealized gains on investments, net of tax	1			1		1			1
Adjustments to Additional Paid in Capital, Contributions from Parent						$ 300				300
Foreign currency translation	(4)			(4)
Stock-based compensation, distributions to noncontrolling interests and other (in shares)		946,000
Stock-based compensation, distributions to noncontrolling interests, and other	$ 107	$ 93	(1)		15
Ending Balance (in shares) at Dec. 31, 2015	179,470,213	179,470,000				138,632,324	138,632,000
Ending Balance at Dec. 31, 2015	$ 8,772					$ 5,673	$ 1,386	$ 1,585	$ 2	$ 2,700
Ending Balance at Dec. 31, 2015	$ 8,795	$ 4,123	$ 4,794	$ (145)	$ 23

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Basis of Presentation	ORGANIZATION AND BASIS OF PRESENTATION Corporate Structure DTE Energy owns the following businesses: • DTE Electric is a public utility engaged in the generation, purchase, distribution, and sale of electricity to approximately 2.2 million customers in southeastern Michigan; • DTE Gas is a public gas utility engaged in the purchase, storage, transportation, distribution, and sale of natural gas to approximately 1.2 million customers throughout Michigan and the sale of storage and transportation capacity; and • Other businesses involved in 1) natural gas pipelines, gathering, and storage; 2) power and industrial projects; and 3) energy marketing and trading operations. DTE Electric and DTE Gas are regulated by the MPSC. Certain activities of DTE Electric and DTE Gas, as well as various other aspects of businesses under DTE Energy are regulated by the FERC. In addition, the Registrants are regulated by other federal and state regulatory agencies including the NRC, the EPA, the MDEQ, and the CFTC. Basis of Presentation The accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The information in these combined notes relates to each of the Registrants as noted in the Index of Combined Notes to Consolidated Financial Statements. However, DTE Electric does not make any representation as to information related solely to DTE Energy or the subsidiaries of DTE Energy other than itself. Certain prior year balances for the Registrants were reclassified to match the current year's Consolidated Financial Statements presentation. Such revisions include amounts reclassified to separate Operating Revenues and Fuel, purchased power, and gas between Utility operations and Non-utility operations and from Operations and maintenance to Fuel, purchased power, and gas — non-utility related to the Power and Industrial Projects segment. The reclassifications did not affect DTE Energy's Net Income for the prior periods, as such, they are not deemed material to the previously issued Consolidated Financial Statements. For reclassifications of deferred tax assets and liabilities arising from ASU 2015-17 see Note 3 to the Consolidated Financial Statements, "New Accounting Pronouncements". Principles of Consolidation The Registrants consolidate all majority-owned subsidiaries and investments in entities in which they have controlling influence. Non-majority owned investments are accounted for using the equity method when the Registrants are able to significantly influence the operating policies of the investee. When the Registrants do not influence the operating policies of an investee, the cost method is used. These Consolidated Financial Statements also reflect the Registrants' proportionate interests in certain jointly-owned utility plants. The Registrants eliminate all intercompany balances and transactions. The Registrants evaluate whether an entity is a VIE whenever reconsideration events occur. The Registrants consolidate VIEs for which they are the primary beneficiary. If a Registrant is not the primary beneficiary and an ownership interest is held, the VIE is accounted for under the equity method of accounting. When assessing the determination of the primary beneficiary, a Registrant considers all relevant facts and circumstances, including: the power, through voting or similar rights, to direct the activities of the VIE that most significantly impact the VIE's economic performance and the obligation to absorb the expected losses and/or the right to receive the expected returns of the VIE. The Registrants perform ongoing reassessments of all VIEs to determine if the primary beneficiary status has changed. Legal entities within DTE Energy's Power and Industrial Projects segment enter into long-term contractual arrangements with customers to supply energy-related products or services. The entities are generally designed to pass-through the commodity risk associated with these contracts to the customers, with DTE Energy retaining operational and customer default risk. These entities generally are VIEs and consolidated when DTE Energy is the primary beneficiary. In addition, DTE Energy has interests in certain VIEs through which control of all significant activities is shared with partners, and therefore are accounted for under the equity method. DTE Energy has variable interests in VIEs through certain of its long-term purchase and sale contracts. DTE Electric has variable interests in VIEs through certain of its long-term purchase contracts. As of December 31, 2015 , the carrying amount of assets and liabilities in DTE Energy's Consolidated Statements of Financial Position that relate to its variable interests under long-term purchase and sale contracts are predominantly related to working capital accounts and generally represent the amounts owed by or to DTE Energy for the deliveries associated with the current billing cycle under the contracts. As of December 31, 2015 , the carrying amount of assets and liabilities in DTE Electric's Consolidated Statements of Financial Position that relate to its variable interests under long-term purchase contracts are predominantly related to working capital accounts and generally represent the amounts owed by DTE Electric for the deliveries associated with the current billing cycle under the contracts. The Registrants have not provided any significant form of financial support associated with these long-term contracts. There is no significant potential exposure to loss as a result of DTE Energy's variable interests through these long-term purchase and sale contracts. In addition, there is no significant potential exposure to loss as a result of DTE Electric's variable interests through these long-term purchase contracts. In 2001, DTE Electric financed a regulatory asset related to Fermi 2 and certain other regulatory assets through the sale of rate reduction bonds by a wholly-owned special purpose entity, Securitization. DTE Electric performed servicing activities including billing and collecting surcharge revenue for Securitization. The remaining amounts due on the rate reduction bonds were paid in March 2015. The associated regulatory assets were fully amortized by March 31, 2015. Subsequent to the pay-down of the bonds, Securitization is no longer a VIE but continues to be consolidated by the Registrants as a voting interest entity. The maximum risk exposure for consolidated VIEs is reflected on the Registrants' Consolidated Statements of Financial Position. For non-consolidated VIEs, the maximum risk exposure is generally limited to its investment and amounts which it has guaranteed. The following table summarizes the major Consolidated Statements of Financial Position items for consolidated VIEs as of December 31, 2015 and 2014 . All assets and liabilities of a consolidated VIE are presented where it has been determined that a consolidated VIE has either (1) assets that can be used only to settle obligations of the VIE or (2) liabilities for which creditors do not have recourse to the general credit of the primary beneficiary. Securitization, included in the DTE Energy table below for December 31, 2014, also relates to DTE Electric. VIEs, in which DTE Energy holds a majority voting interest and is the primary beneficiary, that meet the definition of a business and whose assets can be used for purposes other than the settlement of the VIE's obligations have been excluded from the table below. December 31, 2015 December 31, 2014 Total Securitization Other Total (In millions) ASSETS Cash and cash equivalents $ 14 $ — $ 7 $ 7 Restricted cash 8 96 8 104 Accounts receivable 18 26 15 41 Inventories 82 — 67 67 Property, plant, and equipment, net 66 — 81 81 Securitized regulatory assets — 34 — 34 Other current and long-term assets 4 1 6 7 $ 192 $ 157 $ 184 $ 341 LIABILITIES Accounts payable and accrued current liabilities $ 13 $ 3 $ 8 $ 11 Current portion long-term debt, including capital leases 8 105 10 115 Current regulatory liabilities — 32 — 32 Mortgage bonds, notes, and other 10 — 15 15 Capital lease obligations — — 3 3 Other current and long-term liabilities 6 9 6 15 $ 37 $ 149 $ 42 $ 191 Amounts for DTE Energy's non-consolidated VIEs as of December 31, 2015 and 2014 are as follows: December 31, 2015 December 31, 2014 (In millions) Investment in equity method investees $ 136 $ 134 Notes receivable $ 15 $ 15 Equity Method Investments Investments in non-consolidated affiliates that are not controlled by the Registrants, but over which they have significant influence, are accounted for using the equity method. At December 31, 2015 and 2014, DTE Energy's share of the underlying equity in the net assets of the investees exceeded the carrying amounts of Investments in equity method investees by $81 million , respectively. The difference is being amortized over the life of the underlying assets. Equity method investees are described below: Investments % Owned Segment 2015 2014 2015 2014 Description (In millions) Significant Equity Method Investees Gas Storage and Pipelines NEXUS Pipeline $ 89 $ 16 50% 50% A proposed 255-mile pipeline to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers Vector Pipeline 96 98 40% 40% 348-mile pipeline connecting Chicago, Michigan, and Ontario market centers Millennium Pipeline 111 110 26% 26% 182-mile pipeline serving markets in the Northeast $ 296 $ 224 Other Equity Method Investees Other Segments 218 210 $ 514 $ 434 The balance in Other Equity Method Investees are individually insignificant and are primarily from the Power and Industrial Projects segment. These investments are comprised of projects that deliver energy and utility-type products and services to an industrial customer, sell electricity from renewable energy projects under long-term power purchase agreements, and produce and sell metallurgical coke. For further information by segment, see Note 20 to the Consolidated Financial Statements, " Segment and Related Information ".

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Revenues The Registrants' revenues from the sale and delivery of electricity, and DTE Energy's revenues from the sale, delivery, and storage of natural gas are recognized as services are provided. DTE Electric and DTE Gas record revenues for electricity and gas provided but unbilled at the end of each month. Rates for DTE Electric and DTE Gas include provisions to adjust billings for fluctuations in fuel and purchased power costs, cost of natural gas, and certain other costs. Revenues are adjusted for differences between actual costs subject to reconciliation and the amounts billed in current rates. Under or over recovered revenues related to these cost recovery mechanisms are included in Regulatory assets or liabilities on the Registrants' Consolidated Statements of Financial Position and are recovered or returned to customers through adjustments to the billing factors. For further discussion of recovery mechanisms authorized by the MPSC, see Note 8 to the Consolidated Financial Statements, " Regulatory Matters ". DTE Energy's non-utility businesses recognize revenues as services are provided and products are delivered. For discussion of derivative contracts, see Note 12 to the Consolidated Financial Statements, " Financial and Other Derivative Instruments ". Other Income Other income for the Registrants is recognized for non-operating income such as equity earnings, allowance for equity funds used during construction, and contract services. DTE Energy's Power and Industrial Projects segment also recognizes Other income in connection with the sale of membership interests in reduced emissions fuel facilities to investors. In exchange for the cash received, the investors will receive a portion of the economic attributes of the facilities, including income tax attributes. The transactions are not treated as a sale of membership interests for financial reporting purposes. Other income is considered earned when refined coal is produced and tax credits are generated. Power and Industrial Projects recognized approximately $83 million , $78 million , and $81 million of Other income for the years ended December 31, 2015 , 2014 , and 2013 , respectively. For information on equity earnings by segment, see Note 20 to the Consolidated Financial Statements, " Segment and Related Information ". Accounting for ISO Transactions DTE Electric participates in the energy market through MISO. MISO requires that DTE Electric submit hourly day-ahead, real-time, and FTR bids and offers for energy at locations across the MISO region. DTE Electric accounts for MISO transactions on a net hourly basis in each of the day-ahead, real-time, and FTR markets and net transactions across all MISO energy market locations. In any single hour DTE Electric records net purchases in Fuel, purchased power, and gas — utility and net sales in Operating Revenues — Utility operations on the Registrants' Consolidated Statements of Operations. The Energy Trading segment participates in the energy markets through various independent system operators and regional transmission organizations (ISOs and RTOs). These markets require that Energy Trading submits hourly day-ahead, real-time bids and offers for energy at locations across each region. Energy Trading submits bids in the annual and monthly auction revenue rights and FTR auctions to the regional transmission organizations. Energy Trading accounts for these transactions on a net hourly basis for the day-ahead, real-time, and FTR markets. These transactions are related to trading contracts which, if derivatives, are presented on a net basis in Operating Revenues — Non-utility operations, and if non-derivatives, the realized gains and losses for sales are recorded in Operating Revenues — Non-utility operations and purchases are recorded in Fuel, purchased power, and gas — non-utility in the DTE Energy Consolidated Statements of Operations. DTE Electric and Energy Trading record accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual costs when invoices are received from MISO and other ISOs and RTOs. Changes in Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including Net Income. The amounts recorded to Accumulated other comprehensive income (loss) for the Registrants include unrealized gains and losses on available-for-sale securities and changes in benefit obligations, consisting of deferred actuarial losses and prior service costs. The amounts recorded to Accumulated other comprehensive income (loss) relating solely to DTE Energy also include unrealized gains and losses from derivatives accounted for as cash flow hedges, DTE Energy's interest in other comprehensive income of equity investees which comprise the net unrealized gains and losses on investments, and foreign currency translation adjustments. Refer to Note 18 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets ", regarding the transfer of a portion of DTE Electric benefit obligations during the year. The following table summarizes the changes in DTE Energy's Accumulated other comprehensive income (loss) by component for the years ended December 31, 2015 and 2014 : Changes in Accumulated Other Comprehensive Income (Loss) by Component (a) Net Net Benefit Foreign Total (In millions) Balance, December 31, 2013 $ (4 ) $ (6 ) $ (126 ) $ — $ (136 ) Other comprehensive income (loss) before reclassifications — 1 (25 ) (2 ) (26 ) Amounts reclassified from Accumulated other comprehensive income — — 7 — 7 Net current-period Other comprehensive income (loss) — 1 (18 ) (2 ) (19 ) Balance, December 31, 2014 $ (4 ) $ (5 ) $ (144 ) $ (2 ) $ (155 ) Other comprehensive income (loss) before reclassifications — 1 2 (4 ) (1 ) Amounts reclassified from Accumulated other comprehensive income — — 11 — 11 Net current-period Other comprehensive income (loss) — 1 13 (4 ) 10 Balance, December 31, 2015 $ (4 ) $ (4 ) $ (131 ) $ (6 ) $ (145 ) ______________________________________ (a) All amounts are net of tax, except for Foreign currency translation. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 18 to the Consolidated Financial Statements " Retirement Benefits and Trusteed Assets "). The following table summarizes the changes in DTE Electric's Accumulated other comprehensive income (loss) by component for the years ended December 31, 2015 and 2014 : Changes in Accumulated Other Comprehensive Income (Loss) by Component (a) Net Unrealized Gain on Investments Benefit Obligations (b) Total (In millions) Balance, December 31, 2013 $ 1 $ (17 ) $ (16 ) Other comprehensive loss before reclassifications — (12 ) (12 ) Amounts reclassified from Accumulated other comprehensive income — 2 2 Net current-period Other comprehensive loss — (10 ) (10 ) Balance, December 31, 2014 $ 1 $ (27 ) $ (26 ) Other comprehensive income before reclassifications 1 — 1 Transfer of amounts from Accumulated other comprehensive income to affiliate — 27 27 Amounts reclassified from Accumulated other comprehensive income — — — Net current-period Other comprehensive income 1 27 28 Balance, December 31, 2015 $ 2 $ — $ 2 ______________________________________ (a) All amounts are net of tax. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 18 to the Consolidated Financial Statements " Retirement Benefits and Trusteed Assets "). Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include cash on hand, cash in banks, and temporary investments purchased with remaining maturities of three months or less. Restricted cash consists of funds held to satisfy requirements of certain debt and DTE Energy partnership operating agreements. Restricted cash designated for interest and principal payments within one year is classified as a Current Asset. Receivables Accounts receivable are primarily composed of trade receivables and unbilled revenue. The Registrants' Accounts receivable are stated at net realizable value. The allowance for doubtful accounts for DTE Electric and DTE Gas is generally calculated using the aging approach that utilizes rates developed in reserve studies. DTE Electric and DTE Gas establish an allowance for uncollectible accounts based on historical losses and management’s assessment of existing economic conditions, customer trends, and other factors. Customer accounts are generally considered delinquent if the amount billed is not received by the due date, which is typically in 21 days, however, factors such as assistance programs may delay aggressive action. DTE Electric and DTE Gas assess late payment fees on trade receivables based on past-due terms with customers. Customer accounts are written off when collection efforts have been exhausted. The time period for write-off is 150 days after service has been terminated. The customer allowance for doubtful accounts for DTE Energy's other businesses is calculated based on specific review of probable future collections based on receivable balances in excess of 30 days. DTE Energy unbilled revenues of $620 million and $773 million , including $237 million and $250 million of DTE Electric unbilled revenues, are included in Customer Accounts receivable at December 31, 2015 and 2014 , respectively. Notes Receivable Notes receivable, or financing receivables, for DTE Energy are primarily comprised of capital lease receivables and loans and are included in Notes receivable and Other current assets on DTE Energy’s Consolidated Statements of Financial Position. Notes receivable, or financing receivables, for DTE Electric are primarily comprised of loans. Notes receivable are typically considered delinquent when payment is not received for periods ranging from 60 to 120 days. The Registrants cease accruing interest (nonaccrual status), consider a note receivable impaired, and establish an allowance for credit loss when it is probable that all principal and interest amounts due will not be collected in accordance with the contractual terms of the note receivable. Cash payments received on nonaccrual status notes receivable, that do not bring the account contractually current, are first applied to contractually owed past due interest, with any remainder applied to principal. Accrual of interest is generally resumed when the note receivable becomes contractually current. In determining the allowance for credit losses for notes receivable, the Registrants consider the historical payment experience and other factors that are expected to have a specific impact on the counterparty’s ability to pay. In addition, the Registrants monitor the credit ratings of the counterparties from which they have Notes receivable. Inventories Inventory related to utility operations is generally valued at average cost. Inventory related to non-utility operations is valued at the lower of cost or market. DTE Gas' natural gas inventory of $65 million and $43 million as of December 31, 2015 and 2014 , respectively, is determined using the last-in, first-out (LIFO) method. The replacement cost of gas remaining in storage exceeded the LIFO cost by $60 million and $110 million at December 31, 2015 and 2014 , respectively. Property, Retirement and Maintenance, and Depreciation and Amortization Property is stated at cost and includes construction-related labor, materials, overheads, and AFUDC for utility property. The cost of utility properties retired is charged to accumulated depreciation. Expenditures for maintenance and repairs are charged to expense when incurred, except for Fermi 2. Utility property at DTE Electric and DTE Gas is depreciated over its estimated useful life using straight-line rates approved by the MPSC. DTE Energy's non-utility property is depreciated over its estimated useful life using the straight-line method. Depreciation and amortization expense also includes the amortization of certain regulatory assets for the Registrants. Approximately $4 million and $16 million of expenses related to Fermi 2 refueling outages were accrued at December 31, 2015 and 2014 , respectively. Amounts are accrued on a pro-rata basis, generally over an 18 -month period, that coincides with scheduled refueling outages at Fermi 2. This accrual of outage costs matches the regulatory recovery of these costs in rates set by the MPSC. See Note 8 to the Consolidated Financial Statements, " Regulatory Matters ". The cost of nuclear fuel is capitalized. The amortization of nuclear fuel is included within Fuel, purchased power, and gas — utility in the DTE Energy Consolidated Statements of Operations, and Fuel and purchased power in the DTE Electric Consolidated Statements of Operations, and is recorded using the units-of-production method. Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If the carrying amount of the asset exceeds the expected discounted future cash flows generated by the asset, an impairment loss is recognized resulting in the asset being written down to its estimated fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less costs to sell. Intangible Assets DTE Energy has certain Intangible assets as shown below: December 31, 2015 2014 (In millions) Emission allowances $ 1 $ 1 Renewable energy credits 38 45 Contract intangible assets 117 122 156 168 Less accumulated amortization 62 57 Intangible assets, net 94 111 Less current intangible assets 5 9 $ 89 $ 102 DTE Electric has certain Intangible assets as shown below: December 31, 2015 2014 (In millions) Emission allowances $ 1 $ 1 Renewable energy credits 38 45 39 46 Less current intangible assets 5 9 $ 34 $ 37 Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the businesses by the Registrants. DTE Energy amortizes contract Intangible assets on a straight-line basis over the expected period of benefit, ranging from 1 to 26 years. DTE Energy's Intangible assets amortization expense was $11 million in 2015 , $12 million in 2014 , and $14 million in 2013 . The following table summarizes DTE Energy's estimated contract intangible amortization expense expected to be recognized during each year through 2020 : Estimated amortization expense (In millions) 2016 $ 10 2017 $ 7 2018 $ 7 2019 $ 7 2020 $ 5 Excise and Sales Taxes The Registrants record the billing of excise and sales taxes as a receivable with an offsetting payable to the applicable taxing authority, with no net impact on the Registrants' Consolidated Statements of Operations. Deferred Debt Costs The costs related to the issuance of long-term debt are deferred and amortized over the life of each debt issue. The deferred amounts are included in Other long-term assets on the Registrant's Consolidated Statements of Financial Position. In accordance with MPSC regulations applicable to DTE Energy’s electric and gas utilities the unamortized discount, premium, and expense related to utility debt redeemed with a refinancing are amortized over the life of the replacement issue. Discount, premium, and expense on early redemptions of debt associated with DTE Energy's non-utility operations are charged to earnings. Investments in Debt and Equity Securities The Registrants generally classify investments in debt and equity securities as either trading or available-for-sale and have recorded such investments at market value with unrealized gains or losses included in earnings or in Other comprehensive income or loss, respectively. Changes in the fair value of Fermi 2 nuclear decommissioning investments are recorded as adjustments to Regulatory assets or liabilities, due to a recovery mechanism from customers. The Registrants' equity investments are reviewed for impairment each reporting period. If the assessment indicates that the impairment is other than temporary, a loss is recognized resulting in the equity investment being written down to its estimated fair value. See Note 11 of the Consolidated Financial Statements, " Fair Value ". Government Grants Grants are recognized when there is reasonable assurance that the grant will be received and that any conditions associated with the grant will be met. When grants are received related to Property, plant, and equipment, the Registrants reduce the cost of the assets on their Consolidated Statements of Financial Position, resulting in lower depreciation expense over the life of the associated asset. Grants received related to expenses are reflected as a reduction of the associated expense in the period in which the expense is incurred. DTE Energy Foundation DTE Energy's charitable contributions to the DTE Energy Foundation were $12 million , $25 million , and $18 million for the years ended December 31, 2015 , 2014 , and 2013 , respectively. The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute to and assist charitable organizations. Other Accounting Policies See the following notes for other accounting policies impacting the Registrants’ Consolidated Financial Statements: Note Title 7 Asset Retirement Obligations 8 Regulatory Matters 9 Income Taxes 11 Fair Value 12 Financial and Other Derivative Instruments 19 Stock-Based Compensation

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2015
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. The objectives of this ASU are to improve upon revenue recognition requirements by providing a single comprehensive model to determine the measurement of revenue and timing of recognition. The core principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. This ASU also requires expanded qualitative and quantitative disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. In July 2015, the FASB deferred implementation of the revenue standard to be effective for the first interim period within annual reporting periods beginning after December 15, 2017. The standard is to be applied retrospectively and early adoption is permitted in the preceding year. The Registrants are currently assessing the impact of this ASU on their Consolidated Financial Statements. In February 2015, the FASB issued ASU No. 2015-02, Amendments to the Consolidation Analysis , which changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. The ASU affects (1) limited partnerships and similar legal entities, (2) evaluating fees paid to a decision maker or a service provider as a variable interest, (3) the effect of fee arrangements on the primary beneficiary determination, (4) the effect of related parties on the primary beneficiary determination, and (5) certain investment funds. It is effective for the Registrants for the first interim period within annual reporting periods beginning after December 15, 2015 and early adoption is permitted. The Registrants are currently assessing the impact of this ASU on their Consolidated Financial Statements. In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs . This ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This ASU is effective for reporting periods beginning after December 15, 2015 and interim periods therein. It is to be applied retrospectively and early adoption is permitted. Had the Registrants early adopted this ASU it would have decreased assets and liabilities on DTE Energy’s and DTE Electric’s Consolidated Statements of Financial Position by $74 million and $36 million , respectively, at December 31, 2015, and $73 million and $35 million , respectively, at December 31, 2014. In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330), Simplifying the Measurement of Inventory . The ASU replaces the current lower of cost or market test with a lower of cost or net realizable value test when cost is determined on a first-in, first-out or average cost basis. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. It is to be applied prospectively and early adoption is permitted. The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes . This ASU requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. This ASU is effective for reporting periods beginning after December 15, 2016, including interim periods therein. It may be applied either prospectively or retrospectively, and early adoption is permitted. The Registrants adopted this ASU at December 31, 2015. The adoption of this ASU impacted DTE Energy’s and DTE Electric’s Consolidated Statements of Financial Position by decreasing assets and liabilities for 2014 by $75 million and $2 million , respectively.

Acquisitions and Exit Activitie

Acquisitions and Exit Activities	12 Months Ended
	Dec. 31, 2015
Business Acquisition, Integration, Restructuring and Other Related Costs [Abstract]
Acquisitions and Exit Activities	ACQUISITIONS AND EXIT ACTIVITIES Acquisitions On January 21, 2015, DTE Electric closed on an acquisition of a 732 MW simple-cycle natural gas facility in Carson City, Michigan from The LS Power Group. The facility will serve to meet customer needs during periods of peak demand. DTE Electric has completed its valuation analysis to arrive at the fair value of the assets acquired. The cash consideration and total purchase price of approximately $241 million was allocated based on the underlying fair value of the assets acquired, which was primarily Property, plant, and equipment. The pro forma results of operations have not been presented for DTE Electric as the effects of the acquisition were not material to either Registrant's Consolidated Statements of Operations. On October 1, 2015, DTE Electric closed on an acquisition of a 350 MW simple-cycle natural gas facility in East China Township, Michigan from a non-utility affiliate of DTE Energy. The facility will serve to meet customer needs during periods of peak demand. DTE Electric has completed its purchase accounting. The cash consideration and total purchase price of approximately $69 million was based on the net book value of the assets acquired, which was primarily Property, plant, and equipment. The pro forma results of operations have not been presented for DTE Electric as the effects of the acquisition were not material to its Consolidated Statements of Operations. Exit Activities On December 17, 2015, DTE Energy announced the closure of the Shenango coke battery plant in response to a sharp downturn in the North American steel industry. The plant, which is included in the Power and Industrial Projects segment, is located in Pittsburgh, PA. As a result of the closure, DTE Energy recorded a one-time pre-tax non-cash impairment charge of $111 million . The charge included $96 million to fully impair the long-lived assets, employee severance expenses related to the workforce reduction of approximately 170 employees for $3 million , and other expenses, including write downs of inventory, of $12 million . DTE Energy's coke production has been shifted to a larger, more efficient coke battery plant in the Power and Industrial Projects segment. Production of coke from the Shenango coke battery plant ceased in January 2016. A summary of the charges in the Consolidated Statements of Operations resulting from DTE Energy's exit activities is shown below: 2015 (In millions) Fuel, purchased power, and gas — non-utility $ 5 Operation and maintenance 10 Asset (gains) losses and impairments, net 96 Total Exit Activity Charges $ 111 For amounts accrued at December 31, 2015 related to these exit activities, DTE Energy expects future cash payments of approximately $7 million to be made in 2016. DTE Energy anticipates incurring additional costs, including environmental remediation costs, in connection with the closure. An estimate of the amount of additional costs and timing of the activities cannot be determined at December 31, 2015 as alternatives are currently being evaluated, however, the likelihood of these costs being material to DTE Energy's Consolidated Financial Statements is remote.

Property, Plant, and Equipment

Property, Plant, and Equipment	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant, and Equipment	PROPERTY, PLANT, AND EQUIPMENT The following is a summary of Property, plant, and equipment by classification as of December 31: 2015 2014 Property, plant, and equipment (In millions) DTE Electric Generation $ 11,767 $ 10,712 Distribution 7,816 7,414 Other 1,808 1,679 Total DTE Electric 21,391 19,805 DTE Gas Distribution 3,124 2,946 Storage 453 448 Transmission and other 890 863 Total DTE Gas 4,467 4,257 Non-utility and other 2,263 2,476 Total DTE Energy 28,121 26,538 Less accumulated depreciation and amortization DTE Electric Generation (4,346 ) (3,863 ) Distribution (2,707 ) (2,822 ) Other (593 ) (531 ) Total DTE Electric (7,646 ) (7,216 ) DTE Gas Distribution (1,163 ) (1,130 ) Storage (147 ) (142 ) Transmission and other (370 ) (363 ) Total DTE Gas (1,680 ) (1,635 ) Non-utility and other (761 ) (867 ) Total DTE Energy (10,087 ) (9,718 ) Net DTE Energy Property, plant, and equipment $ 18,034 $ 16,820 Net DTE Electric Property, plant, and equipment $ 13,745 $ 12,589 AFUDC and interest capitalized was approximately $34 million and $37 million for DTE Energy for the years ended December 31, 2015 and 2014 , respectively, including AFUDC capitalized of approximately $31 million and $32 million for DTE Electric for the years ended December 31, 2015 and 2014 , respectively. The composite depreciation rate for DTE Electric was approximately 3.5% in 2015 and 3.4% in 2014 and 2013 . The composite depreciation rate for DTE Gas was 2.6% in 2015 and 2.4% in 2014 and 2013 . The average estimated useful life for each major class of utility Property, plant, and equipment as of December 31, 2015 follows: Estimated Useful Lives in Years Utility Generation Distribution Storage DTE Electric 40 41 N/A DTE Gas N/A 50 53 The estimated useful lives for DTE Electric's Other utility assets range from 5 to 62 years, while the estimated useful lives for DTE Gas' Transmission and other utility assets range from 5 to 70 years. The estimated useful lives for major classes of DTE Energy's non-utility assets and facilities range from 3 to 55 years. The following is a summary of Depreciation and amortization expense for DTE Energy, including DTE Electric: 2015 2014 2013 (In millions) Property, plant, and equipment $ 740 $ 683 $ 630 Regulatory assets and liabilities 150 159 163 Securitized regulatory assets (a) (38 ) 303 301 $ 852 $ 1,145 $ 1,094 The following is a summary of Depreciation and amortization expense for DTE Electric: 2015 2014 2013 (In millions) Property, plant, and equipment $ 545 $ 489 $ 457 Regulatory assets and liabilities 126 135 138 Securitized regulatory assets (a) (38 ) 303 301 $ 633 $ 927 $ 896 _______________________________________ (a) Securitization surcharges ended in December 2014 with remaining over recovery refunded to customers in 2015. Securitization bonds were paid and Securitization regulatory assets amortization was completed in 2015. The $38 million credit represents the final adjustments to close out the Securitization program. Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 3 to 15 years for DTE Energy and 5 to 15 years for DTE Electric. The following balances for capitalized software relate to DTE Energy, including DTE Electric: Year Ended December 31, 2015 2014 2013 (In millions) Amortization expense of capitalized software $ 98 $ 77 $ 71 Gross carrying value of capitalized software $ 770 $ 668 Accumulated amortization of capitalized software $ 439 $ 335 The following balances for capitalized software relate to DTE Electric: Year Ended December 31, 2015 2014 2013 (In millions) Amortization expense of capitalized software $ 80 $ 71 $ 64 Gross carrying value of capitalized software $ 664 $ 590 Accumulated amortization of capitalized software $ 369 $ 293 Property under capital leases for the Registrants is as follows: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Gross property under capital leases $ 48 $ 35 $ 22 $ 9 Accumulated amortization of property under capital leases $ 26 $ 27 $ 1 $ 5

Jointly-Owned Utility Plant

Jointly-Owned Utility Plant	12 Months Ended
	Dec. 31, 2015
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Jointly-Owned Utility Plant	JOINTLY-OWNED UTILITY PLANT DTE Electric has joint ownership interest in two power plants, Belle River and Ludington Hydroelectric Pumped Storage. DTE Electric’s share of direct expenses of the jointly-owned plants are included in Fuel, purchased power, and gas — utility and Operation and maintenance expenses in the DTE Energy Consolidated Statements of Operations and Fuel and purchased power and Operation and maintenance expenses in the DTE Electric Consolidated Statements of Operations. Ownership information of the two utility plants as of December 31, 2015 was as follows: Belle River Ludington Hydroelectric Pumped Storage In service date 1984-1985 1973 Total plant capacity 1,270 MW 1,955 MW Ownership interest (a) 49% Investment in Property, plant, and equipment (in millions) $ 1,779 $ 443 Accumulated depreciation (in millions) $ 1,053 $ 154 _______________________________________ (a) DTE Electric's ownership interest is 63% in Unit No. 1, 81% of the facilities applicable to Belle River used jointly by the Belle River and St. Clair Power Plants and 75% in common facilities used at Unit No. 2. Belle River The Michigan Public Power Agency (MPPA) has an ownership interest in Belle River Unit No. 1 and other related facilities. The MPPA is entitled to 19% of the total capacity and energy of the plant and is responsible for the same percentage of the plant’s operation, maintenance, and capital improvement costs. Ludington Hydroelectric Pumped Storage Consumers Energy Company has an ownership interest in the Ludington Hydroelectric Pumped Storage Plant. Consumers Energy is entitled to 51% of the total capacity and energy of the plant and is responsible for the same percentage of the plant’s operation, maintenance, and capital improvement costs.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS DTE Electric has a legal retirement obligation for the decommissioning costs for its Fermi 1 and Fermi 2 nuclear plants, dismantlement of facilities located on leased property, and various other operations. DTE Electric has conditional retirement obligations for asbestos and PCB removal at certain of its power plants and various distribution equipment. DTE Gas has conditional retirement obligations for gas pipelines, certain service centers, compressor and gate stations. The Registrants recognize such obligations as liabilities at fair market value when they are incurred, which generally is at the time the associated assets are placed in service. Fair value is measured using expected future cash outflows discounted at the Registrants' credit-adjusted risk-free rate. For its utility operations, the Registrants recognize in the Consolidated Statements of Operations removal costs in accordance with regulatory treatment. Any differences between costs recognized related to asset retirement and those reflected in rates are recognized as either a Regulatory asset or liability on the Consolidated Statements of Financial Position. If a reasonable estimate of fair value cannot be made in the period in which the retirement obligation is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. Natural gas storage system and certain other distribution assets for DTE Gas and substations, manholes, and certain other distribution assets for DTE Electric have an indeterminate life. Therefore, no liability has been recorded for these assets. A reconciliation of the asset retirement obligations for 2015 follows: DTE Energy DTE Electric (In millions) Asset retirement obligations at December 31, 2014 $ 1,962 $ 1,796 Accretion 119 111 Liabilities incurred 33 33 Revision in estimated cash flows 80 80 Asset retirement obligations at December 31, 2015 $ 2,194 $ 2,020 The Revision in estimated cash flows was principally attributed to the impact of the Coal Combustion Residuals on DTE Electric's coal ash storage facility AROs. Refer to Note 17 to the Consolidated Financial Statements, " Commitments and Contingencies ", for discussion of the implications of the Coal Combustion Residuals. Approximately $1.8 billion of the asset retirement obligations represent nuclear decommissioning liabilities that are funded through a surcharge to electric customers over the life of the Fermi 2 nuclear plant. The NRC has jurisdiction over the decommissioning of nuclear power plants and requires minimum decommissioning funding based upon a formula. The MPSC and FERC regulate the recovery of costs of decommissioning nuclear power plants and both require the use of external trust funds to finance the decommissioning of Fermi 2. Rates approved by the MPSC provide for the recovery of decommissioning costs of Fermi 2 and the disposal of low-level radioactive waste. DTE Electric is continuing to fund FERC jurisdictional amounts for decommissioning even though explicit provisions are not included in FERC rates. DTE Electric believes the MPSC and FERC collections will be adequate to fund the estimated cost of decommissioning. The decommissioning assets, anticipated earnings thereon, and future revenues from decommissioning collections will be used to decommission Fermi 2. DTE Electric expects the liabilities to be reduced to zero at the conclusion of the decommissioning activities. If amounts remain in the trust funds for Fermi 2 following the completion of the decommissioning activities, those amounts will be disbursed based on rulings by the MPSC and FERC. A portion of the funds recovered through the Fermi 2 decommissioning surcharge and deposited in external trust accounts is designated for the removal of non-radioactive assets and returning the site to greenfield. This removal and greenfielding is not considered a legal liability. Therefore, it is not included in the asset retirement obligation, but is reflected as the Nuclear decommissioning liability. The decommissioning of Fermi 1 is funded by DTE Electric. Contributions to the Fermi 1 trust are discretionary. For additional discussion of Nuclear decommissioning trust fund assets, see Note 11 to the Consolidated Financial Statements, " Fair Value ".

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	REGULATORY MATTERS Regulation DTE Electric and DTE Gas are subject to the regulatory jurisdiction of the MPSC, which issues orders pertaining to rates, recovery of certain costs, including the costs of generating facilities and regulatory assets, conditions of service, accounting, and operating-related matters. DTE Electric is also regulated by the FERC with respect to financing authorization and wholesale electric activities. Regulation results in differences in the application of generally accepted accounting principles between regulated and non-regulated businesses. The Registrants are unable to predict the outcome of the unresolved regulatory matters discussed herein. Resolution of these matters is dependent upon future MPSC orders and appeals, which may materially impact the Consolidated Financial Statements of the Registrants. Regulatory Assets and Liabilities DTE Electric and DTE Gas are required to record Regulatory assets and liabilities for certain transactions that would have been treated as revenue or expense in non-regulated businesses. Continued applicability of regulatory accounting treatment requires that rates be designed to recover specific costs of providing regulated services and be charged to and collected from customers. Future regulatory changes or changes in the competitive environment could result in the discontinuance of this accounting treatment for Regulatory assets and liabilities for some or all of the Registrants' businesses and may require the write-off of the portion of any Regulatory asset or liability that was no longer probable of recovery through regulated rates. Management believes that currently available facts support the continued use of Regulatory assets and liabilities and that all Regulatory assets and liabilities are recoverable or refundable in the current regulatory environment. The following are balances and a brief description of the Registrants' Regulatory assets and liabilities at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 Assets (In millions) Recoverable pension and other postretirement costs: Pension $ 2,112 $ 2,284 $ 1,592 $ 1,743 Other postretirement costs 256 234 198 191 Asset retirement obligation 565 448 565 448 Recoverable Michigan income taxes 248 267 203 220 Removal costs asset 118 15 118 15 Unamortized loss on reacquired debt 63 67 41 44 Other recoverable income taxes 61 66 61 66 Deferred environmental costs 54 59 — — Transitional Reconciliation Mechanism 43 14 43 14 Cost to achieve Performance Excellence Process 33 54 28 46 Accrued PSCR/GCR revenue 12 61 — 34 Recoverable income taxes related to Securitized regulatory assets — 19 — 19 Other 159 139 137 119 3,724 3,727 2,986 2,959 Less amount included in Current Assets (32 ) (76 ) (17 ) (46 ) $ 3,692 $ 3,651 $ 2,969 $ 2,913 Securitized regulatory assets $ — $ 34 $ — $ 34 DTE Energy DTE Electric 2015 2014 2015 2014 Liabilities (In millions) Removal costs liability $ 291 $ 308 $ — $ — Renewable energy 197 227 197 227 Negative pension offset 46 67 — — Accrued PSCR/GCR refund 37 — 15 — Refundable income taxes 23 33 — — Energy optimization 10 24 — 14 Fermi 2 refueling outage 4 16 4 16 Securitization over recovery — 71 — 71 Refundable revenue decoupling/deferred gain — 63 — 63 Other 2 11 2 4 $ 610 $ 820 $ 218 $ 395 Less amount included in Current Liabilities (41 ) (153 ) (19 ) (150 ) $ 569 $ 667 $ 199 $ 245 As noted below, certain Regulatory assets for which costs have been incurred have been included (or are expected to be included, for costs incurred subsequent to the most recently approved rate case) in DTE Electric's or DTE Gas' rate base, thereby providing a return on invested costs (except as noted). Certain other regulatory assets are not included in rate base but accrue recoverable carrying charges until surcharges to collect the assets are billed. Certain Regulatory assets do not result from cash expenditures and therefore do not represent investments included in rate base or have offsetting liabilities that reduce rate base. ASSETS • Recoverable pension and other postretirement costs — Accounting rules for pension and other postretirement benefit costs require, among other things, the recognition in Other comprehensive income of the actuarial gains or losses and the prior service costs that arise during the period but that are not immediately recognized as components of net periodic benefit costs. DTE Electric and DTE Gas record the impact of actuarial gains or losses and prior service costs as a Regulatory asset since the traditional rate setting process allows for the recovery of pension and other postretirement costs. The asset will reverse as the deferred items are amortized and recognized as components of net periodic benefit costs. (a) • Asset retirement obligation — This obligation is for Fermi 2 decommissioning costs. The asset captures the timing differences between expense recognition and current recovery in rates and will reverse over the remaining life of the related plant. (a) • Recoverable Michigan income taxes — In July 2007, the MBT was enacted by the State of Michigan. State deferred tax liabilities were established for DTE Energy’s utilities and offsetting Regulatory assets were recorded as the impacts of the deferred tax liabilities will be reflected in rates as the related taxable temporary differences reverse and flow through current income tax expense. In May 2011, the MBT was repealed and the MCIT was enacted. The Regulatory asset was remeasured to reflect the impact of the MCIT tax rate. (a) • Removal costs asset — Receivable for the recovery of asset removal expenditures in excess of amounts collected from customers. • Unamortized loss on reacquired debt — The unamortized discount, premium, and expense related to debt redeemed with a refinancing are deferred, amortized, and recovered over the life of the replacement issue. • Other recoverable income taxes — Income taxes receivable from DTE Electric’s customers representing the difference in property-related deferred income taxes and amounts previously reflected in DTE Electric’s rates. This asset will reverse over the remaining life of the related plant. (a) • Deferred environmental costs — The MPSC approved the deferral of investigation and remediation costs associated with DTE Gas' former MGP sites. Amortization of deferred costs is over a ten -year period beginning in the year after costs were incurred, with recovery (net of any insurance proceeds) through base rate filings. (a) • Transitional Reconciliation Mechanism ( TRM) — The MPSC approved the recovery of the deferred net incremental revenue requirement associated with the transition of PLD customers to DTE Electric's distribution system, effective July 1, 2014. Annual reconciliations will be filed and surcharges will be implemented to recover approved amounts. • Cost to achieve Performance Excellence Process (PEP) — The MPSC authorized the deferral of costs to implement the PEP. These costs consist of employee severance, project management, and consultant support. These costs are amortized over a ten -year period beginning with the year subsequent to the year the costs were deferred. • Accrued PSCR/GCR revenue — Receivable for the temporary under-recovery of and carrying costs on fuel and purchased power costs incurred by DTE Electric which are recoverable through the PSCR mechanism and temporary under-recovery of and carrying costs on gas costs incurred by DTE Gas which are recoverable through the GCR mechanism. • Recoverable income taxes related to Securitized regulatory assets — Receivable for the recovery of income taxes to be paid on the non-bypassable securitization bond surcharge. A non-bypassable securitization tax surcharge, which ended in December 2014, was in place to recover the income tax over a 14 -year period. (a) • Securitized regulatory assets — The net book balance of the Fermi 2 nuclear plant was written off in 1998 and an equivalent regulatory asset was established. In 2001, the Fermi 2 regulatory asset and certain other regulatory assets were securitized pursuant to PA 142 and an MPSC order. A non-bypassable securitization bond surcharge, which ended in December 2014, was in place to recover the Securitized regulatory asset over a 14 -year period. ________________________________________________ (a) Regulatory assets not earning a return or accruing carrying charges. LIABILITIES • Removal costs liability — The amount collected from customers for the funding of future asset removal activities. • Renewable energy — Amounts collected in rates in excess of renewable energy expenditures. • Negative pension offset — DTE Gas' negative pension costs are not included as a reduction to its authorized rates; therefore, DTE Gas is accruing a Regulatory liability to eliminate the impact on earnings of the negative pension expense accrued. This Regulatory liability will reverse to the extent DTE Gas' pension expense is positive in future years. • Accrued PSCR/GCR refund — Liability for the temporary over-recovery of and a return on power supply costs and transmission costs incurred by DTE Electric which are recoverable through the PSCR mechanism and temporary over-recovery of and a return on gas costs incurred by DTE Gas which are recoverable through the GCR mechanism. • Refundable income taxes — Income taxes refundable to DTE Gas' customers representing the difference in property-related deferred income taxes payable and amounts recognized pursuant to MPSC authorization. • Energy optimization (EO) — Amounts collected in rates in excess of energy optimization expenditures. • Fermi 2 refueling outage — Accrued liability for refueling outage at Fermi 2 pursuant to MPSC authorization. • Securitization over recovery — Over recovery of securitization bond expenses. • Refundable revenue decoupling/deferred gain — Amounts were originally accrued as refundable to DTE Electric customers for the change in revenue resulting from the difference between actual average sales per customer compared to the base level of average sales per customer established by the MPSC. In 2012, the MCOA issued a decision reversing the MPSC's decision to authorize a RDM for DTE Electric. The revenue decoupling liability was reversed and, after receiving an order from the MPSC to defer the resulting gain for future amortization, DTE Electric created a regulatory liability representing its obligation to refund the gain. The deferred gain was amortized into earnings in 2014 and 2015. 2014 Electric Rate Case Filing DTE Electric filed a rate case with the MPSC on December 19, 2014 requesting an increase in base rates of $370 million based on a projected twelve-month period ending June 30, 2016. The requested increase in base rates was due primarily to an increase in net plant resulting from infrastructure investments, plant acquisitions, environmental compliance, and reliability improvement projects. The rate filing also included projected changes in sales, working capital, operation and maintenance expenses, return on equity, and capital structure. On July 1, 2015, DTE Electric realized an annual revenue increase of $230 million consisting of $190 million of self-implemented base rate increase related to the December 19, 2014 rate request and $40 million associated with the required elimination of a credit surcharge. On December 11, 2015, the MPSC issued an order approving an annual revenue increase of $238 million for service rendered on or after December 17, 2015. The rate order also provided for a reduction of the return on equity from 10.5% to 10.3% on a capital structure of 50% debt and 50% equity. On December 22, 2015, DTE Electric petitioned the MPSC for a rehearing and clarification of several issues related to the December 11, 2015 MPSC rate order. The three main issues addressed in the rehearing request were related to the recovery of the cost of the operating license for Fermi 3, the capitalization of the cost of tree trimming, and costs related to certain land and a building located near DTE Electric's Detroit headquarters. On January 19, 2016, the MPSC issued an order authorizing DTE Electric to begin amortization of the cost of the Fermi 3 operating license over a 20 -year period without a return on the unamortized balance. The MPSC denied the capitalization of the tree trimming costs and the cost related to the land and building. DTE Electric recorded a disallowance of $10 million related to tree trim costs in the fourth quarter of 2015 which was previously capitalized as of September 30, 2015. The land and building have economic value independent of recovery through rates and therefore no impairment charge was recorded for these assets. The MPSC order also stated that any changes to the revenue deficiency will be addressed in a final rehearing order in this case. 2016 Electric Rate Case Filing DTE Electric filed a rate case with the MPSC on February 1, 2016 requesting an increase in base rates of $344 million based on a projected twelve-month period ending July 31, 2017. The requested increase in base rates is due primarily to an increase in net plant resulting from infrastructure investments, environmental compliance, and reliability improvement projects. The rate filing also includes projected changes in sales, operation and maintenance expenses, and working capital. The rate filing also requests an increase in return on equity from 10.3% to 10.5% on a capital structure of 50% equity and 50% debt. DTE Electric anticipates self-implementing a rate increase in August 2016 with an MPSC order expected by February 2017. PSCR Proceedings The PSCR process is designed to allow DTE Electric to recover all of its power supply costs if incurred under reasonable and prudent policies and practices. DTE Electric's power supply costs include fuel and related transportation costs, purchased and net interchange power costs, nitrogen oxide and sulfur dioxide emission allowances costs, urea costs, transmission costs, and MISO costs. The MPSC reviews these costs, policies, and practices for prudence in annual plan and reconciliation filings. 2012 PSCR Year — In March 2013, DTE Electric filed its 2012 PSCR reconciliation that included purchased power costs related to the manual shutdown of the Fermi 2 nuclear power plant in June 2012 caused by the failure of one of the plant's two non-safety related feed-water pumps. The plant was restarted on July 30, 2012, which restored production to approximately 68% of full capacity. In September 2013, the repair to the plant was completed and production was returned to full capacity. DTE Electric was able to purchase sufficient power from MISO to continue to provide uninterrupted service to customers. On June 30, 2015, the MPSC issued an order that disallowed approximately $19 million of Fermi 2 related purchased power costs. DTE Electric recorded the impact of this disallowance in the second quarter of 2015. Customer Settlement In July 2014, an industrial customer of DTE Electric filed a complaint with the MPSC alleging they had been overcharged for the period of February 2008 through March 2014, and sought payment from DTE Electric of $22 million , plus interest. In July 2015, the MPSC issued an order that found the customer is entitled to a refund in the amount of $20 million , plus interest calculated at 7% per annum. In July 2015, DTE Electric issued a customer refund of $25 million , inclusive of interest. Approximately $16 million of the refund obligation is expected to be recovered through the PSCR and other regulatory mechanisms. DTE Electric does not expect this order to have a material impact to its Consolidated Statements of Operations. 2015 DTE Gas Rate Case Filing DTE Gas filed a rate case with the MPSC on December 18, 2015 requesting an increase in base rates of $183 million based on a projected twelve-month period ending October 31, 2017. The requested increase in base rates is due primarily to an increase in net plant of $800 million , inclusive of IRM capital investments being recovered through approved IRM surcharge filings. The rate filing also includes projected changes in sales, operation and maintenance expenses, and working capital. The rate filing also requests an increase in return on equity from 10.5% to 10.75% on a capital structure of 52% equity and 48% debt. DTE Gas anticipates self-implementing a rate increase in November 2016 with an MPSC order expected by December 2016. Concurrent with the MPSC order in this rate case, the existing IRM surcharge will be terminated. However, in this rate case filing, DTE Gas requested to implement a new IRM surcharge to become effective in January 2017. DTE Gas IRM In November 2014, DTE Gas filed an application with the MPSC for approval of an increased IRM surcharge to recover an additional $47 million of annual capital expenditures in 2016 and 2017 for its gas main renewal program. In November 2015, the MPSC issued an order authorizing an expansion of its gas main renewal program and an increase in the IRM surcharge of $16 million for 2016 and $31 million for 2017. The 2017 increase is subject to a reduction to the 2016 level if the 2016 target is not met. The IRM surcharge authorized by the order in this filing will become effective in July 2016 and will be terminated upon the implementation of base rates requested in the December 18, 2015 rate case filing.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Income Tax Summary DTE Energy files a consolidated federal income tax return. DTE Electric is a part of the consolidated federal income tax return of DTE Energy. DTE Energy and its subsidiaries file consolidated and/or separate company income tax returns in various states and localities, including a consolidated return in the State of Michigan. DTE Electric is part of the Michigan consolidated income tax return of DTE Energy. The federal, state and local income tax expense for DTE Electric is determined on an individual company basis with no allocation of tax expenses or benefits from other affiliates of DTE Energy. DTE Electric had an income tax receivable from DTE Energy of $6 million and $29 million at December 31, 2015 and 2014 , respectively. The Registrants' total Income Tax Expense varied from the statutory federal income tax rate for the following reasons: 2015 2014 2013 DTE Energy (In millions) Income Before Income Taxes $ 950 $ 1,275 $ 922 Income tax expense at 35% statutory rate $ 333 $ 446 $ 323 Production tax credits (122 ) (119 ) (68 ) Investment tax credits (7 ) (6 ) (6 ) Depreciation (4 ) (4 ) (4 ) AFUDC - Equity (8 ) (7 ) (5 ) Employee Stock Ownership Plan dividends (5 ) (4 ) (4 ) Domestic production activities deduction — — (14 ) State and local income taxes, net of federal benefit 35 51 37 Enactment of New York Corporate Income Tax Legislation, net of federal benefit — 8 — Other, net 8 (1 ) (5 ) Income Tax Expense $ 230 $ 364 $ 254 Effective income tax rate 24.2 % 28.5 % 27.5 % 2015 2014 2013 DTE Electric (In millions) Income Before Income Taxes $ 836 $ 830 $ 741 Income tax expense at 35% statutory rate $ 293 $ 291 $ 260 Production tax credits (31 ) (22 ) (15 ) Investment tax credits (5 ) (5 ) (5 ) Depreciation 3 3 3 AFUDC - Equity (7 ) (7 ) (5 ) Employee Stock Ownership Plan dividends (3 ) (3 ) (2 ) Domestic production activities deduction — (2 ) (18 ) State and local income taxes, net of federal benefit 43 43 41 Other, net (1 ) — (5 ) Income Tax Expense $ 292 $ 298 $ 254 Effective income tax rate 34.9 % 35.9 % 34.3 % Components of the Registrants' Income Tax Expense were as follows: 2015 2014 2013 DTE Energy (In millions) Current income tax expense (benefit) Federal $ (3 ) $ (16 ) $ 74 State and other income tax (4 ) 24 16 Total current income taxes (7 ) 8 90 Deferred income tax expense Federal 178 289 122 State and other income tax 59 67 42 Total deferred income taxes 237 356 164 Total $ 230 $ 364 $ 254 2015 2014 2013 DTE Electric (In millions) Current income tax expense (benefit) Federal $ (26 ) $ (19 ) $ 123 State and other income tax (2 ) 20 23 Total current income taxes (28 ) 1 146 Deferred income tax expense Federal 252 251 68 State and other income tax 68 46 40 Total deferred income taxes 320 297 108 Total $ 292 $ 298 $ 254 Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts in the Consolidated Financial Statements. Consistent with rate making treatment, deferred taxes are offset in the tables below for temporary differences which have related Regulatory assets and liabilities. The Registrants' deferred tax assets (liabilities) were comprised of the following at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Property, plant, and equipment $ (4,211 ) $ (3,832 ) $ (3,468 ) $ (3,152 ) Securitized regulatory assets 5 (2 ) 5 (3 ) Tax credit carry-forwards 465 296 53 — Pension and benefits (301 ) (152 ) (193 ) (43 ) Federal net operating loss carry-forward 177 — 142 — State and local net operating loss carry-forwards 63 39 16 — Investments in equity method investees (82 ) (84 ) — — Other (4 ) 65 (53 ) 12 (3,888 ) (3,670 ) (3,498 ) (3,186 ) Less valuation allowance (35 ) (31 ) — — Long-term deferred income tax liabilities $ (3,923 ) $ (3,701 ) $ (3,498 ) $ (3,186 ) Deferred income tax assets $ 1,088 $ 861 $ 453 $ 357 Deferred income tax liabilities (5,011 ) (4,562 ) (3,951 ) (3,543 ) $ (3,923 ) $ (3,701 ) $ (3,498 ) $ (3,186 ) Tax credit carry forwards for DTE Energy include $181 million of general business credits that expire from 2034 through 2035 and $284 million of alternative minimum tax credits that may be carried forward indefinitely. The alternative minimum tax credits are production tax credits earned prior to 2006 but not utilized. The majority of these alternative minimum tax credits were generated from projects that had received a private letter ruling (PLR) from the IRS. These PLRs provide assurance as to the appropriateness of using these credits to offset taxable income, however, these tax credits are subject to IRS audit and adjustment. DTE Energy has a federal net operating loss carry-forward available for use on the tax return of $517 million as of December 31, 2015 , which includes approximately $9 million related to windfall tax benefits attributable to stock-based compensation for which a benefit will be recorded in additional paid-in capital if and when realized. The federal net operating loss carry-forward expires in 2035 . No valuation allowance is required for the federal net operating loss deferred tax asset. The above tables exclude unamortized investment tax credits that are shown separately on the Registrants' Consolidated Statements of Financial Position. Investment tax credits are deferred and amortized to income over the average life of the related property. DTE Energy has state and local deferred tax assets related to net operating loss carry-forwards of $63 million and $39 million at December 31, 2015 and 2014 , respectively. The state and local net operating loss carry-forwards expire from 2016 through 2035 . DTE Energy has recorded valuation allowances at December 31, 2015 and 2014 of approximately $35 million and $31 million , respectively, with respect to these deferred tax assets. In assessing the realizability of deferred tax assets, DTE Energy considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. DTE Electric has state and local deferred tax assets related to net operating loss carry-forwards of $16 million at December 31, 2015 , while there was no state and local deferred tax asset related to net operating loss carry-forwards at December 31, 2014 . No valuation allowance is required for DTE Electric's state and local net operating loss carry-forwards. Uncertain Tax Positions A reconciliation of the beginning and ending amount of unrecognized tax benefits for the Registrants is as follows: 2015 2014 2013 DTE Energy (In millions) Balance at January 1 $ 9 $ 10 $ 11 Lapse of statute of limitations (6 ) (1 ) (1 ) Balance at December 31 $ 3 $ 9 $ 10 2015 2014 2013 DTE Electric (In millions) Balance at January 1 $ 4 $ 4 $ 4 Balance at December 31 $ 4 $ 4 $ 4 DTE Energy had $2 million of unrecognized tax benefits at December 31, 2015 and 2014 , that, if recognized, would favorably impact its effective tax rate. DTE Energy does not anticipate any material decrease in unrecognized tax benefits in the next twelve months. DTE Electric had $3 million and $2 million of unrecognized tax benefits at December 31, 2015 and 2014 , respectively, that, if recognized, would favorably impact its effective tax rate. DTE Electric does not anticipate any material decrease in unrecognized tax benefits in the next twelve months. The Registrants recognize interest and penalties pertaining to income taxes in Interest expense and Other expenses, respectively, on their Consolidated Statements of Operations. Accrued interest pertaining to income taxes for both DTE Energy and DTE Electric totaled $1 million at December 31, 2015 and 2014 . The Registrants had no accrued penalties pertaining to income taxes. The Registrants recognized interest expense (income) related to income taxes of a nominal amount in 2015 , 2014 , and 2013 . In 2015 , DTE Energy, including DTE Electric, settled a federal tax audit for the 2013 tax year. DTE Energy's federal income tax returns for 2014 and subsequent years remain subject to examination by the IRS. DTE Energy's MBT and MCIT returns for the year 2008 and subsequent years remain subject to examination by the State of Michigan. DTE Energy also files tax returns in numerous state and local jurisdictions with varying statutes of limitation.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE DTE Energy reports both basic and diluted earnings per share. The calculation of diluted earnings per share assumes the issuance of potentially dilutive common shares outstanding during the period from the exercise of stock options. A reconciliation of both calculations is presented in the following table as of December 31: 2015 2014 2013 (In millions, expect per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 727 $ 905 $ 661 Average number of common shares outstanding 179 177 175 Weighted average net restricted shares outstanding — — 1 Dividends declared — common shares $ 508 $ 475 $ 453 Dividends declared — net restricted shares 2 1 1 Total distributed earnings $ 510 $ 476 $ 454 Net Income less distributed earnings $ 217 $ 429 $ 207 Distributed (dividends per common share) $ 2.84 $ 2.69 $ 2.59 Undistributed 1.21 2.42 1.17 Total Basic Earnings per Common Share $ 4.05 $ 5.11 $ 3.76 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 727 $ 905 $ 661 Average number of common shares outstanding 179 177 175 Weighted average net restricted shares outstanding — — 1 Dividends declared — common shares $ 508 $ 475 $ 453 Dividends declared — net restricted shares 2 1 1 Total distributed earnings $ 510 $ 476 $ 454 Net Income less distributed earnings $ 217 $ 429 $ 207 Distributed (dividends per common share) $ 2.84 $ 2.69 $ 2.59 Undistributed 1.21 2.41 1.17 Total Diluted Earnings per Common Share $ 4.05 $ 5.10 $ 3.76

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value	FAIR VALUE Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, which refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable inputs. The Registrants make certain assumptions they believe that market participants would use in pricing assets or liabilities, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. Credit risk of the Registrants and their counterparties is incorporated in the valuation of assets and liabilities through the use of credit reserves, the impact of which was immaterial at December 31, 2015 and 2014 . The Registrants believe they use valuation techniques that maximize the use of observable market-based inputs and minimize the use of unobservable inputs. A fair value hierarchy has been established that prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. All assets and liabilities are required to be classified in their entirety based on the lowest level of input that is significant to the fair value measurement in its entirety. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability, and may affect the valuation of the asset or liability and its placement within the fair value hierarchy. The Registrants classify fair value balances based on the fair value hierarchy defined as follows: • Level 1 — Consists of unadjusted quoted prices in active markets for identical assets or liabilities that the Registrants have the ability to access as of the reporting date. • Level 2 — Consists of inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. • Level 3 — Consists of unobservable inputs for assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost-benefit constraints. The following table presents assets and liabilities for DTE Energy measured and recorded at fair value on a recurring basis as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Netting (a) Net Balance Level 1 Level 2 Level 3 Netting (a) Net Balance (In millions) Assets: Cash equivalents (b) $ 13 $ 3 $ — $ — $ 16 $ 13 $ 99 $ — $ — $ 112 Nuclear decommissioning trusts 759 477 — — 1,236 792 449 — — 1,241 Other investments (c) 149 — — — 149 100 50 — — 150 Derivative assets: Commodity Contracts: Natural Gas 193 91 103 (285 ) 102 555 140 92 (681 ) 106 Electricity — 239 68 (232 ) 75 — 295 47 (280 ) 62 Other 2 — 3 (2 ) 3 42 — 3 (42 ) 3 Other derivative contracts (d) — 12 — (9 ) 3 — 4 — (3 ) 1 Total derivative assets 195 342 174 (528 ) 183 597 439 142 (1,006 ) 172 Total $ 1,116 $ 822 $ 174 $ (528 ) $ 1,584 $ 1,502 $ 1,037 $ 142 $ (1,006 ) $ 1,675 Liabilities: Derivative liabilities: Commodity Contracts: Natural Gas $ (218 ) $ (57 ) $ (108 ) $ 294 $ (89 ) $ (578 ) $ (78 ) $ (62 ) $ 679 $ (39 ) Electricity — (243 ) (62 ) 253 (52 ) — (290 ) (52 ) 298 (44 ) Other (2 ) — (8 ) 8 (2 ) (32 ) (9 ) (4 ) 45 — Other derivative contracts (d) — (7 ) — 7 — — (5 ) — 3 (2 ) Total derivative liabilities (220 ) (307 ) (178 ) 562 (143 ) (610 ) (382 ) (118 ) 1,025 (85 ) Total $ (220 ) $ (307 ) $ (178 ) $ 562 $ (143 ) $ (610 ) $ (382 ) $ (118 ) $ 1,025 $ (85 ) Net Assets (Liabilities) at the end of the period $ 896 $ 515 $ (4 ) $ 34 $ 1,441 $ 892 $ 655 $ 24 $ 19 $ 1,590 Assets: Current $ 174 $ 284 $ 128 $ (441 ) $ 145 $ 582 $ 504 $ 109 $ (955 ) $ 240 Noncurrent (e) 942 538 46 (87 ) 1,439 920 533 33 (51 ) 1,435 Total Assets $ 1,116 $ 822 $ 174 $ (528 ) $ 1,584 $ 1,502 $ 1,037 $ 142 $ (1,006 ) $ 1,675 Liabilities: Current $ (174 ) $ (260 ) $ (87 ) $ 464 $ (57 ) $ (572 ) $ (357 ) $ (112 ) $ 964 $ (77 ) Noncurrent (46 ) (47 ) (91 ) 98 (86 ) (38 ) (25 ) (6 ) 61 (8 ) Total Liabilities $ (220 ) $ (307 ) $ (178 ) $ 562 $ (143 ) $ (610 ) $ (382 ) $ (118 ) $ 1,025 $ (85 ) Net Assets (Liabilities) at the end of the period $ 896 $ 515 $ (4 ) $ 34 $ 1,441 $ 892 $ 655 $ 24 $ 19 $ 1,590 _______________________________________ (a) Amounts represent the impact of master netting agreements that allow DTE Energy to net gain and loss positions and cash collateral held or placed with the same counterparties. (b) At December 31, 2015 , available-for-sale securities of $16 million included $8 million and $8 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2014 , available-for-sale securities of $112 million , included $105 million and $7 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. (c) Excludes cash surrender value of life insurance investments. (d) Primarily includes foreign currency exchange contracts. (e) Includes $149 million and $150 million at December 31, 2015 and 2014 , respectively, of other investments that are included in DTE Energy's Consolidated Statements of Financial Position in Other investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Net Balance Level 1 Level 2 Level 3 Net Balance (In millions) Assets: Cash equivalents (a) $ 5 $ 3 $ — $ 8 $ 5 $ 99 $ — $ 104 Nuclear decommissioning trusts 759 477 — 1,236 792 449 — 1,241 Other investments 8 — — 8 97 50 — 147 Derivative assets — FTRs — — 3 3 — — 3 3 Total $ 772 $ 480 $ 3 $ 1,255 $ 894 $ 598 $ 3 $ 1,495 Assets: Current $ 5 $ 3 $ 3 $ 11 $ 5 $ 99 $ 3 $ 107 Noncurrent 767 477 — 1,244 889 499 — 1,388 Total Assets $ 772 $ 480 $ 3 $ 1,255 $ 894 $ 598 $ 3 $ 1,495 _______________________________________ (a) At December 31, 2015 , available-for-sale securities of $8 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. At December 31, 2014 , available-for-sale securities of $104 million included $96 million and $8 million of cash equivalents included in Restricted cash and Other investments, respectively, on DTE Electric's Consolidated Statements of Financial Position. Cash Equivalents Cash equivalents include investments with maturities of three months or less when purchased. The cash equivalents shown in the fair value table are comprised of short-term investments and money market funds. Nuclear Decommissioning Trusts and Other Investments The nuclear decommissioning trusts and other investments hold debt and equity securities directly and indirectly through institutional mutual funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The institutional mutual funds hold exchange-traded equity or debt securities and are valued based on stated NAVs. Non-exchange-traded fixed income securities are valued based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee determines that another price source is considered to be preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, the Registrants selectively corroborate the fair value of securities by comparison of market-based price sources. Investment policies and procedures are determined by DTE Energy's Trust Investments Department which reports to DTE Energy's Vice President and Treasurer. Derivative Assets and Liabilities Derivative assets and liabilities are comprised of physical and financial derivative contracts, including futures, forwards, options, and swaps that are both exchange-traded and over-the-counter traded contracts. Various inputs are used to value derivatives depending on the type of contract and availability of market data. Exchange-traded derivative contracts are valued using quoted prices in active markets. The Registrants consider the following criteria in determining whether a market is considered active: frequency in which pricing information is updated, variability in pricing between sources or over time, and the availability of public information. Other derivative contracts are valued based upon a variety of inputs including commodity market prices, broker quotes, interest rates, credit ratings, default rates, market-based seasonality, and basis differential factors. The Registrants monitor the prices that are supplied by brokers and pricing services and may use a supplemental price source or change the primary price source of an index if prices become unavailable or another price source is determined to be more representative of fair value. The Registrants have obtained an understanding of how these prices are derived. Additionally, the Registrants selectively corroborate the fair value of their transactions by comparison of market-based price sources. Mathematical valuation models are used for derivatives for which external market data is not readily observable, such as contracts which extend beyond the actively traded reporting period. The Registrants have established a Risk Management Committee whose responsibilities include directly or indirectly ensuring all valuation methods are applied in accordance with predefined policies. The development and maintenance of the Registrants' forward price curves has been assigned to DTE Energy's Risk Management Department, which is separate and distinct from the trading functions within DTE Energy. The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Energy for the years ended December 31, 2015 and 2014 : Year Ended December 31, 2015 Year Ended December 31, 2014 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of December 31 $ 30 $ (5 ) $ (1 ) $ 24 $ (52 ) $ 13 $ 3 $ (36 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 — — — — (2 ) — — (2 ) Total gains (losses): Included in earnings (44 ) 44 (8 ) (8 ) (40 ) 25 (5 ) (20 ) Recorded in Regulatory assets/liabilities — — 12 12 — — 8 8 Purchases, issuances, and settlements: Purchases — 2 — 2 — 1 — 1 Issuances — — — — — (3 ) — (3 ) Settlements 9 (35 ) (8 ) (34 ) 124 (41 ) (7 ) 76 Net Assets (Liabilities) as of December 31 $ (5 ) $ 6 $ (5 ) $ (4 ) $ 30 $ (5 ) $ (1 ) $ 24 The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ (135 ) $ 13 $ (7 ) $ (129 ) $ 35 $ 9 $ (4 ) $ 40 The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Electric for the years ended December 31, 2015 and 2014 : Year Ended December 31, 2015 2014 (In millions) Net Assets as of December 31 $ 3 $ 3 Change in fair value recorded in Regulatory assets/liabilities 12 8 Purchases, issuances, and settlements: Settlements (12 ) (8 ) Net Assets as of December 31 $ 3 $ 3 The amount of total gains (losses) included in Regulatory assets and liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 3 $ 3 Derivatives are transferred between levels primarily due to changes in the source data used to construct price curves as a result of changes in market liquidity. Transfers in and transfers out are reflected as if they had occurred at the beginning of the period. There were no transfers between Levels 1 and 2 for the Registrants during the years ended December 31, 2015 and 2014 , and there were no transfers from or into Level 3 for DTE Electric during the same periods. The following tables present the unobservable inputs related to DTE Energy's Level 3 assets and liabilities as of December 31, 2015 and 2014 : December 31, 2015 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 103 $ (108 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.50 ) — $ 2.77 /MMBtu $ (0.19 )/MMBtu Electricity $ 68 $ (62 ) Discounted Cash Flow Forward basis price (per MWh) $ (11 ) — $ 14 /MWh $ 2 /MWh December 31, 2014 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 92 $ (62 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (2.28 ) — $ 7.83 /MMBtu $ (0.22 )/MMBtu Electricity $ 47 $ (52 ) Discounted Cash Flow Forward basis price (per MWh) $ (14 ) — $ 15 /MWh $ 4 /MWh The unobservable inputs used in the fair value measurement of the electricity and natural gas commodity types consist of inputs that are less observable due in part to lack of available broker quotes, supported by little, if any, market activity at the measurement date or are based on internally developed models. Certain basis prices (i.e., the difference in pricing between two locations) included in the valuation of natural gas and electricity contracts were deemed unobservable. The inputs listed above would have a direct impact on the fair values of the above security types if they were adjusted. A significant increase (decrease) in the basis price would result in a higher (lower) fair value for long positions, with offsetting impacts to short positions. Fair Value of Financial Instruments The fair value of financial instruments included in the table below is determined by using quoted market prices when available. When quoted prices are not available, pricing services may be used to determine the fair value with reference to observable interest rate indexes. The Registrants have obtained an understanding of how the fair values are derived. The Registrants also selectively corroborate the fair value of their transactions by comparison of market-based price sources. Discounted cash flow analyses based upon estimated current borrowing rates are also used to determine fair value when quoted market prices are not available. The fair values of notes receivable, excluding capital leases, are generally estimated using discounted cash flow techniques that incorporate market interest rates as well as assumptions about the remaining life of the loans and credit risk. Depending on the information available, other valuation techniques may be used that rely on internal assumptions and models. Valuation policies and procedures for the Registrants are determined by DTE Energy's Treasury Department which reports to DTE Energy's Vice President and Treasurer. The following table presents the carrying amount and fair value of financial instruments for DTE Energy as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Carrying Fair Value Carrying Fair Value Amount Level 1 Level 2 Level 3 Amount Level 1 Level 2 Level 3 (In millions) Notes receivable, excluding capital leases $ 32 $ — $ — $ 32 $ 41 $ — $ — $ 41 Dividends payable $ 131 $ 131 $ — $ — $ 122 $ 122 $ — $ — Short-term borrowings $ 499 $ — $ 499 $ — $ 398 $ — $ 398 $ — Long-term debt, excluding capital leases $ 9,285 $ 496 $ 8,136 $ 1,203 $ 8,606 $ 489 $ 8,308 $ 706 The following table presents the carrying amount and fair value of financial instruments for DTE Electric as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Carrying Fair Value Carrying Fair Value Amount Level 1 Level 2 Level 3 Amount Level 1 Level 2 Level 3 (In millions) Notes receivable, excluding capital leases $ 5 $ — $ — $ 5 $ 12 $ — $ — $ 12 Notes receivable — affiliates $ — $ — $ — $ — $ 8 $ — $ — $ 8 Short-term borrowings — affiliates $ 75 $ — $ — $ 75 $ 84 $ — $ — $ 84 Short-term borrowings — other $ 272 $ — $ 272 $ — 50 $ — $ 50 $ — Long-term debt, excluding capital leases $ 5,624 $ — $ 5,432 $ 545 $ 5,259 $ — $ 5,341 $ 496 For further fair value information on financial and derivative instruments see Note 12 to the Consolidated Financial Statements, " Financial and Other Derivative Instruments ". Nuclear Decommissioning Trust Funds DTE Electric has a legal obligation to decommission its nuclear power plants following the expiration of its operating licenses. This obligation is reflected as an ARO on DTE Electric's Consolidated Statements of Financial Position. Rates approved by the MPSC provide for the recovery of decommissioning costs of Fermi 2 and the disposal of low-level radioactive waste. DTE Electric is continuing to fund FERC jurisdictional amounts for decommissioning even though explicit provisions are not included in FERC rates. See Note 7 to the Consolidated Financial Statements, " Asset Retirement Obligations ". The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: December 31, 2015 December 31, 2014 (In millions) Fermi 2 $ 1,211 $ 1,221 Fermi 1 3 3 Low-level radioactive waste 22 17 Total $ 1,236 $ 1,241 The costs of securities sold are determined on the basis of specific identification. The following table sets forth DTE Electric's gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds: Year Ended December 31, 2015 2014 2013 (In millions) Realized gains $ 39 $ 54 $ 83 Realized losses $ (33 ) $ (33 ) $ (41 ) Proceeds from sales of securities $ 885 $ 1,146 $ 1,118 Realized gains and losses from the sale of securities for the Fermi 2 and the low-level radioactive waste funds are recorded to the Regulatory asset and Nuclear decommissioning liability. The following table sets forth DTE Electric's fair value and unrealized gains and losses for the nuclear decommissioning trust funds: December 31, 2015 December 31, 2014 Fair Unrealized Unrealized Losses Fair Unrealized Unrealized Losses (In millions) Equity securities $ 731 $ 195 $ (68 ) $ 756 $ 204 $ (39 ) Debt securities 499 16 (4 ) 474 21 (2 ) Cash and cash equivalents 6 — — 11 — — $ 1,236 $ 211 $ (72 ) $ 1,241 $ 225 $ (41 ) The debt securities at December 31, 2015 and 2014 had an average maturity of approximately 6 years and 7 years , respectively. Securities held in the Nuclear decommissioning trust funds are classified as available-for-sale. As DTE Electric does not have the ability to hold impaired investments for a period of time sufficient to allow for the anticipated recovery of market value, all unrealized losses are considered to be other-than-temporary impairments. Unrealized losses incurred by the Fermi 2 trust are recognized as a Regulatory asset. Other Securities At December 31, 2015 and 2014 , the Registrants' securities were comprised primarily of money market and equity securities. There were no unrealized losses on available-for-sale securities which were reclassified out of Other comprehensive income (loss) and realized into Net Income for DTE Energy or DTE Electric during the years ended December 31, 2015 and 2014 . Gains related to trading securities held at December 31, 2015 , 2014 , and 2013 were $1 million , $14 million , and $22 million , respectively, for DTE Energy, including $1 million , $12 million , and $19 million , respectively, relating to DTE Electric. The trading gains or losses related to the Rabbi Trust assets are allocated from DTE Energy to DTE Electric.

Financial and Other Derivative

Financial and Other Derivative Instruments	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Financial and Other Derivative Instruments	FINANCIAL AND OTHER DERIVATIVE INSTRUMENTS The Registrants recognize all derivatives at their fair value as Derivative assets or liabilities on their respective Consolidated Statements of Financial Position unless they qualify for certain scope exceptions, including the normal purchases and normal sales exception. Further, derivatives that qualify and are designated for hedge accounting are classified as either hedges of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge); or as hedges of the fair value of a recognized asset or liability or of an unrecognized firm commitment (fair value hedge). For cash flow hedges, the portion of the derivative gain or loss that is effective in offsetting the change in the value of the underlying exposure is deferred in Accumulated other comprehensive income (loss) and later reclassified into earnings when the underlying transaction occurs. Gains or losses from the ineffective portion of cash flow hedges are recognized in earnings immediately. For fair value hedges, changes in fair values for the derivative and hedged item are recognized in earnings each period. For derivatives that do not qualify or are not designated for hedge accounting, changes in fair value are recognized in earnings each period. The Registrants' primary market risk exposure is associated with commodity prices, credit, and interest rates. The Registrants have risk management policies to monitor and manage market risks. The Registrants use derivative instruments to manage some of the exposure. DTE Energy uses derivative instruments for trading purposes in its Energy Trading segment. Contracts classified as derivative instruments include electricity, natural gas, oil, certain coal forwards, futures, options, swaps, and foreign currency exchange contracts. Items not classified as derivatives include natural gas inventory, pipeline transportation contracts, renewable energy credits, and natural gas storage assets. DTE Electric — DTE Electric generates, purchases, distributes, and sells electricity. DTE Electric uses forward energy contracts to manage changes in the price of electricity and fuel. Substantially all of these contracts meet the normal purchases and normal sales exception and are therefore accounted for under the accrual method. Other derivative contracts are MTM and recoverable through the PSCR mechanism when settled. This results in the deferral of unrealized gains and losses as Regulatory assets or liabilities until realized. DTE Gas — DTE Gas purchases, stores, transports, distributes and sells natural gas, and sells storage and transportation capacity. DTE Gas has fixed-priced contracts for portions of its expected natural gas supply requirements through March 2018. Substantially all of these contracts meet the normal purchases and normal sales exception and are therefore accounted for under the accrual method. DTE Gas may also sell forward transportation and storage capacity contracts. Forward transportation and storage contracts are generally not derivatives and are therefore accounted for under the accrual method. Gas Storage and Pipelines — This segment is primarily engaged in services related to the transportation and storage of natural gas. Primarily fixed-priced contracts are used in the marketing and management of transportation and storage services. Generally these contracts are not derivatives and are therefore accounted for under the accrual method. Power and Industrial Projects — This segment manages and operates energy and pulverized coal projects, a coke battery, reduced emissions fuel projects, landfill gas recovery, and power generation assets. Primarily fixed-price contracts are used in the marketing and management of the segment assets. These contracts are generally not derivatives and are therefore accounted for under the accrual method. Energy Trading — Commodity Price Risk — Energy Trading markets and trades electricity, natural gas physical products, and energy financial instruments, and provides energy and asset management services utilizing energy commodity derivative instruments. Forwards, futures, options, and swap agreements are used to manage exposure to the risk of market price and volume fluctuations in its operations. These derivatives are accounted for by recording changes in fair value to earnings unless hedge accounting criteria are met. Energy Trading — Foreign Currency Exchange Risk — Energy Trading has foreign currency exchange forward contracts to economically hedge fixed Canadian dollar commitments existing under natural gas and power purchase and sale contracts and natural gas transportation contracts. DTE Energy enters into these contracts to mitigate price volatility with respect to fluctuations of the Canadian dollar relative to the U.S. dollar. These derivatives are accounted for by recording changes in fair value to earnings unless hedge accounting criteria are met. Corporate and Other — Interest Rate Risk — DTE Energy may use interest rate swaps, treasury locks, and other derivatives to hedge the risk associated with interest rate market volatility. Credit Risk — DTE Energy maintains credit policies that significantly minimize overall credit risk. These policies include an evaluation of potential customers’ and counterparties’ financial condition, including the viability of underlying productive assets, credit rating, collateral requirements, or other credit enhancements such as letters of credit or guarantees. DTE Energy generally uses standardized agreements that allow the netting of positive and negative transactions associated with a single counterparty. DTE Energy maintains a provision for credit losses based on factors surrounding the credit risk of its customers, historical trends, and other information. Based on DTE Energy’s credit policies and its December 31, 2015 provision for credit losses, DTE Energy’s exposure to counterparty nonperformance is not expected to have a material adverse effect on DTE Energy's Consolidated Financial Statements. Derivative Activities DTE Energy manages its MTM risk on a portfolio basis based upon the delivery period of its contracts and the individual components of the risks within each contract. Accordingly, it records and manages the energy purchase and sale obligations under its contracts in separate components based on the commodity (e.g. electricity or natural gas), the product (e.g. electricity for delivery during peak or off-peak hours), the delivery location (e.g. by region), the risk profile (e.g. forward or option), and the delivery period (e.g. by month and year). The following describes the categories of activities represented by their operating characteristics and key risks: • Asset Optimization — Represents derivative activity associated with assets owned and contracted by DTE Energy, including forward natural gas purchases and sales, natural gas transportation, and storage capacity. Changes in the value of derivatives in this category typically economically offset changes in the value of underlying non-derivative positions, which do not qualify for fair value accounting. The difference in accounting treatment of derivatives in this category and the underlying non-derivative positions can result in significant earnings volatility. • Marketing and Origination — Represents derivative activity transacted by originating substantially hedged positions with wholesale energy marketers, producers, end-users, utilities, retail aggregators, and alternative energy suppliers. • Fundamentals Based Trading — Represents derivative activity transacted with the intent of taking a view, capturing market price changes, or putting capital at risk. This activity is speculative in nature as opposed to hedging an existing exposure. • Other — Includes derivative activity at DTE Electric related to FTRs. Changes in the value of derivative contracts at DTE Electric are recorded as Derivative assets or liabilities, with an offset to Regulatory assets or liabilities as the settlement value of these contracts will be included in the PSCR mechanism when realized. The following table presents the fair value of derivative instruments as of December 31, 2015 and 2014 for DTE Energy: December 31, 2015 December 31, 2014 Derivative Derivative Derivative Derivative (In millions) Derivatives not designated as hedging instruments: Foreign currency exchange contracts $ 12 $ (7 ) $ 4 $ (5 ) Commodity Contracts: Natural Gas 387 (383 ) 787 (718 ) Electricity 307 (305 ) 342 (342 ) Other 5 (10 ) 45 (45 ) Total derivatives not designated as hedging instruments: $ 711 $ (705 ) $ 1,178 $ (1,110 ) Current $ 570 $ (521 ) $ 1,083 $ (1,041 ) Noncurrent 141 (184 ) 95 (69 ) Total derivatives $ 711 $ (705 ) $ 1,178 $ (1,110 ) The following table presents the fair value of derivative instruments as of December 31, 2015 and 2014 for DTE Electric: December 31, 2015 2014 (In millions) FTRs — Other current assets $ 3 $ 3 Total derivatives not designated as hedging instrument $ 3 $ 3 Certain of DTE Energy's derivative positions are subject to netting arrangements which provide for offsetting of asset and liability positions as well as related cash collateral. Such netting arrangements generally do not have restrictions. Under such netting arrangements, DTE Energy offsets the fair value of derivative instruments with cash collateral received or paid for those contracts executed with the same counterparty, which reduces DTE Energy's Total Assets and Liabilities. Cash collateral is allocated between the fair value of derivative instruments and customer accounts receivable and payable with the same counterparty on a pro rata basis to the extent there is exposure. Any cash collateral remaining, after the exposure is netted to zero, is reflected in Accounts receivable and Accounts payable as collateral paid or received, respectively. DTE Energy also provides and receives collateral in the form of letters of credit which can be offset against net Derivative assets and liabilities as well as Accounts receivable and payable. DTE Energy had issued letters of credit of approximately $7 million at December 31, 2015 and 2014 , which could be used to offset net Derivative liabilities. Letters of credit received from third parties which could be used to offset net Derivative assets were $2 million and $5 million at December 31, 2015 and 2014 , respectively. Such balances of letters of credit are excluded from the tables below and are not netted with the recognized assets and liabilities in DTE Energy's Consolidated Statements of Financial Position. For contracts with certain clearing agents the fair value of derivative instruments is netted against realized positions with the net balance reflected as either 1) a Derivative asset or liability or 2) an Account receivable or payable. Other than certain clearing agents, Accounts receivable and Accounts payable that are subject to netting arrangements have not been offset against the fair value of Derivative assets and liabilities. Certain contracts that have netting arrangements have not been offset in DTE Energy's Consolidated Statements of Financial Position. The impact of netting these derivative instruments and cash collateral related to such contracts is not material. Only the gross amounts for these derivative instruments are included in the table below. For DTE Energy, the total cash collateral posted, net of cash collateral received, was $37 million and $61 million as of December 31, 2015 and 2014 , respectively. There was $2 million of cash collateral related to unrealized positions to net against Derivative assets while Derivative liabilities are shown net of cash collateral of $36 million as of December 31, 2015 . There was no cash collateral related to unrealized positions to net against Derivative assets while Derivative liabilities are shown net of cash collateral of $19 million as of December 31, 2014 . DTE Energy recorded cash collateral paid of $6 million and cash collateral received of $3 million not related to unrealized derivative positions as of December 31, 2015 . DTE Energy recorded cash collateral paid of $44 million and cash collateral received of $2 million not related to unrealized derivative positions as of December 31, 2014 . These amounts are included in Accounts receivable and Accounts payable and are recorded net by counterparty. The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy at December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Gross Amounts of Recognized Assets (Liabilities) Gross Amounts Offset in the Consolidated Statements of Financial Position Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position Gross Amounts of Recognized Assets (Liabilities) Gross Amounts Offset in the Consolidated Statements of Financial Position Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position (In millions) Derivative assets: Commodity Contracts: Natural Gas $ 387 $ (285 ) $ 102 $ 787 $ (681 ) $ 106 Electricity 307 (232 ) 75 342 (280 ) 62 Other 5 (2 ) 3 45 (42 ) 3 Other derivative contracts (a) 12 (9 ) 3 4 (3 ) 1 Total derivative assets $ 711 $ (528 ) $ 183 $ 1,178 $ (1,006 ) $ 172 Derivative liabilities: Commodity Contracts: Natural Gas $ (383 ) $ 294 $ (89 ) $ (718 ) $ 679 $ (39 ) Electricity (305 ) 253 (52 ) (342 ) 298 (44 ) Other (10 ) 8 (2 ) (45 ) 45 — Other derivative contracts (a) (7 ) 7 — (5 ) 3 (2 ) Total derivative liabilities $ (705 ) $ 562 $ (143 ) $ (1,110 ) $ 1,025 $ (85 ) _______________________________________ (a) Primarily includes foreign currency exchange contracts. The following table presents the netting offsets of Derivative assets and liabilities showing the reconciliation of derivative instruments to DTE Energy's Consolidated Statements of Financial Position at December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Derivative Assets Derivative Liabilities Derivative Assets Derivative Liabilities Current Noncurrent Current Noncurrent Current Noncurrent Current Noncurrent (In millions) Total fair value of derivatives $ 570 $ 141 $ (521 ) $ (184 ) $ 1,083 $ 95 $ (1,041 ) $ (69 ) Counterparty netting (441 ) (85 ) 441 85 (955 ) (51 ) 955 51 Collateral adjustment — (2 ) 23 13 — — 9 10 Total derivatives as reported $ 129 $ 54 $ (57 ) $ (86 ) $ 128 $ 44 $ (77 ) $ (8 ) The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations for years ended December 31, 2015 and 2014 is as follows: Location of Gain Gain (Loss) Recognized in Derivatives not Designated as Hedging Instruments 2015 2014 (In millions) Foreign currency exchange contracts Operating Revenues — Non-utility operations $ 3 $ (2 ) Commodity Contracts: Natural Gas Operating Revenues — Non-utility operations (34 ) (30 ) Natural Gas Fuel, purchased power, and gas — non-utility (44 ) (5 ) Electricity Operating Revenues — Non-utility operations 54 123 Other Operating Revenues — Non-utility operations (7 ) (7 ) Total $ (28 ) $ 79 Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility. The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of December 31, 2015 : Commodity Number of Units Natural Gas (MMBtu) 1,740,824,930 Electricity (MWh) 27,668,865 Oil (Gallons) 21,756,000 Foreign Currency Exchange (Canadian dollars) 72,328,008 Various subsidiaries of DTE Energy have entered into contracts which contain ratings triggers and are guaranteed by DTE Energy. These contracts contain provisions which allow the counterparties to require that DTE Energy post cash or letters of credit as collateral in the event that DTE Energy’s credit rating is downgraded below investment grade. Certain of these provisions (known as “hard triggers”) state specific circumstances under which DTE Energy can be required to post collateral upon the occurrence of a credit downgrade, while other provisions (known as “soft triggers”) are not as specific. For contracts with soft triggers, it is difficult to estimate the amount of collateral which may be requested by counterparties and/or which DTE Energy may ultimately be required to post. The amount of such collateral which could be requested fluctuates based on commodity prices (primarily natural gas, power, and coal) and the provisions and maturities of the underlying transactions. As of December 31, 2015 , DTE Energy's contractual obligation to post collateral in the form of cash or letters of credit in the event of a downgrade to below investment grade, under both hard trigger and soft trigger provisions, was approximately $412 million . As of December 31, 2015 , DTE Energy had approximately $592 million of derivatives in net liability positions, for which hard triggers exist. Collateral of approximately $5 million has been posted against such liabilities, including cash and letters of credit. Associated derivative net asset positions for which contractual offset exists were approximately $500 million . The net remaining amount of approximately $87 million is derived from the $412 million noted above.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2015
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	LONG-TERM DEBT Long-Term Debt DTE Energy's long-term debt outstanding and weighted average interest rates (a) of debt outstanding at December 31 were: 2015 2014 (In millions) Mortgage bonds, notes, and other DTE Energy Debt, Unsecured 4.4% due 2016 to 2033 $ 1,947 $ 1,647 DTE Electric Taxable Debt, Principally Secured 4.4% due 2016 to 2045 5,314 4,824 DTE Electric Tax-Exempt Revenue Bonds (b) 5.2% due 2020 to 2030 310 330 DTE Gas Taxable Debt, Principally Secured 4.9% due 2018 to 2045 1,124 1,099 Other Long-Term Debt, Including Non-Recourse Debt 110 121 DTE Energy Total Long-Term Debt 8,805 8,021 Less amount due within one year for DTE Energy (465 ) (161 ) $ 8,340 $ 7,860 DTE Electric Securitization Bonds 6.6% due 2015 $ — $ 105 Less amount due within one year — (105 ) $ — $ — DTE Energy Junior Subordinated Debentures 6.5% due 2061 $ 280 $ 280 5.25% due 2062 200 200 $ 480 $ 480 DTE Electric's long-term debt outstanding and weighted average interest rates (a) of debt outstanding at December 31 were: 2015 2014 (In millions) Mortgage bonds, notes, and other DTE Electric Taxable Debt, Principally Secured 4.4% due 2016 to 2045 $ 5,314 $ 4,824 DTE Electric Tax-Exempt Revenue Bonds (b) 5.2% due 2020 to 2030 310 330 DTE Electric Total Long-Term Debt 5,624 5,154 Less amount due within one year for DTE Electric (151 ) (10 ) $ 5,473 $ 5,144 DTE Electric Securitization Bonds 6.6% due 2015 $ — $ 105 Less amount due within one year — (105 ) $ — $ — _______________________________________ (a) Weighted average interest rates as of December 31, 2015 are shown below the description of each category of debt. (b) DTE Electric Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds. Debt Issuances In 2015 , the following debt was issued: Company Month Type Interest Rate Maturity Amount (In millions) DTE Electric March Mortgage Bonds (a) 3.70% 2045 $ 500 DTE Energy June Senior Notes (b) 3.30% 2022 300 DTE Gas August Mortgage Bonds (c) 3.35% 2027 40 DTE Gas August Mortgage Bonds (c) 4.21% 2045 125 $ 965 _______________________________________ (a) Proceeds were used for the redemption of long-term debt, repayment of short-term borrowings, and general corporate purposes. (b) Proceeds were used for general corporate purposes. (c) Proceeds were used for the redemption of long-term debt and general corporate purposes. Debt Redemptions In 2015 , the following debt was redeemed: Company Month Type Interest Rate Maturity Amount (In millions) DTE Electric March Securitization Bonds 6.62% 2015 $ 105 DTE Electric March Mortgage Bonds 7.904% 2016 10 DTE Gas September Senior Notes 5.94% 2015 140 DTE Electric December Tax-Exempt Revenue Bonds 5.00% 2015 20 DTE Energy Various Other Long-Term Debt Various 2015 11 $ 286 The following table shows the Registrants' scheduled debt maturities, excluding any unamortized discount or premium on debt: 2016 2017 2018 2019 2020 2021 and Thereafter Total (In millions) DTE Energy (a) $ 465 $ 9 $ 407 $ 427 $ 688 $ 7,304 $ 9,300 DTE Electric $ 151 $ — $ 300 $ — $ 632 $ 4,552 $ 5,635 _______________________________________ (a) Amounts include DTE Electric's scheduled debt maturities. Junior Subordinated Debentures At December 31, 2015 , DTE Energy had $280 million of 6.5% Junior Subordinated Debentures due 2061 and $200 million of 5.25% Junior Subordinated Debentures due 2062. DTE Energy has the right to defer interest payments on the debt securities. Should DTE Energy exercise this right, it cannot declare or pay dividends on, or redeem, purchase or acquire, any of its capital stock during the deferral period. Any deferred interest payments will bear additional interest at the rate associated with the related debt issue. As of December 31, 2015 , no interest payments have been deferred on the debt securities. Cross Default Provisions Substantially all of the net utility properties of DTE Electric and DTE Gas are subject to the lien of mortgages. Should DTE Electric or DTE Gas fail to timely pay their indebtedness under these mortgages, such failure may create cross defaults in the indebtedness of DTE Energy.

Preferred and Preference Securi

Preferred and Preference Securities	12 Months Ended
	Dec. 31, 2015
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred and Preference Securities	PREFERRED AND PREFERENCE SECURITIES As of December 31, 2015 , the amount of authorized and unissued stock is as follows: Company Type of Stock Par Value Shares Authorized DTE Energy Preferred $ — 5,000,000 DTE Electric Preferred $ 100 6,747,484 DTE Electric Preference $ 1 30,000,000 DTE Gas Preferred $ 1 7,000,000 DTE Gas Preference $ 1 4,000,000

Short-Term Credit Arrangements

Short-Term Credit Arrangements and Borrowings	12 Months Ended
	Dec. 31, 2015
Short-term Debt [Abstract]
Short-Term Credit Arrangements and Borrowings	SHORT-TERM CREDIT ARRANGEMENTS AND BORROWINGS DTE Energy, DTE Electric, and DTE Gas have unsecured revolving credit agreements that can be used for general corporate borrowings, but are intended to provide liquidity support for each of the companies’ commercial paper programs. Borrowings under the facilities are available at prevailing short-term interest rates. Additionally, DTE Energy has other facilities to support letter of credit issuance. The agreements require DTE Energy, DTE Electric, and DTE Gas to maintain a total funded debt to capitalization ratio of no more than 0.65 to 1. In the agreements, “total funded debt” means all indebtedness of each respective company and their consolidated subsidiaries, including capital lease obligations, hedge agreements, and guarantees of third parties’ debt, but excluding contingent obligations, nonrecourse and junior subordinated debt, and certain equity-linked securities and, except for calculations at the end of the second quarter, certain DTE Gas short-term debt. “Capitalization” means the sum of (a) total funded debt plus (b) “consolidated net worth,” which is equal to consolidated total equity of each respective company and their consolidated subsidiaries (excluding pension effects under certain FASB statements), as determined in accordance with accounting principles generally accepted in the United States of America. At December 31, 2015 , the total funded debt to total capitalization ratios for DTE Energy, DTE Electric, and DTE Gas were 0.51 to 1, 0.51 to 1, and 0.48 to 1, respectively, and are in compliance with this financial covenant. The availability under the facilities in place at December 31, 2015 is shown in the following table: DTE Energy DTE Electric DTE Gas Total (In millions) Unsecured letter of credit facility, expiring in February 2017 $ 100 $ — $ — $ 100 Unsecured letter of credit facility, expiring in September 2017 70 — — 70 Unsecured revolving credit facility, expiring April 2020 1,200 400 300 1,900 1,370 400 300 2,070 Amounts outstanding at December 31, 2015 Commercial paper issuances 33 272 194 499 Letters of credit 130 — — 130 163 272 194 629 Net availability at December 31, 2015 $ 1,207 $ 128 $ 106 $ 1,441 DTE Energy has other outstanding letters of credit which are not included in the above described facilities totaling approximately $17 million which are used for various corporate purposes. The weighted average interest rate for short-term borrowings was 0.6% and 0.4% at December 31, 2015 and 2014 , respectively, for DTE Energy. The weighted average interest rate for short-term borrowings was 0.7% and 0.5% at December 31, 2015 and 2014 , respectively, for DTE Electric. In conjunction with maintaining certain exchange traded risk management positions, DTE Energy may be required to post collateral with its clearing agent. DTE Energy has a demand financing agreement for up to $100 million with its clearing agent. The agreement, as amended, also allows for up to $50 million of additional margin financing provided that DTE Energy posts a letter of credit for the incremental amount and allows the right of setoff with posted collateral. At December 31, 2015 , a $25 million letter of credit was in place, raising the capacity under this facility to $125 million . The $25 million letter of credit is included in the table above. The amount outstanding under this agreement was $103 million and $37 million at December 31, 2015 and 2014 , respectively and was fully offset by the posted collateral. Dividend Restrictions Certain of DTE Energy’s credit facilities contain a provision requiring DTE Energy to maintain a total funded debt to capitalization ratio, as defined in the agreements, of no more than 0.65 to 1, which has the effect of limiting the amount of dividends DTE Energy can pay in order to maintain compliance with this provision. At December 31, 2015 , the effect of this provision was to restrict the payment of approximately $920 million of Retained earnings totaling $4.8 billion . There are no other effective limitations with respect to DTE Energy’s ability to pay dividends.

Capital and Operating Leases

Capital and Operating Leases	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Capital and Operating Leases	CAPITAL AND OPERATING LEASES Lessee - Operating Lease — The Registrants lease various assets under operating leases, including coal railcars, office buildings, a warehouse, computers, vehicles, and other equipment. The lease arrangements expire at various dates through 2046 . The Registrants' future minimum lease payments under non-cancelable leases at December 31, 2015 were: DTE Energy DTE Electric Operating Operating (In millions) 2016 $ 37 $ 24 2017 30 18 2018 25 15 2019 21 14 2020 13 10 Thereafter 71 35 Total minimum lease payments $ 197 $ 116 Rental expense for DTE Energy operating leases was $43 million in 2015 , $38 million in 2014 , and $34 million in 2013 , including rental expense for DTE Electric operating leases of $32 million in 2015 , $26 million in 2014 , and $28 million in 2013 . Lessor - Capital Lease — DTE Energy leases a portion of its pipeline system to the Vector Pipeline through a capital lease contract that expires in 2020, with renewal options extending for five years. DTE Energy owns a 40% interest in the Vector Pipeline. In addition, DTE Energy has an energy services agreement, a portion of which is accounted for as a capital lease. The agreement expires in 2019, with a three or five year renewal option. The components of DTE Energy's net investment in capital leases at December 31, 2015 , were as follows: DTE Energy Capital Leases (In millions) 2016 $ 13 2017 13 2018 13 2019 10 2020 9 Thereafter — Total minimum future lease receipts 58 Residual value of leased pipeline 40 Less unearned income (27 ) Net investment in capital lease 71 Less current portion (6 ) $ 65

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	COMMITMENTS AND CONTINGENCIES Environmental DTE Electric Air — DTE Electric is subject to the EPA ozone and fine particulate transport and acid rain regulations that limit power plant emissions of sulfur dioxide and nitrogen oxides. The EPA and the State of Michigan have issued emission reduction regulations relating to ozone, fine particulate, regional haze, mercury, and other air pollution. These rules have led to controls on fossil-fueled power plants to reduce nitrogen oxide, sulfur dioxide, mercury and other emissions. Additional rulemakings are expected over the next few years which could require additional controls for sulfur dioxide, nitrogen oxides, and hazardous air pollutants. The Cross State Air Pollution Rule (CSAPR), required further reductions of sulfur dioxide and nitrogen oxides emissions beginning in January 2015. DTE Electric expects to meet its obligations under CSAPR. In November 2015, the EPA proposed an update to the CSAPR ozone season program by issuing the CSAPR Update Rule. The proposed rule was subsequently published in the Federal Register in December 2015. Beginning in 2017, this proposal would reduce summertime (May - September) emissions of oxides of nitrogen (NOX) from power plants in 23 states in the eastern half of the U.S., including DTE Energy facilities. The CSAPR Update Rule is intended to reduce air quality impacts of the interstate transport of air pollution on downwind areas' ability to meet the 2008 ozone standard and to respond to the July 2015 remand of certain CSAPR budgets by the U.S. Court of Appeals for the D.C. Circuit. EPA expects to promulgate the final rule in the summer of 2016. It is not possible to quantify the impact of this rulemaking at this time. The Mercury and Air Toxics Standards (MATS) rule, formerly known as the Electric Generating Unit Maximum Achievable Control Technology (EGU MACT) Rule was finalized in December 2011. The MATS rule required reductions of mercury and other hazardous air pollutants beginning in April 2015. DTE Electric requested and was granted compliance date extensions for all relevant units to April 2016. DTE Electric has tested several technologies as MATS compliance alternatives to Flue Gas Desulfurization (FGD) systems to determine technological and economic feasibility. Dry Sorbent Injection (DSI) and Activated Carbon Injection (ACI) technologies were deemed feasible and their implementation will allow units that would not have been economical for FGD installations to continue operation in compliance with MATS. In November 2014, the U.S. Supreme Court agreed to review a challenge to the MATS rule based on a narrowly focused question of how the EPA considered costs in regulating air pollutants emitted by electric utilities. In June 2015, the U.S. Supreme Court reversed the decision of the Court of Appeals for the D.C. District and remanded the MATS rule to the Court of Appeals for further consideration based on their decision that the EPA must consider costs prior to deciding to regulate under the provisions of the Clean Air Act. Subsequently, in December 2015, the Court of Appeals ordered a remand of the MATS rule back to the EPA without staying the rule. DTE Electric does not expect this decision to have a material effect on its compliance plans at this time. The EPA proposed revised air quality standards for ground level ozone in November 2014 and specifically requested comments on the form and level of the ozone standards. The standards were finalized in October 2015. The State of Michigan will recommend designations by October 2016 and the EPA will finalize designations by October 2017. DTE Electric cannot predict the financial impact of the revised ozone standards at this time. In July 2009, DTE Energy received a NOV/FOV from the EPA alleging, among other things, that five DTE Electric power plants violated New Source Performance standards, Prevention of Significant Deterioration requirements, and operating permit requirements under the Clean Air Act. In June 2010, the EPA issued a NOV/FOV making similar allegations related to a project and outage at Unit 2 of the Monroe Power Plant. In March 2013, DTE Energy received a supplemental NOV from the EPA relating to the July 2009 NOV/FOV. The supplemental NOV alleged additional violations relating to the New Source Review provisions under the Clean Air Act, among other things. In August 2010, the U.S. Department of Justice, at the request of the EPA, brought a civil suit in the U.S. District Court for the Eastern District of Michigan against DTE Energy and DTE Electric, related to the June 2010 NOV/FOV and the outage work performed at Unit 2 of the Monroe Power Plant, but not relating to the July 2009 NOV/FOV. Among other relief, the EPA requested the court to require DTE Electric to install and operate the best available control technology at Unit 2 of the Monroe Power Plant. Further, the EPA requested the court to issue a preliminary injunction to require DTE Electric to (i) begin the process of obtaining the necessary permits for the Monroe Unit 2 modification and (ii) offset the pollution from Monroe Unit 2 through emissions reductions from DTE Electric's fleet of coal-fired power plants until the new control equipment is operating. In August 2011, the U.S. District Court judge granted DTE Energy's motion for summary judgment in the civil case, dismissing the case and entering judgment in favor of DTE Energy and DTE Electric. In October 2011, the EPA caused to be filed a Notice of Appeal to the Court of Appeals for the Sixth Circuit. In March 2013, the Court of Appeals remanded the case to the U.S. District Court for review of the procedural component of the New Source Review notification requirements. In September 2013, the EPA caused to be filed a motion seeking leave to amend their complaint regarding the June 2010 NOV/FOV adding additional claims related to outage work performed at the Trenton Channel and Belle River power plants as well as additional claims related to work performed at the Monroe Power Plant. In addition, the Sierra Club caused to be filed a motion to add a claim regarding the River Rouge Power Plant. In March 2014, the U.S. District Court judge granted again DTE Energy's motion for summary judgment dismissing the civil case related to Monroe Unit 2. In April 2014, the U.S. District Court judge granted motions filed by the EPA and the Sierra Club to amend their New Source Review complaint adding additional claims for Monroe Units 1, 2 and 3, Belle River Units 1 and 2, Trenton Channel Unit 9 and denied the claims related to River Rouge Power Plant that were brought by the Sierra Club. In June 2014, the EPA filed a motion requesting certification for appeal of the March 2014 summary judgment decision. In October 2014, the EPA and the U.S. Department of Justice filed the anticipated notice of appeal of the U.S. District Court judge's dismissal of the Monroe Unit 2 case. The amended New Source Review claims are all stayed until the appeal is resolved by the Court of Appeals for the Sixth Circuit. Oral arguments for the appeal occurred in December 2015. The Registrants believe that the plants and generating units identified by the EPA and the Sierra Club have complied with all applicable federal environmental regulations. Depending upon the outcome of discussions with the EPA regarding the two NOVs/FOVs, DTE Electric could be required to install additional pollution control equipment at some or all of the power plants in question, implement early retirement of facilities where control equipment is not economical, engage in supplemental environmental programs, and/or pay fines. The Registrants cannot predict the financial impact or outcome of this matter, or the timing of its resolution. The EPA is implementing regulatory actions under the Clean Air Act to address emissions of GHGs from the utility sector and other sectors of the economy. Among these actions, the EPA has finalized performance standards for emissions of carbon dioxide from new and existing electric generating units (EGUs). The carbon standards for new sources are not expected to have a material impact on DTE Electric, since DTE Electric has no plans to build new coal-fired generation and any potential new gas generation will be able to comply with the standards. It is not possible to determine the potential impact of the final carbon standards (also known as the EPA Clean Power Plan) on existing sources at this time. Pending or future legislation or other regulatory actions could have a material impact on DTE Electric's operations and financial position and the rates charged to its customers. Impacts include expenditures for environmental equipment beyond what is currently planned, financing costs related to additional capital expenditures, the purchase of emission credits from market sources, higher costs of purchased power, and the retirement of facilities where control equipment is not economical. DTE Electric would seek to recover these incremental costs through increased rates charged to its utility customers, as authorized by the MPSC. To comply with air pollution requirements, DTE Electric spent approximately $2.3 billion through 2015 . DTE Electric estimates making capital expenditures of approximately $40 million in 2016 . Water — In response to an EPA regulation, DTE Electric would be required to examine alternatives for reducing the environmental impacts of the cooling water intake structures at several of its facilities. Based on the results of completed studies and expected future studies, DTE Electric may be required to install technologies to reduce the impacts of the water intake structures. A final rule became effective in October 2015. The final rule requires studies to be completed by April 2018 to determine the type of technology needed to reduce impacts to fish. DTE Electric has initiated the process of completing the required studies. Final compliance for the installation of any required technology will be determined by each state on a case by case, site specific basis. DTE Electric is currently evaluating the compliance options and working with the State of Michigan on evaluating whether any controls are needed. These evaluations/studies may require modifications to some existing intake structures. It is not possible to quantify the impact of this rulemaking at this time. Contaminated and Other Sites — Prior to the construction of major interstate natural gas pipelines, gas for heating and other uses was manufactured locally from processes involving coal, coke, or oil. The facilities, which produced gas, have been designated as MGP sites. DTE Electric conducted remedial investigations at contaminated sites, including three former MGP sites. The investigations have revealed contamination related to the by-products of gas manufacturing at each MGP site. In addition to the MGP sites, DTE Electric is also in the process of cleaning up other contaminated sites, including the area surrounding an ash landfill, electrical distribution substations, electric generating power plants, and underground and aboveground storage tank locations. The findings of these investigations indicated that the estimated cost to remediate these sites is expected to be incurred over the next several years. At December 31, 2015 and 2014 , DTE Electric had $8 million and $10 million accrued for remediation, respectively. Any change in assumptions, such as remediation techniques, nature and extent of contamination, and regulatory requirements, could impact the estimate of remedial action costs for the sites and affect DTE Electric’s financial position and cash flows. DTE Electric believes the likelihood of a material change to the accrued amount is remote based on current knowledge of the conditions at each site. Coal Combustion Residuals and Effluent Limitations Guidelines — A final EPA rule for the disposal of coal combustion residuals, commonly known as coal ash became effective in October 2015. The rule is based on the continued listing of coal ash as a non-hazardous waste and relies on various self-implementation design and performance standards. DTE Electric owns and operates three permitted engineered coal ash storage facilities to dispose of coal ash from coal-fired power plants and operates a number of smaller impoundments at its power plants. At certain facilities, the rule requires the installation of monitoring wells, compliance with groundwater standards, and the closure of basins at the end of the useful life of the associated power plant. At other facilities, the rule requires ash laden waters be moved from earthen basins to steel and concrete tanks. In November 2015, the EPA finalized effluent limitations guidelines for the steam electric power generating industry which may require additional controls to be installed between 2018 and 2023. Certain effluent limitations guidelines requirements will be required to be performed in conjunction with the coal combustion residuals requirements. Costs associated with the building of new facilities over the next seven years to comply with coal combustion residuals requirements and effluent limitations guidelines are estimated to be approximately $290 million . See Note 7 to the Consolidated Financial Statements, " Asset Retirement Obligations ", for estimated costs of closure of old facilities. DTE Gas Contaminated and Other Sites — DTE Gas owns or previously owned, 14 former MGP sites. Investigations have revealed contamination related to the by-products of gas manufacturing at each site. Cleanup of five of the MGP sites is complete and the sites are closed. DTE Gas has also completed partial closure of two additional sites. Cleanup activities associated with the remaining sites will continue over the next several years. The MPSC has established a cost deferral and rate recovery mechanism for investigation and remediation costs incurred at former MGP sites. In addition to the MGP sites, DTE Gas is also in the process of cleaning up other contaminated sites, including gate stations, gas pipeline releases, and underground storage tank locations. As of December 31, 2015 and 2014 , DTE Gas had $22 million and $24 million accrued for remediation, respectively. Any change in assumptions, such as remediation techniques, nature and extent of contamination, and regulatory requirements, could impact the estimate of remedial action costs for the sites and affect DTE Gas' financial position and cash flows. DTE Gas anticipates the cost amortization methodology approved by the MPSC, which allows for amortization of the MGP costs over a ten -year period beginning with the year subsequent to the year the MGP costs were incurred, will prevent environmental costs from having a material adverse impact on DTE Gas' results of operations. Non-utility DTE Energy’s non-utility businesses are subject to a number of environmental laws and regulations dealing with the protection of the environment from various pollutants. The Michigan coke battery facility received and responded to information requests from the EPA that resulted in the issuance of a NOV in June 2007 alleging potential maximum achievable control technologies and new source review violations. The EPA is in the process of reviewing DTE Energy’s position of demonstrated compliance and has not initiated escalated enforcement. At this time, DTE Energy cannot predict the impact of this issue but expects no further action. Furthermore, the Michigan coke battery facility is the subject of an investigation by the MDEQ concerning visible emissions readings that resulted from DTE Energy self reporting to MDEQ questionable activities by an employee of a contractor hired by DTE Energy to perform the visible emissions readings. At this time, DTE Energy cannot predict the impact of this investigation. The Shenango coke battery received two NOVs from the Pennsylvania Department of Environmental Protection (PADEP) in 2010 alleging violations of the permit for the Pennsylvania coke battery facility in connection with coal pile storm water runoff. DTE Energy settled the alleged violations by implementing best management practices to address the issues and repair/upgrade its wastewater treatment plant. DTE Energy received a construction permit to upgrade its existing waste water treatment system. Due to the December 2015 decision to close the Shenango coke battery in January 2016, DTE Energy will not proceed with the upgrade to its wastewater treatment system. The Shenango coke battery received an NOV from the Allegheny County, PA Health Department pertaining to excessive opacity readings from fugitive sources in excess of its standards for the Pennsylvania coke battery facility. Fugitive sources at the plant are in full compliance with the applicable Federal Opacity Standards. DTE Energy agreed to a Consent Order and Agreement with Allegheny County pursuant to which DTE Energy paid a fine of $300,000 and spent $300,000 for a supplemental environmental project. In May 2014, the Group Against Smog & Pollution (GASP) filed a complaint alleging that DTE Energy's coke battery facility in Pennsylvania was in violation of visible emissions limits under the Federal Clean Air Act and/or Article XXI of the Allegheny County, PA Health Department's Rules and Regulations. DTE Energy believed that the GASP suit was without merit and filed a motion to dismiss in July 2014. In March 2015, the U.S. District Court granted DTE Energy's motion for dismissal. In April 2015, GASP filed a notice of appeal. In January 2016, the U.S. Court of Appeals for the Third Circuit affirmed the judgment of dismissal. Other In 2010, the EPA finalized a new 1 -hour sulfur dioxide ambient air quality standard that requires states to submit plans for non-attainment areas to be in compliance by 2018. Michigan's non-attainment area includes DTE Energy facilities in southwest Detroit and areas of Wayne County. Modeling runs by the MDEQ suggest that emission reductions may be required by significant sources of sulfur dioxide emissions in these areas, including DTE Electric power plants and DTE Energy's Michigan coke battery facility. As part of the state implementation plan process, DTE Energy has worked with MDEQ to develop air permits reflecting significant SO2 emission reductions that, in combination with other non-DTE Energy sources emission reduction strategies, will help the state attain the standard and sustain its attainment. Since several non-DTE Energy sources are also part of the proposed compliance plan, DTE Energy is unable to determine the full impact of the final required emissions reductions at this time. Nuclear Operations Property Insurance DTE Electric maintains property insurance policies specifically for the Fermi 2 plant. These policies cover such items as replacement power and property damage. NEIL is the primary supplier of the insurance policies. DTE Electric maintains a policy for extra expenses, including replacement power costs necessitated by Fermi 2’s unavailability due to an insured event. This policy has a 12-week waiting period and provides an aggregate $490 million of coverage over a three -year period. DTE Electric has $1.5 billion in primary coverage and $1.25 billion of excess coverage for stabilization, decontamination, debris removal, repair and/or replacement of property, and decommissioning. The combined coverage limit for total property damage is $2.75 billion . The total limit for property damage for non-nuclear events is $2 billion and an aggregate of $328 million of coverage for extra expenses over a two -year period. On January 13, 2015, the Terrorism Risk Insurance Program Reauthorization Act of 2015 was signed, extending TRIA through December 31, 2020. For multiple terrorism losses caused by acts of terrorism not covered under the TRIA occurring within one year after the first loss from terrorism, the NEIL policies would make available to all insured entities up to $3.2 billion , plus any amounts recovered from reinsurance, government indemnity, or other sources to cover losses. Under NEIL policies, DTE Electric could be liable for maximum assessments of up to approximately $45 million per event if the loss associated with any one event at any nuclear plant should exceed the accumulated funds available to NEIL. Public Liability Insurance As required by federal law, DTE Electric maintains $375 million of public liability insurance for a nuclear incident. For liabilities arising from a terrorist act outside the scope of TRIA, the policy is subject to one industry aggregate limit of $300 million . Further, under the Price-Anderson Amendments Act of 2005, deferred premium charges up to $127 million could be levied against each licensed nuclear facility, but not more than $19 million per year per facility. Thus, deferred premium charges could be levied against all owners of licensed nuclear facilities in the event of a nuclear incident at any of these facilities. Nuclear Fuel Disposal Costs In accordance with the Federal Nuclear Waste Policy Act of 1982, DTE Electric has a contract with the DOE for the future storage and disposal of spent nuclear fuel from Fermi 2 that required DTE Electric to pay the DOE a fee of 1 mill per kWh of Fermi 2 electricity generated and sold. The fee was a component of nuclear fuel expense. The DOE's Yucca Mountain Nuclear Waste Repository program for the acceptance and disposal of spent nuclear fuel was terminated in 2011. DTE Electric is a party in the litigation against the DOE for both past and future costs associated with the DOE's failure to accept spent nuclear fuel under the timetable set forth in the Federal Nuclear Waste Policy Act of 1982. In July 2012, DTE Electric executed a settlement agreement with the federal government for costs associated with the DOE's delay in acceptance of spent nuclear fuel from Fermi 2 for permanent storage. The settlement agreement, including extensions, provides for a claims process and payment of delay-related costs experienced by DTE Electric through 2016. DTE Electric's claims are being settled and paid on a timely basis. The settlement proceeds reduce the cost of the dry cask storage facility assets and provide reimbursement for related operating expenses. The 1 mill per kWh DOE fee was reduced to zero effective May 16, 2014. DTE Electric currently employs a spent nuclear fuel storage strategy utilizing a fuel pool and a newly completed dry cask storage facility. The dry cask storage facility is expected to provide sufficient spent fuel storage capability for the life of the plant as defined by the original operating license. The federal government continues to maintain its legal obligation to accept spent nuclear fuel from Fermi 2 for permanent storage. Issues relating to long-term waste disposal policy and to the disposition of funds contributed by DTE Electric ratepayers to the federal waste fund await future governmental action. Synthetic Fuel Guarantees DTE Energy discontinued the operations of its synthetic fuel production facilities throughout the United States as of December 31, 2007. DTE Energy provided certain guarantees and indemnities in conjunction with the sales of interests in its synfuel facilities. The guarantees cover potential commercial, environmental, oil price, and tax-related obligations that will survive until 90 days after expiration of all applicable statutes of limitations. DTE Energy estimates that its maximum potential liability under these guarantees at December 31, 2015 is approximately $850 million . Payment under these guarantees is considered remote. REF Guarantees DTE Energy has provided certain guarantees and indemnities in conjunction with the sales of interests in or lease of its REF facilities. The guarantees cover potential commercial, environmental, and tax-related obligations that will survive until 90 days after expiration of all applicable statutes of limitations. DTE Energy estimates that its maximum potential liability under these guarantees at December 31, 2015 is approximately $268 million . Payment under these guarantees is considered remote. Other Guarantees In certain limited circumstances, the Registrants enter into contractual guarantees. The Registrants may guarantee another entity’s obligation in the event it fails to perform and may provide guarantees in certain indemnification agreements. Finally, the Registrants may provide indirect guarantees for the indebtedness of others. DTE Energy’s guarantees are not individually material with maximum potential payments totaling $56 million at December 31, 2015 . Payment under these guarantees is considered remote. DTE Energy is periodically required to obtain performance surety bonds in support of obligations to various governmental entities and other companies in connection with its operations. As of December 31, 2015 , DTE Energy had approximately $55 million of performance bonds outstanding. In the event that such bonds are called for nonperformance, DTE Energy would be obligated to reimburse the issuer of the performance bond. DTE Energy is released from the performance bonds as the contractual performance is completed and does not believe that a material amount of any currently outstanding performance bonds will be called. Labor Contracts There are several bargaining units for DTE Energy's approximately 4,900 represented employees, including DTE Electric's approximately 2,600 represented employees. The majority of the represented employees are under contracts that expire in 2016 and 2017. Purchase Commitments As of December 31, 2015 , the Registrants were party to numerous long-term purchase commitments relating to a variety of goods and services required for their businesses. These agreements primarily consist of fuel supply commitments and renewable energy contracts for the Registrants, as well as energy trading contracts for DTE Energy. The Registrants estimate the following commitments from 2016 through 2051 for DTE Energy, and 2016 through 2033 for DTE Electric, as detailed in the following table: DTE Energy DTE Electric (In millions) 2016 $ 2,038 $ 493 2017 1,160 412 2018 611 240 2019 397 120 2020 353 88 2021 and thereafter 3,043 992 $ 7,602 $ 2,345 DTE Energy and DTE Electric expect that 2016 annual capital expenditures and contributions to equity method investees will be approximately $2.7 billion and $1.6 billion , respectively. The Registrants have made certain commitments in connection with the estimated 2016 annual capital expenditures and contributions to equity method investees. Bankruptcies Certain of the Registrants' customers and suppliers have filed for bankruptcy protection under the U.S. Bankruptcy Code. The Registrants regularly review contingent matters relating to these customers and suppliers and their purchase and sale contracts, and record provisions for amounts considered at risk of probable loss in the allowance for doubtful accounts. The Registrants believe their accrued amounts are adequate for probable loss. Michigan Sales and Use Tax Litigation In 2010, the Michigan Department of Treasury finalized a sales and use tax audit of DTE Electric for the period from January 2003 to September 2006. It determined that DTE Electric’s electric distribution equipment was not eligible for an industrial-processing exemption and therefore was subject to the use tax. DTE Electric paid the tax for the period under audit and filed a claim in the Michigan Court of Claims disputing the tax determination. DTE Electric has continued to apply an appropriate industrial-processing exemption percentage, where applicable, for purchases in the years subsequent to 2006. The Michigan Court of Claims found in favor of DTE Electric, and that determination was subsequently appealed to the Michigan Supreme Court. In July 2015, the Michigan Supreme Court issued an opinion finding that DTE Electric was eligible for a partial industrial-processing exemption on its electric distribution equipment based on the proportion of exempt use of that equipment. The Supreme Court reversed the lower court decision in part and remanded the case to the Michigan Court of Claims. DTE Electric reached a settlement with the Michigan Department of Treasury in February 2016 and will receive a partial refund of amounts previously paid. Other Contingencies The Registrants are involved in certain other legal, regulatory, administrative, and environmental proceedings before various courts, arbitration panels, and governmental agencies concerning claims arising in the ordinary course of business. These proceedings include certain contract disputes, additional environmental reviews and investigations, audits, inquiries from various regulators, and pending judicial matters. The Registrants cannot predict the final disposition of such proceedings. The Registrants regularly review legal matters and record provisions for claims that they can estimate and are considered probable of loss. The resolution of these pending proceedings is not expected to have a material effect on the Registrants' Consolidated Financial Statements in the periods they are resolved. For a discussion of contingencies related to regulatory matters and derivatives see Notes 8 and 12 to the Consolidated Financial Statements, " Regulatory Matters " and " Financial and Other Derivative Instruments ", respectively.

Retirement Benefits and Trustee

Retirement Benefits and Trusteed Assets	12 Months Ended
	Dec. 31, 2015
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Retirement Benefits and Trusteed Assets	RETIREMENT BENEFITS AND TRUSTEED ASSETS Pension Plan Benefits DTE Energy has qualified defined benefit retirement plans for eligible represented and non-represented employees. The plans are noncontributory and provide traditional retirement benefits based on the employees’ years of benefit service, average final compensation, and age at retirement. In addition, certain represented and non-represented employees are covered under cash balance provisions that determine benefits on annual employer contributions and interest credits. DTE Energy also maintains supplemental nonqualified, noncontributory, retirement benefit plans for selected management employees. These plans provide for benefits that supplement those provided by DTE Energy’s other retirement plans. DTE Electric participates in various plans that provide pension and other postretirement benefits for DTE Energy and its affiliates. The plans are sponsored by DTE Energy Corporate Services, LLC (LLC), a subsidiary of DTE Energy. DTE Electric is allocated net periodic benefit costs for its share of the amounts of the combined plans. Effective January 1, 2012 for the Registrants' non-represented employees, and in June 2011 for certain DTE Energy represented employees and March 2013 for the majority of DTE Electric represented employees, the Registrants discontinued offering a defined benefit retirement plan to newly hired employees. In its place, the Registrants will annually contribute an amount equivalent to 4% ( 8% for certain DTE Gas represented employees) of an employee's eligible pay to the employee's defined contribution retirement savings plan. The Registrants' policy is to fund pension costs by contributing amounts consistent with the provisions of the Pension Protection Act of 2006 and additional amounts when it deems appropriate. DTE Energy contributed $177 million , including $145 million of DTE Electric contributions, to the qualified pension plans in 2015 . At the discretion of management, and depending upon financial market conditions, DTE Energy anticipates making up to $180 million in contributions, including $145 million of DTE Electric contributions, to the pension plans in 2016 . Net pension cost for DTE Energy includes the following components: 2015 2014 2013 (In millions) Service cost $ 100 $ 83 $ 94 Interest cost 210 212 192 Expected return on plan assets (296 ) (273 ) (266 ) Amortization of net actuarial loss 205 157 208 Special termination benefits 2 — — Net pension cost $ 221 $ 179 $ 228 2015 2014 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial loss $ 19 $ 805 Amortization of net actuarial loss (205 ) (157 ) Prior service credit — (7 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (186 ) $ 641 Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 35 $ 820 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 162 $ 206 Net pension cost for DTE Electric includes the following components: 2015 2014 2013 (In millions) Service cost $ 77 $ 64 $ 73 Interest cost 160 162 146 Expected return on plan assets (210 ) (194 ) (184 ) Amortization of: Net actuarial loss 147 110 148 Prior service cost 1 2 1 Special termination benefits 1 — — Net pension cost $ 176 $ 144 $ 184 2015 2014 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial (gain) loss $ (13 ) $ 614 Amortization of net actuarial loss (147 ) (110 ) Prior service credit — (2 ) Amortization of prior service cost (1 ) (2 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (161 ) $ 500 Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 15 $ 644 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 115 $ 149 Prior service cost $ 1 $ 1 The following table reconciles the obligations, assets, and funded status of the plans as well as the amounts recognized as prepaid pension cost or pension liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Accumulated benefit obligation, end of year $ 4,569 $ 4,853 $ 3,401 $ 3,712 Change in projected benefit obligation Projected benefit obligation, beginning of year $ 5,269 $ 4,380 $ 4,018 $ 3,341 Service cost 100 83 75 64 Interest cost 210 212 156 162 Plan amendments — (7 ) — (2 ) Actuarial (gain) loss (357 ) 836 (273 ) 634 Transfer due to plan sponsorship change — — (99 ) — Special termination benefits 2 — — — Benefits paid (253 ) (235 ) (192 ) (181 ) Projected benefit obligation, end of year $ 4,971 $ 5,269 $ 3,685 $ 4,018 Change in plan assets Plan assets at fair value, beginning of year $ 3,981 $ 3,720 $ 2,812 $ 2,632 Actual return on plan assets (79 ) 301 (56 ) 212 Company contributions 183 195 145 149 Benefits paid (253 ) (235 ) (192 ) (181 ) Plan assets at fair value, end of year $ 3,832 $ 3,981 $ 2,709 $ 2,812 Funded status of the plans $ (1,139 ) $ (1,288 ) $ (976 ) $ (1,206 ) Amount recorded as: Current liabilities $ (6 ) $ (8 ) $ — $ (6 ) Noncurrent liabilities (1,133 ) (1,280 ) (976 ) (1,200 ) $ (1,139 ) $ (1,288 ) $ (976 ) $ (1,206 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 180 $ 194 $ — $ 44 Prior service credit (1 ) (1 ) — — $ 179 $ 193 $ — $ 44 Amounts recognized in Regulatory assets (see Note 8 - "Regulatory Matters") Net actuarial loss $ 2,113 $ 2,285 $ 1,588 $ 1,738 Prior service cost (credit) (1 ) (1 ) 4 5 $ 2,112 $ 2,284 $ 1,592 $ 1,743 At December 31, 2015 , the benefits related to the Registrants' qualified and nonqualified pension plans expected to be paid in each of the next five years and in the aggregate for the five fiscal years thereafter are as follows: DTE Energy DTE Electric (In millions) 2016 $ 274 $ 213 2017 285 221 2018 297 231 2019 306 238 2020 314 244 2021-2025 1,662 1,279 Total $ 3,138 $ 2,426 Assumptions used in determining the projected benefit obligation and net pension costs of the Registrants are: 2015 2014 2013 Projected benefit obligation Discount rate 4.50% 4.12% 4.95% Rate of compensation increase 4.65% 4.65% 4.20% Net pension costs Discount rate 4.12% 4.95% 4.15% Rate of compensation increase 4.65% 4.20% 4.20% Expected long-term rate of return on plan assets 7.75% 7.75% 8.25% The Registrants employ a formal process in determining the long-term rate of return for various asset classes. Management reviews historic financial market risks and returns and long-term historic relationships between the asset classes of equities, fixed income, and other assets, consistent with the widely accepted capital market principle that asset classes with higher volatility generate a greater return over the long-term. Current market factors such as inflation, interest rates, asset class risks, and asset class returns are evaluated and considered before long-term capital market assumptions are determined. The long-term portfolio return is also established employing a consistent formal process, with due consideration of diversification, active investment management, and rebalancing. Peer data is reviewed to check for reasonableness. As a result of this process, the Registrants have long-term rate of return assumptions for the pension plans of 7.75% and other postretirement benefit plans of 8.00% for 2016 . The Registrants believe these rates are a reasonable assumption for the long-term rate of return on plan assets for 2016 given the current investment strategy. The Registrants employ a total return investment approach whereby a mix of equities, fixed income, and other investments are used to maximize the long-term return on plan assets consistent with prudent levels of risk, with consideration given to the liquidity needs of the plan. Risk tolerance is established through consideration of future plan cash flows, plan funded status, and corporate financial considerations. The investment portfolio contains a diversified blend of equity, fixed income, and other investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks, growth and value stocks, and large and small market capitalizations. Fixed income securities generally include market duration bonds of companies from diversified industries, mortgage-backed securities, non-U.S. securities, bank loans, and U.S. Treasuries. Pension assets include long duration U.S. government and diversified corporate bonds intended to partially mitigate liability volatility caused by changes in discount rates. Other assets, such as private markets and hedge funds, are used to enhance long-term returns while improving portfolio diversification. Derivatives may be utilized in a risk controlled manner, to potentially increase the portfolio beyond the market value of invested assets and/or reduce portfolio investment risk. Investment risk is measured and monitored on an ongoing basis through annual liability measurements, periodic asset/liability studies, and quarterly investment portfolio reviews. Target allocations for the Registrants' pension plan assets as of December 31, 2015 are listed below: U.S. Large Capitalization (Cap) Equity Securities 22 % U.S. Small Cap and Mid Cap Equity Securities 5 Non-U.S. Equity Securities 20 Fixed Income Securities 25 Hedge Funds and Similar Investments 20 Private Equity and Other 8 100 % The following tables provide the fair value measurement amounts for the Registrants' pension plan assets at December 31, 2015 and 2014 (a): December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (In millions) DTE Energy asset category: Short-term Investments (b) $ 23 $ — $ — $ 23 $ 46 $ — $ — $ 46 Equity Securities U.S. Large Cap (c) 842 — — 842 899 — — 899 U.S. Small Cap and Mid Cap (d) 219 — — 219 225 — — 225 Non-U.S. (e) 510 251 — 761 526 219 — 745 Fixed Income Securities (f) 5 1,024 — 1,029 7 1,113 — 1,120 Hedge Funds and Similar Investments (g) 220 96 452 768 226 95 438 759 Private Equity and Other (h) — — 190 190 — — 187 187 Securities Lending (i) (129 ) (25 ) — (154 ) (189 ) (50 ) — (239 ) Securities Lending Collateral (i) 129 25 — 154 189 50 — 239 DTE Energy Total $ 1,819 $ 1,371 $ 642 $ 3,832 $ 1,929 $ 1,427 $ 625 $ 3,981 DTE Electric asset category: Short-term Investments (b) $ 16 $ — $ — $ 16 $ 33 $ — $ — $ 33 Equity Securities U.S. Large Cap (c) 599 — — 599 638 — — 638 U.S. Small Cap and Mid Cap (d) 157 — — 157 162 — — 162 Non-U.S. (e) 367 178 — 545 378 157 — 535 Fixed Income Securities (f) 4 699 — 703 5 758 — 763 Hedge Funds and Similar Investments (g) 158 69 325 552 163 68 315 546 Private Equity and Other (h) — — 137 137 — — 135 135 Securities Lending (i) (93 ) (18 ) — (111 ) (136 ) (36 ) — (172 ) Securities Lending Collateral (i) 93 18 — 111 136 36 — 172 DTE Electric Total $ 1,301 $ 946 $ 462 $ 2,709 $ 1,379 $ 983 $ 450 $ 2,812 _______________________________________ (a) For a description of levels within the fair value hierarchy, see Note 11 to the Consolidated Financial Statements, " Fair Value ". (b) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (c) This category comprises both actively and not actively managed portfolios that track the S&P 500 low cost equity index funds. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (d) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (e) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (f) This category includes corporate bonds from diversified industries, U.S. Treasuries, and mortgage-backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as Level 2 assets. (g) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded debt and equity, publicly traded mutual funds, commingled and limited partnership funds, and non-exchange traded securities. Pricing for Level 1 and Level 2 assets in this category is obtained from quoted prices in actively traded markets and quoted prices from broker or pricing services. Non-exchange traded securities held in commingled funds are classified as Level 2 assets. Valuations for some Level 3 assets in this category may be based on limited observable inputs as there may be little, if any, publicly available pricing. (h) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. Pricing for investments in this category is based on limited observable inputs as there is little, if any, publicly available pricing. Valuations for assets in this category may be based on discounted cash flow analyses, relevant publicly-traded comparables, and comparable transactions. (i) In 2014, the Registrants began a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' pension trusts to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. The pension trust holds debt and equity securities directly and indirectly through commingled funds and institutional mutual funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The commingled funds and institutional mutual funds hold exchange-traded equity or debt securities and are valued based on stated NAVs. Non-exchange traded fixed income securities are valued by the trustee based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee challenges an assigned price and determines that another price source is considered to be preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, the Registrants selectively corroborate the fair values of securities by comparison of market-based price sources. The following table provides a reconciliation of beginning and ending balances of DTE Energy's pension plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Year Ended December 31, 2015 Year Ended December 31, 2014 Hedge Funds Private Equity Total Hedge Funds Private Equity Total (In millions) Beginning Balance at January 1 $ 438 $ 187 $ 625 $ 395 $ 170 $ 565 Total realized/unrealized gains (losses) 10 10 20 22 16 38 Purchases, sales, and settlements: Purchases 4 32 36 22 31 53 Sales — (39 ) (39 ) (1 ) (30 ) (31 ) Ending Balance at December 31 $ 452 $ 190 $ 642 $ 438 $ 187 $ 625 The amount of total gains for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period $ 10 $ (3 ) $ 7 $ 21 $ 11 $ 32 The following table provides a reconciliation of beginning and ending balances of DTE Electric's pension plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Year Ended December 31, 2015 Year Ended December 31, 2014 Hedge Funds Private Equity Total Hedge Funds Private Equity Total (In millions) Beginning Balance at January 1 $ 315 $ 135 $ 450 $ 285 $ 122 407 Total realized/unrealized gains (losses) 7 7 14 15 12 27 Purchases, sales, and settlements: Purchases 3 23 26 16 22 38 Sales — (28 ) (28 ) (1 ) (21 ) (22 ) Ending Balance at December 31 $ 325 $ 137 $ 462 $ 315 $ 135 $ 450 The amount of total gains for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period $ 7 $ (2 ) $ 5 $ 15 $ 8 $ 23 There were no transfers from or into Level 3 and there were no significant transfers between Level 2 and Level 1 in the years ended December 31, 2015 and 2014 for either of the Registrants. Other Postretirement Benefits The Registrants participate in defined benefit plans sponsored by the LLC that provide certain other postretirement health care and life insurance benefits for employees who are eligible for these benefits. The Registrants' policy is to fund certain trusts to meet its other postretirement benefit obligations. Separate qualified VEBA and other benefit trusts exist. DTE Energy contributed $199 million to these trusts, including $175 million of DTE Electric contributions, for the defined benefit other postretirement medical and life insurance benefit plans during 2015 . At the discretion of management, DTE Energy anticipates making up to $20 million of contributions, through contributions from DTE Gas, to the trusts in 2016 . Starting in 2012, in lieu of offering future employees defined benefit post-employment health care and life insurance benefits, the Registrants allocate a fixed amount per year to an account in a defined contribution VEBA for each employee. These accounts are managed either by the Registrant (for non-represented and certain represented groups) or by the Utility Workers of America (UWUA) for Local 223 employees. DTE Energy contributions to the VEBA for these accounts were $5 million in 2015 , $4 million in 2014 , and $2 million in 2013 , including DTE Electric contributions of $3 million in 2015 , $2 million in 2014 , and $1 million in 2013 . Beginning in 2013, the Registrants replaced the defined benefit employer-sponsored retiree medical, prescription drug, and dental coverage with a notional allocation to a Retiree Reimbursement Account. This change applies to both current and future Medicare eligible non-represented and future represented retirees, spouses, surviving spouses, or same sex domestic partners when the youngest of the retiree's covered household turns age 65 . The amount of the annual allocation to each participant is determined by the employee's retirement date, and increases each year for each eligible participant at the lower of the rate of medical inflation or 2% . Net other postretirement credit for DTE Energy includes the following components: 2015 2014 2013 (In millions) Service cost $ 34 $ 34 $ 47 Interest cost 81 89 88 Expected return on plan assets (131 ) (122 ) (110 ) Amortization of: Net actuarial loss 43 20 64 Prior service credit (126 ) (144 ) (131 ) Net other postretirement credit $ (99 ) $ (123 ) $ (42 ) 2015 2014 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial (gain) loss $ (68 ) $ 192 Amortization of net actuarial loss (43 ) (20 ) Amortization of prior service credit 126 144 Total recognized in Regulatory assets and Other comprehensive income (loss) $ 15 $ 316 Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (84 ) $ 193 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 32 $ 43 Prior service credit $ (118 ) $ (126 ) Net other postretirement credit for DTE Electric includes the following components: 2015 2014 2013 (In millions) Service cost $ 25 $ 26 $ 35 Interest cost 62 68 67 Expected return on plan assets (90 ) (85 ) (74 ) Amortization of: Net actuarial loss 31 14 47 Prior service credit (95 ) (109 ) (100 ) Net other postretirement credit $ (67 ) $ (86 ) $ (25 ) 2015 2014 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial (gain) loss $ (57 ) $ 144 Amortization of net actuarial loss (31 ) (14 ) Amortization of prior service credit 95 109 Total recognized in Regulatory assets and Other comprehensive income (loss) $ 7 $ 239 Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (60 ) $ 153 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 22 $ 31 Prior service credit $ (89 ) $ (94 ) The following table reconciles the obligations, assets, and funded status of the plans including amounts recorded as Accrued postretirement liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Change in accumulated postretirement benefit obligation Accumulated postretirement benefit obligation, beginning of year $ 2,044 $ 1,878 $ 1,558 $ 1,430 Service cost 34 34 25 26 Interest cost 81 89 62 68 Actuarial (gain) loss (224 ) 131 (166 ) 100 Benefits paid (89 ) (88 ) (65 ) (66 ) Accumulated postretirement benefit obligation, end of year $ 1,846 $ 2,044 $ 1,414 $ 1,558 Change in plan assets Plan assets at fair value, beginning of year $ 1,528 $ 1,527 $ 1,038 $ 1,061 Actual return on plan assets (25 ) 62 (19 ) 41 Company contributions 199 24 175 — Benefits paid (85 ) (85 ) (63 ) (64 ) Plan assets at fair value, end of year $ 1,617 $ 1,528 $ 1,131 $ 1,038 Funded status, end of year $ (229 ) $ (516 ) $ (283 ) $ (520 ) Amount recorded as: Noncurrent assets $ — $ — $ 24 $ — Current liabilities (1 ) (1 ) — — Noncurrent liabilities (228 ) (515 ) (307 ) (520 ) $ (229 ) $ (516 ) $ (283 ) $ (520 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 24 $ 34 $ — $ — Prior service credit (2 ) (5 ) — — $ 22 $ 29 $ — $ — Amounts recognized in Regulatory assets (see Note 8 - "Regulatory Matters") Net actuarial loss $ 387 $ 488 $ 297 $ 385 Prior service credit (131 ) (254 ) (99 ) (194 ) $ 256 $ 234 $ 198 $ 191 At December 31, 2015 , the benefits expected to be paid, including prescription drug benefits, in each of the next five years and in the aggregate for the five fiscal years thereafter for the Registrants are as follows: DTE Energy DTE Electric (In millions) 2016 $ 100 $ 77 2017 105 81 2018 108 84 2019 113 88 2020 116 90 2021-2025 621 476 Total $ 1,163 $ 896 Assumptions used in determining the accumulated postretirement benefit obligation and net other postretirement benefit costs of the Registrants are: 2015 2014 2013 Accumulated postretirement benefit obligation Discount rate 4.50% 4.10% 4.95% Health care trend rate pre- and post- 65 6.25 / 6.75% 7.50 / 6.50% 7.50 / 6.50% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2027 2025 / 2024 2025 / 2024 Other postretirement benefit costs Discount rate (prior to interim remeasurement) 4.10% 4.95% 4.15% Discount rate (post interim remeasurement) N/A N/A 4.30% Expected long-term rate of return on plan assets 8.00% 8.00% 8.25% Health care trend rate pre- and post- 65 7.50 / 6.50% 7.50 / 6.50% 7.00% Ultimate health care trend rate 4.50% 4.50% 5.00% Year in which ultimate reached pre- and post- 65 2025 / 2024 2025 / 2024 2021 A one percentage point increase in health care cost trend rates would have increased the total service cost and interest cost components of benefit costs for DTE Energy by $6 million , including $4 million for DTE Electric, in 2015 and would have increased the accumulated benefit obligation for DTE Energy by $100 million , including $74 million for DTE Electric, at December 31, 2015 . A one percentage point decrease in the health care cost trend rates would have decreased the total service and interest cost components of benefit costs for DTE Energy by $5 million , including $4 million for DTE Electric, in 2015 and would have decreased the accumulated benefit obligation for DTE Energy by $86 million , including $64 million for DTE Electric, at December 31, 2015 . The process used in determining the long-term rate of return for assets and the investment approach for the other postretirement benefit plans is similar to those previously described for the pension plans. Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2015 are listed below: U.S. Large Cap Equity Securities 17 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 20 Fixed Income Securities 25 Hedge Funds and Similar Investments 20 Private Equity and Other 14 100 % The following tables provide the fair value measurement amounts for the Registrants' other postretirement benefit plan assets at December 31, 2015 and 2014 (a): December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total DTE Energy asset category: (In millions) Short-term Investments (b) $ 7 $ — $ — $ 7 $ 6 $ — $ — $ 6 Equity Securities U.S. Large Cap (c) 264 — — 264 266 — — 266 U.S. Small Cap and Mid Cap (d) 138 — — 138 149 — — 149 Non-U.S. (e) 262 55 — 317 222 59 — 281 Fixed Income Securities (f) 23 390 — 413 15 360 — 375 Hedge Funds and Similar Investments (g) 109 45 171 325 107 45 168 320 Private Equity and Other (h) — — 153 153 — — 131 131 Securities Lending (i) (122 ) (6 ) — (128 ) (141 ) (17 ) — (158 ) Securities Lending Collateral (i) 122 6 — 128 141 17 — 158 DTE Energy Total $ 803 $ 490 $ 324 $ 1,617 $ 765 $ 464 $ 299 $ 1,528 DTE Electric asset category: Short-term Investments (b) $ 5 $ — $ — $ 5 $ 4 $ — $ — $ 4 Equity Securities U.S. Large Cap (c) 183 — — 183 179 — — 179 U.S. Small Cap and Mid Cap (d) 97 — — 97 102 — — 102 Non-U.S. (e) 184 37 — 221 151 39 — 190 Fixed Income Securities (f) 17 272 — 289 11 243 — 254 Hedge Funds and Similar Investments (g) 76 32 119 227 73 31 114 218 Private Equity and Other (h) — — 109 109 — — 91 91 Securities Lending (i) (87 ) (4 ) — (91 ) (98 ) (11 ) — (109 ) Securities Lending Collateral (i) 87 4 — 91 98 11 — 109 DTE Electric Total $ 562 $ 341 $ 228 $ 1,131 $ 520 $ 313 $ 205 $ 1,038 _______________________________________ (a) For a description of levels within the fair value hierarchy see Note 11 to the Consolidated Financial Statements, " Fair Value ". (b) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (c) This category comprises both actively and not actively managed portfolios that track the S&P 500 low cost equity index funds. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (d) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (e) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (f) This category includes corporate bonds from diversified industries, U.S. Treasuries, bank loans, and mortgage backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as Level 2 assets. (g) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded debt and equity, publicly traded mutual funds, commingled and limited partnership funds, and non-exchange traded securities. Pricing for Level 1 and Level 2 assets in this category is obtained from quoted prices in actively traded markets and quoted prices from broker or pricing services. Non-exchange traded securities held in commingled funds are classified as Level 2 assets. Valuations for some Level 3 assets in this category may be based on limited observable inputs as there may be little, if any, publicly available pricing. (h) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. Pricing for investments in this category is based on limited observable inputs as there is little, if any, publicly available pricing. Valuations for assets in this category may be based on discounted cash flow analyses, relevant publicly-traded comparables, and comparable transactions. (i) In 2014, the Registrants began a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' VEBA trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. The DTE Energy Company Master VEBA Trust holds debt and equity securities directly and indirectly through commingled funds and institutional mutual funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The commingled funds and institutional mutual funds hold exchange-traded equity or debt securities and are valued based on NAVs. Non-exchange traded fixed income securities are valued by the trustee based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee challenges an assigned price and determines that another price source is considered to be preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, the Registrants selectively corroborate the fair values of securities by comparison of market-based price sources. The following table provides a reconciliation of beginning and ending balances of DTE Energy's other postretirement benefit plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Year Ended December 31, 2015 Year Ended December 31, 2014 Hedge Funds Private Total Hedge Funds Private Total (In millions) Beginning Balance at January 1 $ 168 $ 131 $ 299 $ 159 $ 101 $ 260 Total realized/unrealized gains (losses) 4 9 13 8 9 17 Purchases, sales, and settlements: Purchases 11 34 45 9 33 42 Sales (12 ) (21 ) (33 ) (8 ) (12 ) (20 ) Ending Balance at December 31 $ 171 $ 153 $

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2015
Share-based Compensation [Abstract]
Stock-based Compensation	STOCK-BASED COMPENSATION DTE Energy’s stock incentive program permits the grant of incentive stock options, non-qualifying stock options, stock awards, performance shares, and performance units to employees and members of its Board of Directors. As a result of a stock award, a settlement of an award of performance shares, or by exercise of a participant’s stock option, DTE Energy may deliver common stock from its authorized but unissued common stock and/or from outstanding common stock acquired by or on behalf of DTE Energy in the name of the participant. Key provisions of the stock incentive program are: • Authorized limit is 14,500,000 shares of common stock; • Prohibits the grant of a stock option with an exercise price that is less than the fair market value of DTE Energy’s stock on the date of the grant; and • Imposes the following award limits to a single participant in a single calendar year, (1) options for more than 500,000 shares of common stock; (2) stock awards for more than 150,000 shares of common stock; (3) performance share awards for more than 300,000 shares of common stock (based on the maximum payout under the award); or (4) more than 1,000,000 performance units, which have a face amount of $1.00 each. DTE Energy records compensation expense at fair value over the vesting period for all awards it grants. The following table summarizes the components of stock-based compensation for DTE Energy: 2015 2014 2013 (In millions) Stock-based compensation expense $ 34 $ 103 $ 99 Tax benefit $ 13 $ 40 $ 38 Stock-based compensation cost capitalized in Property, plant, and equipment $ 5 $ 16 $ 15 Stock Options Options are exercisable according to the terms of the individual stock option award agreements and expire ten years after the date of the grant. The option exercise price equals the fair value of the stock on the date that the option was granted. Stock options vest ratably over a three -year period. The following table summarizes DTE Energy's stock option activity for the year ended December 31, 2015 : Number of Options Weighted Average Exercise Price Aggregate Intrinsic Options outstanding at December 31, 2014 444,278 $ 43.56 Exercised (178,017 ) $ 45.07 Forfeited or expired (3,979 ) $ 44.72 Options outstanding and exercisable at December 31, 2015 262,282 $ 42.52 $ 10 As of December 31, 2015 , the weighted average remaining contractual life for the exercisable shares is 2.80 years. As of December 31, 2015 , all options were vested. No options vested during 2015 . There were no options granted during 2015 , 2014 , or 2013 . The intrinsic value of options exercised for the years ended December 31, 2015 , 2014 , and 2013 was $7 million , $11 million , and $12 million , respectively. No option expense was recognized for 2015 , 2014 , or 2013 . The number, weighted average exercise price, and weighted average remaining contractual life of DTE Energy options outstanding as of December 31, 2015 were as follows: Range of Exercise Prices Number of Options Weighted Average Weighted Average $ 27.00 — $ 38.00 22,083 $ 27.70 3.16 $ 38.01 — $ 42.00 80,434 $ 41.79 2.16 $ 42.01 — $ 45.00 116,665 $ 43.90 3.79 $ 45.01 — $ 50.00 43,100 $ 47.75 1.15 262,282 $ 42.52 2.80 Restricted Stock Awards Stock awards granted under the plan are restricted for varying periods, generally for three years . Participants have all rights of a shareholder with respect to a stock award, including the right to receive dividends and vote the shares. Prior to vesting in stock awards, the participant: (i) may not sell, transfer, pledge, exchange, or otherwise dispose of shares; (ii) shall not retain custody of the share certificates; and (iii) will deliver to DTE Energy a stock power with respect to each stock award upon request. The stock awards are recorded at cost that approximates fair value on the date of grant. The cost is amortized to compensation expense over the vesting period. Stock award activity for DTE Energy for the years ended December 31 was: 2015 2014 2013 Fair value of awards vested (in millions) $ 9 $ 11 $ 8 Restricted common shares awarded 144,300 159,590 127,785 Weighted average market price of shares awarded $ 83.43 $ 70.09 $ 64.72 Compensation cost charged against income (in millions) $ 10 $ 10 $ 23 The following table summarizes DTE Energy’s restricted stock awards activity for the year ended December 31, 2015 : Restricted Weighted Average Balance at December 31, 2014 416,318 $ 62.82 Grants 144,300 $ 83.43 Forfeitures (12,721 ) $ 74.78 Vested and issued (165,453 ) $ 55.73 Balance at December 31, 2015 382,444 $ 73.26 Performance Share Awards Performance shares awarded under the plan are for a specified number of shares of DTE Energy common stock that entitle the holder to receive a cash payment, shares of DTE Energy common stock, or a combination thereof. The final value of the award is determined by the achievement of certain performance objectives and market conditions. The awards vest at the end of a specified period, usually three years . Awards granted in 2014 and 2015 were primarily deemed to be equity awards. The DTE Energy stock price and number of probable shares attributable to market conditions for such equity awards are fair valued only at the grant date. Performance shares awarded prior to 2014 are liability awards and are remeasured to fair value at each reporting period. DTE Energy accounts for performance share awards by accruing compensation expense over the vesting period based on: (i) the number of shares expected to be paid which is based on the probable achievement of performance objectives; and (ii) the closing stock price market value. The settlement of the award is based on the closing price at the settlement date. DTE Energy recorded compensation expense for performance share awards as follows: 2015 2014 2013 (In millions) Compensation expense $ 24 $ 93 $ 77 Cash settlements (a) $ 13 $ 11 $ 9 Stock settlements (a) $ 71 $ 61 $ 56 _______________________________________ (a) Sum of cash and stock settlements approximates the intrinsic value of the awards. During the vesting period, the recipient of a performance share award has no shareholder rights. During the period beginning on the date the performance shares are awarded and ending on the certification date of the performance objectives, the number of performance shares awarded will be increased, assuming full dividend reinvestment at the fair market value on the dividend payment date. The cumulative number of performance shares will be adjusted to determine the final payment based on the performance objectives achieved. Performance share awards are nontransferable and are subject to risk of forfeiture. The following table summarizes DTE Energy’s performance share activity for the period ended December 31, 2015 : Performance Shares Weighted Average Balance at December 31, 2014 1,554,697 $ 69.32 Grants 467,288 $ 83.85 Forfeitures (47,067 ) $ 76.22 Payouts (532,700 ) $ — Balance at December 31, 2015 1,442,218 $ 75.85 Unrecognized Compensation Costs As of December 31, 2015 , DTE Energy's total unrecognized compensation cost related to non-vested stock incentive plan arrangements and the weighted average recognition period was as follows: Unrecognized Weighted Average (In millions) (In years) Stock awards $ 11 1.11 Performance shares 37 0.97 $ 48 1.00 Allocated Stock-Based Compensation DTE Electric received an allocation of costs from DTE Energy associated with stock-based compensation. DTE Electric's allocation for 2015 , 2014 , and 2013 for stock-based compensation expense was approximately $21 million , $62 million , and $58 million , respectively.

Segment and Related Information

Segment and Related Information	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Segment and Related Information	SEGMENT AND RELATED INFORMATION DTE Energy sets strategic goals, allocates resources, and evaluates performance based on the following structure: Electric segment consists principally of DTE Electric, which is engaged in the generation, purchase, distribution, and sale of electricity to approximately 2.2 million residential, commercial, and industrial customers in southeastern Michigan. Gas segment consists principally of DTE Gas, which is engaged in the purchase, storage, transportation, distribution, and sale of natural gas to approximately 1.2 million residential, commercial, and industrial customers throughout Michigan and the sale of storage and transportation capacity. Gas Storage and Pipelines consists of natural gas pipeline, gathering, and storage businesses. Power and Industrial Projects is comprised primarily of projects that deliver energy and utility-type products and services to industrial, commercial, and institutional customers, produce reduced emissions fuel, and sell electricity from renewable energy projects. Energy Trading consists of energy marketing and trading operations. Corporate and Other includes various holding company activities, holds certain non-utility debt, and energy-related investments. The federal income tax provisions or benefits of DTE Energy’s subsidiaries are determined on an individual company basis and recognize the tax benefit of tax credits and net operating losses, if applicable. The state and local income tax provisions of the utility subsidiaries are determined on an individual company basis and recognize the tax benefit of various tax credits and net operating losses, if applicable. The subsidiaries record federal, state, and local income taxes payable to or receivable from DTE Energy based on the federal, state, and local tax provisions of each company. Inter-segment billing for goods and services exchanged between segments is based upon tariffed or market-based prices of the provider and primarily consists of the sale of reduced emissions fuel, power sales, and natural gas sales in the following segments: Year Ended December 31, 2015 2014 2013 (In millions) Electric $ 36 $ 29 $ 26 Gas 3 6 4 Gas Storage and Pipelines 8 9 3 Power and Industrial Projects 785 794 816 Energy Trading 32 33 43 Corporate and Other 4 3 (24 ) $ 868 $ 874 $ 868 Financial data of DTE Energy's business segments follows: Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2015 Operating Revenues — Utility operations $ 4,901 1,376 — — — — (39 ) $ 6,238 Operating Revenues — Non-utility operations $ — — 243 2,224 2,459 2 (829 ) $ 4,099 Depreciation and amortization $ 637 104 30 78 2 1 — $ 852 Interest income $ — (7 ) (8 ) (8 ) (2 ) (52 ) 64 $ (13 ) Interest expense $ 258 62 24 32 6 132 (64 ) $ 450 Equity in earnings of equity method investees $ 2 6 47 8 — 3 — $ 66 Income Tax Expense (Benefit) $ 290 72 70 (140 ) (15 ) (47 ) — $ 230 Net Income (Loss) Attributable to DTE Energy Company $ 542 132 107 16 (22 ) (48 ) — $ 727 Investment in equity method investees $ 10 9 296 183 — 16 — $ 514 Capital expenditures and acquisitions $ 1,785 273 161 36 6 — — $ 2,261 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 19,539 4,299 1,047 860 590 3,530 (1,128 ) $ 28,737 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2014 Operating Revenues — Utility operations $ 5,283 1,636 — — — — (35 ) $ 6,884 Operating Revenues — Non-utility operations $ — — 203 2,289 3,762 2 (839 ) $ 5,417 Depreciation and amortization $ 933 99 34 77 1 1 — $ 1,145 Interest income $ (1 ) (7 ) (6 ) (5 ) — (48 ) 57 $ (10 ) Interest expense $ 250 57 22 28 7 122 (57 ) $ 429 Equity in earnings of equity method investees $ 1 7 35 5 — — — $ 48 Income Tax Expense (Benefit) $ 296 78 53 (100 ) 77 (40 ) — $ 364 Net Income (Loss) Attributable to DTE Energy Company $ 528 140 82 90 122 (57 ) — $ 905 Investment in equity method investees $ 8 10 224 184 — 8 — $ 434 Capital expenditures and acquisitions $ 1,561 224 184 77 3 — — $ 2,049 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 18,713 4,247 883 998 755 3,209 (906 ) $ 27,899 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2013 Operating Revenues — Utility operations $ 5,199 1,474 — — — — (30 ) $ 6,643 Operating Revenues — Non-utility operations $ — — 132 1,950 1,771 3 (838 ) $ 3,018 Depreciation and amortization $ 902 95 23 72 1 1 — $ 1,094 Interest income $ (1 ) (7 ) (7 ) (6 ) — (51 ) 63 $ (9 ) Interest expense $ 268 58 18 27 8 120 (63 ) $ 436 Equity in earnings of equity method investees $ 1 6 44 8 — — — $ 59 Income Tax Expense (Benefit) $ 252 77 45 (45 ) (38 ) (37 ) — $ 254 Net Income (Loss) Attributable to DTE Energy Company $ 484 143 70 66 (58 ) (44 ) — $ 661 Investment in equity method investees $ 9 10 201 189 — 6 — $ 415 Capital expenditures and acquisitions $ 1,325 209 245 93 3 1 — $ 1,876 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 17,508 3,920 823 1,054 624 2,945 (939 ) $ 25,935

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS DTE Electric has agreements with affiliated companies to sell energy for resale, purchase fuel and power, provide fuel supply services, and provide power plant operation and maintenance services. DTE Electric has agreements with certain DTE Energy affiliates where DTE Electric charges the affiliates for their use of the shared capital assets of DTE Electric. A shared services company accumulates various corporate support services expenses and charges various subsidiaries of DTE Energy, including DTE Electric. DTE Electric records federal, state, and local income taxes payable to or receivable from DTE Energy based on its federal, state, and local tax provisions. The following is a summary of DTE Electric's transactions with affiliated companies: 2015 2014 2013 (In millions) Revenues Energy sales $ 2 $ 2 $ 2 Other services $ 6 $ 5 $ 7 Shared capital assets $ 33 $ 26 $ 23 Costs Fuel and purchased power $ 9 $ 4 $ 4 Other services and interest $ 2 $ (1 ) $ (1 ) Corporate expenses (net) $ 334 $ 304 $ 334 Other Dividends declared $ 395 $ 370 $ 342 Dividends paid $ 395 $ 370 $ 342 Capital contribution from DTE Energy $ 300 $ 190 $ 400 DTE Electric's Accounts receivable and Accounts payable related to Affiliates are payable upon demand and are generally settled in cash within a monthly business cycle. Notes receivable and Short-term borrowings related to Affiliates are subject to a credit agreement with DTE Energy whereby short-term excess cash or cash shortfalls are remitted to or funded by DTE Energy. This credit arrangement involves the charge and payment of interest at market-based rates. Refer to DTE Electric's Consolidated Statements of Financial Position for affiliate balances at December 31, 2015 and 2014 . For DTE Electric, there were no charitable contributions to the DTE Energy Foundation for the years ended December 31, 2015 and 2014 , while there were $18 million in contributions for the year ended December 31, 2013 . The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute and assist charitable organizations. See the following notes for other related party transactions impacting DTE Electric’s Consolidated Financial Statements: Note Title 4 Acquisitions and Exit Activities 18 Retirement Benefits and Trusteed Assets 19 Stock-Based Compensation

Supplementary Quarterly Financi

Supplementary Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Supplemental Quarterly Financial Information (Unaudited)	SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (UNAUDITED) DTE Energy Quarterly earnings per share may not equal full year totals, since quarterly computations are based on weighted average common shares outstanding during each quarter. First Second Third Fourth Year (In millions, except per share amounts) 2015 Operating Revenues $ 2,984 $ 2,268 $ 2,598 $ 2,487 $ 10,337 Operating Income $ 461 $ 204 $ 440 $ 134 $ 1,239 Net Income Attributable to DTE Energy Company $ 273 $ 109 $ 265 $ 80 $ 727 Basic Earnings per Share $ 1.53 $ 0.61 $ 1.47 $ 0.45 $ 4.05 Diluted Earnings per Share $ 1.53 $ 0.61 $ 1.47 $ 0.45 $ 4.05 2014 Operating Revenues $ 3,930 $ 2,698 $ 2,595 $ 3,078 $ 12,301 Operating Income $ 560 $ 249 $ 239 $ 542 $ 1,590 Net Income Attributable to DTE Energy Company $ 326 $ 124 $ 156 $ 299 $ 905 Basic Earnings per Share $ 1.84 $ 0.70 $ 0.88 $ 1.68 $ 5.11 Diluted Earnings per Share $ 1.84 $ 0.70 $ 0.88 $ 1.68 $ 5.10 DTE Electric First Second Third Fourth Year (In millions) 2015 Operating Revenues $ 1,203 $ 1,147 $ 1,385 $ 1,165 $ 4,900 Operating Income $ 268 $ 214 $ 400 $ 192 $ 1,074 Net Income $ 137 $ 99 $ 216 $ 92 $ 544 2014 Operating Revenues $ 1,410 $ 1,281 $ 1,357 $ 1,234 $ 5,282 Operating Income $ 271 $ 259 $ 272 $ 250 $ 1,052 Net Income $ 137 $ 130 $ 136 $ 129 $ 532

Valuation and Qualifying Accoun

Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
Valuation and Qualifying Accounts	DTE Energy Company Schedule II — Valuation and Qualifying Accounts Year Ending December 31, 2015 2014 2013 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 54 $ 55 $ 62 Additions: Charged to costs and expenses 93 95 94 Charged to other accounts (a) 14 20 23 Deductions (b) (112 ) (116 ) (124 ) Balance at End of Period $ 49 $ 54 $ 55 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off. DTE Electric Company Schedule II — Valuation and Qualifying Accounts Year Ending December 31, 2015 2014 2013 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Electric's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 29 $ 28 $ 35 Additions: Charged to costs and expenses 51 50 52 Charged to other accounts (a) 6 10 11 Deductions (b) (58 ) (59 ) (70 ) Balance at End of Period $ 28 $ 29 $ 28 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off.

Significant Accounting Polici32

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The information in these combined notes relates to each of the Registrants as noted in the Index of Combined Notes to Consolidated Financial Statements. However, DTE Electric does not make any representation as to information related solely to DTE Energy or the subsidiaries of DTE Energy other than itself.
Reclassification	Certain prior year balances for the Registrants were reclassified to match the current year's Consolidated Financial Statements presentation. Such revisions include amounts reclassified to separate Operating Revenues and Fuel, purchased power, and gas between Utility operations and Non-utility operations and from Operations and maintenance to Fuel, purchased power, and gas — non-utility related to the Power and Industrial Projects segment. The reclassifications did not affect DTE Energy's Net Income for the prior periods, as such, they are not deemed material to the previously issued Consolidated Financial Statements.
Principles of Consolidation	Principles of Consolidation The Registrants consolidate all majority-owned subsidiaries and investments in entities in which they have controlling influence. Non-majority owned investments are accounted for using the equity method when the Registrants are able to significantly influence the operating policies of the investee. When the Registrants do not influence the operating policies of an investee, the cost method is used. These Consolidated Financial Statements also reflect the Registrants' proportionate interests in certain jointly-owned utility plants. The Registrants eliminate all intercompany balances and transactions. The Registrants evaluate whether an entity is a VIE whenever reconsideration events occur. The Registrants consolidate VIEs for which they are the primary beneficiary. If a Registrant is not the primary beneficiary and an ownership interest is held, the VIE is accounted for under the equity method of accounting. When assessing the determination of the primary beneficiary, a Registrant considers all relevant facts and circumstances, including: the power, through voting or similar rights, to direct the activities of the VIE that most significantly impact the VIE's economic performance and the obligation to absorb the expected losses and/or the right to receive the expected returns of the VIE. The Registrants perform ongoing reassessments of all VIEs to determine if the primary beneficiary status has changed. Legal entities within DTE Energy's Power and Industrial Projects segment enter into long-term contractual arrangements with customers to supply energy-related products or services. The entities are generally designed to pass-through the commodity risk associated with these contracts to the customers, with DTE Energy retaining operational and customer default risk. These entities generally are VIEs and consolidated when DTE Energy is the primary beneficiary. In addition, DTE Energy has interests in certain VIEs through which control of all significant activities is shared with partners, and therefore are accounted for under the equity method. DTE Energy has variable interests in VIEs through certain of its long-term purchase and sale contracts. DTE Electric has variable interests in VIEs through certain of its long-term purchase contracts. As of December 31, 2015 , the carrying amount of assets and liabilities in DTE Energy's Consolidated Statements of Financial Position that relate to its variable interests under long-term purchase and sale contracts are predominantly related to working capital accounts and generally represent the amounts owed by or to DTE Energy for the deliveries associated with the current billing cycle under the contracts. As of December 31, 2015 , the carrying amount of assets and liabilities in DTE Electric's Consolidated Statements of Financial Position that relate to its variable interests under long-term purchase contracts are predominantly related to working capital accounts and generally represent the amounts owed by DTE Electric for the deliveries associated with the current billing cycle under the contracts. The Registrants have not provided any significant form of financial support associated with these long-term contracts. There is no significant potential exposure to loss as a result of DTE Energy's variable interests through these long-term purchase and sale contracts. In addition, there is no significant potential exposure to loss as a result of DTE Electric's variable interests through these long-term purchase contracts. In 2001, DTE Electric financed a regulatory asset related to Fermi 2 and certain other regulatory assets through the sale of rate reduction bonds by a wholly-owned special purpose entity, Securitization. DTE Electric performed servicing activities including billing and collecting surcharge revenue for Securitization. The remaining amounts due on the rate reduction bonds were paid in March 2015. The associated regulatory assets were fully amortized by March 31, 2015. Subsequent to the pay-down of the bonds, Securitization is no longer a VIE but continues to be consolidated by the Registrants as a voting interest entity. The maximum risk exposure for consolidated VIEs is reflected on the Registrants' Consolidated Statements of Financial Position. For non-consolidated VIEs, the maximum risk exposure is generally limited to its investment and amounts which it has guaranteed. The following table summarizes the major Consolidated Statements of Financial Position items for consolidated VIEs as of December 31, 2015 and 2014 . All assets and liabilities of a consolidated VIE are presented where it has been determined that a consolidated VIE has either (1) assets that can be used only to settle obligations of the VIE or (2) liabilities for which creditors do not have recourse to the general credit of the primary beneficiary. Securitization, included in the DTE Energy table below for December 31, 2014, also relates to DTE Electric. VIEs, in which DTE Energy holds a majority voting interest and is the primary beneficiary, that meet the definition of a business and whose assets can be used for purposes other than the settlement of the VIE's obligations have been excluded from the table below.
Revenues	Revenues The Registrants' revenues from the sale and delivery of electricity, and DTE Energy's revenues from the sale, delivery, and storage of natural gas are recognized as services are provided. DTE Electric and DTE Gas record revenues for electricity and gas provided but unbilled at the end of each month. Rates for DTE Electric and DTE Gas include provisions to adjust billings for fluctuations in fuel and purchased power costs, cost of natural gas, and certain other costs. Revenues are adjusted for differences between actual costs subject to reconciliation and the amounts billed in current rates. Under or over recovered revenues related to these cost recovery mechanisms are included in Regulatory assets or liabilities on the Registrants' Consolidated Statements of Financial Position and are recovered or returned to customers through adjustments to the billing factors. For further discussion of recovery mechanisms authorized by the MPSC, see Note 8 to the Consolidated Financial Statements, " Regulatory Matters ". DTE Energy's non-utility businesses recognize revenues as services are provided and products are delivered.
Accounting For ISO Transactions	Accounting for ISO Transactions DTE Electric participates in the energy market through MISO. MISO requires that DTE Electric submit hourly day-ahead, real-time, and FTR bids and offers for energy at locations across the MISO region. DTE Electric accounts for MISO transactions on a net hourly basis in each of the day-ahead, real-time, and FTR markets and net transactions across all MISO energy market locations. In any single hour DTE Electric records net purchases in Fuel, purchased power, and gas — utility and net sales in Operating Revenues — Utility operations on the Registrants' Consolidated Statements of Operations. The Energy Trading segment participates in the energy markets through various independent system operators and regional transmission organizations (ISOs and RTOs). These markets require that Energy Trading submits hourly day-ahead, real-time bids and offers for energy at locations across each region. Energy Trading submits bids in the annual and monthly auction revenue rights and FTR auctions to the regional transmission organizations. Energy Trading accounts for these transactions on a net hourly basis for the day-ahead, real-time, and FTR markets. These transactions are related to trading contracts which, if derivatives, are presented on a net basis in Operating Revenues — Non-utility operations, and if non-derivatives, the realized gains and losses for sales are recorded in Operating Revenues — Non-utility operations and purchases are recorded in Fuel, purchased power, and gas — non-utility in the DTE Energy Consolidated Statements of Operations. DTE Electric and Energy Trading record accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual costs when invoices are received from MISO and other ISOs and RTOs.
Changes in Accumulated Other Comprehensive Income (Loss)	Changes in Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including Net Income. The amounts recorded to Accumulated other comprehensive income (loss) for the Registrants include unrealized gains and losses on available-for-sale securities and changes in benefit obligations, consisting of deferred actuarial losses and prior service costs. The amounts recorded to Accumulated other comprehensive income (loss) relating solely to DTE Energy also include unrealized gains and losses from derivatives accounted for as cash flow hedges, DTE Energy's interest in other comprehensive income of equity investees which comprise the net unrealized gains and losses on investments, and foreign currency translation adjustments.
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include cash on hand, cash in banks, and temporary investments purchased with remaining maturities of three months or less. Restricted cash consists of funds held to satisfy requirements of certain debt and DTE Energy partnership operating agreements. Restricted cash designated for interest and principal payments within one year is classified as a Current Asset.
Receivables	Receivables Accounts receivable are primarily composed of trade receivables and unbilled revenue. The Registrants' Accounts receivable are stated at net realizable value. The allowance for doubtful accounts for DTE Electric and DTE Gas is generally calculated using the aging approach that utilizes rates developed in reserve studies. DTE Electric and DTE Gas establish an allowance for uncollectible accounts based on historical losses and management’s assessment of existing economic conditions, customer trends, and other factors. Customer accounts are generally considered delinquent if the amount billed is not received by the due date, which is typically in 21 days, however, factors such as assistance programs may delay aggressive action. DTE Electric and DTE Gas assess late payment fees on trade receivables based on past-due terms with customers. Customer accounts are written off when collection efforts have been exhausted. The time period for write-off is 150 days after service has been terminated. The customer allowance for doubtful accounts for DTE Energy's other businesses is calculated based on specific review of probable future collections based on receivable balances in excess of 30 days. DTE Energy unbilled revenues of $620 million and $773 million , including $237 million and $250 million of DTE Electric unbilled revenues, are included in Customer Accounts receivable at December 31, 2015 and 2014 , respectively. Notes Receivable Notes receivable, or financing receivables, for DTE Energy are primarily comprised of capital lease receivables and loans and are included in Notes receivable and Other current assets on DTE Energy’s Consolidated Statements of Financial Position. Notes receivable, or financing receivables, for DTE Electric are primarily comprised of loans. Notes receivable are typically considered delinquent when payment is not received for periods ranging from 60 to 120 days. The Registrants cease accruing interest (nonaccrual status), consider a note receivable impaired, and establish an allowance for credit loss when it is probable that all principal and interest amounts due will not be collected in accordance with the contractual terms of the note receivable. Cash payments received on nonaccrual status notes receivable, that do not bring the account contractually current, are first applied to contractually owed past due interest, with any remainder applied to principal. Accrual of interest is generally resumed when the note receivable becomes contractually current. In determining the allowance for credit losses for notes receivable, the Registrants consider the historical payment experience and other factors that are expected to have a specific impact on the counterparty’s ability to pay. In addition, the Registrants monitor the credit ratings of the counterparties from which they have Notes receivable.
Inventories	Inventories Inventory related to utility operations is generally valued at average cost. Inventory related to non-utility operations is valued at the lower of cost or market.
Property, Retirement and Maintenance, and Depreciation and Amortization	Property, Retirement and Maintenance, and Depreciation and Amortization Property is stated at cost and includes construction-related labor, materials, overheads, and AFUDC for utility property. The cost of utility properties retired is charged to accumulated depreciation. Expenditures for maintenance and repairs are charged to expense when incurred, except for Fermi 2. Utility property at DTE Electric and DTE Gas is depreciated over its estimated useful life using straight-line rates approved by the MPSC. DTE Energy's non-utility property is depreciated over its estimated useful life using the straight-line method. Depreciation and amortization expense also includes the amortization of certain regulatory assets for the Registrants. Approximately $4 million and $16 million of expenses related to Fermi 2 refueling outages were accrued at December 31, 2015 and 2014 , respectively. Amounts are accrued on a pro-rata basis, generally over an 18 -month period, that coincides with scheduled refueling outages at Fermi 2. This accrual of outage costs matches the regulatory recovery of these costs in rates set by the MPSC. See Note 8 to the Consolidated Financial Statements, " Regulatory Matters ". The cost of nuclear fuel is capitalized. The amortization of nuclear fuel is included within Fuel, purchased power, and gas — utility in the DTE Energy Consolidated Statements of Operations, and Fuel and purchased power in the DTE Electric Consolidated Statements of Operations, and is recorded using the units-of-production method. Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 3 to 15 years for DTE Energy and 5 to 15 years for DTE Electric.
Long-Lived Assets	Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If the carrying amount of the asset exceeds the expected discounted future cash flows generated by the asset, an impairment loss is recognized resulting in the asset being written down to its estimated fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less costs to sell.
Intangible Assets	Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the businesses by the Registrants. DTE Energy amortizes contract Intangible assets on a straight-line basis over the expected period of benefit, ranging from 1 to 26 years.
Income Taxes	Excise and Sales Taxes The Registrants record the billing of excise and sales taxes as a receivable with an offsetting payable to the applicable taxing authority, with no net impact on the Registrants' Consolidated Statements of Operations. Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts in the Consolidated Financial Statements. Consistent with rate making treatment, deferred taxes are offset in the tables below for temporary differences which have related Regulatory assets and liabilities. The federal income tax provisions or benefits of DTE Energy’s subsidiaries are determined on an individual company basis and recognize the tax benefit of tax credits and net operating losses, if applicable. The state and local income tax provisions of the utility subsidiaries are determined on an individual company basis and recognize the tax benefit of various tax credits and net operating losses, if applicable. The subsidiaries record federal, state, and local income taxes payable to or receivable from DTE Energy based on the federal, state, and local tax provisions of each company.
Deferred Debt Costs	Deferred Debt Costs The costs related to the issuance of long-term debt are deferred and amortized over the life of each debt issue. The deferred amounts are included in Other long-term assets on the Registrant's Consolidated Statements of Financial Position. In accordance with MPSC regulations applicable to DTE Energy’s electric and gas utilities the unamortized discount, premium, and expense related to utility debt redeemed with a refinancing are amortized over the life of the replacement issue. Discount, premium, and expense on early redemptions of debt associated with DTE Energy's non-utility operations are charged to earnings.
Investments in Debt and Equity Securities	Investments in Debt and Equity Securities The Registrants generally classify investments in debt and equity securities as either trading or available-for-sale and have recorded such investments at market value with unrealized gains or losses included in earnings or in Other comprehensive income or loss, respectively. Changes in the fair value of Fermi 2 nuclear decommissioning investments are recorded as adjustments to Regulatory assets or liabilities, due to a recovery mechanism from customers. The Registrants' equity investments are reviewed for impairment each reporting period. If the assessment indicates that the impairment is other than temporary, a loss is recognized resulting in the equity investment being written down to its estimated fair value.
Government Grants	Government Grants Grants are recognized when there is reasonable assurance that the grant will be received and that any conditions associated with the grant will be met. When grants are received related to Property, plant, and equipment, the Registrants reduce the cost of the assets on their Consolidated Statements of Financial Position, resulting in lower depreciation expense over the life of the associated asset. Grants received related to expenses are reflected as a reduction of the associated expense in the period in which the expense is incurred.
DTE Energy Foundation	The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute to and assist charitable organizations
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers. The objectives of this ASU are to improve upon revenue recognition requirements by providing a single comprehensive model to determine the measurement of revenue and timing of recognition. The core principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. This ASU also requires expanded qualitative and quantitative disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. In July 2015, the FASB deferred implementation of the revenue standard to be effective for the first interim period within annual reporting periods beginning after December 15, 2017. The standard is to be applied retrospectively and early adoption is permitted in the preceding year. The Registrants are currently assessing the impact of this ASU on their Consolidated Financial Statements. In February 2015, the FASB issued ASU No. 2015-02, Amendments to the Consolidation Analysis , which changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. The ASU affects (1) limited partnerships and similar legal entities, (2) evaluating fees paid to a decision maker or a service provider as a variable interest, (3) the effect of fee arrangements on the primary beneficiary determination, (4) the effect of related parties on the primary beneficiary determination, and (5) certain investment funds. It is effective for the Registrants for the first interim period within annual reporting periods beginning after December 15, 2015 and early adoption is permitted. The Registrants are currently assessing the impact of this ASU on their Consolidated Financial Statements. In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs . This ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This ASU is effective for reporting periods beginning after December 15, 2015 and interim periods therein. It is to be applied retrospectively and early adoption is permitted. Had the Registrants early adopted this ASU it would have decreased assets and liabilities on DTE Energy’s and DTE Electric’s Consolidated Statements of Financial Position by $74 million and $36 million , respectively, at December 31, 2015, and $73 million and $35 million , respectively, at December 31, 2014. In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330), Simplifying the Measurement of Inventory . The ASU replaces the current lower of cost or market test with a lower of cost or net realizable value test when cost is determined on a first-in, first-out or average cost basis. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. It is to be applied prospectively and early adoption is permitted. The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements. In November 2015, the FASB issued ASU No. 2015-17, Balance Sheet Classification of Deferred Taxes . This ASU requires that all deferred tax assets and liabilities, along with any related valuation allowance, be classified as noncurrent on the balance sheet. This ASU is effective for reporting periods beginning after December 15, 2016, including interim periods therein. It may be applied either prospectively or retrospectively, and early adoption is permitted. The Registrants adopted this ASU at December 31, 2015. The adoption of this ASU impacted DTE Energy’s and DTE Electric’s Consolidated Statements of Financial Position by decreasing assets and liabilities for 2014 by $75 million and $2 million , respectively.
Asset Retirement Obligations	DTE Electric has a legal retirement obligation for the decommissioning costs for its Fermi 1 and Fermi 2 nuclear plants, dismantlement of facilities located on leased property, and various other operations. DTE Electric has conditional retirement obligations for asbestos and PCB removal at certain of its power plants and various distribution equipment. DTE Gas has conditional retirement obligations for gas pipelines, certain service centers, compressor and gate stations. The Registrants recognize such obligations as liabilities at fair market value when they are incurred, which generally is at the time the associated assets are placed in service. Fair value is measured using expected future cash outflows discounted at the Registrants' credit-adjusted risk-free rate. For its utility operations, the Registrants recognize in the Consolidated Statements of Operations removal costs in accordance with regulatory treatment. Any differences between costs recognized related to asset retirement and those reflected in rates are recognized as either a Regulatory asset or liability on the Consolidated Statements of Financial Position. If a reasonable estimate of fair value cannot be made in the period in which the retirement obligation is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. Natural gas storage system and certain other distribution assets for DTE Gas and substations, manholes, and certain other distribution assets for DTE Electric have an indeterminate life. Therefore, no liability has been recorded for these assets.
Regulatory Assets and Liabilities	DTE Electric and DTE Gas are required to record Regulatory assets and liabilities for certain transactions that would have been treated as revenue or expense in non-regulated businesses. Continued applicability of regulatory accounting treatment requires that rates be designed to recover specific costs of providing regulated services and be charged to and collected from customers. Future regulatory changes or changes in the competitive environment could result in the discontinuance of this accounting treatment for Regulatory assets and liabilities for some or all of the Registrants' businesses and may require the write-off of the portion of any Regulatory asset or liability that was no longer probable of recovery through regulated rates. Management believes that currently available facts support the continued use of Regulatory assets and liabilities and that all Regulatory assets and liabilities are recoverable or refundable in the current regulatory environment.
Fair Value Measurement	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, which refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable inputs. The Registrants make certain assumptions they believe that market participants would use in pricing assets or liabilities, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. Credit risk of the Registrants and their counterparties is incorporated in the valuation of assets and liabilities through the use of credit reserves, the impact of which was immaterial at December 31, 2015 and 2014 . The Registrants believe they use valuation techniques that maximize the use of observable market-based inputs and minimize the use of unobservable inputs. A fair value hierarchy has been established that prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. All assets and liabilities are required to be classified in their entirety based on the lowest level of input that is significant to the fair value measurement in its entirety. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability, and may affect the valuation of the asset or liability and its placement within the fair value hierarchy. The Registrants classify fair value balances based on the fair value hierarchy defined as follows: • Level 1 — Consists of unadjusted quoted prices in active markets for identical assets or liabilities that the Registrants have the ability to access as of the reporting date. • Level 2 — Consists of inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. • Level 3 — Consists of unobservable inputs for assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost-benefit constraints.
Nuclear Decommissioning Trusts and Other Investments	Nuclear Decommissioning Trusts and Other Investments The nuclear decommissioning trusts and other investments hold debt and equity securities directly and indirectly through institutional mutual funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The institutional mutual funds hold exchange-traded equity or debt securities and are valued based on stated NAVs. Non-exchange-traded fixed income securities are valued based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee determines that another price source is considered to be preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, the Registrants selectively corroborate the fair value of securities by comparison of market-based price sources. Investment policies and procedures are determined by DTE Energy's Trust Investments Department which reports to DTE Energy's Vice President and Treasurer.
Derivative Assets and Liabilities	Derivative Assets and Liabilities Derivative assets and liabilities are comprised of physical and financial derivative contracts, including futures, forwards, options, and swaps that are both exchange-traded and over-the-counter traded contracts. Various inputs are used to value derivatives depending on the type of contract and availability of market data. Exchange-traded derivative contracts are valued using quoted prices in active markets. The Registrants consider the following criteria in determining whether a market is considered active: frequency in which pricing information is updated, variability in pricing between sources or over time, and the availability of public information. Other derivative contracts are valued based upon a variety of inputs including commodity market prices, broker quotes, interest rates, credit ratings, default rates, market-based seasonality, and basis differential factors. The Registrants monitor the prices that are supplied by brokers and pricing services and may use a supplemental price source or change the primary price source of an index if prices become unavailable or another price source is determined to be more representative of fair value. The Registrants have obtained an understanding of how these prices are derived. Additionally, the Registrants selectively corroborate the fair value of their transactions by comparison of market-based price sources. Mathematical valuation models are used for derivatives for which external market data is not readily observable, such as contracts which extend beyond the actively traded reporting period. The Registrants have established a Risk Management Committee whose responsibilities include directly or indirectly ensuring all valuation methods are applied in accordance with predefined policies. The development and maintenance of the Registrants' forward price curves has been assigned to DTE Energy's Risk Management Department, which is separate and distinct from the trading functions within DTE Energy.
Fair Value Transfer	Derivatives are transferred between levels primarily due to changes in the source data used to construct price curves as a result of changes in market liquidity. Transfers in and transfers out are reflected as if they had occurred at the beginning of the period.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The fair value of financial instruments included in the table below is determined by using quoted market prices when available. When quoted prices are not available, pricing services may be used to determine the fair value with reference to observable interest rate indexes. The Registrants have obtained an understanding of how the fair values are derived. The Registrants also selectively corroborate the fair value of their transactions by comparison of market-based price sources. Discounted cash flow analyses based upon estimated current borrowing rates are also used to determine fair value when quoted market prices are not available. The fair values of notes receivable, excluding capital leases, are generally estimated using discounted cash flow techniques that incorporate market interest rates as well as assumptions about the remaining life of the loans and credit risk. Depending on the information available, other valuation techniques may be used that rely on internal assumptions and models. Valuation policies and procedures for the Registrants are determined by DTE Energy's Treasury Department which reports to DTE Energy's Vice President and Treasurer.
Derivatives	The Registrants recognize all derivatives at their fair value as Derivative assets or liabilities on their respective Consolidated Statements of Financial Position unless they qualify for certain scope exceptions, including the normal purchases and normal sales exception. Further, derivatives that qualify and are designated for hedge accounting are classified as either hedges of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge); or as hedges of the fair value of a recognized asset or liability or of an unrecognized firm commitment (fair value hedge). For cash flow hedges, the portion of the derivative gain or loss that is effective in offsetting the change in the value of the underlying exposure is deferred in Accumulated other comprehensive income (loss) and later reclassified into earnings when the underlying transaction occurs. Gains or losses from the ineffective portion of cash flow hedges are recognized in earnings immediately. For fair value hedges, changes in fair values for the derivative and hedged item are recognized in earnings each period. For derivatives that do not qualify or are not designated for hedge accounting, changes in fair value are recognized in earnings each period. The Registrants' primary market risk exposure is associated with commodity prices, credit, and interest rates. The Registrants have risk management policies to monitor and manage market risks. The Registrants use derivative instruments to manage some of the exposure. DTE Energy uses derivative instruments for trading purposes in its Energy Trading segment. Contracts classified as derivative instruments include electricity, natural gas, oil, certain coal forwards, futures, options, swaps, and foreign currency exchange contracts. Items not classified as derivatives include natural gas inventory, pipeline transportation contracts, renewable energy credits, and natural gas storage assets.
Derivatives, Offsetting Fair Value Amounts	Certain of DTE Energy's derivative positions are subject to netting arrangements which provide for offsetting of asset and liability positions as well as related cash collateral. Such netting arrangements generally do not have restrictions. Under such netting arrangements, DTE Energy offsets the fair value of derivative instruments with cash collateral received or paid for those contracts executed with the same counterparty, which reduces DTE Energy's Total Assets and Liabilities. Cash collateral is allocated between the fair value of derivative instruments and customer accounts receivable and payable with the same counterparty on a pro rata basis to the extent there is exposure. Any cash collateral remaining, after the exposure is netted to zero, is reflected in Accounts receivable and Accounts payable as collateral paid or received, respectively. DTE Energy also provides and receives collateral in the form of letters of credit which can be offset against net Derivative assets and liabilities as well as Accounts receivable and payable. DTE Energy had issued letters of credit of approximately $7 million at December 31, 2015 and 2014 , which could be used to offset net Derivative liabilities. Letters of credit received from third parties which could be used to offset net Derivative assets were $2 million and $5 million at December 31, 2015 and 2014 , respectively. Such balances of letters of credit are excluded from the tables below and are not netted with the recognized assets and liabilities in DTE Energy's Consolidated Statements of Financial Position. For contracts with certain clearing agents the fair value of derivative instruments is netted against realized positions with the net balance reflected as either 1) a Derivative asset or liability or 2) an Account receivable or payable. Other than certain clearing agents, Accounts receivable and Accounts payable that are subject to netting arrangements have not been offset against the fair value of Derivative assets and liabilities. Certain contracts that have netting arrangements have not been offset in DTE Energy's Consolidated Statements of Financial Position. The impact of netting these derivative instruments and cash collateral related to such contracts is not material. Only the gross amounts for these derivative instruments are included in the table below.
Derivatives, Methods of Accounting, Derivatives Not Designated or Qualifying as Hedges	Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility.
Stock-Based Compensation	DTE Energy records compensation expense at fair value over the vesting period for all awards it grants.

Organization and Basis of Pre33

Organization and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 2015
Variable Interest Entity, Consolidated, Carrying Amount, Assets and Liabilities, Net [Abstract]
Schedule of Variable Interest Entities	The following table summarizes the major Consolidated Statements of Financial Position items for consolidated VIEs as of December 31, 2015 and 2014 . All assets and liabilities of a consolidated VIE are presented where it has been determined that a consolidated VIE has either (1) assets that can be used only to settle obligations of the VIE or (2) liabilities for which creditors do not have recourse to the general credit of the primary beneficiary. Securitization, included in the DTE Energy table below for December 31, 2014, also relates to DTE Electric. VIEs, in which DTE Energy holds a majority voting interest and is the primary beneficiary, that meet the definition of a business and whose assets can be used for purposes other than the settlement of the VIE's obligations have been excluded from the table below. December 31, 2015 December 31, 2014 Total Securitization Other Total (In millions) ASSETS Cash and cash equivalents $ 14 $ — $ 7 $ 7 Restricted cash 8 96 8 104 Accounts receivable 18 26 15 41 Inventories 82 — 67 67 Property, plant, and equipment, net 66 — 81 81 Securitized regulatory assets — 34 — 34 Other current and long-term assets 4 1 6 7 $ 192 $ 157 $ 184 $ 341 LIABILITIES Accounts payable and accrued current liabilities $ 13 $ 3 $ 8 $ 11 Current portion long-term debt, including capital leases 8 105 10 115 Current regulatory liabilities — 32 — 32 Mortgage bonds, notes, and other 10 — 15 15 Capital lease obligations — — 3 3 Other current and long-term liabilities 6 9 6 15 $ 37 $ 149 $ 42 $ 191
Summary of Amounts For Nonconsolidated Variable Interest Entities	Amounts for DTE Energy's non-consolidated VIEs as of December 31, 2015 and 2014 are as follows: December 31, 2015 December 31, 2014 (In millions) Investment in equity method investees $ 136 $ 134 Notes receivable $ 15 $ 15
Equity Method Investments	Equity method investees are described below: Investments % Owned Segment 2015 2014 2015 2014 Description (In millions) Significant Equity Method Investees Gas Storage and Pipelines NEXUS Pipeline $ 89 $ 16 50% 50% A proposed 255-mile pipeline to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers Vector Pipeline 96 98 40% 40% 348-mile pipeline connecting Chicago, Michigan, and Ontario market centers Millennium Pipeline 111 110 26% 26% 182-mile pipeline serving markets in the Northeast $ 296 $ 224 Other Equity Method Investees Other Segments 218 210 $ 514 $ 434

Significant Accounting Polici34

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in DTE Energy's Accumulated other comprehensive income (loss) by component for the years ended December 31, 2015 and 2014 : Changes in Accumulated Other Comprehensive Income (Loss) by Component (a) Net Net Benefit Foreign Total (In millions) Balance, December 31, 2013 $ (4 ) $ (6 ) $ (126 ) $ — $ (136 ) Other comprehensive income (loss) before reclassifications — 1 (25 ) (2 ) (26 ) Amounts reclassified from Accumulated other comprehensive income — — 7 — 7 Net current-period Other comprehensive income (loss) — 1 (18 ) (2 ) (19 ) Balance, December 31, 2014 $ (4 ) $ (5 ) $ (144 ) $ (2 ) $ (155 ) Other comprehensive income (loss) before reclassifications — 1 2 (4 ) (1 ) Amounts reclassified from Accumulated other comprehensive income — — 11 — 11 Net current-period Other comprehensive income (loss) — 1 13 (4 ) 10 Balance, December 31, 2015 $ (4 ) $ (4 ) $ (131 ) $ (6 ) $ (145 ) ______________________________________ (a) All amounts are net of tax, except for Foreign currency translation. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 18 to the Consolidated Financial Statements " Retirement Benefits and Trusteed Assets "). The following table summarizes the changes in DTE Electric's Accumulated other comprehensive income (loss) by component for the years ended December 31, 2015 and 2014 : Changes in Accumulated Other Comprehensive Income (Loss) by Component (a) Net Unrealized Gain on Investments Benefit Obligations (b) Total (In millions) Balance, December 31, 2013 $ 1 $ (17 ) $ (16 ) Other comprehensive loss before reclassifications — (12 ) (12 ) Amounts reclassified from Accumulated other comprehensive income — 2 2 Net current-period Other comprehensive loss — (10 ) (10 ) Balance, December 31, 2014 $ 1 $ (27 ) $ (26 ) Other comprehensive income before reclassifications 1 — 1 Transfer of amounts from Accumulated other comprehensive income to affiliate — 27 27 Amounts reclassified from Accumulated other comprehensive income — — — Net current-period Other comprehensive income 1 27 28 Balance, December 31, 2015 $ 2 $ — $ 2 ______________________________________ (a) All amounts are net of tax. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 18 to the Consolidated Financial Statements " Retirement Benefits and Trusteed Assets ").
Schedule of Finite-Lived Intangible Assets by Major Class	DTE Energy has certain Intangible assets as shown below: December 31, 2015 2014 (In millions) Emission allowances $ 1 $ 1 Renewable energy credits 38 45 Contract intangible assets 117 122 156 168 Less accumulated amortization 62 57 Intangible assets, net 94 111 Less current intangible assets 5 9 $ 89 $ 102 DTE Electric has certain Intangible assets as shown below: December 31, 2015 2014 (In millions) Emission allowances $ 1 $ 1 Renewable energy credits 38 45 39 46 Less current intangible assets 5 9 $ 34 $ 37
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The following table summarizes DTE Energy's estimated contract intangible amortization expense expected to be recognized during each year through 2020 : Estimated amortization expense (In millions) 2016 $ 10 2017 $ 7 2018 $ 7 2019 $ 7 2020 $ 5

Acquisitions and Exit Activit35

Acquisitions and Exit Activities (Tables)	12 Months Ended
	Dec. 31, 2015
Business Acquisition, Integration, Restructuring and Other Related Costs [Abstract]
Restructuring and Related Costs	A summary of the charges in the Consolidated Statements of Operations resulting from DTE Energy's exit activities is shown below: 2015 (In millions) Fuel, purchased power, and gas — non-utility $ 5 Operation and maintenance 10 Asset (gains) losses and impairments, net 96 Total Exit Activity Charges $ 111

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
PP&E by Classification, Summary of Depreciation and Amortization	The following is a summary of Property, plant, and equipment by classification as of December 31: 2015 2014 Property, plant, and equipment (In millions) DTE Electric Generation $ 11,767 $ 10,712 Distribution 7,816 7,414 Other 1,808 1,679 Total DTE Electric 21,391 19,805 DTE Gas Distribution 3,124 2,946 Storage 453 448 Transmission and other 890 863 Total DTE Gas 4,467 4,257 Non-utility and other 2,263 2,476 Total DTE Energy 28,121 26,538 Less accumulated depreciation and amortization DTE Electric Generation (4,346 ) (3,863 ) Distribution (2,707 ) (2,822 ) Other (593 ) (531 ) Total DTE Electric (7,646 ) (7,216 ) DTE Gas Distribution (1,163 ) (1,130 ) Storage (147 ) (142 ) Transmission and other (370 ) (363 ) Total DTE Gas (1,680 ) (1,635 ) Non-utility and other (761 ) (867 ) Total DTE Energy (10,087 ) (9,718 ) Net DTE Energy Property, plant, and equipment $ 18,034 $ 16,820 Net DTE Electric Property, plant, and equipment $ 13,745 $ 12,589 The following is a summary of Depreciation and amortization expense for DTE Energy, including DTE Electric: 2015 2014 2013 (In millions) Property, plant, and equipment $ 740 $ 683 $ 630 Regulatory assets and liabilities 150 159 163 Securitized regulatory assets (a) (38 ) 303 301 $ 852 $ 1,145 $ 1,094 The following is a summary of Depreciation and amortization expense for DTE Electric: 2015 2014 2013 (In millions) Property, plant, and equipment $ 545 $ 489 $ 457 Regulatory assets and liabilities 126 135 138 Securitized regulatory assets (a) (38 ) 303 301 $ 633 $ 927 $ 896 _______________________________________ (a) Securitization surcharges ended in December 2014 with remaining over recovery refunded to customers in 2015. Securitization bonds were paid and Securitization regulatory assets amortization was completed in 2015. The $38 million credit represents the final adjustments to close out the Securitization program.
Schedule of Utility Property, Plant, and Equipment	The average estimated useful life for each major class of utility Property, plant, and equipment as of December 31, 2015 follows: Estimated Useful Lives in Years Utility Generation Distribution Storage DTE Electric 40 41 N/A DTE Gas N/A 50 53
Schedule of Capitalized Software	The following balances for capitalized software relate to DTE Energy, including DTE Electric: Year Ended December 31, 2015 2014 2013 (In millions) Amortization expense of capitalized software $ 98 $ 77 $ 71 Gross carrying value of capitalized software $ 770 $ 668 Accumulated amortization of capitalized software $ 439 $ 335 The following balances for capitalized software relate to DTE Electric: Year Ended December 31, 2015 2014 2013 (In millions) Amortization expense of capitalized software $ 80 $ 71 $ 64 Gross carrying value of capitalized software $ 664 $ 590 Accumulated amortization of capitalized software $ 369 $ 293
Schedule of Capital Leased Assets	Property under capital leases for the Registrants is as follows: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Gross property under capital leases $ 48 $ 35 $ 22 $ 9 Accumulated amortization of property under capital leases $ 26 $ 27 $ 1 $ 5

Jointly-Owned Utility Plant (Ta

Jointly-Owned Utility Plant (Tables)	12 Months Ended
	Dec. 31, 2015
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Schedule of Jointly-Owned Utility Plants	Ownership information of the two utility plants as of December 31, 2015 was as follows: Belle River Ludington Hydroelectric Pumped Storage In service date 1984-1985 1973 Total plant capacity 1,270 MW 1,955 MW Ownership interest (a) 49% Investment in Property, plant, and equipment (in millions) $ 1,779 $ 443 Accumulated depreciation (in millions) $ 1,053 $ 154 _______________________________________ (a) DTE Electric's ownership interest is 63% in Unit No. 1, 81% of the facilities applicable to Belle River used jointly by the Belle River and St. Clair Power Plants and 75% in common facilities used at Unit No. 2.

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2015
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligations	A reconciliation of the asset retirement obligations for 2015 follows: DTE Energy DTE Electric (In millions) Asset retirement obligations at December 31, 2014 $ 1,962 $ 1,796 Accretion 119 111 Liabilities incurred 33 33 Revision in estimated cash flows 80 80 Asset retirement obligations at December 31, 2015 $ 2,194 $ 2,020

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2015
Regulatory Assets and Liabilities Disclosure [Abstract]
Schedule of Regulatory Assets	The following are balances and a brief description of the Registrants' Regulatory assets and liabilities at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 Assets (In millions) Recoverable pension and other postretirement costs: Pension $ 2,112 $ 2,284 $ 1,592 $ 1,743 Other postretirement costs 256 234 198 191 Asset retirement obligation 565 448 565 448 Recoverable Michigan income taxes 248 267 203 220 Removal costs asset 118 15 118 15 Unamortized loss on reacquired debt 63 67 41 44 Other recoverable income taxes 61 66 61 66 Deferred environmental costs 54 59 — — Transitional Reconciliation Mechanism 43 14 43 14 Cost to achieve Performance Excellence Process 33 54 28 46 Accrued PSCR/GCR revenue 12 61 — 34 Recoverable income taxes related to Securitized regulatory assets — 19 — 19 Other 159 139 137 119 3,724 3,727 2,986 2,959 Less amount included in Current Assets (32 ) (76 ) (17 ) (46 ) $ 3,692 $ 3,651 $ 2,969 $ 2,913 Securitized regulatory assets $ — $ 34 $ — $ 34
Schedule of Regulatory Liabilities	DTE Energy DTE Electric 2015 2014 2015 2014 Liabilities (In millions) Removal costs liability $ 291 $ 308 $ — $ — Renewable energy 197 227 197 227 Negative pension offset 46 67 — — Accrued PSCR/GCR refund 37 — 15 — Refundable income taxes 23 33 — — Energy optimization 10 24 — 14 Fermi 2 refueling outage 4 16 4 16 Securitization over recovery — 71 — 71 Refundable revenue decoupling/deferred gain — 63 — 63 Other 2 11 2 4 $ 610 $ 820 $ 218 $ 395 Less amount included in Current Liabilities (41 ) (153 ) (19 ) (150 ) $ 569 $ 667 $ 199 $ 245

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The Registrants' total Income Tax Expense varied from the statutory federal income tax rate for the following reasons: 2015 2014 2013 DTE Energy (In millions) Income Before Income Taxes $ 950 $ 1,275 $ 922 Income tax expense at 35% statutory rate $ 333 $ 446 $ 323 Production tax credits (122 ) (119 ) (68 ) Investment tax credits (7 ) (6 ) (6 ) Depreciation (4 ) (4 ) (4 ) AFUDC - Equity (8 ) (7 ) (5 ) Employee Stock Ownership Plan dividends (5 ) (4 ) (4 ) Domestic production activities deduction — — (14 ) State and local income taxes, net of federal benefit 35 51 37 Enactment of New York Corporate Income Tax Legislation, net of federal benefit — 8 — Other, net 8 (1 ) (5 ) Income Tax Expense $ 230 $ 364 $ 254 Effective income tax rate 24.2 % 28.5 % 27.5 % 2015 2014 2013 DTE Electric (In millions) Income Before Income Taxes $ 836 $ 830 $ 741 Income tax expense at 35% statutory rate $ 293 $ 291 $ 260 Production tax credits (31 ) (22 ) (15 ) Investment tax credits (5 ) (5 ) (5 ) Depreciation 3 3 3 AFUDC - Equity (7 ) (7 ) (5 ) Employee Stock Ownership Plan dividends (3 ) (3 ) (2 ) Domestic production activities deduction — (2 ) (18 ) State and local income taxes, net of federal benefit 43 43 41 Other, net (1 ) — (5 ) Income Tax Expense $ 292 $ 298 $ 254 Effective income tax rate 34.9 % 35.9 % 34.3 %
Schedule of Components of Income Tax Expense (Benefit)	Components of the Registrants' Income Tax Expense were as follows: 2015 2014 2013 DTE Energy (In millions) Current income tax expense (benefit) Federal $ (3 ) $ (16 ) $ 74 State and other income tax (4 ) 24 16 Total current income taxes (7 ) 8 90 Deferred income tax expense Federal 178 289 122 State and other income tax 59 67 42 Total deferred income taxes 237 356 164 Total $ 230 $ 364 $ 254 2015 2014 2013 DTE Electric (In millions) Current income tax expense (benefit) Federal $ (26 ) $ (19 ) $ 123 State and other income tax (2 ) 20 23 Total current income taxes (28 ) 1 146 Deferred income tax expense Federal 252 251 68 State and other income tax 68 46 40 Total deferred income taxes 320 297 108 Total $ 292 $ 298 $ 254
Schedule of Deferred Tax Assets and Liabilities	The Registrants' deferred tax assets (liabilities) were comprised of the following at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Property, plant, and equipment $ (4,211 ) $ (3,832 ) $ (3,468 ) $ (3,152 ) Securitized regulatory assets 5 (2 ) 5 (3 ) Tax credit carry-forwards 465 296 53 — Pension and benefits (301 ) (152 ) (193 ) (43 ) Federal net operating loss carry-forward 177 — 142 — State and local net operating loss carry-forwards 63 39 16 — Investments in equity method investees (82 ) (84 ) — — Other (4 ) 65 (53 ) 12 (3,888 ) (3,670 ) (3,498 ) (3,186 ) Less valuation allowance (35 ) (31 ) — — Long-term deferred income tax liabilities $ (3,923 ) $ (3,701 ) $ (3,498 ) $ (3,186 ) Deferred income tax assets $ 1,088 $ 861 $ 453 $ 357 Deferred income tax liabilities (5,011 ) (4,562 ) (3,951 ) (3,543 ) $ (3,923 ) $ (3,701 ) $ (3,498 ) $ (3,186 )
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the beginning and ending amount of unrecognized tax benefits for the Registrants is as follows: 2015 2014 2013 DTE Energy (In millions) Balance at January 1 $ 9 $ 10 $ 11 Lapse of statute of limitations (6 ) (1 ) (1 ) Balance at December 31 $ 3 $ 9 $ 10 2015 2014 2013 DTE Electric (In millions) Balance at January 1 $ 4 $ 4 $ 4 Balance at December 31 $ 4 $ 4 $ 4

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	A reconciliation of both calculations is presented in the following table as of December 31: 2015 2014 2013 (In millions, expect per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 727 $ 905 $ 661 Average number of common shares outstanding 179 177 175 Weighted average net restricted shares outstanding — — 1 Dividends declared — common shares $ 508 $ 475 $ 453 Dividends declared — net restricted shares 2 1 1 Total distributed earnings $ 510 $ 476 $ 454 Net Income less distributed earnings $ 217 $ 429 $ 207 Distributed (dividends per common share) $ 2.84 $ 2.69 $ 2.59 Undistributed 1.21 2.42 1.17 Total Basic Earnings per Common Share $ 4.05 $ 5.11 $ 3.76 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 727 $ 905 $ 661 Average number of common shares outstanding 179 177 175 Weighted average net restricted shares outstanding — — 1 Dividends declared — common shares $ 508 $ 475 $ 453 Dividends declared — net restricted shares 2 1 1 Total distributed earnings $ 510 $ 476 $ 454 Net Income less distributed earnings $ 217 $ 429 $ 207 Distributed (dividends per common share) $ 2.84 $ 2.69 $ 2.59 Undistributed 1.21 2.41 1.17 Total Diluted Earnings per Common Share $ 4.05 $ 5.10 $ 3.76

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2015
Fair Value Disclosures [Abstract]
Assets and Liabilities Recorded at Fair Value on a Recurring Basis	The following table presents assets and liabilities for DTE Energy measured and recorded at fair value on a recurring basis as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Netting (a) Net Balance Level 1 Level 2 Level 3 Netting (a) Net Balance (In millions) Assets: Cash equivalents (b) $ 13 $ 3 $ — $ — $ 16 $ 13 $ 99 $ — $ — $ 112 Nuclear decommissioning trusts 759 477 — — 1,236 792 449 — — 1,241 Other investments (c) 149 — — — 149 100 50 — — 150 Derivative assets: Commodity Contracts: Natural Gas 193 91 103 (285 ) 102 555 140 92 (681 ) 106 Electricity — 239 68 (232 ) 75 — 295 47 (280 ) 62 Other 2 — 3 (2 ) 3 42 — 3 (42 ) 3 Other derivative contracts (d) — 12 — (9 ) 3 — 4 — (3 ) 1 Total derivative assets 195 342 174 (528 ) 183 597 439 142 (1,006 ) 172 Total $ 1,116 $ 822 $ 174 $ (528 ) $ 1,584 $ 1,502 $ 1,037 $ 142 $ (1,006 ) $ 1,675 Liabilities: Derivative liabilities: Commodity Contracts: Natural Gas $ (218 ) $ (57 ) $ (108 ) $ 294 $ (89 ) $ (578 ) $ (78 ) $ (62 ) $ 679 $ (39 ) Electricity — (243 ) (62 ) 253 (52 ) — (290 ) (52 ) 298 (44 ) Other (2 ) — (8 ) 8 (2 ) (32 ) (9 ) (4 ) 45 — Other derivative contracts (d) — (7 ) — 7 — — (5 ) — 3 (2 ) Total derivative liabilities (220 ) (307 ) (178 ) 562 (143 ) (610 ) (382 ) (118 ) 1,025 (85 ) Total $ (220 ) $ (307 ) $ (178 ) $ 562 $ (143 ) $ (610 ) $ (382 ) $ (118 ) $ 1,025 $ (85 ) Net Assets (Liabilities) at the end of the period $ 896 $ 515 $ (4 ) $ 34 $ 1,441 $ 892 $ 655 $ 24 $ 19 $ 1,590 Assets: Current $ 174 $ 284 $ 128 $ (441 ) $ 145 $ 582 $ 504 $ 109 $ (955 ) $ 240 Noncurrent (e) 942 538 46 (87 ) 1,439 920 533 33 (51 ) 1,435 Total Assets $ 1,116 $ 822 $ 174 $ (528 ) $ 1,584 $ 1,502 $ 1,037 $ 142 $ (1,006 ) $ 1,675 Liabilities: Current $ (174 ) $ (260 ) $ (87 ) $ 464 $ (57 ) $ (572 ) $ (357 ) $ (112 ) $ 964 $ (77 ) Noncurrent (46 ) (47 ) (91 ) 98 (86 ) (38 ) (25 ) (6 ) 61 (8 ) Total Liabilities $ (220 ) $ (307 ) $ (178 ) $ 562 $ (143 ) $ (610 ) $ (382 ) $ (118 ) $ 1,025 $ (85 ) Net Assets (Liabilities) at the end of the period $ 896 $ 515 $ (4 ) $ 34 $ 1,441 $ 892 $ 655 $ 24 $ 19 $ 1,590 _______________________________________ (a) Amounts represent the impact of master netting agreements that allow DTE Energy to net gain and loss positions and cash collateral held or placed with the same counterparties. (b) At December 31, 2015 , available-for-sale securities of $16 million included $8 million and $8 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2014 , available-for-sale securities of $112 million , included $105 million and $7 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. (c) Excludes cash surrender value of life insurance investments. (d) Primarily includes foreign currency exchange contracts. (e) Includes $149 million and $150 million at December 31, 2015 and 2014 , respectively, of other investments that are included in DTE Energy's Consolidated Statements of Financial Position in Other investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Net Balance Level 1 Level 2 Level 3 Net Balance (In millions) Assets: Cash equivalents (a) $ 5 $ 3 $ — $ 8 $ 5 $ 99 $ — $ 104 Nuclear decommissioning trusts 759 477 — 1,236 792 449 — 1,241 Other investments 8 — — 8 97 50 — 147 Derivative assets — FTRs — — 3 3 — — 3 3 Total $ 772 $ 480 $ 3 $ 1,255 $ 894 $ 598 $ 3 $ 1,495 Assets: Current $ 5 $ 3 $ 3 $ 11 $ 5 $ 99 $ 3 $ 107 Noncurrent 767 477 — 1,244 889 499 — 1,388 Total Assets $ 772 $ 480 $ 3 $ 1,255 $ 894 $ 598 $ 3 $ 1,495 _______________________________________ (a) At December 31, 2015 , available-for-sale securities of $8 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. At December 31, 2014 , available-for-sale securities of $104 million included $96 million and $8 million of cash equivalents included in Restricted cash and Other investments, respectively, on DTE Electric's Consolidated Statements of Financial Position.
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis Level 3 Roll Forward	The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Energy for the years ended December 31, 2015 and 2014 : Year Ended December 31, 2015 Year Ended December 31, 2014 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of December 31 $ 30 $ (5 ) $ (1 ) $ 24 $ (52 ) $ 13 $ 3 $ (36 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 — — — — (2 ) — — (2 ) Total gains (losses): Included in earnings (44 ) 44 (8 ) (8 ) (40 ) 25 (5 ) (20 ) Recorded in Regulatory assets/liabilities — — 12 12 — — 8 8 Purchases, issuances, and settlements: Purchases — 2 — 2 — 1 — 1 Issuances — — — — — (3 ) — (3 ) Settlements 9 (35 ) (8 ) (34 ) 124 (41 ) (7 ) 76 Net Assets (Liabilities) as of December 31 $ (5 ) $ 6 $ (5 ) $ (4 ) $ 30 $ (5 ) $ (1 ) $ 24 The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ (135 ) $ 13 $ (7 ) $ (129 ) $ 35 $ 9 $ (4 ) $ 40 The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Electric for the years ended December 31, 2015 and 2014 : Year Ended December 31, 2015 2014 (In millions) Net Assets as of December 31 $ 3 $ 3 Change in fair value recorded in Regulatory assets/liabilities 12 8 Purchases, issuances, and settlements: Settlements (12 ) (8 ) Net Assets as of December 31 $ 3 $ 3 The amount of total gains (losses) included in Regulatory assets and liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 3 $ 3
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques	The following tables present the unobservable inputs related to DTE Energy's Level 3 assets and liabilities as of December 31, 2015 and 2014 : December 31, 2015 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 103 $ (108 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.50 ) — $ 2.77 /MMBtu $ (0.19 )/MMBtu Electricity $ 68 $ (62 ) Discounted Cash Flow Forward basis price (per MWh) $ (11 ) — $ 14 /MWh $ 2 /MWh December 31, 2014 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 92 $ (62 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (2.28 ) — $ 7.83 /MMBtu $ (0.22 )/MMBtu Electricity $ 47 $ (52 ) Discounted Cash Flow Forward basis price (per MWh) $ (14 ) — $ 15 /MWh $ 4 /MWh
Fair Value of Financial Instruments	The following table presents the carrying amount and fair value of financial instruments for DTE Energy as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Carrying Fair Value Carrying Fair Value Amount Level 1 Level 2 Level 3 Amount Level 1 Level 2 Level 3 (In millions) Notes receivable, excluding capital leases $ 32 $ — $ — $ 32 $ 41 $ — $ — $ 41 Dividends payable $ 131 $ 131 $ — $ — $ 122 $ 122 $ — $ — Short-term borrowings $ 499 $ — $ 499 $ — $ 398 $ — $ 398 $ — Long-term debt, excluding capital leases $ 9,285 $ 496 $ 8,136 $ 1,203 $ 8,606 $ 489 $ 8,308 $ 706 The following table presents the carrying amount and fair value of financial instruments for DTE Electric as of December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Carrying Fair Value Carrying Fair Value Amount Level 1 Level 2 Level 3 Amount Level 1 Level 2 Level 3 (In millions) Notes receivable, excluding capital leases $ 5 $ — $ — $ 5 $ 12 $ — $ — $ 12 Notes receivable — affiliates $ — $ — $ — $ — $ 8 $ — $ — $ 8 Short-term borrowings — affiliates $ 75 $ — $ — $ 75 $ 84 $ — $ — $ 84 Short-term borrowings — other $ 272 $ — $ 272 $ — 50 $ — $ 50 $ — Long-term debt, excluding capital leases $ 5,624 $ — $ 5,432 $ 545 $ 5,259 $ — $ 5,341 $ 496
Fair Value of Nuclear Decommissioning Trust Fund Assets	The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: December 31, 2015 December 31, 2014 (In millions) Fermi 2 $ 1,211 $ 1,221 Fermi 1 3 3 Low-level radioactive waste 22 17 Total $ 1,236 $ 1,241
Schedule of Realized Gain (Loss) for Nuclear Decomissioning Trust Funds	The following table sets forth DTE Electric's gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds: Year Ended December 31, 2015 2014 2013 (In millions) Realized gains $ 39 $ 54 $ 83 Realized losses $ (33 ) $ (33 ) $ (41 ) Proceeds from sales of securities $ 885 $ 1,146 $ 1,118
Fair Value and Unrealized Gains and Losses for Nuclear Decommissioning Trust Funds	The following table sets forth DTE Electric's fair value and unrealized gains and losses for the nuclear decommissioning trust funds: December 31, 2015 December 31, 2014 Fair Unrealized Unrealized Losses Fair Unrealized Unrealized Losses (In millions) Equity securities $ 731 $ 195 $ (68 ) $ 756 $ 204 $ (39 ) Debt securities 499 16 (4 ) 474 21 (2 ) Cash and cash equivalents 6 — — 11 — — $ 1,236 $ 211 $ (72 ) $ 1,241 $ 225 $ (41 )

Financial and Other Derivativ43

Financial and Other Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following table presents the fair value of derivative instruments as of December 31, 2015 and 2014 for DTE Energy: December 31, 2015 December 31, 2014 Derivative Derivative Derivative Derivative (In millions) Derivatives not designated as hedging instruments: Foreign currency exchange contracts $ 12 $ (7 ) $ 4 $ (5 ) Commodity Contracts: Natural Gas 387 (383 ) 787 (718 ) Electricity 307 (305 ) 342 (342 ) Other 5 (10 ) 45 (45 ) Total derivatives not designated as hedging instruments: $ 711 $ (705 ) $ 1,178 $ (1,110 ) Current $ 570 $ (521 ) $ 1,083 $ (1,041 ) Noncurrent 141 (184 ) 95 (69 ) Total derivatives $ 711 $ (705 ) $ 1,178 $ (1,110 ) The following table presents the fair value of derivative instruments as of December 31, 2015 and 2014 for DTE Electric: December 31, 2015 2014 (In millions) FTRs — Other current assets $ 3 $ 3 Total derivatives not designated as hedging instrument $ 3 $ 3
Netting Offsets of Derivative Assets and Liabilities	The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy at December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Gross Amounts of Recognized Assets (Liabilities) Gross Amounts Offset in the Consolidated Statements of Financial Position Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position Gross Amounts of Recognized Assets (Liabilities) Gross Amounts Offset in the Consolidated Statements of Financial Position Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position (In millions) Derivative assets: Commodity Contracts: Natural Gas $ 387 $ (285 ) $ 102 $ 787 $ (681 ) $ 106 Electricity 307 (232 ) 75 342 (280 ) 62 Other 5 (2 ) 3 45 (42 ) 3 Other derivative contracts (a) 12 (9 ) 3 4 (3 ) 1 Total derivative assets $ 711 $ (528 ) $ 183 $ 1,178 $ (1,006 ) $ 172 Derivative liabilities: Commodity Contracts: Natural Gas $ (383 ) $ 294 $ (89 ) $ (718 ) $ 679 $ (39 ) Electricity (305 ) 253 (52 ) (342 ) 298 (44 ) Other (10 ) 8 (2 ) (45 ) 45 — Other derivative contracts (a) (7 ) 7 — (5 ) 3 (2 ) Total derivative liabilities $ (705 ) $ 562 $ (143 ) $ (1,110 ) $ 1,025 $ (85 ) _______________________________________ (a) Primarily includes foreign currency exchange contracts
Netting Offsets of Derivative Assets and Liabilities Reconciliation to the Statements of Financial Position	The following table presents the netting offsets of Derivative assets and liabilities showing the reconciliation of derivative instruments to DTE Energy's Consolidated Statements of Financial Position at December 31, 2015 and 2014 : December 31, 2015 December 31, 2014 Derivative Assets Derivative Liabilities Derivative Assets Derivative Liabilities Current Noncurrent Current Noncurrent Current Noncurrent Current Noncurrent (In millions) Total fair value of derivatives $ 570 $ 141 $ (521 ) $ (184 ) $ 1,083 $ 95 $ (1,041 ) $ (69 ) Counterparty netting (441 ) (85 ) 441 85 (955 ) (51 ) 955 51 Collateral adjustment — (2 ) 23 13 — — 9 10 Total derivatives as reported $ 129 $ 54 $ (57 ) $ (86 ) $ 128 $ 44 $ (77 ) $ (8 )
Gain (Loss) Recognized in Income on Derivatives	The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations for years ended December 31, 2015 and 2014 is as follows: Location of Gain Gain (Loss) Recognized in Derivatives not Designated as Hedging Instruments 2015 2014 (In millions) Foreign currency exchange contracts Operating Revenues — Non-utility operations $ 3 $ (2 ) Commodity Contracts: Natural Gas Operating Revenues — Non-utility operations (34 ) (30 ) Natural Gas Fuel, purchased power, and gas — non-utility (44 ) (5 ) Electricity Operating Revenues — Non-utility operations 54 123 Other Operating Revenues — Non-utility operations (7 ) (7 ) Total $ (28 ) $ 79
Volume of Commodity Contracts	The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of December 31, 2015 : Commodity Number of Units Natural Gas (MMBtu) 1,740,824,930 Electricity (MWh) 27,668,865 Oil (Gallons) 21,756,000 Foreign Currency Exchange (Canadian dollars) 72,328,008

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Long-term Debt, Unclassified [Abstract]
Schedule of Long-term Debt Instruments	DTE Energy's long-term debt outstanding and weighted average interest rates (a) of debt outstanding at December 31 were: 2015 2014 (In millions) Mortgage bonds, notes, and other DTE Energy Debt, Unsecured 4.4% due 2016 to 2033 $ 1,947 $ 1,647 DTE Electric Taxable Debt, Principally Secured 4.4% due 2016 to 2045 5,314 4,824 DTE Electric Tax-Exempt Revenue Bonds (b) 5.2% due 2020 to 2030 310 330 DTE Gas Taxable Debt, Principally Secured 4.9% due 2018 to 2045 1,124 1,099 Other Long-Term Debt, Including Non-Recourse Debt 110 121 DTE Energy Total Long-Term Debt 8,805 8,021 Less amount due within one year for DTE Energy (465 ) (161 ) $ 8,340 $ 7,860 DTE Electric Securitization Bonds 6.6% due 2015 $ — $ 105 Less amount due within one year — (105 ) $ — $ — DTE Energy Junior Subordinated Debentures 6.5% due 2061 $ 280 $ 280 5.25% due 2062 200 200 $ 480 $ 480 DTE Electric's long-term debt outstanding and weighted average interest rates (a) of debt outstanding at December 31 were: 2015 2014 (In millions) Mortgage bonds, notes, and other DTE Electric Taxable Debt, Principally Secured 4.4% due 2016 to 2045 $ 5,314 $ 4,824 DTE Electric Tax-Exempt Revenue Bonds (b) 5.2% due 2020 to 2030 310 330 DTE Electric Total Long-Term Debt 5,624 5,154 Less amount due within one year for DTE Electric (151 ) (10 ) $ 5,473 $ 5,144 DTE Electric Securitization Bonds 6.6% due 2015 $ — $ 105 Less amount due within one year — (105 ) $ — $ — _______________________________________ (a) Weighted average interest rates as of December 31, 2015 are shown below the description of each category of debt. (b) DTE Electric Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds.
Schedule of Issued Debt	In 2015 , the following debt was issued: Company Month Type Interest Rate Maturity Amount (In millions) DTE Electric March Mortgage Bonds (a) 3.70% 2045 $ 500 DTE Energy June Senior Notes (b) 3.30% 2022 300 DTE Gas August Mortgage Bonds (c) 3.35% 2027 40 DTE Gas August Mortgage Bonds (c) 4.21% 2045 125 $ 965 _______________________________________ (a) Proceeds were used for the redemption of long-term debt, repayment of short-term borrowings, and general corporate purposes. (b) Proceeds were used for general corporate purposes. (c) Proceeds were used for the redemption of long-term debt and general corporate purposes.
Schedule of Extinguishment of Debt	In 2015 , the following debt was redeemed: Company Month Type Interest Rate Maturity Amount (In millions) DTE Electric March Securitization Bonds 6.62% 2015 $ 105 DTE Electric March Mortgage Bonds 7.904% 2016 10 DTE Gas September Senior Notes 5.94% 2015 140 DTE Electric December Tax-Exempt Revenue Bonds 5.00% 2015 20 DTE Energy Various Other Long-Term Debt Various 2015 11 $ 286
Schedule of Maturities of Long-term Debt	The following table shows the Registrants' scheduled debt maturities, excluding any unamortized discount or premium on debt: 2016 2017 2018 2019 2020 2021 and Thereafter Total (In millions) DTE Energy (a) $ 465 $ 9 $ 407 $ 427 $ 688 $ 7,304 $ 9,300 DTE Electric $ 151 $ — $ 300 $ — $ 632 $ 4,552 $ 5,635 _______________________________________ (a) Amounts include DTE Electric's scheduled debt maturities.

Preferred and Preference Secu45

Preferred and Preference Securities (Tables)	12 Months Ended
	Dec. 31, 2015
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Schedule of Preferred and Preference Securities	As of December 31, 2015 , the amount of authorized and unissued stock is as follows: Company Type of Stock Par Value Shares Authorized DTE Energy Preferred $ — 5,000,000 DTE Electric Preferred $ 100 6,747,484 DTE Electric Preference $ 1 30,000,000 DTE Gas Preferred $ 1 7,000,000 DTE Gas Preference $ 1 4,000,000

Short-Term Credit Arrangement46

Short-Term Credit Arrangements and Borrowings (Tables)	12 Months Ended
	Dec. 31, 2015
Short-term Debt [Abstract]
Schedule of Line of Credit Facilities	The availability under the facilities in place at December 31, 2015 is shown in the following table: DTE Energy DTE Electric DTE Gas Total (In millions) Unsecured letter of credit facility, expiring in February 2017 $ 100 $ — $ — $ 100 Unsecured letter of credit facility, expiring in September 2017 70 — — 70 Unsecured revolving credit facility, expiring April 2020 1,200 400 300 1,900 1,370 400 300 2,070 Amounts outstanding at December 31, 2015 Commercial paper issuances 33 272 194 499 Letters of credit 130 — — 130 163 272 194 629 Net availability at December 31, 2015 $ 1,207 $ 128 $ 106 $ 1,441

Capital and Operating Leases (T

Capital and Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2015
Leases [Abstract]
Schedule of Future Minimum Lease Payments for Operating Leases	The Registrants' future minimum lease payments under non-cancelable leases at December 31, 2015 were: DTE Energy DTE Electric Operating Operating (In millions) 2016 $ 37 $ 24 2017 30 18 2018 25 15 2019 21 14 2020 13 10 Thereafter 71 35 Total minimum lease payments $ 197 $ 116
Schedule of Future Minimum Lease Receivables for Capital Leases	The components of DTE Energy's net investment in capital leases at December 31, 2015 , were as follows: DTE Energy Capital Leases (In millions) 2016 $ 13 2017 13 2018 13 2019 10 2020 9 Thereafter — Total minimum future lease receipts 58 Residual value of leased pipeline 40 Less unearned income (27 ) Net investment in capital lease 71 Less current portion (6 ) $ 65

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Long-term Purchase Commitments	The Registrants estimate the following commitments from 2016 through 2051 for DTE Energy, and 2016 through 2033 for DTE Electric, as detailed in the following table: DTE Energy DTE Electric (In millions) 2016 $ 2,038 $ 493 2017 1,160 412 2018 611 240 2019 397 120 2020 353 88 2021 and thereafter 3,043 992 $ 7,602 $ 2,345

Retirement Benefits and Trust49

Retirement Benefits and Trusteed Assets (Tables)	12 Months Ended
	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures	DTE Energy contributed the following amounts of DTE Energy common stock to the DTE Energy Company Master VEBA Trust for funding its other postretirement benefit plans: Date Number of Shares Price per Share Amount (In millions) February 17, 2015 1,427,835 $81.91 $ 117 $ 117
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Net Benefit Costs	Net pension cost for DTE Energy includes the following components: 2015 2014 2013 (In millions) Service cost $ 100 $ 83 $ 94 Interest cost 210 212 192 Expected return on plan assets (296 ) (273 ) (266 ) Amortization of net actuarial loss 205 157 208 Special termination benefits 2 — — Net pension cost $ 221 $ 179 $ 228 Net pension cost for DTE Electric includes the following components: 2015 2014 2013 (In millions) Service cost $ 77 $ 64 $ 73 Interest cost 160 162 146 Expected return on plan assets (210 ) (194 ) (184 ) Amortization of: Net actuarial loss 147 110 148 Prior service cost 1 2 1 Special termination benefits 1 — — Net pension cost $ 176 $ 144 $ 184
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	2015 2014 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial loss $ 19 $ 805 Amortization of net actuarial loss (205 ) (157 ) Prior service credit — (7 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (186 ) $ 641 Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 35 $ 820 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 162 $ 206 2015 2014 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial (gain) loss $ (13 ) $ 614 Amortization of net actuarial loss (147 ) (110 ) Prior service credit — (2 ) Amortization of prior service cost (1 ) (2 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (161 ) $ 500 Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 15 $ 644 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 115 $ 149 Prior service cost $ 1 $ 1
Schedule of Defined Benefit Plans Disclosures	The following table reconciles the obligations, assets, and funded status of the plans as well as the amounts recognized as prepaid pension cost or pension liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Accumulated benefit obligation, end of year $ 4,569 $ 4,853 $ 3,401 $ 3,712 Change in projected benefit obligation Projected benefit obligation, beginning of year $ 5,269 $ 4,380 $ 4,018 $ 3,341 Service cost 100 83 75 64 Interest cost 210 212 156 162 Plan amendments — (7 ) — (2 ) Actuarial (gain) loss (357 ) 836 (273 ) 634 Transfer due to plan sponsorship change — — (99 ) — Special termination benefits 2 — — — Benefits paid (253 ) (235 ) (192 ) (181 ) Projected benefit obligation, end of year $ 4,971 $ 5,269 $ 3,685 $ 4,018 Change in plan assets Plan assets at fair value, beginning of year $ 3,981 $ 3,720 $ 2,812 $ 2,632 Actual return on plan assets (79 ) 301 (56 ) 212 Company contributions 183 195 145 149 Benefits paid (253 ) (235 ) (192 ) (181 ) Plan assets at fair value, end of year $ 3,832 $ 3,981 $ 2,709 $ 2,812 Funded status of the plans $ (1,139 ) $ (1,288 ) $ (976 ) $ (1,206 ) Amount recorded as: Current liabilities $ (6 ) $ (8 ) $ — $ (6 ) Noncurrent liabilities (1,133 ) (1,280 ) (976 ) (1,200 ) $ (1,139 ) $ (1,288 ) $ (976 ) $ (1,206 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 180 $ 194 $ — $ 44 Prior service credit (1 ) (1 ) — — $ 179 $ 193 $ — $ 44 Amounts recognized in Regulatory assets (see Note 8 - "Regulatory Matters") Net actuarial loss $ 2,113 $ 2,285 $ 1,588 $ 1,738 Prior service cost (credit) (1 ) (1 ) 4 5 $ 2,112 $ 2,284 $ 1,592 $ 1,743
Schedule of Expected Benefit Payments	At December 31, 2015 , the benefits related to the Registrants' qualified and nonqualified pension plans expected to be paid in each of the next five years and in the aggregate for the five fiscal years thereafter are as follows: DTE Energy DTE Electric (In millions) 2016 $ 274 $ 213 2017 285 221 2018 297 231 2019 306 238 2020 314 244 2021-2025 1,662 1,279 Total $ 3,138 $ 2,426
Schedule of Assumptions Used	Assumptions used in determining the projected benefit obligation and net pension costs of the Registrants are: 2015 2014 2013 Projected benefit obligation Discount rate 4.50% 4.12% 4.95% Rate of compensation increase 4.65% 4.65% 4.20% Net pension costs Discount rate 4.12% 4.95% 4.15% Rate of compensation increase 4.65% 4.20% 4.20% Expected long-term rate of return on plan assets 7.75% 7.75% 8.25%
Schedule of Allocation of Plan Assets	Target allocations for the Registrants' pension plan assets as of December 31, 2015 are listed below: U.S. Large Capitalization (Cap) Equity Securities 22 % U.S. Small Cap and Mid Cap Equity Securities 5 Non-U.S. Equity Securities 20 Fixed Income Securities 25 Hedge Funds and Similar Investments 20 Private Equity and Other 8 100 % The following tables provide the fair value measurement amounts for the Registrants' pension plan assets at December 31, 2015 and 2014 (a): December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total (In millions) DTE Energy asset category: Short-term Investments (b) $ 23 $ — $ — $ 23 $ 46 $ — $ — $ 46 Equity Securities U.S. Large Cap (c) 842 — — 842 899 — — 899 U.S. Small Cap and Mid Cap (d) 219 — — 219 225 — — 225 Non-U.S. (e) 510 251 — 761 526 219 — 745 Fixed Income Securities (f) 5 1,024 — 1,029 7 1,113 — 1,120 Hedge Funds and Similar Investments (g) 220 96 452 768 226 95 438 759 Private Equity and Other (h) — — 190 190 — — 187 187 Securities Lending (i) (129 ) (25 ) — (154 ) (189 ) (50 ) — (239 ) Securities Lending Collateral (i) 129 25 — 154 189 50 — 239 DTE Energy Total $ 1,819 $ 1,371 $ 642 $ 3,832 $ 1,929 $ 1,427 $ 625 $ 3,981 DTE Electric asset category: Short-term Investments (b) $ 16 $ — $ — $ 16 $ 33 $ — $ — $ 33 Equity Securities U.S. Large Cap (c) 599 — — 599 638 — — 638 U.S. Small Cap and Mid Cap (d) 157 — — 157 162 — — 162 Non-U.S. (e) 367 178 — 545 378 157 — 535 Fixed Income Securities (f) 4 699 — 703 5 758 — 763 Hedge Funds and Similar Investments (g) 158 69 325 552 163 68 315 546 Private Equity and Other (h) — — 137 137 — — 135 135 Securities Lending (i) (93 ) (18 ) — (111 ) (136 ) (36 ) — (172 ) Securities Lending Collateral (i) 93 18 — 111 136 36 — 172 DTE Electric Total $ 1,301 $ 946 $ 462 $ 2,709 $ 1,379 $ 983 $ 450 $ 2,812 _______________________________________ (a) For a description of levels within the fair value hierarchy, see Note 11 to the Consolidated Financial Statements, " Fair Value ". (b) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (c) This category comprises both actively and not actively managed portfolios that track the S&P 500 low cost equity index funds. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (d) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (e) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (f) This category includes corporate bonds from diversified industries, U.S. Treasuries, and mortgage-backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as Level 2 assets. (g) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded debt and equity, publicly traded mutual funds, commingled and limited partnership funds, and non-exchange traded securities. Pricing for Level 1 and Level 2 assets in this category is obtained from quoted prices in actively traded markets and quoted prices from broker or pricing services. Non-exchange traded securities held in commingled funds are classified as Level 2 assets. Valuations for some Level 3 assets in this category may be based on limited observable inputs as there may be little, if any, publicly available pricing. (h) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. Pricing for investments in this category is based on limited observable inputs as there is little, if any, publicly available pricing. Valuations for assets in this category may be based on discounted cash flow analyses, relevant publicly-traded comparables, and comparable transactions. (i) In 2014, the Registrants began a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' pension trusts to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements.
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets	The following table provides a reconciliation of beginning and ending balances of DTE Energy's pension plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Year Ended December 31, 2015 Year Ended December 31, 2014 Hedge Funds Private Equity Total Hedge Funds Private Equity Total (In millions) Beginning Balance at January 1 $ 438 $ 187 $ 625 $ 395 $ 170 $ 565 Total realized/unrealized gains (losses) 10 10 20 22 16 38 Purchases, sales, and settlements: Purchases 4 32 36 22 31 53 Sales — (39 ) (39 ) (1 ) (30 ) (31 ) Ending Balance at December 31 $ 452 $ 190 $ 642 $ 438 $ 187 $ 625 The amount of total gains for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period $ 10 $ (3 ) $ 7 $ 21 $ 11 $ 32 The following table provides a reconciliation of beginning and ending balances of DTE Electric's pension plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Year Ended December 31, 2015 Year Ended December 31, 2014 Hedge Funds Private Equity Total Hedge Funds Private Equity Total (In millions) Beginning Balance at January 1 $ 315 $ 135 $ 450 $ 285 $ 122 407 Total realized/unrealized gains (losses) 7 7 14 15 12 27 Purchases, sales, and settlements: Purchases 3 23 26 16 22 38 Sales — (28 ) (28 ) (1 ) (21 ) (22 ) Ending Balance at December 31 $ 325 $ 137 $ 462 $ 315 $ 135 $ 450 The amount of total gains for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period $ 7 $ (2 ) $ 5 $ 15 $ 8 $ 23
Other Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Net Benefit Costs	Net other postretirement credit for DTE Electric includes the following components: 2015 2014 2013 (In millions) Service cost $ 25 $ 26 $ 35 Interest cost 62 68 67 Expected return on plan assets (90 ) (85 ) (74 ) Amortization of: Net actuarial loss 31 14 47 Prior service credit (95 ) (109 ) (100 ) Net other postretirement credit $ (67 ) $ (86 ) $ (25 ) Net other postretirement credit for DTE Energy includes the following components: 2015 2014 2013 (In millions) Service cost $ 34 $ 34 $ 47 Interest cost 81 89 88 Expected return on plan assets (131 ) (122 ) (110 ) Amortization of: Net actuarial loss 43 20 64 Prior service credit (126 ) (144 ) (131 ) Net other postretirement credit $ (99 ) $ (123 ) $ (42 )
Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block]	2015 2014 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial (gain) loss $ (68 ) $ 192 Amortization of net actuarial loss (43 ) (20 ) Amortization of prior service credit 126 144 Total recognized in Regulatory assets and Other comprehensive income (loss) $ 15 $ 316 Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (84 ) $ 193 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 32 $ 43 Prior service credit $ (118 ) $ (126 ) 2015 2014 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial (gain) loss $ (57 ) $ 144 Amortization of net actuarial loss (31 ) (14 ) Amortization of prior service credit 95 109 Total recognized in Regulatory assets and Other comprehensive income (loss) $ 7 $ 239 Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (60 ) $ 153 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 22 $ 31 Prior service credit $ (89 ) $ (94 )
Schedule of Defined Benefit Plans Disclosures	The following table reconciles the obligations, assets, and funded status of the plans including amounts recorded as Accrued postretirement liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2015 2014 2015 2014 (In millions) Change in accumulated postretirement benefit obligation Accumulated postretirement benefit obligation, beginning of year $ 2,044 $ 1,878 $ 1,558 $ 1,430 Service cost 34 34 25 26 Interest cost 81 89 62 68 Actuarial (gain) loss (224 ) 131 (166 ) 100 Benefits paid (89 ) (88 ) (65 ) (66 ) Accumulated postretirement benefit obligation, end of year $ 1,846 $ 2,044 $ 1,414 $ 1,558 Change in plan assets Plan assets at fair value, beginning of year $ 1,528 $ 1,527 $ 1,038 $ 1,061 Actual return on plan assets (25 ) 62 (19 ) 41 Company contributions 199 24 175 — Benefits paid (85 ) (85 ) (63 ) (64 ) Plan assets at fair value, end of year $ 1,617 $ 1,528 $ 1,131 $ 1,038 Funded status, end of year $ (229 ) $ (516 ) $ (283 ) $ (520 ) Amount recorded as: Noncurrent assets $ — $ — $ 24 $ — Current liabilities (1 ) (1 ) — — Noncurrent liabilities (228 ) (515 ) (307 ) (520 ) $ (229 ) $ (516 ) $ (283 ) $ (520 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 24 $ 34 $ — $ — Prior service credit (2 ) (5 ) — — $ 22 $ 29 $ — $ — Amounts recognized in Regulatory assets (see Note 8 - "Regulatory Matters") Net actuarial loss $ 387 $ 488 $ 297 $ 385 Prior service credit (131 ) (254 ) (99 ) (194 ) $ 256 $ 234 $ 198 $ 191
Schedule of Expected Benefit Payments	At December 31, 2015 , the benefits expected to be paid, including prescription drug benefits, in each of the next five years and in the aggregate for the five fiscal years thereafter for the Registrants are as follows: DTE Energy DTE Electric (In millions) 2016 $ 100 $ 77 2017 105 81 2018 108 84 2019 113 88 2020 116 90 2021-2025 621 476 Total $ 1,163 $ 896
Schedule of Assumptions Used	Assumptions used in determining the accumulated postretirement benefit obligation and net other postretirement benefit costs of the Registrants are: 2015 2014 2013 Accumulated postretirement benefit obligation Discount rate 4.50% 4.10% 4.95% Health care trend rate pre- and post- 65 6.25 / 6.75% 7.50 / 6.50% 7.50 / 6.50% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2027 2025 / 2024 2025 / 2024 Other postretirement benefit costs Discount rate (prior to interim remeasurement) 4.10% 4.95% 4.15% Discount rate (post interim remeasurement) N/A N/A 4.30% Expected long-term rate of return on plan assets 8.00% 8.00% 8.25% Health care trend rate pre- and post- 65 7.50 / 6.50% 7.50 / 6.50% 7.00% Ultimate health care trend rate 4.50% 4.50% 5.00% Year in which ultimate reached pre- and post- 65 2025 / 2024 2025 / 2024 2021
Schedule of Allocation of Plan Assets	Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2015 are listed below: U.S. Large Cap Equity Securities 17 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 20 Fixed Income Securities 25 Hedge Funds and Similar Investments 20 Private Equity and Other 14 100 % The following tables provide the fair value measurement amounts for the Registrants' other postretirement benefit plan assets at December 31, 2015 and 2014 (a): December 31, 2015 December 31, 2014 Level 1 Level 2 Level 3 Total Level 1 Level 2 Level 3 Total DTE Energy asset category: (In millions) Short-term Investments (b) $ 7 $ — $ — $ 7 $ 6 $ — $ — $ 6 Equity Securities U.S. Large Cap (c) 264 — — 264 266 — — 266 U.S. Small Cap and Mid Cap (d) 138 — — 138 149 — — 149 Non-U.S. (e) 262 55 — 317 222 59 — 281 Fixed Income Securities (f) 23 390 — 413 15 360 — 375 Hedge Funds and Similar Investments (g) 109 45 171 325 107 45 168 320 Private Equity and Other (h) — — 153 153 — — 131 131 Securities Lending (i) (122 ) (6 ) — (128 ) (141 ) (17 ) — (158 ) Securities Lending Collateral (i) 122 6 — 128 141 17 — 158 DTE Energy Total $ 803 $ 490 $ 324 $ 1,617 $ 765 $ 464 $ 299 $ 1,528 DTE Electric asset category: Short-term Investments (b) $ 5 $ — $ — $ 5 $ 4 $ — $ — $ 4 Equity Securities U.S. Large Cap (c) 183 — — 183 179 — — 179 U.S. Small Cap and Mid Cap (d) 97 — — 97 102 — — 102 Non-U.S. (e) 184 37 — 221 151 39 — 190 Fixed Income Securities (f) 17 272 — 289 11 243 — 254 Hedge Funds and Similar Investments (g) 76 32 119 227 73 31 114 218 Private Equity and Other (h) — — 109 109 — — 91 91 Securities Lending (i) (87 ) (4 ) — (91 ) (98 ) (11 ) — (109 ) Securities Lending Collateral (i) 87 4 — 91 98 11 — 109 DTE Electric Total $ 562 $ 341 $ 228 $ 1,131 $ 520 $ 313 $ 205 $ 1,038 _______________________________________ (a) For a description of levels within the fair value hierarchy see Note 11 to the Consolidated Financial Statements, " Fair Value ". (b) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (c) This category comprises both actively and not actively managed portfolios that track the S&P 500 low cost equity index funds. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (d) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (e) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as Level 2 assets. (f) This category includes corporate bonds from diversified industries, U.S. Treasuries, bank loans, and mortgage backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as Level 2 assets. (g) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded debt and equity, publicly traded mutual funds, commingled and limited partnership funds, and non-exchange traded securities. Pricing for Level 1 and Level 2 assets in this category is obtained from quoted prices in actively traded markets and quoted prices from broker or pricing services. Non-exchange traded securities held in commingled funds are classified as Level 2 assets. Valuations for some Level 3 assets in this category may be based on limited observable inputs as there may be little, if any, publicly available pricing. (h) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. Pricing for investments in this category is based on limited observable inputs as there is little, if any, publicly available pricing. Valuations for assets in this category may be based on discounted cash flow analyses, relevant publicly-traded comparables, and comparable transactions. (i) In 2014, the Registrants began a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' VEBA trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2015 are listed below: U.S. Large Cap Equity Securities 17 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 20 Fixed Income Securities 25 Hedge Funds and Similar Investments 20 Private Equity and Other 14 100 %
Schedule of Effect of Significant Unobservable Inputs, Changes in Plan Assets	The following table provides a reconciliation of beginning and ending balances of DTE Energy's other postretirement benefit plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Year Ended December 31, 2015 Year Ended December 31, 2014 Hedge Funds Private Total Hedge Funds Private Total (In millions) Beginning Balance at January 1 $ 168 $ 131 $ 299 $ 159 $ 101 $ 260 Total realized/unrealized gains (losses) 4 9 13 8 9 17 Purchases, sales, and settlements: Purchases 11 34 45 9 33 42 Sales (12 ) (21 ) (33 ) (8 ) (12 ) (20 ) Ending Balance at December 31 $ 171 $ 153 $ 324 $ 168 $ 131 $ 299 The amount of total gains for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period $ — $ 3 $ 3 $ 7 $ 8 $ 15 The following table provides a reconciliation of beginning and ending balances of DTE Electric's other postretirement benefit plan assets measured at fair value on a recurring basis where the determination of fair value includes significant unobservable inputs (Level 3): Year Ended December 31, 2015 Year Ended December 31, 2014 Hedge Funds Private Total Hedge Funds Private Total (In millions) Beginning Balance at January 1 $ 114 $ 91 $ 205 $ 111 $ 71 $ 182 Total realized/unrealized gains (losses) 3 6 9 5 6 11 Purchases, sales, and settlements: Purchases 11 26 37 4 22 26 Sales (9 ) (14 ) (23 ) (6 ) (8 ) (14 ) Ending Balance at December 31 $ 119 $ 109 $ 228 $ 114 $ 91 $ 205 The amount of total gains for the period attributable to the change in unrealized gains or losses related to assets still held at the end of the period $ — $ 2 $ 2 $ 5 $ 5 $ 10

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Share-based Compensation [Abstract]
Schedule of Employee Service Stock-based Compensation, Allocation of Recognized Period Costs	The following table summarizes the components of stock-based compensation for DTE Energy: 2015 2014 2013 (In millions) Stock-based compensation expense $ 34 $ 103 $ 99 Tax benefit $ 13 $ 40 $ 38 Stock-based compensation cost capitalized in Property, plant, and equipment $ 5 $ 16 $ 15
Schedule of Stock-based Compensation, Stock Options, Activity	The following table summarizes DTE Energy's stock option activity for the year ended December 31, 2015 : Number of Options Weighted Average Exercise Price Aggregate Intrinsic Options outstanding at December 31, 2014 444,278 $ 43.56 Exercised (178,017 ) $ 45.07 Forfeited or expired (3,979 ) $ 44.72 Options outstanding and exercisable at December 31, 2015 262,282 $ 42.52 $ 10
Schedule of Stock-based Compensation, Shares Authorized under Stock Option Plans, by Exercise Price Range	The number, weighted average exercise price, and weighted average remaining contractual life of DTE Energy options outstanding as of December 31, 2015 were as follows: Range of Exercise Prices Number of Options Weighted Average Weighted Average $ 27.00 — $ 38.00 22,083 $ 27.70 3.16 $ 38.01 — $ 42.00 80,434 $ 41.79 2.16 $ 42.01 — $ 45.00 116,665 $ 43.90 3.79 $ 45.01 — $ 50.00 43,100 $ 47.75 1.15 262,282 $ 42.52 2.80
Schedule of Stock-based Compensation, Restricted Stock Units Award Activity	Stock award activity for DTE Energy for the years ended December 31 was: 2015 2014 2013 Fair value of awards vested (in millions) $ 9 $ 11 $ 8 Restricted common shares awarded 144,300 159,590 127,785 Weighted average market price of shares awarded $ 83.43 $ 70.09 $ 64.72 Compensation cost charged against income (in millions) $ 10 $ 10 $ 23
Schedule of Stock-based Compensation, Restricted Stock Activity Rollforward	The following table summarizes DTE Energy’s restricted stock awards activity for the year ended December 31, 2015 : Restricted Weighted Average Balance at December 31, 2014 416,318 $ 62.82 Grants 144,300 $ 83.43 Forfeitures (12,721 ) $ 74.78 Vested and issued (165,453 ) $ 55.73 Balance at December 31, 2015 382,444 $ 73.26
Stock-based Compensation Expense	DTE Energy recorded compensation expense for performance share awards as follows: 2015 2014 2013 (In millions) Compensation expense $ 24 $ 93 $ 77 Cash settlements (a) $ 13 $ 11 $ 9 Stock settlements (a) $ 71 $ 61 $ 56 _______________________________________ (a) Sum of cash and stock settlements approximates the intrinsic value of the awards.
Schedule of Stock-based Compensation, Performance Shares Activity Rollforward	The following table summarizes DTE Energy’s performance share activity for the period ended December 31, 2015 : Performance Shares Weighted Average Balance at December 31, 2014 1,554,697 $ 69.32 Grants 467,288 $ 83.85 Forfeitures (47,067 ) $ 76.22 Payouts (532,700 ) $ — Balance at December 31, 2015 1,442,218 $ 75.85
Schedule of Unrecognized Compensation Cost, Nonvested Awards	As of December 31, 2015 , DTE Energy's total unrecognized compensation cost related to non-vested stock incentive plan arrangements and the weighted average recognition period was as follows: Unrecognized Weighted Average (In millions) (In years) Stock awards $ 11 1.11 Performance shares 37 0.97 $ 48 1.00

Segment and Related Informati51

Segment and Related Information (Tables)	12 Months Ended
	Dec. 31, 2015
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Inter-segment billing for goods and services exchanged between segments is based upon tariffed or market-based prices of the provider and primarily consists of the sale of reduced emissions fuel, power sales, and natural gas sales in the following segments: Year Ended December 31, 2015 2014 2013 (In millions) Electric $ 36 $ 29 $ 26 Gas 3 6 4 Gas Storage and Pipelines 8 9 3 Power and Industrial Projects 785 794 816 Energy Trading 32 33 43 Corporate and Other 4 3 (24 ) $ 868 $ 874 $ 868 Financial data of DTE Energy's business segments follows: Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2015 Operating Revenues — Utility operations $ 4,901 1,376 — — — — (39 ) $ 6,238 Operating Revenues — Non-utility operations $ — — 243 2,224 2,459 2 (829 ) $ 4,099 Depreciation and amortization $ 637 104 30 78 2 1 — $ 852 Interest income $ — (7 ) (8 ) (8 ) (2 ) (52 ) 64 $ (13 ) Interest expense $ 258 62 24 32 6 132 (64 ) $ 450 Equity in earnings of equity method investees $ 2 6 47 8 — 3 — $ 66 Income Tax Expense (Benefit) $ 290 72 70 (140 ) (15 ) (47 ) — $ 230 Net Income (Loss) Attributable to DTE Energy Company $ 542 132 107 16 (22 ) (48 ) — $ 727 Investment in equity method investees $ 10 9 296 183 — 16 — $ 514 Capital expenditures and acquisitions $ 1,785 273 161 36 6 — — $ 2,261 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 19,539 4,299 1,047 860 590 3,530 (1,128 ) $ 28,737 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2014 Operating Revenues — Utility operations $ 5,283 1,636 — — — — (35 ) $ 6,884 Operating Revenues — Non-utility operations $ — — 203 2,289 3,762 2 (839 ) $ 5,417 Depreciation and amortization $ 933 99 34 77 1 1 — $ 1,145 Interest income $ (1 ) (7 ) (6 ) (5 ) — (48 ) 57 $ (10 ) Interest expense $ 250 57 22 28 7 122 (57 ) $ 429 Equity in earnings of equity method investees $ 1 7 35 5 — — — $ 48 Income Tax Expense (Benefit) $ 296 78 53 (100 ) 77 (40 ) — $ 364 Net Income (Loss) Attributable to DTE Energy Company $ 528 140 82 90 122 (57 ) — $ 905 Investment in equity method investees $ 8 10 224 184 — 8 — $ 434 Capital expenditures and acquisitions $ 1,561 224 184 77 3 — — $ 2,049 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 18,713 4,247 883 998 755 3,209 (906 ) $ 27,899 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2013 Operating Revenues — Utility operations $ 5,199 1,474 — — — — (30 ) $ 6,643 Operating Revenues — Non-utility operations $ — — 132 1,950 1,771 3 (838 ) $ 3,018 Depreciation and amortization $ 902 95 23 72 1 1 — $ 1,094 Interest income $ (1 ) (7 ) (7 ) (6 ) — (51 ) 63 $ (9 ) Interest expense $ 268 58 18 27 8 120 (63 ) $ 436 Equity in earnings of equity method investees $ 1 6 44 8 — — — $ 59 Income Tax Expense (Benefit) $ 252 77 45 (45 ) (38 ) (37 ) — $ 254 Net Income (Loss) Attributable to DTE Energy Company $ 484 143 70 66 (58 ) (44 ) — $ 661 Investment in equity method investees $ 9 10 201 189 — 6 — $ 415 Capital expenditures and acquisitions $ 1,325 209 245 93 3 1 — $ 1,876 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 17,508 3,920 823 1,054 624 2,945 (939 ) $ 25,935

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The following is a summary of DTE Electric's transactions with affiliated companies: 2015 2014 2013 (In millions) Revenues Energy sales $ 2 $ 2 $ 2 Other services $ 6 $ 5 $ 7 Shared capital assets $ 33 $ 26 $ 23 Costs Fuel and purchased power $ 9 $ 4 $ 4 Other services and interest $ 2 $ (1 ) $ (1 ) Corporate expenses (net) $ 334 $ 304 $ 334 Other Dividends declared $ 395 $ 370 $ 342 Dividends paid $ 395 $ 370 $ 342 Capital contribution from DTE Energy $ 300 $ 190 $ 400

Supplementary Quarterly Finan53

Supplementary Quarterly Financial Information (Unaudited ) (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	DTE Energy Quarterly earnings per share may not equal full year totals, since quarterly computations are based on weighted average common shares outstanding during each quarter. First Second Third Fourth Year (In millions, except per share amounts) 2015 Operating Revenues $ 2,984 $ 2,268 $ 2,598 $ 2,487 $ 10,337 Operating Income $ 461 $ 204 $ 440 $ 134 $ 1,239 Net Income Attributable to DTE Energy Company $ 273 $ 109 $ 265 $ 80 $ 727 Basic Earnings per Share $ 1.53 $ 0.61 $ 1.47 $ 0.45 $ 4.05 Diluted Earnings per Share $ 1.53 $ 0.61 $ 1.47 $ 0.45 $ 4.05 2014 Operating Revenues $ 3,930 $ 2,698 $ 2,595 $ 3,078 $ 12,301 Operating Income $ 560 $ 249 $ 239 $ 542 $ 1,590 Net Income Attributable to DTE Energy Company $ 326 $ 124 $ 156 $ 299 $ 905 Basic Earnings per Share $ 1.84 $ 0.70 $ 0.88 $ 1.68 $ 5.11 Diluted Earnings per Share $ 1.84 $ 0.70 $ 0.88 $ 1.68 $ 5.10 DTE Electric First Second Third Fourth Year (In millions) 2015 Operating Revenues $ 1,203 $ 1,147 $ 1,385 $ 1,165 $ 4,900 Operating Income $ 268 $ 214 $ 400 $ 192 $ 1,074 Net Income $ 137 $ 99 $ 216 $ 92 $ 544 2014 Operating Revenues $ 1,410 $ 1,281 $ 1,357 $ 1,234 $ 5,282 Operating Income $ 271 $ 259 $ 272 $ 250 $ 1,052 Net Income $ 137 $ 130 $ 136 $ 129 $ 532

Valuation and Qualifying Acco54

Valuation and Qualifying Accounts (Tables)	12 Months Ended
	Dec. 31, 2015
Valuation and Qualifying Accounts [Abstract]
Summary of Valuation Allowance [Table Text Block]	Valuation and Qualifying Accounts Year Ending December 31, 2015 2014 2013 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 54 $ 55 $ 62 Additions: Charged to costs and expenses 93 95 94 Charged to other accounts (a) 14 20 23 Deductions (b) (112 ) (116 ) (124 ) Balance at End of Period $ 49 $ 54 $ 55 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off. DTE Electric Company Schedule II — Valuation and Qualifying Accounts Year Ending December 31, 2015 2014 2013 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Electric's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 29 $ 28 $ 35 Additions: Charged to costs and expenses 51 50 52 Charged to other accounts (a) 6 10 11 Deductions (b) (58 ) (59 ) (70 ) Balance at End of Period $ 28 $ 29 $ 28 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off.

Organization and Basis of Pre55

Organization and Basis of Presentation (Details Textuals) customer in Millions, $ in Millions	Dec. 31, 2015USD ($)customer	Dec. 31, 2014USD ($)
Entity Information [Line Items]
Number of electric utility customers	2.2
Number of gas utility customers	1.2
Amount in excess of carrying amount | $	$ 81	$ 81

Organization and Basis of Pre56

Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Assets [Abstract]
Cash and cash equivalents	$ 37	$ 48	$ 52	$ 65
Restricted cash	23	120
Accounts receivable	1,276	1,504
Property, plant, and equipment, net	18,034	16,820
Securitized regulatory assets	0	34
Total Assets	28,737	27,899	$ 25,935
Liabilities [Abstract]
Current portion long-term debt, including capital leases	473	274
Current regulatory liabilities	41	153
Mortgage bonds, notes, and other	8,340	7,860
Capital lease obligations	15	3
Variable Interest Entity, Primary Beneficiary, Restricted
Assets [Abstract]
Cash and cash equivalents	14	7
Restricted cash	8	104
Accounts receivable	18	41
Inventories	82	67
Property, plant, and equipment, net	66	81
Securitized regulatory assets	0	34
Other current and long-term assets	4	7
Total Assets	192	341
Liabilities [Abstract]
Accounts payable and accrued current liabilities	13	11
Current portion long-term debt, including capital leases	8	115
Current regulatory liabilities	0	32
Mortgage bonds, notes, and other	10	15
Capital lease obligations	0	3
Other current and long-term liabilities	6	15
Total Liabilities	$ 37	191
Variable Interest Entity, Primary Beneficiary Securitization
Assets [Abstract]
Cash and cash equivalents		0
Restricted cash		96
Accounts receivable		26
Inventories		0
Property, plant, and equipment, net		0
Securitized regulatory assets		34
Other current and long-term assets		1
Total Assets		157
Liabilities [Abstract]
Accounts payable and accrued current liabilities		3
Current portion long-term debt, including capital leases		105
Current regulatory liabilities		32
Mortgage bonds, notes, and other		0
Capital lease obligations		0
Other current and long-term liabilities		9
Total Liabilities		149
Variable Interest Entity, Primary Beneficiary Other, Restricted
Assets [Abstract]
Cash and cash equivalents		7
Restricted cash		8
Accounts receivable		15
Inventories		67
Property, plant, and equipment, net		81
Securitized regulatory assets		0
Other current and long-term assets		6
Total Assets		184
Liabilities [Abstract]
Accounts payable and accrued current liabilities		8
Current portion long-term debt, including capital leases		10
Current regulatory liabilities		0
Mortgage bonds, notes, and other		15
Capital lease obligations		3
Other current and long-term liabilities		6
Total Liabilities		$ 42

Organization and Basis of Pre57

Organization and Basis of Presentation (Non Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Variable Interest Entity [Line Items]
Investments in equity method investees	$ 514	$ 434	$ 415
Notes receivable	85	90
Variable Interest Entity, NonConsolidated
Variable Interest Entity [Line Items]
Investments in equity method investees	136	134
Notes receivable	$ 15	$ 15

Organization and Basis of Pre58

Organization and Basis of Presentation Equity Method Investees (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Equity Method Investments [Line Items]
Investments in equity method investees	$ 514	$ 434	$ 415
Gas Storage and Pipelines
Schedule of Equity Method Investments [Line Items]
Investments in equity method investees	296	224
Gas Storage and Pipelines | NEXUS Pipeline
Schedule of Equity Method Investments [Line Items]
Investments in equity method investees	$ 89	$ 16
Equity Method Investment, Ownership Percentage	50.00%	50.00%
Gas Storage and Pipelines | Vector Pipeline
Schedule of Equity Method Investments [Line Items]
Investments in equity method investees	$ 96	$ 98
Equity Method Investment, Ownership Percentage	40.00%	40.00%
Gas Storage and Pipelines | Millennium Pipeline
Schedule of Equity Method Investments [Line Items]
Investments in equity method investees	$ 111	$ 110
Equity Method Investment, Ownership Percentage	26.00%	26.00%
Other Segments
Schedule of Equity Method Investments [Line Items]
Investments in equity method investees	$ 218	$ 210

Significant Accounting Policics

Significant Accounting Policics (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (155)	$ (136)
Other comprehensive income (loss) before reclassifications	(1)	(26)
Amounts reclassified from Accumulated other comprehensive income	11	7
Net current-period Other comprehensive income (loss)	10	(19)	$ 22
Ending balance	(145)	(155)	(136)
Net Unrealized Loss on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(4)	(4)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from Accumulated other comprehensive income	0	0
Net current-period Other comprehensive income (loss)	0	0
Ending balance	(4)	(4)	(4)
Net Unrealized Gain/(Loss) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5)	(6)
Other comprehensive income (loss) before reclassifications	1	1
Amounts reclassified from Accumulated other comprehensive income	0	0
Net current-period Other comprehensive income (loss)	1	1
Ending balance	(4)	(5)	(6)
Benefit Obligations (b)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(144)	(126)
Other comprehensive income (loss) before reclassifications	2	(25)
Amounts reclassified from Accumulated other comprehensive income	11	7
Net current-period Other comprehensive income (loss)	13	(18)
Ending balance	(131)	(144)	(126)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(2)	0
Other comprehensive income (loss) before reclassifications	(4)	(2)
Amounts reclassified from Accumulated other comprehensive income	0	0
Net current-period Other comprehensive income (loss)	(4)	(2)
Ending balance	(6)	(2)	0
DTE Electric
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(26)	(16)
Other comprehensive income (loss) before reclassifications	1	(12)
Transfer of amounts from Accumulated other comprehensive income to affiliate	27
Amounts reclassified from Accumulated other comprehensive income	0	2
Net current-period Other comprehensive income (loss)	28	(10)	6
Ending balance	2	(26)	(16)
DTE Electric | Net Unrealized Gain/(Loss) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	1	1
Other comprehensive income (loss) before reclassifications	1	0
Transfer of amounts from Accumulated other comprehensive income to affiliate	0
Amounts reclassified from Accumulated other comprehensive income	0	0
Net current-period Other comprehensive income (loss)	1	0
Ending balance	2	1	1
DTE Electric | Benefit Obligations (b)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(27)	(17)
Other comprehensive income (loss) before reclassifications	0	(12)
Transfer of amounts from Accumulated other comprehensive income to affiliate	27
Amounts reclassified from Accumulated other comprehensive income	0	2
Net current-period Other comprehensive income (loss)	27	(10)
Ending balance	$ 0	$ (27)	$ (17)

Significant Accounting Polici60

Significant Accounting Policies (Intangible Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	$ 156	$ 168
Less accumulated amortization	62	57
Intangible assets, net	94	111
Less current intangible assets	5	9
Intangible assets	89	102
Emission allowances
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	1	1
Renewable energy credits
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	38	45
Contract intangible assets
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	117	122
DTE Electric
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross (Excluding Goodwill)	39	46
Less current intangible assets	5	9
Intangible assets	34	37
DTE Electric | Emission allowances
Finite-Lived Intangible Assets [Line Items]
Indefinite-Lived Intangible Assets (Excluding Goodwill)	1	1
DTE Electric | Renewable energy credits
Finite-Lived Intangible Assets [Line Items]
Intangible Assets, Gross	$ 38	$ 45

Significant Accounting Polici61

Significant Accounting Policies (Future Amortization Expense Intangible Assets) (Details) $ in Millions	Dec. 31, 2015USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2,016	$ 10
2,017	7
2,018	7
2,019	7
2,020	$ 5

Significant Accounting Polici62

Significant Accounting Policies (Details Textuals) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Significant Accounting Policies [Line Items]
Other income	$ 209,000,000	$ 196,000,000	$ 201,000,000
Receivables due date	21 days
Threshold period past due for write-off of trade accounts receivable	150 days
Specific review of probable future collections based on receivable balances in excess of 90 days	30 days
Unbilled revenues	$ 1,276,000,000	1,504,000,000
Regulatory liabilities	$ 610,000,000	820,000,000
Property maintenance accrual period	18 months
Amortization of Intangible Assets	$ 11,000,000	12,000,000	14,000,000
Excise and sales taxes net impact on statement of operations	0
Charitable contributions	12,000,000	25,000,000	18,000,000
Power and Industrial Projects
Significant Accounting Policies [Line Items]
Other income	83,000,000	78,000,000	81,000,000
Unbilled Revenues
Significant Accounting Policies [Line Items]
Unbilled revenues	620,000,000	773,000,000
DTE Electric
Significant Accounting Policies [Line Items]
Other income	60,000,000	62,000,000	$ 54,000,000
Unbilled revenues	657,000,000	688,000,000
Regulatory liabilities	218,000,000	395,000,000
DTE Electric | Unbilled Revenues
Significant Accounting Policies [Line Items]
Unbilled revenues	$ 237,000,000	250,000,000
Minimum
Significant Accounting Policies [Line Items]
Notes receivable considered delinquent period	60 days
Finite-lived intangible asset, useful life	1 year
Maximum
Significant Accounting Policies [Line Items]
Notes receivable considered delinquent period	120 days
Finite-lived intangible asset, useful life	26 years
Public Utilities, Inventory, Natural Gas
Significant Accounting Policies [Line Items]
LIFO inventory amount	$ 65,000,000	43,000,000
Excess of replacement costs over stated LIFO value	60,000,000	110,000,000
Fermi 2 refueling outage
Significant Accounting Policies [Line Items]
Regulatory liabilities	4,000,000	16,000,000
Fermi 2 refueling outage | DTE Electric
Significant Accounting Policies [Line Items]
Regulatory liabilities	$ 4,000,000	$ 16,000,000

New Accounting Pronouncements (

New Accounting Pronouncements (Details) - New Accounting Pronouncement, Early Adoption, Effect - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Decrease in deferred tax asset		$ 75
Decrease in deferred tax liability		2
Assets | Pro Forma
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance cost	$ (74)	(73)
Liability | Pro Forma
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Debt issuance cost	$ (36)	$ (35)

Acquisitions and Exit Activit64

Acquisitions and Exit Activities (Acquisitions) (Details) - DTE Electric $ in Millions	Oct. 01, 2015USD ($)MW	Jan. 21, 2015USD ($)MW	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)
Business Acquisition [Line Items]
Total purchase price			$ 310	$ 0	$ 0
Natural Gas Facility in Carson City Michigan
Business Acquisition [Line Items]
Gas facility capacity | MW		732
Total purchase price		$ 241
Natural Gas Facility in East China Township Michigan
Business Acquisition [Line Items]
Gas facility capacity | MW	350
Cash consideration and total purchase price	$ 69

Acquisitions and Exit Activit65

Acquisitions and Exit Activities (Exit Activities) (Details) - Facility Closing $ in Millions	Dec. 17, 2015USD ($)employee	Dec. 31, 2015USD ($)
Restructuring Cost and Reserve [Line Items]
Total Exit Activity Charges		$ 111
Charge to fully impair long-lived assets	$ 96
Number of employees related to workforce reduction | employee	170
Severance expense	$ 3
Inventory write down	$ 12
Future exit costs		$ 7

Acquisitions and Exit Activit66

Acquisitions and Exit Activities (Restructuring and Related Costs) (Details) - Facility Closing $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Restructuring Cost and Reserve [Line Items]
Total Exit Activity Charges	$ 111
Fuel, purchased power, and gas — non-utility
Restructuring Cost and Reserve [Line Items]
Total Exit Activity Charges	5
Operation and maintenance
Restructuring Cost and Reserve [Line Items]
Total Exit Activity Charges	10
Asset (gains) losses and impairments, net
Restructuring Cost and Reserve [Line Items]
Total Exit Activity Charges	$ 96

Property, Plant, and Equipmen67

Property, Plant, and Equipment (Summary of Property by Classification) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	$ 28,121	$ 26,538
Less accumulated depreciation and amortization	(10,087)	(9,718)
Net Property, plant, and equipment	18,034	16,820
Non-utility and other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	2,263	2,476
Less accumulated depreciation and amortization	(761)	(867)
DTE Electric
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	21,391	19,805
Less accumulated depreciation and amortization	(7,646)	(7,216)
Net Property, plant, and equipment	13,745	12,589
DTE Electric | Generation
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	11,767	10,712
Less accumulated depreciation and amortization	(4,346)	(3,863)
DTE Electric | Distribution
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	7,816	7,414
Less accumulated depreciation and amortization	(2,707)	(2,822)
DTE Electric | Other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	1,808	1,679
Less accumulated depreciation and amortization	(593)	(531)
DTE Gas
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	4,467	4,257
Less accumulated depreciation and amortization	(1,680)	(1,635)
DTE Gas | Distribution
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	3,124	2,946
Less accumulated depreciation and amortization	(1,163)	(1,130)
DTE Gas | Storage
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	453	448
Less accumulated depreciation and amortization	(147)	(142)
DTE Gas | Transmission and other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	890	863
Less accumulated depreciation and amortization	$ (370)	$ (363)

Property, Plant, and Equipmen68

Property, Plant, and Equipment (Average Estimated Useful Life of Each Major Class) (Details)	12 Months Ended
	Dec. 31, 2015
DTE Electric
Public Utility Property, Plant, and Equipment [Line Items]
Useful Life - Generation	40 years
Useful Life - Distribution	41 years
DTE Gas
Public Utility Property, Plant, and Equipment [Line Items]
Useful Life - Distribution	50 years
Useful Life - Storage	53 years

Property, Plant, and Equipmen69

Property, Plant, and Equipment (Depreciation and Amortization) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	$ 740	$ 683	$ 630
Regulatory assets and liabilities	150	159	163
Securitized regulatory assets	38	(303)	(301)
Depreciation and amortization	852	1,145	1,094
Depreciation and amortization	852	1,145	1,094
DTE Electric
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	545	489	457
Regulatory assets and liabilities	126	135	138
Securitized regulatory assets	38	(303)	(301)
Depreciation and amortization	633	927	896
Depreciation and amortization	$ 633	$ 927	$ 896

Property, Plant, and Equipmen70

Property, Plant, and Equipment (Capitalized Software) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Property, Plant, and Equipment [Line Items]
Amortization expense of capitalized software	$ 98	$ 77	$ 71
Gross carrying value of capitalized software	770	668
Accumulated amortization of capitalized software	439	335
DTE Electric
Property, Plant, and Equipment [Line Items]
Amortization expense of capitalized software	80	71	$ 64
Gross carrying value of capitalized software	664	590
Accumulated amortization of capitalized software	$ 369	$ 293

Property, Plant, and Equipmen71

Property, Plant, and Equipment (Capital Leases) (Details) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Capital Leased Assets [Line Items]
Gross property under capital leases	$ 48	$ 35
Accumulated amortization of property under capital leases	26	27
DTE Electric
Capital Leased Assets [Line Items]
Gross property under capital leases	22	9
Accumulated amortization of property under capital leases	$ 1	$ 5

Property, Plant, and Equipmen72

Property, Plant, and Equipment (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Public Utility Property, Plant, and Equipment [Line Items]
AFUDC capitalized	$ 34	$ 37
DTE Gas
Public Utility Property, Plant, and Equipment [Line Items]
Disclosure of composite depreciation rate for plants in service	2.60%	2.40%	2.40%
DTE Electric
Public Utility Property, Plant, and Equipment [Line Items]
Disclosure of composite depreciation rate for plants in service	3.50%	3.40%	3.40%
DTE Electric
Public Utility Property, Plant, and Equipment [Line Items]
AFUDC capitalized	$ 31	$ 32
Other | DTE Electric | Minimum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	5 years
Other | DTE Electric | Maximum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	62 years
Transmission and other | DTE Gas | Minimum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	5 years
Transmission and other | DTE Gas | Maximum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	70 years
Non-utility and other | Minimum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	3 years
Non-utility and other | Maximum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	55 years
Computer Software, Intangible Asset | Minimum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	3 years
Computer Software, Intangible Asset | Maximum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	15 years
Computer Software, Intangible Asset | DTE Electric | Minimum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	5 years
Computer Software, Intangible Asset | DTE Electric | Maximum
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	15 years

Jointly-Owned Utility Plant (De

Jointly-Owned Utility Plant (Details) $ in Millions	Dec. 31, 2015USD ($)MW
Belle River
Jointly-Owned Utility Plant Interests [Line Items]
Total plant capacity | MW	1,270
Investment in Property, plant, and equipment (in millions)	$ 1,779
Accumulated depreciation (in millions)	$ 1,053
Ludington Hydroelectric Pumped Storage
Jointly-Owned Utility Plant Interests [Line Items]
Total plant capacity | MW	1,955
Ownership interest	49.00%
Investment in Property, plant, and equipment (in millions)	$ 443
Accumulated depreciation (in millions)	$ 154

Jointly-Owned Utility Plant (74

Jointly-Owned Utility Plant (Detail Textuals)	Dec. 31, 2015facilities
Jointly-Owned Utility Plant Interests [Line Items]
Number of power plants owned	2
Belle River Unit 1
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	63.00%
Belle River Facilities used jointly by Belle River and St. Clair Power Plants
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	81.00%
Belle River Unit 2
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	75.00%
Belle River
Jointly-Owned Utility Plant Interests [Line Items]
Percent of the total capacity and energy of the plant	19.00%
Ludington Hydroelectric Pumped Storage
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	49.00%
Percent of the total capacity and energy of the plant	51.00%

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at December 31, 2014	$ 1,962
Accretion	119
Liabilities incurred	33
Revision in estimated cash flows	80
Asset retirement obligations at December 31, 2015	2,194
DTE Electric
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at December 31, 2014	1,796
Accretion	111
Liabilities incurred	33
Revision in estimated cash flows	80
Asset retirement obligations at December 31, 2015	$ 2,020

Asset Retirement Obligations 76

Asset Retirement Obligations (Details Textuals) - Fermi 2	Dec. 31, 2015USD ($)
Asset Retirement Obligations [Line Items]
Nuclear decommissioning liabilities funded through surcharge and included in ARO balance	$ 1,800,000,000
Liabilities balance upon completion of decommissioning	$ 0

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Regulatory Assets [Line Items]
Regulatory Assets	$ 3,724	$ 3,727
Less amount included in Current Assets	(32)	(76)
Regulatory Assets, Noncurrent	3,692	3,651
Securitized regulatory assets	0	34
Pension
Regulatory Assets [Line Items]
Regulatory Assets	2,112	2,284
Other postretirement costs
Regulatory Assets [Line Items]
Regulatory Assets	256	234
Asset retirement obligation
Regulatory Assets [Line Items]
Regulatory Assets	565	448
Recoverable Michigan income taxes
Regulatory Assets [Line Items]
Regulatory Assets	248	267
Removal costs asset
Regulatory Assets [Line Items]
Regulatory Assets	118	15
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory Assets	63	67
Other recoverable income taxes
Regulatory Assets [Line Items]
Regulatory Assets	61	66
Deferred environmental costs
Regulatory Assets [Line Items]
Regulatory Assets	54	59
Transitional Reconciliation Mechanism
Regulatory Assets [Line Items]
Regulatory Assets	43	14
Cost to achieve Performance Excellence Process
Regulatory Assets [Line Items]
Regulatory Assets	33	54
Accrued PSCR/GCR revenue
Regulatory Assets [Line Items]
Regulatory Assets	12	61
Recoverable income taxes related to Securitized regulatory assets
Regulatory Assets [Line Items]
Regulatory Assets	0	19
Other
Regulatory Assets [Line Items]
Regulatory Assets	159	139
DTE Electric
Regulatory Assets [Line Items]
Regulatory Assets	2,986	2,959
Less amount included in Current Assets	(17)	(46)
Regulatory Assets, Noncurrent	2,969	2,913
Securitized regulatory assets	0	34
DTE Electric | Pension
Regulatory Assets [Line Items]
Regulatory Assets	1,592	1,743
DTE Electric | Other postretirement costs
Regulatory Assets [Line Items]
Regulatory Assets	198	191
DTE Electric | Asset retirement obligation
Regulatory Assets [Line Items]
Regulatory Assets	565	448
DTE Electric | Recoverable Michigan income taxes
Regulatory Assets [Line Items]
Regulatory Assets	203	220
DTE Electric | Removal costs asset
Regulatory Assets [Line Items]
Regulatory Assets	118	15
DTE Electric | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory Assets	41	44
DTE Electric | Other recoverable income taxes
Regulatory Assets [Line Items]
Regulatory Assets	61	66
DTE Electric | Deferred environmental costs
Regulatory Assets [Line Items]
Regulatory Assets	0	0
DTE Electric | Transitional Reconciliation Mechanism
Regulatory Assets [Line Items]
Regulatory Assets	43	14
DTE Electric | Cost to achieve Performance Excellence Process
Regulatory Assets [Line Items]
Regulatory Assets	28	46
DTE Electric | Accrued PSCR/GCR revenue
Regulatory Assets [Line Items]
Regulatory Assets	0	34
DTE Electric | Recoverable income taxes related to Securitized regulatory assets
Regulatory Assets [Line Items]
Regulatory Assets	0	19
DTE Electric | Other
Regulatory Assets [Line Items]
Regulatory Assets	$ 137	$ 119

Regulatory Matters Regulatory M

Regulatory Matters Regulatory Matters (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 610	$ 820
Less amount included in Current Liabilities	(41)	(153)
Regulatory liabilities	569	667
Removal costs liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	291	308
Renewable energy
Regulatory Liabilities [Line Items]
Regulatory liabilities	197	227
Pension
Regulatory Liabilities [Line Items]
Regulatory liabilities	46	67
Accrued PSCR/GCR refund
Regulatory Liabilities [Line Items]
Regulatory liabilities	37	0
Refundable income taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	23	33
Energy optimization
Regulatory Liabilities [Line Items]
Regulatory liabilities	10	24
Fermi 2 refueling outage
Regulatory Liabilities [Line Items]
Regulatory liabilities	4	16
Securitization over recovery
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	71
Refundable revenue decoupling/deferred gain
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	63
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	2	11
DTE Electric
Regulatory Liabilities [Line Items]
Regulatory liabilities	218	395
Less amount included in Current Liabilities	(19)	(150)
Regulatory liabilities	199	245
DTE Electric | Removal costs liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	0
DTE Electric | Renewable energy
Regulatory Liabilities [Line Items]
Regulatory liabilities	197	227
DTE Electric | Pension
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	0
DTE Electric | Accrued PSCR/GCR refund
Regulatory Liabilities [Line Items]
Regulatory liabilities	15	0
DTE Electric | Refundable income taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	0
DTE Electric | Energy optimization
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	14
DTE Electric | Fermi 2 refueling outage
Regulatory Liabilities [Line Items]
Regulatory liabilities	4	16
DTE Electric | Securitization over recovery
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	71
DTE Electric | Refundable revenue decoupling/deferred gain
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	63
DTE Electric | Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 2	$ 4

Regulatory Matters (Details Tex

Regulatory Matters (Details Textuals) $ in Millions

Feb. 01, 2016USD ($)

Jan. 19, 2016

Dec. 18, 2015USD ($)

Dec. 11, 2015USD ($)

Dec. 10, 2015

Jul. 01, 2015USD ($)

Dec. 19, 2014USD ($)

Nov. 30, 2015USD ($)

Jul. 31, 2015USD ($)

Dec. 31, 2014

Jul. 31, 2014USD ($)

Mar. 31, 2013feed_water_pump

Dec. 31, 2015USD ($)

Dec. 31, 2015

Jun. 30, 2015USD ($)

Nov. 30, 2014USD ($)

Jul. 30, 2012

Regulatory Assets [Line Items]

Deferral of investigation and remediation of costs associated with gas utilities former MGP sites

10 years

Amortization period of cost to achieve deferral

10 years

Time period required by non-bypassable securitization bond surcharge to recover securitized regulatory asset

14 years

Power Supply Cost Recovery

Regulatory Assets [Line Items]

Number of failed feed water pumps | feed_water_pump

1

Number of feed water pumps | feed_water_pump

2

DTE Electric

Regulatory Assets [Line Items]

Fermi 2 production level of full capacity

68.00%

Maximum of challenged Fermi 2 outage charges

$ 19

DTE Electric | MPSC

Regulatory Assets [Line Items]

Damages sought

$ 22

Refund amount

$ 20

Interest calculated percent per annum

7.00%

Payment of refund

$ 25

DTE Electric | MPSC | Electric Rate Case Filing 2014

Regulatory Assets [Line Items]

Public utilities, requested rate increase (decrease)

$ 370

Public utilities, annual revenue increase

$ 230

Self-implemented base rate increase

190

Required elimination of a credit surcharge

$ 40

Public utilities, approved rate increase

$ 238

Return on equity

10.30%

10.50%

Capital debt structure

50.00%

Capital equity structure

50.00%

Disallowance amount

$ 10

DTE Electric | PSCR

Regulatory Assets [Line Items]

Estimated recovery amount

$ 16

DTE Gas | MPSC

Regulatory Assets [Line Items]

Infrastructure recovery mechanism surcharge

$ 47

Surcharge

$ 16

Surcharge due year two

$ 31

DTE Gas | MPSC | DTE Gas Rate Case Filing 2015

Regulatory Assets [Line Items]

Public utilities, requested rate increase (decrease)

$ 183

Return on equity

10.50%

Capital debt structure

48.00%

Capital equity structure

52.00%

Increased return on equity

10.75%

Increase in net plant

$ 800

Subsequent Event | DTE Electric | MPSC | Electric Rate Case Filing 2014

Regulatory Assets [Line Items]

Amortization period (in years)

20 years

Subsequent Event | DTE Electric | MPSC | Electric Rate Case Filing 2016

Regulatory Assets [Line Items]

Public utilities, requested rate increase (decrease)

$ 344

Return on equity

10.30%

Capital debt structure

50.00%

Capital equity structure

50.00%

Increased return on equity

10.50%

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Income Tax Expense to the Statutory Federal Income Tax Rate) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Before Income Taxes	$ 950	$ 1,275	$ 922
Income tax expense at 35% statutory rate	333	446	323
Production tax credits	(122)	(119)	(68)
Investment tax credits	(7)	(6)	(6)
Depreciation	(4)	(4)	(4)
AFUDC - Equity	(8)	(7)	(5)
Employee Stock Ownership Plan dividends	(5)	(4)	(4)
Domestic production activities deduction	0	0	(14)
State and local income taxes, net of federal benefit	35	51	37
Enactment of New York Corporate Income Tax Legislation, net of federal benefit	0	8	0
Other, net	8	(1)	(5)
Income Tax Expense (Benefit)	$ 230	$ 364	$ 254
Effective income tax rate (as percent)	24.20%	28.50%	27.50%
DTE Electric
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Before Income Taxes	$ 836	$ 830	$ 741
Income tax expense at 35% statutory rate	293	291	260
Production tax credits	(31)	(22)	(15)
Investment tax credits	(5)	(5)	(5)
Depreciation	3	3	3
AFUDC - Equity	(7)	(7)	(5)
Employee Stock Ownership Plan dividends	(3)	(3)	(2)
Domestic production activities deduction	0	(2)	(18)
State and local income taxes, net of federal benefit	43	43	41
Other, net	(1)	0	(5)
Income Tax Expense (Benefit)	$ 292	$ 298	$ 254
Effective income tax rate (as percent)	34.90%	35.90%	34.30%

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current income tax expense (benefit)
Federal	$ (3)	$ (16)	$ 74
State and other income tax	(4)	24	16
Total current income taxes	(7)	8	90
Deferred income tax expense
Federal	178	289	122
State and other income tax	59	67	42
Total deferred income taxes	237	356	164
Total	230	364	254
DTE Electric
Current income tax expense (benefit)
Federal	(26)	(19)	123
State and other income tax	(2)	20	23
Total current income taxes	(28)	1	146
Deferred income tax expense
Federal	252	251	68
State and other income tax	68	46	40
Total deferred income taxes	320	297	108
Total	$ 292	$ 298	$ 254

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets (Liabilities)) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Components of Deferred Tax Assets and Liabilities [Abstract]
Property, plant, and equipment	$ (4,211)	$ (3,832)
Securitized regulatory assets	5	(2)
Tax credit carry-forwards	465	296
Pension and benefits	(301)	(152)
Federal net operating loss carry-forward	177	0
State and local net operating loss carry-forwards	63	39
Investments in equity method investees	(82)	(84)
Other	(4)	65
Deferred Tax Liabilities, Gross	(3,888)	(3,670)
Less valuation allowance	(35)	(31)
Deferred income tax assets	1,088	861
Deferred income tax liabilities	(5,011)	(4,562)
Deferred income tax liabilities	(3,923)	(3,701)
DTE Electric
Components of Deferred Tax Assets and Liabilities [Abstract]
Property, plant, and equipment	(3,468)	(3,152)
Securitized regulatory assets	5	(3)
Tax credit carry-forwards	53	0
Pension and benefits	(193)	(43)
Federal net operating loss carry-forward	142	0
State and local net operating loss carry-forwards	16	0
Investments in equity method investees	0	0
Other	(53)	12
Deferred Tax Liabilities, Gross	(3,498)	(3,186)
Less valuation allowance	0	0
Deferred income tax assets	453	357
Deferred income tax liabilities	(3,951)	(3,543)
Deferred income tax liabilities	$ (3,498)	$ (3,186)

Income Taxes (Reconciliation 83

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, beginning balance	$ 9	$ 10	$ 11
Lapse of statute of limitations	(6)	(1)	(1)
Unrecognized Tax Benefits, ending balance	3	9	10
DTE Electric
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized Tax Benefits, beginning balance	4	4	4
Unrecognized Tax Benefits, ending balance	$ 4	$ 4	$ 4

Income Taxes (Details Textuals)

Income Taxes (Details Textuals) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Entity Information [Line Items]
Deferred tax asset, general business tax credit carryforwards	$ 181,000,000
Deferred tax asset, alternative minimum tax credit carryforwards	284,000,000
State and local net operating loss carry-forwards	63,000,000	$ 39,000,000
Valuation allowance	35,000,000	31,000,000
Unrecognized tax benefits that would impact effective tax rate	2,000,000	2,000,000
Interest on income taxes accrued	1,000,000	1,000,000
Income tax penalties accrued	0
Federal
Entity Information [Line Items]
Operating loss carryforward	517,000,000
Windfall tax benefit	9,000,000
DTE Electric
Entity Information [Line Items]
Income tax receivable from related party	6,000,000	29,000,000
State and local net operating loss carry-forwards	16,000,000	0
Valuation allowance	0	0
Unrecognized tax benefits that would impact effective tax rate	3,000,000	2,000,000
Interest on income taxes accrued	$ 1,000,000	$ 1,000,000

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Basic Earnings per Share
Net Income	$ 80	$ 265	$ 109	$ 273	$ 299	$ 156	$ 124	$ 326	$ 727	$ 905	$ 661
Average number of common shares outstanding									179	177	175
Weighted average net restricted shares outstanding									0	0	1
Dividends declared — common shares									$ 508	$ 475	$ 453
Dividends declared — net restricted shares									2	1	1
Total distributed earnings									510	476	454
Net Income less distributed earnings									$ 217	$ 429	$ 207
Distributed (dividends per common share) (in dollars per share)									$ 2.84	$ 2.69	$ 2.59
Undistributed (in dollars per share)									1.21	2.42	1.17
Total Basic Earnings per Common Share (in dollars per share)	$ 0.45	$ 1.47	$ 0.61	$ 1.53	$ 1.68	$ 0.88	$ 0.70	$ 1.84	$ 4.05	$ 5.11	$ 3.76
Diluted Earnings per Share
Net Income	$ 80	$ 265	$ 109	$ 273	$ 299	$ 156	$ 124	$ 326	$ 727	$ 905	$ 661
Average number of common shares outstanding									179	177	175
Weighted average net restricted shares outstanding									0	0	1
Dividends declared — common shares									$ 508	$ 475	$ 453
Dividends declared — net restricted shares									2	1	1
Total distributed earnings									510	476	454
Net income less distributed earnings									$ 217	$ 429	$ 207
Distributed (dividends per common share) (in dollars per share)									$ 2.84	$ 2.69	$ 2.59
Undistributed (in dollars per share)									1.21	2.41	1.17
Total Diluted Earnings per Common Share (in dollars per share)	$ 0.45	$ 1.47	$ 0.61	$ 1.53	$ 1.68	$ 0.88	$ 0.70	$ 1.84	$ 4.05	$ 5.10	$ 3.76

Fair Value (Assets and Liabilit

Fair Value (Assets and Liabilities Recorded at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivative Asset [Abstract]
Derivative asset, gross	$ 711	$ 1,178
Derivative asset, Netting	(528)	(1,006)
Derivative assets, net	183	172
Liabilities [Abstract]
Derivative Liabilities	(705)	(1,110)
Derivative liability, netting	562	1,025
Derivative Liabilities, net	(143)	(85)
Current Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(521)	(1,041)
Noncurrent Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(184)	(69)
Natural Gas
Derivative Asset [Abstract]
Derivative asset, gross	387	787
Derivative asset, Netting	(285)	(681)
Derivative assets, net	102	106
Liabilities [Abstract]
Derivative Liabilities	(383)	(718)
Derivative liability, netting	294	679
Derivative Liabilities, net	(89)	(39)
Electricity
Derivative Asset [Abstract]
Derivative asset, gross	307	342
Derivative asset, Netting	(232)	(280)
Derivative assets, net	75	62
Liabilities [Abstract]
Derivative Liabilities	(305)	(342)
Derivative liability, netting	253	298
Derivative Liabilities, net	(52)	(44)
Other
Derivative Asset [Abstract]
Derivative asset, gross	5	45
Derivative asset, Netting	(2)	(42)
Derivative assets, net	3	3
Liabilities [Abstract]
Derivative Liabilities	(10)	(45)
Derivative liability, netting	8	45
Derivative Liabilities, net	(2)	0
Other derivative contracts
Derivative Asset [Abstract]
Derivative asset, gross	12	4
Derivative asset, Netting	(9)	(3)
Derivative assets, net	3	1
Liabilities [Abstract]
Derivative Liabilities	(7)	(5)
Derivative liability, netting	7	3
Derivative Liabilities, net	0	(2)
Recurring
Assets [Abstract]
Cash equivalents	16	112
Nuclear decommissioning trusts	1,236	1,241
Other Investments	149	150
Derivative Asset [Abstract]
Derivative asset, Netting	(528)	(1,006)
Derivative assets, net	183	172
Total assets	1,584	1,675
Liabilities [Abstract]
Derivative liability, netting	562	1,025
Derivative Liabilities, net	(143)	(85)
Net Assets (Liabilities) at the end of the period	1,441	1,590
Net Assets (Liabilities) at the end of the period, netting	34	19
Recurring | Current Asset
Derivative Asset [Abstract]
Derivative asset, Netting	(441)	(955)
Total assets	145	240
Recurring | Noncurrent Asset
Derivative Asset [Abstract]
Derivative asset, Netting	(87)	(51)
Total assets	1,439	1,435
Recurring | Current Derivative Liability
Liabilities [Abstract]
Derivative liability, netting	464	964
Derivative Liabilities, net	(57)	(77)
Recurring | Noncurrent Derivative Liability
Liabilities [Abstract]
Derivative liability, netting	98	61
Derivative Liabilities, net	(86)	(8)
Recurring | Restricted Assets
Assets [Abstract]
Cash equivalents	8	105
Recurring | Other Investments
Assets [Abstract]
Cash equivalents	8	7
Recurring | Natural Gas
Derivative Asset [Abstract]
Derivative asset, Netting	(285)	(681)
Derivative assets, net	102	106
Liabilities [Abstract]
Derivative liability, netting	294	679
Derivative Liabilities, net	(89)	(39)
Recurring | Electricity
Derivative Asset [Abstract]
Derivative asset, Netting	(232)	(280)
Derivative assets, net	75	62
Liabilities [Abstract]
Derivative liability, netting	253	298
Derivative Liabilities, net	(52)	(44)
Recurring | Other
Derivative Asset [Abstract]
Derivative asset, Netting	(2)	(42)
Derivative assets, net	3	3
Liabilities [Abstract]
Derivative liability, netting	8	45
Derivative Liabilities, net	(2)	0
Recurring | Other derivative contracts
Derivative Asset [Abstract]
Derivative asset, Netting	(9)	(3)
Derivative assets, net	3	1
Liabilities [Abstract]
Derivative liability, netting	7	3
Derivative Liabilities, net	0	(2)
Recurring | Level 1
Assets [Abstract]
Cash equivalents	13	13
Nuclear decommissioning trusts	759	792
Other Investments	149	100
Derivative Asset [Abstract]
Derivative asset, gross	195	597
Total assets	1,116	1,502
Liabilities [Abstract]
Derivative Liabilities	(220)	(610)
Net Assets (Liabilities) at the end of the period	896	892
Recurring | Level 1 | Current Asset
Derivative Asset [Abstract]
Total assets	174	582
Recurring | Level 1 | Noncurrent Asset
Derivative Asset [Abstract]
Total assets	942	920
Recurring | Level 1 | Current Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(174)	(572)
Recurring | Level 1 | Noncurrent Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(46)	(38)
Recurring | Level 1 | Natural Gas
Derivative Asset [Abstract]
Derivative asset, gross	193	555
Liabilities [Abstract]
Derivative Liabilities	(218)	(578)
Recurring | Level 1 | Electricity
Derivative Asset [Abstract]
Derivative asset, gross	0	0
Liabilities [Abstract]
Derivative Liabilities	0	0
Recurring | Level 1 | Other
Derivative Asset [Abstract]
Derivative asset, gross	2	42
Liabilities [Abstract]
Derivative Liabilities	(2)	(32)
Recurring | Level 1 | Other derivative contracts
Derivative Asset [Abstract]
Derivative asset, gross	0	0
Liabilities [Abstract]
Derivative Liabilities	0	0
Recurring | Level 2
Assets [Abstract]
Cash equivalents	3	99
Nuclear decommissioning trusts	477	449
Other Investments	0	50
Derivative Asset [Abstract]
Derivative asset, gross	342	439
Total assets	822	1,037
Liabilities [Abstract]
Derivative Liabilities	(307)	(382)
Net Assets (Liabilities) at the end of the period	515	655
Recurring | Level 2 | Current Asset
Derivative Asset [Abstract]
Total assets	284	504
Recurring | Level 2 | Noncurrent Asset
Derivative Asset [Abstract]
Total assets	538	533
Recurring | Level 2 | Current Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(260)	(357)
Recurring | Level 2 | Noncurrent Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(47)	(25)
Recurring | Level 2 | Natural Gas
Derivative Asset [Abstract]
Derivative asset, gross	91	140
Liabilities [Abstract]
Derivative Liabilities	(57)	(78)
Recurring | Level 2 | Electricity
Derivative Asset [Abstract]
Derivative asset, gross	239	295
Liabilities [Abstract]
Derivative Liabilities	(243)	(290)
Recurring | Level 2 | Other
Derivative Asset [Abstract]
Derivative asset, gross	0	0
Liabilities [Abstract]
Derivative Liabilities	0	(9)
Recurring | Level 2 | Other derivative contracts
Derivative Asset [Abstract]
Derivative asset, gross	12	4
Liabilities [Abstract]
Derivative Liabilities	(7)	(5)
Recurring | Level 3
Assets [Abstract]
Cash equivalents	0	0
Nuclear decommissioning trusts	0	0
Other Investments	0	0
Derivative Asset [Abstract]
Derivative asset, gross	174	142
Total assets	174	142
Liabilities [Abstract]
Derivative Liabilities	(178)	(118)
Net Assets (Liabilities) at the end of the period	(4)	24
Recurring | Level 3 | Current Asset
Derivative Asset [Abstract]
Total assets	128	109
Recurring | Level 3 | Noncurrent Asset
Derivative Asset [Abstract]
Total assets	46	33
Recurring | Level 3 | Current Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(87)	(112)
Recurring | Level 3 | Noncurrent Derivative Liability
Liabilities [Abstract]
Derivative Liabilities	(91)	(6)
Recurring | Level 3 | Natural Gas
Derivative Asset [Abstract]
Derivative asset, gross	103	92
Liabilities [Abstract]
Derivative Liabilities	(108)	(62)
Recurring | Level 3 | Electricity
Derivative Asset [Abstract]
Derivative asset, gross	68	47
Liabilities [Abstract]
Derivative Liabilities	(62)	(52)
Recurring | Level 3 | Other
Derivative Asset [Abstract]
Derivative asset, gross	3	3
Liabilities [Abstract]
Derivative Liabilities	(8)	(4)
Recurring | Level 3 | Other derivative contracts
Derivative Asset [Abstract]
Derivative asset, gross	0	0
Liabilities [Abstract]
Derivative Liabilities	0	0
DTE Electric
Assets [Abstract]
Nuclear decommissioning trusts	1,236	1,241
DTE Electric | Recurring
Assets [Abstract]
Cash equivalents	8	104
Nuclear decommissioning trusts	1,236	1,241
Other Investments	8	147
Derivative Asset [Abstract]
Derivative assets, net	3	3
Total assets	1,255	1,495
DTE Electric | Recurring | Current Asset
Derivative Asset [Abstract]
Total assets	11	107
DTE Electric | Recurring | Noncurrent Asset
Derivative Asset [Abstract]
Total assets	1,244	1,388
DTE Electric | Recurring | Restricted Assets
Assets [Abstract]
Cash equivalents		96
DTE Electric | Recurring | Other Investments
Assets [Abstract]
Cash equivalents		8
DTE Electric | Recurring | Level 1
Assets [Abstract]
Cash equivalents	5	5
Nuclear decommissioning trusts	759	792
Other Investments	8	97
Derivative Asset [Abstract]
Derivative asset, gross	0	0
Total assets	772	894
DTE Electric | Recurring | Level 1 | Current Asset
Derivative Asset [Abstract]
Total assets	5	5
DTE Electric | Recurring | Level 1 | Noncurrent Asset
Derivative Asset [Abstract]
Total assets	767	889
DTE Electric | Recurring | Level 2
Assets [Abstract]
Cash equivalents	3	99
Nuclear decommissioning trusts	477	449
Other Investments	0	50
Derivative Asset [Abstract]
Derivative asset, gross	0	0
Total assets	480	598
DTE Electric | Recurring | Level 2 | Current Asset
Derivative Asset [Abstract]
Total assets	3	99
DTE Electric | Recurring | Level 2 | Noncurrent Asset
Derivative Asset [Abstract]
Total assets	477	499
DTE Electric | Recurring | Level 3
Assets [Abstract]
Cash equivalents	0	0
Nuclear decommissioning trusts	0	0
Other Investments	0	0
Derivative Asset [Abstract]
Derivative asset, gross	3	3
Total assets	3	3
DTE Electric | Recurring | Level 3 | Current Asset
Derivative Asset [Abstract]
Total assets	3	3
DTE Electric | Recurring | Level 3 | Noncurrent Asset
Derivative Asset [Abstract]
Total assets	0	0
Equity | Recurring | Other Investments
Assets [Abstract]
Investments at fair value	$ 149	$ 150

Fair Value (Reconciliation of L

Fair Value (Reconciliation of Level 3 Assets and Liabilities at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of December 31	$ 24	$ (36)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	(2)
Total gains (losses):
Included in earnings	(8)	(20)
Recorded in Regulatory assets/liabilities	12	8
Purchases, issuances, and settlements:
Purchases	2	1
Issuances	0	(3)
Settlements	(34)	76
Net Assets (Liabilities) as of December 31	(4)	24
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(129)	40
Natural Gas
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of December 31	30	(52)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	(2)
Total gains (losses):
Included in earnings	(44)	(40)
Recorded in Regulatory assets/liabilities	0	0
Purchases, issuances, and settlements:
Purchases	0	0
Issuances	0	0
Settlements	9	124
Net Assets (Liabilities) as of December 31	(5)	30
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(135)	35
Electricity
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of December 31	(5)	13
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses):
Included in earnings	44	25
Recorded in Regulatory assets/liabilities	0	0
Purchases, issuances, and settlements:
Purchases	2	1
Issuances	0	(3)
Settlements	(35)	(41)
Net Assets (Liabilities) as of December 31	6	(5)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	13	9
Other
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of December 31	(1)	3
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses):
Included in earnings	(8)	(5)
Recorded in Regulatory assets/liabilities	12	8
Purchases, issuances, and settlements:
Purchases	0	0
Issuances	0	0
Settlements	(8)	(7)
Net Assets (Liabilities) as of December 31	(5)	(1)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(7)	(4)
DTE Electric
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of December 31	3	3
Total gains (losses):
Recorded in Regulatory assets/liabilities	12	8
Purchases, issuances, and settlements:
Settlements	(12)	(8)
Net Assets (Liabilities) as of December 31	3	3
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	$ 3	$ 3

Fair Value (Unobservable Inputs

Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	Dec. 31, 2015USD ($)$ / MWh$ / MMBTU	Dec. 31, 2014USD ($)$ / MWh$ / MMBTU
Unobservable Input Valuation Techniques [Line Items]
Derivative asset, gross	$ 711	$ 1,178
Derivative Liabilities	(705)	(1,110)
Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative asset, gross	387	787
Derivative Liabilities	(383)	(718)
Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative asset, gross	307	342
Derivative Liabilities	$ (305)	$ (342)
Level 3 | Discounted Cash Flow Valuation Technique | Natural Gas | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(1.50)	(2.28)
Level 3 | Discounted Cash Flow Valuation Technique | Natural Gas | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	2.77	7.83
Level 3 | Discounted Cash Flow Valuation Technique | Natural Gas | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(0.19)	(0.22)
Level 3 | Discounted Cash Flow Valuation Technique | Electricity | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(11)	(14)
Level 3 | Discounted Cash Flow Valuation Technique | Electricity | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	14	15
Level 3 | Discounted Cash Flow Valuation Technique | Electricity | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	2	4
Recurring | Level 3
Unobservable Input Valuation Techniques [Line Items]
Derivative asset, gross	$ 174	$ 142
Derivative Liabilities	(178)	(118)
Recurring | Level 3 | Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative asset, gross	103	92
Derivative Liabilities	(108)	(62)
Recurring | Level 3 | Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative asset, gross	68	47
Derivative Liabilities	$ (62)	$ (52)

Fair Value (Fair Value of Finan

Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	$ 32	$ 41
Dividends payable	131	122
Short-term borrowings	499	398
Long-term debt, excluding capital leases	9,285	8,606
Estimate of Fair Value Measurement | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Dividends payable	131	122
Short-term borrowings	0	0
Long-term debt, excluding capital leases	496	489
Estimate of Fair Value Measurement | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Dividends payable	0	0
Short-term borrowings	499	398
Long-term debt, excluding capital leases	8,136	8,308
Estimate of Fair Value Measurement | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	32	41
Dividends payable	0	0
Short-term borrowings	0	0
Long-term debt, excluding capital leases	1,203	706
DTE Electric | Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	5	12
Short-term borrowings	272	50
Long-term debt, excluding capital leases	5,624	5,259
DTE Electric | Estimate of Fair Value Measurement | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	0	0
Long-term debt, excluding capital leases	0	0
DTE Electric | Estimate of Fair Value Measurement | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	272	50
Long-term debt, excluding capital leases	5,432	5,341
DTE Electric | Estimate of Fair Value Measurement | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	5	12
Short-term borrowings	0	0
Long-term debt, excluding capital leases	545	496
Affiliated Entity | DTE Electric | Reported Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	8
Short-term borrowings	75	84
Affiliated Entity | DTE Electric | Estimate of Fair Value Measurement | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	0	0
Affiliated Entity | DTE Electric | Estimate of Fair Value Measurement | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	0	0
Affiliated Entity | DTE Electric | Estimate of Fair Value Measurement | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	8
Short-term borrowings	$ 75	$ 84

Fair Value (Fair Value of Nucle

Fair Value (Fair Value of Nuclear Decommissioning Trust Fund Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 1,236	$ 1,241
DTE Electric
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,236	1,241
DTE Electric | Fermi 2
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,211	1,221
DTE Electric | Fermi 1
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	3	3
DTE Electric | Low-level radioactive waste
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	22	17
DTE Electric | Nuclear Decommissioning Trust Fund
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 1,236	$ 1,241

Fair Value (Gains and Losses an

Fair Value (Gains and Losses and Proceeds from the Sale of Securities by the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - Nuclear Decommissioning Trust Fund - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Realized gains	$ 39	$ 54	$ 83
Realized losses	(33)	(33)	(41)
Proceeds from sales of securities	$ 885	$ 1,146	$ 1,118

Fair Value (Fair Value and Unre

Fair Value (Fair Value and Unrealized Gains and Losses for the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trusts	$ 1,236	$ 1,241
Gross Unrealized Gain	211	225
Gross Unrealized Loss	(72)	(41)
Nuclear Decommissioning Trust Fund
Schedule of Available-for-sale Securities [Line Items]
Equity Securities	731	756
Debt Securities	499	474
Cash equivalents	6	11
Equity Securities, Gross Unrealized Gain	195	204
Equity Securities, Gross Unrealized Loss	(68)	(39)
Debt Securities, Gross Unrealized Gain	16	21
Debt Securities, Gross Unrealized Loss	$ (4)	$ (2)

Fair Value (Details Textuals)

Fair Value (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	$ (11)	$ (7)
Trading securities realized gain (loss)	1	14	$ 22
Accumulated Net Unrealized Investment Gain (Loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	0	0
DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	0	(2)
Trading securities realized gain (loss)	1	12	$ 19
DTE Electric | Accumulated Net Unrealized Investment Gain (Loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	$ 0	$ 0
DTE Electric | Nuclear Decommissioning Trust Fund
Fair Value, Option, Quantitative Disclosures [Line Items]
Average maturity of debt securities	6 years	7 years

Financial and Other Derivativ94

Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 711	$ 1,178
Derivative Liabilities	(705)	(1,110)
Natural Gas
Derivatives, Fair Value [Line Items]
Derivative Assets	387	787
Derivative Liabilities	(383)	(718)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	307	342
Derivative Liabilities	(305)	(342)
Other
Derivatives, Fair Value [Line Items]
Derivative Assets	5	45
Derivative Liabilities	(10)	(45)
Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets	711	1,178
Derivative Liabilities	(705)	(1,110)
Not Designated as Hedging Instrument | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	12	4
Derivative Liabilities	(7)	(5)
Not Designated as Hedging Instrument | Natural Gas
Derivatives, Fair Value [Line Items]
Derivative Assets	387	787
Derivative Liabilities	(383)	(718)
Not Designated as Hedging Instrument | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	307	342
Derivative Liabilities	(305)	(342)
Not Designated as Hedging Instrument | Other
Derivatives, Fair Value [Line Items]
Derivative Assets	5	45
Derivative Liabilities	(10)	(45)
Current Derivative Asset
Derivatives, Fair Value [Line Items]
Derivative Assets	570	1,083
Noncurrent Derivative Asset
Derivatives, Fair Value [Line Items]
Derivative Assets	141	95
Current Derivative Liability
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(521)	(1,041)
Noncurrent Derivative Liability
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(184)	(69)
DTE Electric | Not Designated as Hedging Instrument
Derivatives, Fair Value [Line Items]
Derivative Assets	3	3
DTE Electric | Not Designated as Hedging Instrument | Other
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 3	$ 3

Financial and Other Derivativ95

Financial and Other Derivative Instruments (Netting Offsets of Derivative Assets and Liabilites) (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Offsetting Assets [Line Items]
Derivative Assets	$ 711	$ 1,178
Gross Amounts Offset in the Consolidated Statements of Financial Position	(528)	(1,006)
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	183	172
Gross Amounts of Recognized Assets (Liabilities)	(705)	(1,110)
Gross Amounts Offset in the Consolidated Statements of Financial Position	562	1,025
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	(143)	(85)
Natural Gas
Offsetting Assets [Line Items]
Derivative Assets	387	787
Gross Amounts Offset in the Consolidated Statements of Financial Position	(285)	(681)
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	102	106
Gross Amounts of Recognized Assets (Liabilities)	(383)	(718)
Gross Amounts Offset in the Consolidated Statements of Financial Position	294	679
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	(89)	(39)
Electricity
Offsetting Assets [Line Items]
Derivative Assets	307	342
Gross Amounts Offset in the Consolidated Statements of Financial Position	(232)	(280)
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	75	62
Gross Amounts of Recognized Assets (Liabilities)	(305)	(342)
Gross Amounts Offset in the Consolidated Statements of Financial Position	253	298
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	(52)	(44)
Other
Offsetting Assets [Line Items]
Derivative Assets	5	45
Gross Amounts Offset in the Consolidated Statements of Financial Position	(2)	(42)
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	3	3
Gross Amounts of Recognized Assets (Liabilities)	(10)	(45)
Gross Amounts Offset in the Consolidated Statements of Financial Position	8	45
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	(2)	0
Other derivative contracts
Offsetting Assets [Line Items]
Derivative Assets	12	4
Gross Amounts Offset in the Consolidated Statements of Financial Position	(9)	(3)
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	3	1
Gross Amounts of Recognized Assets (Liabilities)	(7)	(5)
Gross Amounts Offset in the Consolidated Statements of Financial Position	7	3
Net Amounts of Assets (Liabilities) Presented in the Consolidated Statements of Financial Position	$ 0	$ (2)

Financial and Other Derivativ96

Financial and Other Derivative Instruments (Netting Offsets Reconciliation to Balance Sheet) (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Derivative Assets:
Derivative Assets	$ 711,000,000	$ 1,178,000,000
Collateral adjustment	(2,000,000)	0
Derivative Asset, Current	129,000,000	128,000,000
Derivative Assets, Noncurrent	54,000,000	44,000,000
Derivative Liabilities:
Derivative Liabilities	(705,000,000)	(1,110,000,000)
Counterparty netting	36,000,000	19,000,000
Derivative Liabilities, Current	(57,000,000)	(77,000,000)
Derivative Liabilities, Noncurrent	(86,000,000)	(8,000,000)
Current Derivative Asset
Derivative Assets:
Derivative Assets	570,000,000	1,083,000,000
Counterparty netting	(441,000,000)	(955,000,000)
Collateral adjustment	0	0
Noncurrent Derivative Asset
Derivative Assets:
Derivative Assets	141,000,000	95,000,000
Counterparty netting	(85,000,000)	(51,000,000)
Collateral adjustment	(2,000,000)	0
Current Derivative Liability
Derivative Liabilities:
Derivative Liabilities	(521,000,000)	(1,041,000,000)
Collateral adjustment	441,000,000	955,000,000
Counterparty netting	23,000,000	9,000,000
Noncurrent Derivative Liability
Derivative Liabilities:
Derivative Liabilities	(184,000,000)	(69,000,000)
Collateral adjustment	85,000,000	51,000,000
Counterparty netting	$ 13,000,000	$ 10,000,000

Financial and Other Derivativ97

Financial and Other Derivative Instruments (Effect of Derivatives not Deisgnated as Hedging Instruments on the Consolidated Statement of Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	$ (28)	$ 79
Foreign currency exchange contracts | Operating Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	3	(2)
Natural Gas | Operating Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	(34)	(30)
Natural Gas | Fuel, purchased power and gas
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	(44)	(5)
Electricity | Operating Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	54	123
Other | Operating Revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	$ (7)	$ (7)

Financial and Other Derivativ98

Financial and Other Derivative Instruments (Cumulative Gross Volume of Derivative Contracts Outstanding) (Details)	Dec. 31, 2015CADMWhMMBTUgal
Natural Gas
Derivative [Line Items]
Derivative outstanding, energy | MMBTU	1,740,824,930
Electricity
Derivative [Line Items]
Derivative outstanding, energy | MWh	27,668,865
Oil (Gallons)
Derivative [Line Items]
Derivative, Number of Instruments Held | gal	21,756,000
Foreign Currency Exchange (Canadian dollars)
Derivative [Line Items]
Foreign Currency Exchange (Canadian dollars) | CAD	CAD 72,328,008

Financial and Other Derivativ99

Financial and Other Derivative Instruments (Details Textuals) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Letters of credit that could be used to offset net derivative liabilities	$ 7,000,000	$ 7,000,000
Letters of credit received that could be used to offset net derivative assets	2,000,000	5,000,000
Cash collateral posted, net of cash collateral received	37,000,000	61,000,000
Derivative asset, counterparty netting	2,000,000	0
Derivative liability, counterparty netting	36,000,000	19,000,000
Cash collateral paid	6,000,000	44,000,000
Cash collateral received	3,000,000	$ 2,000,000
Additional collateral, aggregate fair value	412,000,000
Derivative net liability position aggregate fair value	592,000,000
Collateral already posted fair value	5,000,000
Derivative, net asset position, fair value	500,000,000
Remaining amount of offsets to derivative net liability positions for hard and soft trigger provisions	$ 87,000,000

Long-Term Debt (Long Term Debt

Long-Term Debt (Long Term Debt Outstanding and Weighted Average Interest Rates) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Other Long-Term Debt, Including Non-Recourse Debt	$ 9,300
DTE Energy Total Long-Term Debt	8,805	$ 8,021
Less amount due within one year for DTE Energy	(465)	(161)
Long-term Debt, Excluding Current Maturities	8,340	7,860
Less amount due within one year	0	(105)
Securitization bonds, Excluding Current Maturities	0	0
DTE Energy Junior Subordinated Debentures	$ 480	480
6.5% Junior Subordinated Debentures Due 2061 | Junior Subordinated Debentures
Debt Instrument [Line Items]
Interest rate	6.50%
Maturity date	Dec. 1, 2061
DTE Energy Junior Subordinated Debentures	$ 280	280
5.25% Junior Subordinated Debentures Due 2062 | Junior Subordinated Debentures
Debt Instrument [Line Items]
Interest rate	5.30%
Maturity date	Dec. 1, 2062
DTE Energy Junior Subordinated Debentures	$ 200	200
DTE Energy | DTE Energy Debt, Unsecured | Unsecured Debt
Debt Instrument [Line Items]
Interest rate	4.40%
Maturity start	Jun. 1, 2016
Maturity end	Apr. 15, 2033
Other Long-Term Debt, Including Non-Recourse Debt	$ 1,947	1,647
DTE Electric
Debt Instrument [Line Items]
Other Long-Term Debt, Including Non-Recourse Debt	5,635
DTE Energy Total Long-Term Debt	5,624	5,154
Less amount due within one year for DTE Energy	(151)	(10)
Long-term Debt, Excluding Current Maturities	5,473	5,144
Less amount due within one year	0	(105)
Securitization bonds, Excluding Current Maturities	$ 0	0
DTE Electric | DTE Electric Taxable Debt, Principally Secured | Secured Debt
Debt Instrument [Line Items]
Interest rate	4.40%
Maturity start	Mar. 31, 2016
Maturity end	Mar. 15, 2045
Other Long-Term Debt, Including Non-Recourse Debt	$ 5,314	4,824
DTE Electric | DTE Electric Tax-Exempt Revenue Bonds (b) | Tax-Exempt Revenue Bonds
Debt Instrument [Line Items]
Interest rate	5.20%
Maturity start	Jul. 1, 2020
Maturity end	Dec. 1, 2030
Other Long-Term Debt, Including Non-Recourse Debt	$ 310	330
DTE Electric | DTE Electric Securitization Bonds
Debt Instrument [Line Items]
Interest rate	6.60%
Maturity date	Mar. 15, 2015
DTE Electric Securitization Bonds	$ 0	105
DTE Gas | Other Long-Term Debt
Debt Instrument [Line Items]
Other Long-Term Debt, Including Non-Recourse Debt	$ 110	121
DTE Gas | DTE Gas Taxable Debt, Principally Secured | Secured Debt
Debt Instrument [Line Items]
Interest rate	4.90%
Maturity start	Apr. 15, 2018
Maturity end	Sep. 1, 2045
Other Long-Term Debt, Including Non-Recourse Debt	$ 1,124	$ 1,099

Long-Term Debt (Debt Issuances)

Long-Term Debt (Debt Issuances) (Details)	Dec. 31, 2015USD ($)
Debt Instrument [Line Items]
Amount	$ 965,000,000
DTE Electric | Mortgage Bonds | March 3.70% 2045
Debt Instrument [Line Items]
Interest Rate	3.70%
Amount	$ 500,000,000
DTE Energy | Senior Notes | June 3.30% 2022
Debt Instrument [Line Items]
Interest Rate	3.30%
Amount	$ 300,000,000
DTE Gas | Mortgage Bonds | August 3.35% 2027
Debt Instrument [Line Items]
Interest Rate	3.35%
Amount	$ 40,000,000
DTE Gas | Mortgage Bonds | August 4.21% 2045
Debt Instrument [Line Items]
Interest Rate	4.21%
Amount	$ 125,000,000

Long-Term Debt (Debt Redemption

Long-Term Debt (Debt Redemptions) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Debt Instrument, Redemption [Line Items]
Amount	$ 286
Securitization Bonds | DTE Electric | March 6.62% 2015
Debt Instrument, Redemption [Line Items]
Interest Rate	6.62%
Amount	$ 105
Mortgage Bonds | DTE Electric | March 7.904% 2016
Debt Instrument, Redemption [Line Items]
Interest Rate	7.904%
Amount	$ 10
Senior Notes | DTE Gas | September 5.94% 2015
Debt Instrument, Redemption [Line Items]
Interest Rate	5.94%
Amount	$ 140
Tax-Exempt Revenue Bonds | DTE Electric | December 5.00% 2015
Debt Instrument, Redemption [Line Items]
Interest Rate	5.00%
Amount	$ 20
Other Long-Term Debt | DTE Energy
Debt Instrument, Redemption [Line Items]
Amount	$ 11

Long-Term Debt (Scheduled Debt

Long-Term Debt (Scheduled Debt Maturities) (Details) $ in Millions	Dec. 31, 2015USD ($)
Maturities of Long-term Debt [Abstract]
2,016	$ 465
2,017	9
2,018	407
2,019	427
2,020	688
2021 and Thereafter	7,304
Long-term Debt, Total	9,300
DTE Electric
Maturities of Long-term Debt [Abstract]
2,016	151
2,017	0
2,018	300
2,019	0
2,020	632
2021 and Thereafter	4,552
Long-term Debt, Total	$ 5,635

Long-Term Debt (Details Textual

Long-Term Debt (Details Textuals) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
DTE Energy Junior Subordinated Debentures	$ 480	$ 480
6.5% Junior Subordinated Debentures Due 2061 | Junior Subordinated Debentures
Debt Instrument [Line Items]
DTE Energy Junior Subordinated Debentures	$ 280	280
Interest rate	6.50%
5.25% Junior Subordinated Debentures Due 2062 | Junior Subordinated Debentures
Debt Instrument [Line Items]
DTE Energy Junior Subordinated Debentures	$ 200	$ 200
Interest rate	5.30%

Preferred and Preference Sec105

Preferred and Preference Securities (Details)	Dec. 31, 2015$ / sharesshares
DTE Energy
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 0
Preferred stock, shares authorized (in shares) | shares	5,000,000
DTE Electric
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 100
Preferred stock, shares authorized (in shares) | shares	6,747,484
Preference stock, par value (in dollars per share) | $ / shares	$ 1
Preference stock shares authorized (in shares) | shares	30,000,000
DTE Gas
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 1
Preferred stock, shares authorized (in shares) | shares	7,000,000
Preference stock, par value (in dollars per share) | $ / shares	$ 1
Preference stock shares authorized (in shares) | shares	4,000,000

Short-Term Credit Arrangemen106

Short-Term Credit Arrangements and Borrowings (Details)	Dec. 31, 2015USD ($)
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 2,070,000,000
Amounts outstanding	629,000,000
Net availability	1,441,000,000
DTE Energy
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,370,000,000
Amounts outstanding	163,000,000
Net availability	1,207,000,000
DTE Electric
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	400,000,000
Amounts outstanding	272,000,000
Net availability	128,000,000
DTE Gas
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	300,000,000
Amounts outstanding	194,000,000
Net availability	106,000,000
Letter of Credit
Line Of Credit Facility [Line Items]
Amounts outstanding	130,000,000
Letter of Credit | DTE Energy
Line Of Credit Facility [Line Items]
Amounts outstanding	130,000,000
Letter of Credit | DTE Electric
Line Of Credit Facility [Line Items]
Amounts outstanding	0
Letter of Credit | DTE Gas
Line Of Credit Facility [Line Items]
Amounts outstanding	0
Letter of Credit | Unsecured letter of credit facility, expiring in February 2017
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	100,000,000
Letter of Credit | Unsecured letter of credit facility, expiring in February 2017 | DTE Energy
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	100,000,000
Letter of Credit | Unsecured letter of credit facility, expiring in February 2017 | DTE Electric
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	0
Letter of Credit | Unsecured letter of credit facility, expiring in February 2017 | DTE Gas
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	0
Letter of Credit | Unsecured letter of credit facility, expiring in September 2017
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	70,000,000
Letter of Credit | Unsecured letter of credit facility, expiring in September 2017 | DTE Energy
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	70,000,000
Letter of Credit | Unsecured letter of credit facility, expiring in September 2017 | DTE Electric
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	0
Letter of Credit | Unsecured letter of credit facility, expiring in September 2017 | DTE Gas
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	0
Revolving Credit Facility | Unsecured revolving credit facility, expiring April 2020
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,900,000,000
Revolving Credit Facility | Unsecured revolving credit facility, expiring April 2020 | DTE Energy
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,200,000,000
Revolving Credit Facility | Unsecured revolving credit facility, expiring April 2020 | DTE Electric
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	400,000,000
Revolving Credit Facility | Unsecured revolving credit facility, expiring April 2020 | DTE Gas
Line Of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	300,000,000
Commercial Paper
Line Of Credit Facility [Line Items]
Amounts outstanding	499,000,000
Commercial Paper | DTE Energy
Line Of Credit Facility [Line Items]
Amounts outstanding	33,000,000
Commercial Paper | DTE Electric
Line Of Credit Facility [Line Items]
Amounts outstanding	272,000,000
Commercial Paper | DTE Gas
Line Of Credit Facility [Line Items]
Amounts outstanding	$ 194,000,000

Short-Term Credit Arrangemen107

Short-Term Credit Arrangements and Borrowings (Details Textuals)	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 629,000,000
Weighted average interest rate	0.60%	0.40%
Dividend restriction	$ 920,000,000
Retained earnings	4,794,000,000	$ 4,578,000,000
Effective limitations	$ 0
Maximum
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.65
DTE Energy
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.51
Other outstanding letters of credit	$ 163,000,000
DTE Electric
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.51
Other outstanding letters of credit	$ 272,000,000
Weighted average interest rate	0.70%	0.50%
Retained earnings	$ 1,585,000,000	$ 1,436,000,000
DTE Gas
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.48
Letter of Credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 130,000,000
Letter of Credit | DTE Energy
Short-term Debt [Line Items]
Other outstanding letters of credit	130,000,000
Letter of Credit | DTE Electric
Short-term Debt [Line Items]
Other outstanding letters of credit	0
Demand Financing Agreement | DTE Energy
Short-term Debt [Line Items]
Maximum borrowing capacity	100,000,000
Additional margin financing	50,000,000
Amount outstanding	103,000,000	$ 37,000,000
Demand Financing Agreement Plus Letter of Credit | DTE Energy
Short-term Debt [Line Items]
Maximum borrowing capacity	125,000,000
Other outstanding letters of credit | Letter of Credit | DTE Energy
Short-term Debt [Line Items]
Other outstanding letters of credit	17,000,000
Demand Financing Agreement | Letter of Credit | DTE Energy
Short-term Debt [Line Items]
Maximum borrowing capacity	$ 25,000,000

Capital and Operating Leases (F

Capital and Operating Leases (Future Minimum Lease Payments under Non-Cancelable Leases) (Details) $ in Millions	Dec. 31, 2015USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016	$ 37
2,017	30
2,018	25
2,019	21
2,020	13
Thereafter	71
Total minimum lease payments	197
DTE Electric
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,016	24
2,017	18
2,018	15
2,019	14
2,020	10
Thereafter	35
Total minimum lease payments	$ 116

Capital and Operating (Componen

Capital and Operating (Components of the Net Investment in the Capital Leases) (Details) $ in Millions	Dec. 31, 2015USD ($)
Capital Leases of Lessor [Abstract]
2,016	$ 13
2,017	13
2,018	13
2,019	10
2,020	9
Thereafter	0
Total minimum future lease receipts	58
Residual value of leased pipeline	40
Less unearned income	(27)
Net investment in capital lease	71
Less current portion	(6)
Capital Lease, noncurrent	$ 65

Capital and Operating Leases (D

Capital and Operating Leases (Details Textuals) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Schedule of Lessor Capital Leases [Line Items]
Rent expense	$ 43	$ 38	$ 34
DTE Electric
Schedule of Lessor Capital Leases [Line Items]
Rent expense	$ 32	$ 26	$ 28
Pipeline System Lease
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	5 years
Percent ownership in pipeline	40.00%
Minimum | Energy Services Agreement
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	3 years
Maximum | Energy Services Agreement
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	5 years

Commitments and Contingencie111

Commitments and Contingencies (Purchase Commitments) (Details) $ in Millions	Dec. 31, 2015USD ($)
Purchase Obligation, Fiscal Year Maturity [Abstract]
2,016	$ 2,038
2,017	1,160
2,018	611
2,019	397
2,020	353
2021 and thereafter	3,043
Total Purchase Commitments	7,602
DTE Electric
Purchase Obligation, Fiscal Year Maturity [Abstract]
2,016	493
2,017	412
2,018	240
2,019	120
2,020	88
2021 and thereafter	992
Total Purchase Commitments	$ 2,345

Commitments and Contingencie112

Commitments and Contingencies (Details Textuals)	May. 16, 2014kWh	Nov. 30, 2015USD ($)states	May. 15, 2014$ / MWh	Dec. 31, 2015USD ($)employeefacilitiesdte_instances	Dec. 31, 2010dte_instances	Dec. 31, 2014USD ($)
Loss Contingencies [Line Items]
Number of states containing power plants | states		23
Number of NOVs received | dte_instances					2
Fine related to consent order and agreement with Allegheny County related to NOV				$ 300,000
Estimated expenditures for a supplemental environmental project to enhance particulate collection efficiency				300,000
Sulfur dioxide ambient air quality standard finalized					1 hour
Estimated future capital expenditures for next year				$ 2,700,000,000
DTE Electric
Loss Contingencies [Line Items]
Number of power plants in violation | facilities				5
Number of NOVs/FOVs currently being discussed with the EPA | dte_instances				2
Amount spent to comply with requirements				$ 2,300,000,000
Estimated capital expenditures in next fiscal year				$ 40,000,000
Number of former MGP sites | facilities				3
Accrued for remediation related to the sites				$ 8,000,000		$ 10,000,000
Number of permitted engineered coal ash storage facilities owned | facilities				3
Time period to complete studies on cooling water intake structures impacts on fish - EPA ruling (in years)		7 years
Waiting period of policy (in weeks)				84 days
Aggregate coverage amount				$ 490,000,000
Coverage period (in years)				3 years
Primary coverage				$ 1,500,000,000
Excess coverage for stabilization				1,250,000,000
Coverage maximum for property damage				2,750,000,000
Maximum damages for non-nuclear event				2,000,000,000
Aggregate coverage for extra expense				$ 328,000,000
Extra expense coverage period (in years)				2 years
Maximum time after the first loss from terrorism (in years)				1 year
Maximum NEIL policies against terroism loss				$ 3,200,000,000
Maximum assessments				45,000,000
Public liability insurance				375,000,000
Industry aggregate limit				300,000,000
Maximum deferred premium charges				127,000,000
Maximum amount per year per facility				19,000,000
Fee amount (mill per kWh) | $ / MWh			1
Reduction in fee | kWh	0
Estimated future capital expenditures for next year				$ 1,600,000,000
DTE Gas
Loss Contingencies [Line Items]
Number of former MGP sites | facilities				14
Accrued for remediation related to the sites				$ 22,000,000		$ 24,000,000
Amortization period for MGP costs (in years)				10 years
Synthetic Fuel
Loss Contingencies [Line Items]
Number of days after expiration				90 days
Potential liability				$ 850,000,000
Reduced Emissions Fuel Guarantees
Loss Contingencies [Line Items]
Number of days after expiration				90 days
Potential liability				$ 268,000,000
Guarantee Type, Other
Loss Contingencies [Line Items]
Potential liability				56,000,000
Surety Bond
Loss Contingencies [Line Items]
Performance bonds outstanding				$ 55,000,000
Represented Employees
Loss Contingencies [Line Items]
Number of represented employees | employee				4,900
Represented Employees | DTE Electric
Loss Contingencies [Line Items]
Number of represented employees | employee				2,600
Cleanup completed and site closed | DTE Gas
Loss Contingencies [Line Items]
Number of former MGP sites | facilities				5
Partial closure expected by end of fiscal year | DTE Gas
Loss Contingencies [Line Items]
Number of former MGP sites | facilities				2
Coal Combustion Residual Rule | DTE Electric
Loss Contingencies [Line Items]
Cost associated with building new facilities		$ 290,000,000

Retirement Benefits and Trus113

Retirement Benefits and Trusteed Assets (Pension Plan - Pension Cost Inclusions) (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	$ 100	$ 83	$ 94
Interest cost	210	212	192
Expected return on plan assets	(296)	(273)	(266)
Amortization of net actuarial loss	205	157	208
Special termination benefits	2	0	0
Net cost (credit)	221	179	228
DTE Electric
Defined Benefit Plan, Net Periodic Benefit Cost [Abstract]
Service cost	77	64	73
Interest cost	160	162	146
Expected return on plan assets	(210)	(194)	(184)
Amortization of net actuarial loss	147	110	148
Prior service cost	1	2	1
Special termination benefits	1	0	0
Net cost (credit)	$ 176	$ 144	$ 184

Retirement Benefits and Trus114

Retirement Benefits and Trusteed Assets (Pension Plan - Other Changes in Plan Assets and Benefit Obligations recognized in Reg Assets and OCI) (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial loss	$ 19	$ 805
Amortization of net actuarial loss	(205)	(157)
Prior service credit	0	(7)
Total recognized in Regulatory assets and Other comprehensive income (loss)	(186)	641
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	35	820
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	162	206
DTE Electric
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial loss	(13)	614
Amortization of net actuarial loss	(147)	(110)
Prior service credit	0	(2)
Amortization of prior service cost	(1)	(2)
Total recognized in Regulatory assets and Other comprehensive income (loss)	(161)	500
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	15	644
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	115	149
Future amortization of prior service cost into net periodic benefit cost	$ 1	$ 1

Retirement Benefits and Trus115

Retirement Benefits and Trusteed Assets (Pension Plan - 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
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Accumulated benefit obligation, end of year	4,569	4,853
Change in accumulated postretirement benefit obligation
Projected benefit obligation, beginning of year	5,269	4,380
Service cost	100	83	$ 94
Interest cost	210	212	192
Plan amendments	0	(7)
Actuarial (gain) loss	(357)	836
Transfer due to plan sponsorship change	0	0
Special termination benefits	2	0
Benefits paid	(253)	(235)
Projected benefit obligation, end of year	4,971	5,269	4,380
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	3,981	3,720
Actual return on plan assets	(79)	301
Company contributions	183	195
Benefits paid	(253)	(235)
Plan assets at fair value, end of year	3,832	3,981	3,720
Funded status of the plans	(1,139)	(1,288)
Amount recorded as:
Current liabilities	(6)	(8)
Noncurrent liabilities	(1,133)	(1,280)
Defined benefit plans liabilities	(1,139)	(1,288)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	180	194
Prior service credit	(1)	(1)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	179	193
Amounts recognized in Regulatory assets (see Note 8 - Regulatory Matters)
Net actuarial loss	2,113	2,285
Prior service credit	(1)	(1)
Regulatory Assets	2,112	2,284
Qualified Pension Plan
Change in accumulated postretirement benefit obligation
Service cost	100	83
Interest cost	210	212
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contributions	177
DTE Electric
Amounts recognized in Regulatory assets (see Note 8 - Regulatory Matters)
Regulatory Assets	2,986	2,959
DTE Electric | Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Accumulated benefit obligation, end of year	3,401	3,712
Change in accumulated postretirement benefit obligation
Projected benefit obligation, beginning of year	4,018	3,341
Service cost	77	64	73
Interest cost	160	162	146
Plan amendments	0	(2)
Actuarial (gain) loss	(273)	634
Transfer due to plan sponsorship change	(99)	0
Special termination benefits	0	0
Benefits paid	(192)	(181)
Projected benefit obligation, end of year	3,685	4,018	3,341
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	2,812	2,632
Actual return on plan assets	(56)	212
Company contributions	145	149
Benefits paid	(192)	(181)
Plan assets at fair value, end of year	2,709	2,812	$ 2,632
Funded status of the plans	(976)	(1,206)
Amount recorded as:
Current liabilities	0	(6)
Noncurrent liabilities	(976)	(1,200)
Defined benefit plans liabilities	(976)	(1,206)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	0	44
Prior service credit	0	0
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	0	44
Amounts recognized in Regulatory assets (see Note 8 - Regulatory Matters)
Net actuarial loss	1,588	1,738
Prior service credit	4	5
Regulatory Assets	1,592	1,743
DTE Electric | Qualified Pension Plan
Change in accumulated postretirement benefit obligation
Service cost	75	64
Interest cost	156	$ 162
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Company contributions	$ 145

Retirement Benefits and Trus116

Retirement Benefits and Trusteed Assets (Pension Plan - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) - Pension Plan $ in Millions	Dec. 31, 2015USD ($)
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	$ 274
2,017	285
2,018	297
2,019	306
2,020	314
2021-2025	1,662
Total Expected Future Benefit Payments	3,138
DTE Electric
Defined Benefit Plan, Expected Future Benefit Payments, Fiscal Year Maturity [Abstract]
2,016	213
2,017	221
2,018	231
2,019	238
2,020	244
2021-2025	1,279
Total Expected Future Benefit Payments	$ 2,426

Retirement Benefits and Trus117

Retirement Benefits and Trusteed Assets (Pension Plan - Assumptions used in Determining the PBO and Net Pension Costs) (Details) - Pension Plan	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Projected benefit obligation
Discount rate	4.50%	4.12%	4.95%
Rate of compensation increase	4.65%	4.65%	4.20%
Net pension costs
Discount rate	4.12%	4.95%	4.15%
Rate of compensation increase	4.65%	4.20%	4.20%
Expected long-term rate of return on plan assets	7.75%	7.75%	8.25%

Retirement Benefits and Trus118

Retirement Benefits and Trusteed Assets (Pension Plan - Target Allocations of Plan Assets) (Details) - Pension Plan	12 Months Ended
	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	100.00%
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	22.00%
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	5.00%
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	20.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	25.00%
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	20.00%
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	8.00%

Retirement Benefits and Trus119

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

Retirement Benefits and Trus120

Retirement Benefits and Trusteed Assets (Pension Plan - Fair Value Measurement using Level 3 Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	$ (129)	$ 40
Pension Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	3,981	3,720
Total realized/unrealized gains (losses)	(79)	301
Plan assets at fair value, end of year	3,832	3,981
Pension Plan | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	625	565
Total realized/unrealized gains (losses)	20	38
Purchases	36	53
Sales	(39)	(31)
Plan assets at fair value, end of year	642	625
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	7	32
Pension Plan | Hedge Funds and Similar Investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	759
Plan assets at fair value, end of year	768	759
Pension Plan | Hedge Funds and Similar Investments | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	438	395
Total realized/unrealized gains (losses)	10	22
Purchases	4	22
Sales	0	(1)
Plan assets at fair value, end of year	452	438
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	10	21
Pension Plan | Private Equity and Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	187
Plan assets at fair value, end of year	190	187
Pension Plan | Private Equity and Other | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	187	170
Total realized/unrealized gains (losses)	10	16
Purchases	32	31
Sales	(39)	(30)
Plan assets at fair value, end of year	190	187
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(3)	11
DTE Electric
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	3	3
DTE Electric | Pension Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	2,812	2,632
Total realized/unrealized gains (losses)	(56)	212
Plan assets at fair value, end of year	2,709	2,812
DTE Electric | Pension Plan | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	450	407
Total realized/unrealized gains (losses)	14	27
Purchases	26	38
Sales	(28)	(22)
Plan assets at fair value, end of year	462	450
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	5	23
DTE Electric | Pension Plan | Hedge Funds and Similar Investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	546
Plan assets at fair value, end of year	552	546
DTE Electric | Pension Plan | Hedge Funds and Similar Investments | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	315	285
Total realized/unrealized gains (losses)	7	15
Purchases	3	16
Sales	0	(1)
Plan assets at fair value, end of year	325	315
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	7	15
DTE Electric | Pension Plan | Private Equity and Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	135
Plan assets at fair value, end of year	137	135
DTE Electric | Pension Plan | Private Equity and Other | Level 3
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	135	122
Total realized/unrealized gains (losses)	7	12
Purchases	23	22
Sales	(28)	(21)
Plan assets at fair value, end of year	137	135
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	$ (2)	$ 8

Retirement Benefits and Trus121

Retirement Benefits and Trusteed Assets (OPEB - Postretirement Cost Inclusions) (Details) - Other Postretirement Benefit Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 34	$ 34	$ 47
Interest cost	81	89	88
Expected return on plan assets	(131)	(122)	(110)
Amortization of net actuarial loss	43	20	64
Prior service cost	(126)	(144)	(131)
Net cost (credit)	(99)	(123)	(42)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	25	26	35
Interest cost	62	68	67
Expected return on plan assets	(90)	(85)	(74)
Amortization of net actuarial loss	31	14	47
Prior service cost	(95)	(109)	(100)
Net cost (credit)	$ (67)	$ (86)	$ (25)

Retirement Benefits and Trus122

Retirement Benefits and Trusteed Assets (OPEB - Other Changes in Plan Assets and APBO Recognized in Regulatory Assets and OCI) (Details) - Other Postretirement Benefit Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	$ (68)	$ 192
Amortization of net actuarial loss	(43)	(20)
Amortization of prior service credit	126	144
Total recognized in Regulatory assets and Other comprehensive income (loss)	15	316
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(84)	193
Net actuarial loss	32	43
Prior service credit	(118)	(126)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss	(57)	144
Amortization of net actuarial loss	(31)	(14)
Amortization of prior service credit	95	109
Total recognized in Regulatory assets and Other comprehensive income (loss)	7	239
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(60)	153
Net actuarial loss	22	31
Prior service credit	$ (89)	$ (94)

Retirement Benefits and Trus123

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

Retirement Benefits and Trus124

Retirement Benefits and Trusteed Assets (OPEB - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) - Other Postretirement Benefit Plan $ in Millions	Dec. 31, 2015USD ($)
Defined Benefit Plan Disclosure [Line Items]
2,016	$ 100
2,017	105
2,018	108
2,019	113
2,020	116
2021-2025	621
Total Expected Future Benefit Payments	1,163
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
2,016	77
2,017	81
2,018	84
2,019	88
2,020	90
2021-2025	476
Total Expected Future Benefit Payments	$ 896

Retirement Benefits and Trus125

Retirement Benefits and Trusteed Assets (OPEB - Assumptions used in Determining the PBO and Net Pension Costs) (Details)	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plan Disclosure [Line Items]
Ultimate health care trend rate					4.50%
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Discount rate	4.30%	4.95%	4.50%	4.10%	4.95%	4.15%
Health care trend rate pre- and post- 65			6.25%	7.50%	7.50%
Health care trend post 65			6.75%	6.50%	6.50%
Ultimate health care trend rate			4.50%	4.50%
Discount rate (prior to interim remeasurement)	4.15%	4.30%	4.10%	4.95%
Expected long-term rate of return on plan assets			8.00%	8.00%	8.25%
Health care trend rate pre-65			7.50%	7.50%
Health care trend post 65			6.50%	6.50%
Health care trend rate pre- and post- 65					7.00%
Other Postretirement Benefit Plan | Other postretirement benefit costs
Defined Benefit Plan Disclosure [Line Items]
Ultimate health care trend rate			4.50%	4.50%	5.00%

Retirement Benefits and Trus126

Retirement Benefits and Trusteed Assets (OPEB - Target Allocations of Plan Assets) (Details) - Other Postretirement Benefit Plan	12 Months Ended
	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	100.00%
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	17.00%
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	4.00%
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	20.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	25.00%
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	20.00%
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Target Allocation Percentage of Assets	14.00%

Retirement Benefits and Trus127

Retirement Benefits and Trusteed Assets (OPEB - Fair Value Measurements) (Details) - Other Postretirement Benefit Plan - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	$ 1,617	$ 1,528	$ 1,527
Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	803	765
Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	490	464
Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	324	299	260
Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	7	6
Short-term Investments (b) | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	7	6
Short-term Investments (b) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Short-term Investments (b) | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	264	266
U.S. Large Capitalization (Cap) Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	264	266
U.S. Large Capitalization (Cap) Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
U.S. Large Capitalization (Cap) Equity Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	138	149
U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	138	149
U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
U.S. Small Cap and Mid Cap Equity Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	317	281
Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	262	222
Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	55	59
Non-U.S. Equity Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	413	375
Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	23	15
Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	390	360
Fixed Income Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	325	320
Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	109	107
Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	45	45
Hedge Funds and Similar Investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	171	168	159
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	153	131
Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Private Equity and Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	153	131	101
Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(128)	(158)
Securities Lending (i) | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(122)	(141)
Securities Lending (i) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(6)	(17)
Securities Lending (i) | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	128	158
Securities Lending Collateral (i) | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	122	141
Securities Lending Collateral (i) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	6	17
Securities Lending Collateral (i) | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	1,131	1,038	1,061
DTE Electric | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	562	520
DTE Electric | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	341	313
DTE Electric | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	228	205	182
DTE Electric | Short-term Investments (b)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	5	4
DTE Electric | Short-term Investments (b) | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	5	4
DTE Electric | Short-term Investments (b) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Short-term Investments (b) | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	183	179
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	183	179
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	97	102
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	97	102
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	221	190
DTE Electric | Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	184	151
DTE Electric | Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	37	39
DTE Electric | Non-U.S. Equity Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	289	254
DTE Electric | Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	17	11
DTE Electric | Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	272	243
DTE Electric | Fixed Income Securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	227	218
DTE Electric | Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	76	73
DTE Electric | Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	32	31
DTE Electric | Hedge Funds and Similar Investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	119	114	111
DTE Electric | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	109	91
DTE Electric | Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Private Equity and Other | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	109	91	$ 71
DTE Electric | Securities Lending (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(91)	(109)
DTE Electric | Securities Lending (i) | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(87)	(98)
DTE Electric | Securities Lending (i) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	(4)	(11)
DTE Electric | Securities Lending (i) | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	0	0
DTE Electric | Securities Lending Collateral (i)
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	91	109
DTE Electric | Securities Lending Collateral (i) | Level 1
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	87	98
DTE Electric | Securities Lending Collateral (i) | Level 2
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	4	11
DTE Electric | Securities Lending Collateral (i) | Level 3
Defined Benefit Plan Disclosure [Line Items]
Fair value plan asset	$ 0	$ 0

Retirement Benefits and Trus128

Retirement Benefits and Trusteed Assets (OPEB - Fair Value Measurements using Level 3 Inputs) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	$ (129)	$ 40
Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	1,528	1,527
Total realized/unrealized gains (losses)	(25)	62
Plan assets at fair value, end of year	1,617	1,528
Other Postretirement Benefit Plan | Hedge Funds and Similar Investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	320
Plan assets at fair value, end of year	325	320
Other Postretirement Benefit Plan | Private Equity and Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	131
Plan assets at fair value, end of year	153	131
Level 3 | Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	299	260
Total realized/unrealized gains (losses)	13	17
Purchases	45	42
Sales	(33)	(20)
Plan assets at fair value, end of year	324	299
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	3	15
Level 3 | Other Postretirement Benefit Plan | Hedge Funds and Similar Investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	168	159
Total realized/unrealized gains (losses)	4	8
Purchases	11	9
Sales	(12)	(8)
Plan assets at fair value, end of year	171	168
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	0	7
Level 3 | Other Postretirement Benefit Plan | Private Equity and Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	131	101
Total realized/unrealized gains (losses)	9	9
Purchases	34	33
Sales	(21)	(12)
Plan assets at fair value, end of year	153	131
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	3	8
DTE Electric
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	3	3
DTE Electric | Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	1,038	1,061
Total realized/unrealized gains (losses)	(19)	41
Plan assets at fair value, end of year	1,131	1,038
DTE Electric | Other Postretirement Benefit Plan | Hedge Funds and Similar Investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	218
Plan assets at fair value, end of year	227	218
DTE Electric | Other Postretirement Benefit Plan | Private Equity and Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	91
Plan assets at fair value, end of year	109	91
DTE Electric | Level 3 | Other Postretirement Benefit Plan
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	205	182
Total realized/unrealized gains (losses)	9	11
Purchases	37	26
Sales	(23)	(14)
Plan assets at fair value, end of year	228	205
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	2	10
DTE Electric | Level 3 | Other Postretirement Benefit Plan | Hedge Funds and Similar Investments
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	114	111
Total realized/unrealized gains (losses)	3	5
Purchases	11	4
Sales	(9)	(6)
Plan assets at fair value, end of year	119	114
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	0	5
DTE Electric | Level 3 | Other Postretirement Benefit Plan | Private Equity and Other
Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward]
Plan assets at fair value, beginning of year	91	71
Total realized/unrealized gains (losses)	6	6
Purchases	26	22
Sales	(14)	(8)
Plan assets at fair value, end of year	109	91
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2015 and 2014 and reflected in Operating revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	$ 2	$ 5

Retirement Benefits and Trus129

Retirement Benefits and Trusteed Assets (Schedule of Defined Benefit Plans Disclosures) (Details) - USD ($) $ / shares in Units, $ in Millions	Feb. 17, 2015	Dec. 31, 2015	Dec. 31, 2013
Defined Benefit Plan Disclosure [Line Items]
Contribution of common stock to pension plan			$ 200
Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Contribution of common stock to pension plan		$ 117
VEBA Trust | Other Postretirement Benefit Plan
Defined Benefit Plan Disclosure [Line Items]
Contribution of common stock to pension plan (in shares)	1,427,835
Share Price	$ 81.91
Contribution of common stock to pension plan	$ 117

Retirement Benefits and Trus130

Retirement Benefits and Trusteed Assets (Details Textuals) - USD ($)	Feb. 17, 2015	Mar. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized (less than $1 million in 2012)			$ 49,000,000	$ 48,000,000	$ 41,000,000
Contribution of common stock to pension plan					200,000,000
Transfers into Level 3			0	0
Transfers out of Level 3			0	2,000,000
Grantor Trust Balance			18,000,000	18,000,000
DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized (less than $1 million in 2012)			$ 23,000,000	24,000,000	$ 21,000,000
Retirement Savings Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contribution to employee savings plan			4.00%
Retirement Savings Plan | DTE Gas Represented Employees
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contribution to employee savings plan			8.00%
Qualified Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			$ 177,000,000
Qualified Pension Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			145,000,000
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			$ 183,000,000	$ 195,000,000
Expected return on plan assets			7.75%
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate			4.50%	4.12%	4.95%
Transfers into Level 3			$ 0	$ 0
Transfers out of Level 3			0	0
Pension Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			145,000,000	149,000,000
Pension Plan | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions in next fiscal year			180,000,000
Pension Plan | Maximum | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions in next fiscal year			145,000,000
Other Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			$ 199,000,000	$ 24,000,000
Expected return on plan assets			8.00%
Defined Benefit Plan, Retiree Reimbursement Account, Minimum Age Requirement for Coverage		65 years			65 years
Retiree Health Care Allowance will increase at lower of the rate of medical inflation or a set percentage		2.00%
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components			$ 6,000,000
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation			100,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components			5,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation			$ 86,000,000
Defined Benefit Plan, Term of Employment Contract		4 years
Annual allocation to Retiree Reimbursement Account Per Participant, Retired after January 1, 2013		$ 3,250
Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate		4.30%	4.50%	4.10%	4.95%	4.15%
Contribution of common stock to pension plan			$ 117,000,000
Transfers into Level 3			0	$ 0
Transfers out of Level 3			0	0
Other Postretirement Benefit Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			175,000,000	0
Defined Benefit Plan, Effect of One Percentage Point Increase on Service and Interest Cost Components			4,000,000
Defined Benefit Plan, Effect of One Percentage Point Increase on Accumulated Postretirement Benefit Obligation			74,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Service and Interest Cost Components			4,000,000
Defined Benefit Plan, Effect of One Percentage Point Decrease on Accumulated Postretirement Benefit Obligation			64,000,000
Other Postretirement Benefit Plan | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions in next fiscal year			20,000,000
Retiree Healthcare Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized (less than $1 million in 2012)			5,000,000	4,000,000	$ 2,000,000
Retiree Healthcare Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized (less than $1 million in 2012)			3,000,000	$ 2,000,000	$ 1,000,000
VEBA Trust | Other Postretirement Benefit Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			82,000,000
Contribution of common stock to pension plan	$ 117,000,000
VEBA Trust | Other Postretirement Benefit Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions			$ 58,000,000

Stock-Based Compensation (Compo

Stock-Based Compensation (Components of Stock Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Components of stock based-compensation [Abstract]
Stock-based compensation expense	$ 34	$ 103	$ 99
Tax benefit	13	40	38
Stock-based compensation cost capitalized in Property, plant, and equipment	$ 5	$ 16	$ 15

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock Option Activity) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Number of options (in shares):
Options outstanding beginning of the year (in shares) | shares	444,278
Exercised (in shares) | shares	(178,017)
Forfeited or expired (in shares) | shares	(3,979)
Options outstanding end of the year (in shares) | shares	262,282
Weighted Average Exercise Price (in dollars per share):
Options outstanding beginning of the year (in dollars per share) | $ / shares	$ 43.56
Exercised (in dollars per share) | $ / shares	45.07
Forfeited or expired (in dollars per share) | $ / shares	44.72
Options outstanding end of the year (in dollars per share) | $ / shares	$ 42.52
Outstanding, Intrinsic Value | $	$ 10

Stock-Based Compensation (Numbe

Stock-Based Compensation (Number, Weighted Average Exercise Price and Weighted Average Remaining Contractual Life of Options Outstanding) (Details)	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options (in shares) | shares	262,282
Weighted Average Exercise Price (in dollars per share)	$ 42.52
Weighted Average Remaining Contractual Life (Years)	2 years 9 months 20 days
$27.00 - $38.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 27
Range of Exercise Prices Upper Limit (in dollars per share)	$ 38
Number of Options (in shares) | shares	22,083
Weighted Average Exercise Price (in dollars per share)	$ 27.70
Weighted Average Remaining Contractual Life (Years)	3 years 1 month 29 days
$38.01 - $42.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 38.01
Range of Exercise Prices Upper Limit (in dollars per share)	$ 42
Number of Options (in shares) | shares	80,434
Weighted Average Exercise Price (in dollars per share)	$ 41.79
Weighted Average Remaining Contractual Life (Years)	2 years 1 month 29 days
$42.01 - $45.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 42.01
Range of Exercise Prices Upper Limit (in dollars per share)	$ 45
Number of Options (in shares) | shares	116,665
Weighted Average Exercise Price (in dollars per share)	$ 43.90
Weighted Average Remaining Contractual Life (Years)	3 years 9 months 15 days
$45.01 - $50.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 45.01
Range of Exercise Prices Upper Limit (in dollars per share)	$ 50
Number of Options (in shares) | shares	43,100
Weighted Average Exercise Price (in dollars per share)	$ 47.75
Weighted Average Remaining Contractual Life (Years)	1 year 1 month 23 days

Stock-Based Compensation (Restr

Stock-Based Compensation (Restricted Stock Award Activity) (Details) - Restricted Stock - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested (in millions)	$ 9	$ 11	$ 8
Restricted common shares awarded (in shares)	144,300	159,590	127,785
Weighted average market price of shares awarded (in dollars per share)	$ 83.43	$ 70.09	$ 64.72
Compensation cost charged against income (in millions)	$ 10	$ 10	$ 23

Stock Based-Compensation (Stock

Stock Based-Compensation (Stock Awards Activity Rollforward) (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restricted Stock (in shares):
Balance at beginning of the period (in shares)	416,318
Grants (in shares)	144,300	159,590	127,785
Forfeitures (in shares)	(12,721)
Vested and issued (in shares)	(165,453)
Balance at end of period (in shares)	382,444	416,318
Weighted Average Grant Date Fair Value (in dollars per share):
Balance at beginning of period (in dollars per share)	$ 62.82
Grants (in dollars per share)	83.43	$ 70.09	$ 64.72
Forfeitures (in dollars per share)	74.78
Vested and issued (in dollars per share)	55.73
Balance at end of period (in dollars per share)	$ 73.26	$ 62.82

Stock-Based Compensation (Perfo

Stock-Based Compensation (Performance Share Awards Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation Expense Recorded [Line Items]
Stock-based compensation expense	$ 34	$ 103	$ 99
Performance Shares
Compensation Expense Recorded [Line Items]
Stock-based compensation expense	24	93	77
Cash settlements	13	11	9
Stock settlements	$ 71	$ 61	$ 56

Stock-Based Compensation (Pe137

Stock-Based Compensation (Performance Share Awards Activity) (Details) - Performance Shares	12 Months Ended
	Dec. 31, 2015$ / sharesshares
Performance Shares (in shares):
Balance at beginning of period (in shares) | shares	1,554,697
Grants (in shares) | shares	467,288
Forfeitures (in shares) | shares	(47,067)
Payouts (in shares) | shares	(532,700)
Balance at end of period (in shares) | shares	1,442,218
Weighted Average Grant Date Fair Value (in dollars per share):
Balance at beginning of period (in dollars per share) | $ / shares	$ 69.32
Grants (in dollars per share) | $ / shares	83.85
Forfeitures (in dollars per share) | $ / shares	76.22
Payouts (in dollars per share) | $ / shares	0
Balance at end of period (in dollars per share) | $ / shares	$ 75.85

Stock-Based Compensation (Unrec

Stock-Based Compensation (Unrecognized Compensation Costs) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 48
Weighted Average to be Recognized	1 year
Restricted Stock
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 11
Weighted Average to be Recognized	1 year 1 month 10 days
Performance Shares
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 37
Weighted Average to be Recognized	11 months 18 days

Stock-Based Compensation (Detai

Stock-Based Compensation (Details Textuals)	12 Months Ended
	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Dec. 31, 2013USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized limit of common stock shares	14,500,000
Performance units price per unit	1
Remaining contractual term (in years)	2 years 9 months 20 days
Options vested (in shares)	0
Options grants in period (in shares)	0	0	0
Options, exercises, intrinsic value | $	$ 7,000,000	$ 11,000,000	$ 12,000,000
Stock option expense | $	$ 0	0	0
Employee Stock Option
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee	500,000
Award expiration period	10 years
Award vesting period	3 years
Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee	150,000
Award vesting period	3 years
Compensation cost charged against income (in millions) | $	$ 10,000,000	10,000,000	23,000,000
Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee	300,000
Award vesting period	3 years
Performance Unit
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee	1,000,000
DTE Electric | DTE Energy
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost charged against income (in millions) | $	$ 21,000,000	$ 62,000,000	$ 58,000,000

Segment and Related Informat140

Segment and Related Information (Details Textuals) customer in Millions	Dec. 31, 2015customer
Segment Reporting [Abstract]
Number of electric utility customers	2.2
Number of gas utility customers	1.2

Segment and Related Informat141

Segment and Related Information (Financial Data) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Utility operations									$ 6,238	$ 6,884	$ 6,643
Operating Revenues	$ 2,487	$ 2,598	$ 2,268	$ 2,984	$ 3,078	$ 2,595	$ 2,698	$ 3,930	10,337	12,301	9,661
Non-utility operations									4,099	5,417	3,018
Depreciation and amortization									852	1,145	1,094
Interest income									(13)	(10)	(9)
Interest expense									450	429	436
Equity in earnings of equity method investees									66	48	59
Income Tax Expense (Benefit)									230	364	254
Net Income	80	$ 265	$ 109	$ 273	299	$ 156	$ 124	$ 326	727	905	661
Investments in equity method investees	514				434				514	434	415
Capital expenditures and acquisitions									2,261	2,049	1,876
Goodwill	2,018				2,018				2,018	2,018	2,018
Total Assets	28,737				27,899				28,737	27,899	25,935
Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Investments in equity method investees	296				224				296	224
Operating Segments | DTE Electric
Segment Reporting Information [Line Items]
Utility operations									4,901	5,283	5,199
Non-utility operations									0	0	0
Depreciation and amortization									637	933	902
Interest income									0	(1)	(1)
Interest expense									258	250	268
Equity in earnings of equity method investees									2	1	1
Income Tax Expense (Benefit)									290	296	252
Net Income									542	528	484
Investments in equity method investees	10				8				10	8	9
Capital expenditures and acquisitions									1,785	1,561	1,325
Goodwill	1,208				1,208				1,208	1,208	1,208
Total Assets	19,539				18,713				19,539	18,713	17,508
Operating Segments | DTE Gas
Segment Reporting Information [Line Items]
Utility operations									1,376	1,636	1,474
Non-utility operations									0	0	0
Depreciation and amortization									104	99	95
Interest income									(7)	(7)	(7)
Interest expense									62	57	58
Equity in earnings of equity method investees									6	7	6
Income Tax Expense (Benefit)									72	78	77
Net Income									132	140	143
Investments in equity method investees	9				10				9	10	10
Capital expenditures and acquisitions									273	224	209
Goodwill	743				743				743	743	743
Total Assets	4,299				4,247				4,299	4,247	3,920
Operating Segments | Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Utility operations									0	0	0
Non-utility operations									243	203	132
Depreciation and amortization									30	34	23
Interest income									(8)	(6)	(7)
Interest expense									24	22	18
Equity in earnings of equity method investees									47	35	44
Income Tax Expense (Benefit)									70	53	45
Net Income									107	82	70
Investments in equity method investees	296				224				296	224	201
Capital expenditures and acquisitions									161	184	245
Goodwill	24				24				24	24	24
Total Assets	1,047				883				1,047	883	823
Operating Segments | Power and Industrial Projects
Segment Reporting Information [Line Items]
Utility operations									0	0	0
Non-utility operations									2,224	2,289	1,950
Depreciation and amortization									78	77	72
Interest income									(8)	(5)	(6)
Interest expense									32	28	27
Equity in earnings of equity method investees									8	5	8
Income Tax Expense (Benefit)									(140)	(100)	(45)
Net Income									16	90	66
Investments in equity method investees	183				184				183	184	189
Capital expenditures and acquisitions									36	77	93
Goodwill	26				26				26	26	26
Total Assets	860				998				860	998	1,054
Operating Segments | Energy Trading
Segment Reporting Information [Line Items]
Utility operations									0	0	0
Non-utility operations									2,459	3,762	1,771
Depreciation and amortization									2	1	1
Interest income									(2)	0	0
Interest expense									6	7	8
Equity in earnings of equity method investees									0	0	0
Income Tax Expense (Benefit)									(15)	77	(38)
Net Income									(22)	122	(58)
Investments in equity method investees	0				0				0	0	0
Capital expenditures and acquisitions									6	3	3
Goodwill	17				17				17	17	17
Total Assets	590				755				590	755	624
Corporate and Other
Segment Reporting Information [Line Items]
Utility operations									0	0	0
Non-utility operations									2	2	3
Depreciation and amortization									1	1	1
Interest income									(52)	(48)	(51)
Interest expense									132	122	120
Equity in earnings of equity method investees									3	0	0
Income Tax Expense (Benefit)									(47)	(40)	(37)
Net Income									(48)	(57)	(44)
Investments in equity method investees	16				8				16	8	6
Capital expenditures and acquisitions									0	0	1
Goodwill	0				0				0	0	0
Total Assets	3,530				3,209				3,530	3,209	2,945
Reclassifications and Eliminations
Segment Reporting Information [Line Items]
Utility operations									(39)	(35)	(30)
Operating Revenues									868	874	868
Non-utility operations									(829)	(839)	(838)
Depreciation and amortization									0	0	0
Interest income									64	57	63
Interest expense									(64)	(57)	(63)
Equity in earnings of equity method investees									0	0	0
Income Tax Expense (Benefit)									0	0	0
Net Income									0	0	0
Investments in equity method investees	0				0				0	0	0
Capital expenditures and acquisitions									0	0	0
Goodwill	0				0				0	0	0
Total Assets	$ (1,128)				$ (906)				(1,128)	(906)	(939)
Reclassifications and Eliminations | DTE Electric | Continuing Operations
Segment Reporting Information [Line Items]
Operating Revenues									36	29	26
Reclassifications and Eliminations | DTE Gas | Continuing Operations
Segment Reporting Information [Line Items]
Operating Revenues									3	6	4
Reclassifications and Eliminations | Gas Storage and Pipelines | Continuing Operations
Segment Reporting Information [Line Items]
Operating Revenues									8	9	3
Reclassifications and Eliminations | Power and Industrial Projects | Continuing Operations
Segment Reporting Information [Line Items]
Operating Revenues									785	794	816
Reclassifications and Eliminations | Energy Trading | Continuing Operations
Segment Reporting Information [Line Items]
Operating Revenues									32	33	43
Reclassifications and Eliminations | Corporate and Other | Continuing Operations
Segment Reporting Information [Line Items]
Operating Revenues									$ 4	$ 3	$ (24)

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Related Party Transaction [Line Items]
Dividends declared	$ 510	$ 476	$ 454
Dividends paid	501	470	445
Parent
Related Party Transaction [Line Items]
Dividends declared	395	370	342
Dividends paid	395	370	342
Capital contribution from DTE Energy	300	190	400
DTE Electric
Related Party Transaction [Line Items]
Revenues	6	5	7
Dividends declared	395	370	342
Dividends paid	395	370	342
DTE Electric | Energy sales
Related Party Transaction [Line Items]
Revenue from Related Parties	2	2	2
DTE Electric | Shared capital assets
Related Party Transaction [Line Items]
Revenue from Related Parties	33	26	23
DTE Electric | Fuel and purchased power
Related Party Transaction [Line Items]
Costs	9	4	4
DTE Electric | Other services and interest
Related Party Transaction [Line Items]
Costs	2	(1)	(1)
DTE Electric | Corporate expenses (net)
Related Party Transaction [Line Items]
Costs	$ 334	$ 304	$ 334

Related Party Transactions (Nar

Related Party Transactions (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
DTE Electric | DTE Energy Foundation
Related Party Transaction [Line Items]
Charitable contributions	$ 0	$ 0	$ 18

Supplementary Quarterly Fina144

Supplementary Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Entity Information [Line Items]
Operating Revenues	$ 2,487	$ 2,598	$ 2,268	$ 2,984	$ 3,078	$ 2,595	$ 2,698	$ 3,930	$ 10,337	$ 12,301	$ 9,661
Operating Income	134	440	204	461	542	239	249	560	1,239	1,590	1,203
Net Income	$ 80	$ 265	$ 109	$ 273	$ 299	$ 156	$ 124	$ 326	$ 727	$ 905	$ 661
Basic Earnings per Share (in dollars per share)	$ 0.45	$ 1.47	$ 0.61	$ 1.53	$ 1.68	$ 0.88	$ 0.70	$ 1.84	$ 4.05	$ 5.11	$ 3.76
Diluted Earnings per Share (in dollars per share)	$ 0.45	$ 1.47	$ 0.61	$ 1.53	$ 1.68	$ 0.88	$ 0.70	$ 1.84	$ 4.05	$ 5.10	$ 3.76
DTE Electric
Entity Information [Line Items]
Operating Revenues	$ 1,165	$ 1,385	$ 1,147	$ 1,203	$ 1,234	$ 1,357	$ 1,281	$ 1,410	$ 4,900	$ 5,282	$ 5,197
Operating Income	192	400	214	268	250	272	259	271	1,074	1,052	1,000
Net Income	$ 92	$ 216	$ 99	$ 137	$ 129	$ 136	$ 130	$ 137	$ 544	$ 532	$ 487

Valuation and Qualifying Acc145

Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	$ 54	$ 55	$ 62
Charged to costs and expenses	93	95	94
Charged to other accounts	14	20	23
Deductions	(112)	(116)	(124)
Balance at End of Period	49	54	55
DTE Electric
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	29	28	35
Charged to costs and expenses	51	50	52
Charged to other accounts	6	10	11
Deductions	(58)	(59)	(70)
Balance at End of Period	$ 28	$ 29	$ 28