DTE Energy (DTE) 10-Q 25 Oct 17 2017 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	9 Months Ended
	Sep. 30, 2017shares
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-Q
Document Period End Date	Sep. 30, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	179,390,286
DTE Electric
Entity Registrant Name	DTE ELECTRIC CO
Entity Central Index Key	28,385
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Fiscal Period Focus	Q3
Amendment Flag	false
Entity Common Stock, Shares Outstanding	138,632,324

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Operating Revenues
Utility operations	$ 1,573	$ 1,748	$ 4,714	$ 4,847
Non-utility operations	1,672	1,180	4,622	2,909
Operating Revenues	3,245	2,928	9,336	7,756
Operating Expenses
Fuel, purchased power, and gas — utility	437	503	1,362	1,482
Fuel, purchased power, and gas — non-utility	1,469	1,034	3,897	2,527
Operation and maintenance	566	562	1,725	1,620
Depreciation and amortization	258	230	756	702
Taxes other than income	91	92	297	282
Asset (gains) losses and impairments, net	6	0	9	(1)
Operating Expenses	2,827	2,421	8,046	6,612
Operating Income	418	507	1,290	1,144
Other (Income) and Deductions
Interest expense	146	114	404	341
Interest income	(4)	(3)	(9)	(17)
Other income	(74)	(51)	(204)	(160)
Other expenses	13	12	26	27
Total Other (Income) and Deductions	81	72	217	191
Income Before Income Taxes	337	435	1,073	953
Income Tax Expense	74	110	241	243
Net Income	263	325	832	710
Less: Net Loss Attributable to Noncontrolling Interests	(7)	(13)	(15)	(27)
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 270	$ 338	$ 847	$ 737
Basic Earnings per Common Share
Net Income Attributable to DTE Energy Company (in dollars per share)	$ 1.51	$ 1.88	$ 4.72	$ 4.10
Diluted Earnings per Common Share
Net Income Attributable to DTE Energy Company (in dollars per share)	$ 1.51	$ 1.88	$ 4.72	$ 4.10
Weighted Average Common Shares Outstanding
Basic (in shares)	179	179	179	179
Diluted (in shares)	179	180	179	180
Dividends Declared per Common Share (in dollars per share)	$ 0.825	$ 0.77	$ 2.475	$ 2.23
DTE Electric
Operating Revenues
Utility operations	$ 1,434	$ 1,608	$ 3,827	$ 3,976
Operating Expenses
Fuel and purchased power — utility	428	495	1,097	1,191
Operation and maintenance	349	363	1,068	1,019
Depreciation and amortization	188	176	549	539
Taxes other than income	74	73	229	216
Operating Expenses	1,039	1,107	2,943	2,965
Operating Income	395	501	884	1,011
Other (Income) and Deductions
Interest expense	68	66	206	196
Interest income	0	0	0	(8)
Other income	(21)	(15)	(57)	(48)
Other expenses	11	9	23	22
Total Other (Income) and Deductions	58	60	172	162
Income Before Income Taxes	337	441	712	849
Income Tax Expense	118	156	249	302
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 219	$ 285	$ 463	$ 547

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net Income	$ 263	$ 325	$ 832	$ 710
Net Income	270	338	847	737
Other comprehensive income, net of tax:
Benefit obligations, net of taxes of $2, $2, $6, and $3, respectively	3	4	10	6
Net unrealized gains on investments during the period, net of taxes of $1, respectively	0	1	1	1
Foreign currency translation	2	(1)	2	0
Other comprehensive income	5	4	13	7
Comprehensive income	268	329	845	717
Less: Comprehensive loss attributable to noncontrolling interests	(7)	(13)	(15)	(27)
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company	275	342	860	744
DTE Electric
Net Income	219	285	463	547
Other comprehensive income, net of tax:
Other comprehensive income	0	0	0	0
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company	$ 219	$ 285	$ 463	$ 547

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Tax effect on benefit obligation	$ 2	$ 2	$ 6	$ 3
Tax effect on net unrealized gains on investments during the period	$ 1	$ 1	$ 1	$ 1

Consolidated Statements of Fina

Consolidated Statements of Financial Position (Unaudited) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 63	$ 92
Restricted cash	23	21
Accounts receivable (less allowance for doubtful accounts)
Customer	1,395	1,522
Other	166	71
Inventories
Fuel and gas	453	416
Materials and supplies	363	356
Derivative assets	76	47
Regulatory assets	6	42
Other	270	195
Total Current Assets	2,815	2,762
Investments
Nuclear decommissioning trust funds	1,439	1,320
Investments in equity method investees	971	752
Other	224	201
Total Investments	2,634	2,273
Property
Property, plant, and equipment	30,924	30,029
Accumulated depreciation and amortization	(10,617)	(10,299)
Property, plant, and equipment, net	20,307	19,730
Other Assets
Goodwill	2,293	2,286
Regulatory assets	3,828	3,871
Intangible assets	883	842
Notes receivable	74	73
Derivative assets	62	34
Other	175	170
Total Other Assets	7,315	7,276
Total Assets	33,071	32,041
Accounts payable
Accounts payable	994	1,079
Accrued interest	131	96
Dividends payable	148	148
Short-term borrowings	659	499
Current portion long-term debt, including capital leases	109	14
Derivative liabilities	42	69
Regulatory liabilities	86	34
Short-term borrowings
Other	429	498
Total Current Liabilities	2,598	2,437
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	11,038	10,506
Junior subordinated debentures	756	756
Capital lease obligations	1	7
Total Long-Term Debt (net of current portion)	11,795	11,269
Other Liabilities
Deferred income taxes	4,396	4,162
Regulatory liabilities	489	555
Asset retirement obligations	2,288	2,197
Unamortized investment tax credit	138	93
Derivative liabilities	48	98
Accrued pension liability	922	1,152
Accrued postretirement liability	6	36
Nuclear decommissioning	213	194
Other	325	349
Total Other Liabilities	8,825	8,836
Commitments and Contingencies (Notes 5 and 11)
Equity
Common stock	3,978	4,030
Retained earnings	5,515	5,114
Accumulated other comprehensive income (loss)	(120)	(133)
Total DTE Energy/DTE Electric Company Equity	9,373	9,011
Noncontrolling interests	480	488
Total Equity	9,853	9,499
Total Liabilities and Equity	33,071	32,041
DTE Electric
Current Assets
Cash and cash equivalents	12	13
Accounts receivable (less allowance for doubtful accounts)
Customer	770	728
Affiliates	16	12
Other	86	29
Inventories
Fuel and gas	182	225
Materials and supplies	282	271
Regulatory assets	5	36
Prepaid property tax	107	45
Other	14	18
Total Current Assets	1,474	1,377
Investments
Nuclear decommissioning trust funds	1,439	1,320
Other	35	36
Total Investments	1,474	1,356
Property
Property, plant, and equipment	22,606	22,094
Accumulated depreciation and amortization	(7,921)	(7,721)
Property, plant, and equipment, net	14,685	14,373
Other Assets
Regulatory assets	3,108	3,113
Intangible assets	33	31
Prepaid postretirement costs — affiliates	114	114
Other	124	125
Total Other Assets	3,379	3,383
Total Assets	21,012	20,489
Accounts payable
Affiliates	52	58
Other	371	452
Accrued interest	70	65
Current portion long-term debt, including capital leases	5	6
Regulatory liabilities	70	27
Short-term borrowings
Affiliates	66	117
Other	311	62
Other	146	146
Total Current Liabilities	1,091	933
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	6,016	5,878
Capital lease obligations	1	7
Total Long-Term Debt (net of current portion)	6,017	5,885
Other Liabilities
Deferred income taxes	3,985	3,793
Regulatory liabilities	189	229
Asset retirement obligations	2,094	2,012
Unamortized investment tax credit	136	90
Nuclear decommissioning	213	194
Accrued pension liability — affiliates	826	1,008
Accrued postretirement liability — affiliates	252	269
Other	75	81
Total Other Liabilities	7,770	7,676
Commitments and Contingencies (Notes 5 and 11)
Equity
Common stock	4,206	4,206
Retained earnings	1,926	1,787
Accumulated other comprehensive income (loss)	2	2
Total DTE Energy/DTE Electric Company Equity	6,134	5,995
Total Liabilities and Equity	$ 21,012	$ 20,489

Consolidated Statements of Fin6

Consolidated Statements of Financial Position (Unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Allowance for doubtful accounts	$ 39	$ 41
Shareholder’s Equity
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	179,390,286	179,432,581
Common stock, shares outstanding (in shares)	179,390,286	179,432,581
DTE Electric
Allowance for doubtful accounts	$ 23	$ 25
Shareholder’s Equity
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 (Unaudited) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating Activities
Net Income	$ 832	$ 710
Net Income	847	737
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	756	702
Nuclear fuel amortization	39	44
Allowance for equity funds used during construction	(17)	(15)
Deferred income taxes	261	244
Equity earnings of equity method investees	(77)	(49)
Dividends from equity method investees	55	52
Asset (gains) losses and impairments, net	5	0
Changes in assets and liabilities:
Accounts receivable, net	43	6
Inventories	(41)	10
Accounts payable	25	39
Accrued pension liability	(230)	(1)
Accrued postretirement liability	(30)	(80)
Derivative assets and liabilities	(133)	122
Regulatory assets and liabilities	260	93
Other current and noncurrent assets and liabilities	(198)	(110)
Net cash from operating activities	1,550	1,767
Investing Activities
Plant and equipment expenditures — utility	(1,439)	(1,267)
Plant and equipment expenditures — non-utility	(133)	(75)
Proceeds from sale of nuclear decommissioning trust fund assets	951	1,135
Investment in nuclear decommissioning trust funds	(936)	(1,140)
Distributions from equity method investees	10	8
Contributions to equity method investees	(194)	(199)
Other	(63)	35
Net cash used for investing activities	(1,804)	(1,503)
Financing Activities
Issuance of long-term debt, net of issuance costs	1,010	646
Redemption of long-term debt	(385)	(322)
Repurchase of long-term debt	0	(59)
Short-term borrowings, net	160	(89)
Repurchase of common stock	(51)	(33)
Dividends on common stock	(444)	(393)
Other	(65)	15
Net cash from (used for) financing activities	225	(235)
Net Increase (Decrease) in Cash and Cash Equivalents	(29)	29
Cash and Cash Equivalents at Beginning of Period	92	37
Cash and Cash Equivalents at End of Period	63	66
Supplemental disclosure of non-cash investing and financing activities
Plant and equipment expenditures in accounts payable	222	168
DTE Electric
Operating Activities
Net Income	463	547
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	549	539
Nuclear fuel amortization	39	44
Allowance for equity funds used during construction	(14)	(13)
Deferred income taxes	248	298
Equity earnings of equity method investees	(1)	(1)
Changes in assets and liabilities:
Accounts receivable, net	(104)	(135)
Inventories	32	18
Accounts payable	32	59
Accrued pension liability — affiliates	(182)	9
Accrued postretirement liability — affiliates	(17)	(52)
Regulatory assets and liabilities	223	100
Other current and noncurrent assets and liabilities	(174)	(119)
Net cash from operating activities	1,095	1,295
Investing Activities
Plant and equipment expenditures	(1,103)	(999)
Notes receivable, including affiliates	5
Notes receivable, including affiliates		(64)
Proceeds from sale of nuclear decommissioning trust fund assets	951	1,135
Investment in nuclear decommissioning trust funds	(936)	(1,140)
Other	(5)	40
Net cash used for investing activities	(1,088)	(1,028)
Financing Activities
Issuance of long-term debt, net of issuance costs	435	355
Redemption of long-term debt	(300)	(10)
Repurchase of long-term debt	0	(59)
Short-term borrowings, net — affiliate	(51)	37
Short-term borrowings, net — other	249	(272)
Dividends on common stock	(324)	(315)
Other	(17)	(2)
Net cash from (used for) financing activities	(8)	(266)
Net Increase (Decrease) in Cash and Cash Equivalents	(1)	1
Cash and Cash Equivalents at Beginning of Period	13	15
Cash and Cash Equivalents at End of Period	12	16
Supplemental disclosure of non-cash investing and financing activities
Plant and equipment expenditures in accounts payable	$ 112	$ 118

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity (Unaudited) - 9 months ended Sep. 30, 2017 - USD ($) $ in Millions	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	DTE Electric	DTE ElectricCommon Stock	DTE ElectricAdditional Paid-in Capital	DTE ElectricRetained Earnings	DTE ElectricAccumulated Other Comprehensive Income (Loss)
Beginning Balance (in shares) at Dec. 31, 2016	179,432,581	179,433,000				138,632,324	138,632,000
Beginning Balance at Dec. 31, 2016	$ 9,499	$ 4,030	$ 5,114	$ (133)	$ 488
Beginning Balance at Dec. 31, 2016	9,011					$ 5,995	$ 1,386	$ 2,820	$ 1,787	$ 2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	832		847		(15)
Net Income	847					463			463
Dividends declared on common stock	(444)		(444)			$ (324)			(324)
Repurchase of common stock (in shares)		(524,000)
Repurchase of common stock	(51)	$ (51)
Benefit obligations, net of tax	10			10
Net change in unrealized gains on investments, net of tax	1			1
Foreign currency translation	2			2
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		481,000
Stock-based compensation, net contributions from noncontrolling interests, and other	$ 4	$ (1)	(2)		7
Ending Balance (in shares) at Sep. 30, 2017	179,390,286	179,390,000				138,632,324	138,632,000
Ending Balance at Sep. 30, 2017	$ 9,853	$ 3,978	$ 5,515	$ (120)	$ 480
Ending Balance at Sep. 30, 2017	$ 9,373					$ 6,134	$ 1,386	$ 2,820	$ 1,926	$ 2

Organization and Basis of Prese

Organization and Basis of Presentation	9 Months Ended
	Sep. 30, 2017
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 utility engaged in the purchase, storage, transportation, distribution, and sale of natural gas to approximately 1.3 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 for DTE Energy, the CFTC. Basis of Presentation The Consolidated Financial Statements should be read in conjunction with the Combined Notes to Consolidated Financial Statements included in the combined DTE Energy and DTE Electric 2016 Annual Report on Form 10-K. 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 Consolidated Financial Statements are unaudited but, in the Registrants' opinions include all adjustments necessary to present a fair statement of the results for the interim periods. All adjustments are of a normal recurring nature, except as otherwise disclosed in these Consolidated Financial Statements and Combined Notes to Consolidated Financial Statements. Financial results for this interim period are not necessarily indicative of results that may be expected for any other interim period or for the fiscal year ending December 31, 2017 . 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. 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 owns a 55% interest in SGG, which owns and operates midstream natural gas assets. SGG has contracts through which certain construction risk is designed to pass-through to the customers, with DTE Energy retaining operational and customer default risk. SGG is a VIE with DTE Energy as the primary beneficiary. See Note 4 to the Consolidated Financial Statements, " Acquisition ," for more information. The Registrants hold variable interests in NEXUS, including a 50% ownership interest. NEXUS is a joint venture which is in the process of constructing a 255-mile pipeline to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers. NEXUS is a VIE as it has insufficient equity at risk to finance its activities. The Registrants are not the primary beneficiaries, as the power to direct significant activities is shared between the owners of the equity interests. DTE Energy accounts for NEXUS under the equity method. The Registrants hold ownership interests in certain limited partnerships. The limited partnerships include investment funds which support regional development and economic growth, as well as, an operational business providing energy-related products. These entities are generally VIEs as a result of certain characteristics of the limited partnership voting rights. The ownership interests are accounted for under the equity method as the Registrants are not the primary beneficiaries. 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 September 30, 2017 , 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 September 30, 2017 , 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. The maximum risk exposure for consolidated VIEs is reflected on the Registrants' Consolidated Statements of Financial Position and in Note 11 to the Consolidated Financial Statements, " Commitments and Contingencies ," related to the REF guarantees and indemnities. For non-consolidated VIEs, the maximum risk exposure of the Registrants is generally limited to their investment, notes receivable, future funding commitments, and amounts which DTE Energy has guaranteed. See Note 11 to the Consolidated Financial Statements, " Commitments and Contingencies ," for further discussion of the NEXUS guarantee arrangements. The following table summarizes the major Consolidated Statements of Financial Position items for consolidated VIEs as of September 30, 2017 and December 31, 2016 . 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. 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. September 30, 2017 December 31, 2016 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 31 $ 13 $ 44 $ 36 $ 27 $ 63 Restricted cash — 8 8 — 7 7 Accounts receivable 11 30 41 8 34 42 Inventories 3 84 87 3 112 115 Property, plant, and equipment, net 397 70 467 398 76 474 Goodwill 25 — 25 17 — 17 Intangible assets 576 — 576 586 — 586 Other current and long-term assets 1 — 1 1 1 2 $ 1,044 $ 205 $ 1,249 $ 1,049 $ 257 $ 1,306 LIABILITIES Accounts payable and accrued current liabilities $ 26 $ 29 $ 55 $ 19 $ 32 $ 51 Current portion long-term debt, including capital leases — 3 3 — 5 5 Mortgage bonds, notes, and other — 2 2 — 5 5 Other current and long-term liabilities 1 15 16 2 15 17 $ 27 $ 49 $ 76 $ 21 $ 57 $ 78 _____________________________________ (a) Amounts shown are 100% of SGG's assets and liabilities, of which DTE Energy owns 55% . Amounts for DTE Energy's non-consolidated VIEs are as follows: September 30, 2017 December 31, 2016 (In millions) Investments in equity method investees $ 716 $ 509 Notes receivable $ 17 $ 15 Future funding commitments $ 688 $ 692

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Other Income The following is a summary of DTE Energy's Other income: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Equity earnings of equity method investees $ 26 $ 14 $ 77 $ 49 Income from REF entities 20 20 60 59 Gains from trading securities 6 5 19 15 Allowance for equity funds used during construction 5 5 17 15 Contract services 9 5 17 16 Other 8 2 14 6 $ 74 $ 51 $ 204 $ 160 The following is a summary of DTE Electric's Other income: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Gains from trading securities allocated from DTE Energy $ 6 $ 5 $ 19 $ 15 Contract services 9 5 18 16 Allowance for equity funds used during construction 4 4 14 13 Equity earnings of equity method investees — — 1 1 Other 2 1 5 3 $ 21 $ 15 $ 57 $ 48 Changes in Accumulated Other Comprehensive Income (Loss) For the three and nine months ended September 30, 2017 and 2016 , reclassifications out of Accumulated other comprehensive income (loss) for the Registrants were not material. Changes in Accumulated other comprehensive income (loss) are presented in DTE Energy's Consolidated Statements of Changes in Equity and DTE Electric's Consolidated Statements of Changes in Shareholder's Equity. Income Taxes The effective tax rate of the Registrants are as follows: Effective Tax Rate Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 DTE Energy 22 % 25 % 22 % 25 % DTE Electric 35 % 35 % 35 % 36 % The 3% decrease in DTE Energy's effective tax rate for the three months ended September 30, 2017 was primarily due to higher forecasted production tax credits in 2017 . The 3% decrease in DTE Energy's effective tax rate for the nine months ended September 30, 2017 was primarily due to higher forecasted production tax credits in 2017 and $13 million of excess tax benefits on stock-based compensation recognized in accordance with ASU 2016-09, Improvements to Employee Share-Based Payment Accounting , which was adopted effective July 1, 2016. DTE Energy's total amount of unrecognized tax benefits as of September 30, 2017 and December 31, 2016 was $10 million . The amount, if recognized, that would favorably impact DTE Energy's effective tax rate as of September 30, 2017 and December 31, 2016 was $6 million and $7 million , respectively. DTE Electric's total amount of unrecognized tax benefits as of September 30, 2017 and December 31, 2016 was $13 million , of which $8 million , if recognized, would favorably impact its effective tax rate. The Registrants do not anticipate any material changes to the unrecognized tax benefits in the next twelve months. DTE Electric had income tax receivables with DTE Energy of $9 million at September 30, 2017 and December 31, 2016 . Unrecognized Compensation Costs As of September 30, 2017 , DTE Energy had $71 million of total unrecognized compensation cost related to non-vested stock incentive plan arrangements. That cost is expected to be recognized over a weighted-average period of 1.35 years . Allocated Stock-Based Compensation DTE Electric received an allocation of costs from DTE Energy associated with stock-based compensation of $10 million and $7 million for the three months ended September 30, 2017 and 2016, respectively , while such allocation was $28 million and $26 million for the nine months ended September 30, 2017 and 2016, respectively .

New Accounting Pronouncements

New Accounting Pronouncements	9 Months Ended
	Sep. 30, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS Recently Adopted Pronouncements 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 was applied prospectively. The Registrants adopted this ASU at January 1, 2017. The adoption of the ASU did not have a significant impact on the Registrants' Consolidated Financial Statements. Recently Issued Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), as amended . 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. The standard is to be applied retrospectively. The Registrants will adopt the standard effective January 1, 2018 using the modified retrospective approach. The Registrants are finalizing the assessment of the impact of the ASU, as amended, on their Consolidated Financial Statements. The ASU is not expected to significantly affect the Registrants' results of operations. The Registrants will continue to evaluate the impact of the ASU on existing revenue recognition policies and procedures. Industry-related issues being vetted through the final stages of the American Institute of Certified Public Accountants' Power and Utilities Industry Task Force process will continue to be monitored. The ASU will result in additional disclosures for revenue compared to the current guidance. Accordingly, the Registrants are evaluating information that would be useful for users of the Consolidated Financial Statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), a replacement of Leases (Topic 840) . This guidance requires a lessee to account for leases as finance or operating leases. Both types of leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability on its balance sheet, with differing methodology for income statement recognition. For lessors, the standard modifies the classification criteria and the accounting for sales-type and direct financing leases. Entities will classify leases to determine how to recognize lease-related revenue and expense. This standard is effective for public entities for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. The Registrants do not plan to early adopt the standard. A modified retrospective approach is required for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements, with certain practical expedients permitted. The Registrants expect an increase in assets and liabilities, however, they are currently assessing the impact of this ASU on their Consolidated Financial Statements. This assessment includes monitoring unresolved utility industry implementation guidance. The Registrants have conducted outreach activities across their lines of business and have begun implementation of a third-party software tool that will assist with the initial adoption and ongoing compliance. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . The amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Entities will apply the new guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The ASU is effective for the Registrants beginning after December 15, 2019, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. In March 2017, the FASB issued ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments in this update require that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The standard will be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. The ASU is effective for the Registrants for fiscal years, and interim periods within those years, beginning after December 15, 2017, and early adoption is permitted. The Registrants will adopt the standard effective January 1, 2018. The components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits are disclosed in Note 12 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets ." The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements.

Acquisition

Acquisition	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Acquisition	ACQUISITION Gas Storage and Pipelines Acquisition Effective October 1, 2016 , DTE Energy closed on the purchase of midstream natural gas assets in support of the strategy to continue to grow and earn competitive returns for shareholders. DTE Energy purchased 100% of AGS, located in Pennsylvania and West Virginia, and 40% of SGG, located in West Virginia, from M3 Midstream. In addition, DTE Energy purchased 15% of SGG from Vega Energy Partners, resulting in 55% total ownership of SGG by DTE Energy. Consideration transferred for the entities acquired was approximately $1.2 billion paid in cash and the assumption of SGG debt of $204 million . The $204 million of debt was comprised of DTE Energy's 55% interest in SGG of $112 million and 45% related to noncontrolling interest partners of $92 million . The acquisition was financed through the issuance of equity units and senior notes. These entities are part of DTE Energy's Gas Storage and Pipelines segment which owns and manages a network of natural gas gathering, transmission, and storage facilities servicing the Midwest, Ontario, and Northeast markets. SGG has been deemed to be a VIE, and DTE Energy is the primary beneficiary. Thus, SGG's assets and liabilities are included in DTE Energy's Consolidated Statements of Financial Position. See Note 1 to the Consolidated Financial Statements, " Organization and Basis of Presentation ," for more information. DTE Energy applied purchase accounting to the acquired entities. The excess purchase price over the fair value of net assets acquired was classified as goodwill. September 30, 2017 marked the expiration of the one-year period from the acquisition to revise the fair value of assets acquired and liabilities assumed. As of September 30, 2017 , the final working capital adjustments and certain indemnification claims were settled. The settlements and final revisions to the purchase price allocation resulted in purchase accounting adjustments of approximately $7 million of additional goodwill. The factors contributing to the recognition of goodwill were based on various strategic benefits that are expected to be realized from the AGS and SGG acquisition. The acquisition provides DTE Energy with a platform for midstream growth and access to further investment opportunities in the Appalachian basin, an additional connection to the NEXUS Pipeline which should drive incremental volumes on the NEXUS Pipeline, and a new set of producer relationships that may lead to more partnering opportunities. The goodwill is expected to be deductible for income tax purposes. The final allocation of the purchase price was based on estimated fair values of the AGS and SGG assets acquired and liabilities assumed at the date of acquisition, October 1, 2016 . The components of the final purchase price allocation, inclusive of purchase accounting adjustments, are as follows: (In millions) Assets Cash $ 83 Accounts receivable 24 Inventory 6 Property, plant, and equipment, net 719 Goodwill 275 Customer relationship intangibles 770 Other current assets 1 $ 1,878 Liabilities Accounts payable $ 19 Other current liabilities 11 Long-term debt 204 Other long-term liabilities 20 $ 254 Less: Noncontrolling interest 392 Total cash consideration $ 1,232 The intangible assets recorded as a result of the acquisition pertain to existing customer relationships, which were valued at approximately $770 million as of the acquisition date. The fair value of the intangible assets acquired was estimated by applying the income approach. The income approach was based upon discounted projected future cash flows attributable to the existing contracts and agreements. The fair value measurement was based on significant unobservable inputs, including management estimates and assumptions, and thus represents a Level 3 measurement, pursuant to the applicable accounting guidance. Key estimates and inputs included revenue and expense projections and discount rates based on the risks associated with the entities. The intangible assets are amortized on a straight-line basis over a period of 40 years , which is based on the number of years the assets are expected to economically contribute to the business. The expected economic benefit incorporates existing customer contracts with a weighted-average amortization life of 10 years and expected renewal rates, based on the estimated volume and production lives of gas resources in the region. The fair value of the noncontrolling interest in the table above was derived based on the purchase price DTE Energy paid for the 55% interest in SGG. DTE Energy evaluated pre-acquisition contingencies relating to the purchase that existed as of the acquisition date. Based on the evaluation, DTE Energy determined that $30 million of certain pre-acquisition contingencies, related to repairing existing rights-of-way, were probable in nature and estimable as of the acquisition date. Accordingly, DTE Energy recorded its best estimates for these contingencies as part of purchase accounting, which are included in the Other current and long-term liabilities in the purchase price allocation table above. DTE Energy incurred $15 million of direct transaction costs for the year ended December 31, 2016. These costs were primarily related to advisory fees and included in Operation and maintenance in DTE Energy's 2016 Consolidated Statements of Operations. DTE Energy's 2016 Consolidated Statements of Operations included Operating Revenues — Non-utility operations of $39 million and Net Income of $4 million associated with the acquired entities for the three-month period following the acquisition date, excluding the $15 million transaction costs described above. The pro forma financial information was not presented for DTE Energy because the effects of the acquisition were not material to the Consolidated Statements of Operations.

Regulatory Matters

Regulatory Matters	9 Months Ended
	Sep. 30, 2017
Public Utilities, General Disclosures [Abstract]
Regulatory Matters	REGULATORY MATTERS 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. On August 1, 2016, DTE Electric self-implemented a base rate increase of $245 million . On January 31, 2017, the MPSC issued an order approving an annual revenue increase of $184 million for service rendered on or after February 7, 2017. The MPSC authorized a return on equity of 10.1% . On April 28, 2017, DTE Electric filed to refund its customers their pro-rata share of the revenue collected through the self-implementation surcharge in effect from August 1, 2016 through February 7, 2017. On September 15, 2017, the MPSC approved a settlement authorizing DTE Electric to refund its customers $38.5 million of the self-implementation surcharge during the months of October through December 2017. DTE has recorded a refund liability for the settlement as of September 30, 2017. 2017 Electric Rate Case Filing DTE Electric filed a rate case with the MPSC on April 19, 2017 requesting an increase in base rates of $231 million based on a projected twelve-month period ending October 31, 2018. The requested increase in base rates is primarily due 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 10.1% to 10.5% . To mitigate the impact to its customers resulting from ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715), DTE Electric suggested regulatory accounting treatment for the pension and postretirement cost components previously included as capital overhead. If the MPSC adopts DTE Electric's suggestion, the rate request will be reduced. For further discussion of ASU No. 2017-07, see Note 3 to the Consolidated Financial Statements, " New Accounting Pronouncements ." On September 8, 2017, DTE Electric filed an application with the MPSC for a $125 million self-implemented base rate increase effective November 1, 2017. A final MPSC order in this case is expected by April 2018. 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, NOx and SO 2 emission allowances costs, urea costs, transmission costs, MISO, and other related costs. The MPSC reviews these costs, policies, and practices for prudence in annual plan and reconciliation filings. 2015 PSCR Year — In March 2016, DTE Electric filed its 2015 PSCR reconciliation that included the recovery of approximately $13 million of costs related to the pass through of a billing adjustment associated with a previous MPSC ordered customer refund. On July 12, 2017, the MPSC issued an order that disallowed recovery of this 2015 PSCR billing adjustment pass through of approximately $16 million , inclusive of interest. DTE Electric recorded the impact of the disallowance in the second quarter of 2017 and filed a claim of appeal with the Michigan Court of Appeals in August 2017. Certificate of Necessity On July 31, 2017, DTE Electric filed a request for authority to build a 1,100 megawatt natural gas fueled combined cycle generation facility at DTE Electric's Belle River Power Plant. DTE Electric requested the MPSC to issue three CONs for the following: (1) power supplied by the proposed project is needed, (2) the size, fuel type, and other design characteristics of the proposed project represent the most reasonable and prudent means of meeting the power need, and (3) the estimated capital costs of $989 million for the proposed project will be recoverable in rates from DTE Electric's customers. DTE Electric also reserved the right to revise, amend, or otherwise change the relief it is requesting in any way appropriate, including updating of the cost estimate within the 150 days of the filing date. DTE Electric expects an order in this proceeding from the MPSC by April 28, 2018.

Earnings Per Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Basic earnings per share is calculated by dividing the net income, adjusted for income allocated to participating securities, by the weighted average number of common shares outstanding during the period. Diluted earnings per share reflect the dilution that would occur if any potentially dilutive instruments were exercised or converted into common shares. DTE Energy’s participating securities are restricted shares under the stock incentive program that contain rights to receive non-forfeitable dividends. Equity units, performance shares, and stock options do not receive cash dividends; as such, these awards are not considered participating securities. The following is a reconciliation of DTE Energy's basic and diluted income per share calculation: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 270 $ 338 $ 847 $ 737 Less: Allocation of earnings to net restricted stock awards 1 — 2 1 Net income available to common shareholders — basic $ 269 $ 338 $ 845 $ 736 Average number of common shares outstanding 179 179 179 179 Basic Earnings per Common Share $ 1.51 $ 1.88 $ 4.72 $ 4.10 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 270 $ 338 $ 847 $ 737 Less: Allocation of earnings to net restricted stock awards 1 — 2 1 Net income available to common shareholders — diluted $ 269 $ 338 $ 845 $ 736 Average number of common shares outstanding 179 179 179 179 Incremental shares attributable to: Average dilutive performance share awards and stock options (a) — 1 — 1 Average number of common shares outstanding — diluted 179 180 179 180 Diluted Earnings per Common Share $ 1.51 $ 1.88 $ 4.72 $ 4.10 _______________________________________ (a) The 2016 equity units are potentially dilutive securities but were excluded from the calculation of diluted EPS for the three and nine months ended September 30, 2017 , as the dilutive stock price threshold was not met.

Fair Value

Fair Value	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 . 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: September 30, 2017 December 31, 2016 Level Level Level Netting (a) Net Balance Level Level Level Netting (a) Net Balance (In millions) Assets: Cash equivalents (b) $ 16 $ 3 $ — $ — $ 19 $ 14 $ 3 $ — $ — $ 17 Nuclear decommissioning trusts (c) Equity securities 949 — — — 949 887 — — — 887 Fixed income securities 10 474 — — 484 11 414 — — 425 Cash equivalents 6 — — — 6 8 — — — 8 Other investments (d) Equity securities 120 — — — 120 104 — — — 104 Fixed income securities 63 — — — 63 58 — — — 58 Cash equivalents 4 — — — 4 3 — — — 3 Derivative assets Commodity Contracts Natural Gas 64 104 62 (151 ) 79 216 79 53 (306 ) 42 Electricity — 155 47 (148 ) 54 — 154 39 (157 ) 36 Other — — 4 — 4 — — 2 — 2 Foreign currency exchange contracts — 3 — (2 ) 1 — 6 — (5 ) 1 Total derivative assets 64 262 113 (301 ) 138 216 239 94 (468 ) 81 Total $ 1,232 $ 739 $ 113 $ (301 ) $ 1,783 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Derivative liabilities Commodity Contracts Natural Gas $ (64 ) $ (76 ) $ (64 ) $ 151 $ (53 ) $ (226 ) $ (86 ) $ (149 ) $ 321 $ (140 ) Electricity — (159 ) (40 ) 164 (35 ) — (159 ) (30 ) 163 (26 ) Other — — (2 ) 2 — — — (3 ) 2 (1 ) Foreign currency exchange contracts — (4 ) — 2 (2 ) — (3 ) — 3 — Total derivative liabilities (64 ) (239 ) (106 ) 319 (90 ) (226 ) (248 ) (182 ) 489 (167 ) Total $ (64 ) $ (239 ) $ (106 ) $ 319 $ (90 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,168 $ 500 $ 7 $ 18 $ 1,693 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 Assets: Current $ 65 $ 194 $ 61 $ (225 ) $ 95 $ 205 $ 199 $ 60 $ (400 ) $ 64 Noncurrent 1,167 545 52 (76 ) 1,688 1,096 457 34 (68 ) 1,519 Total Assets $ 1,232 $ 739 $ 113 $ (301 ) $ 1,783 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Current $ (60 ) $ (183 ) $ (54 ) $ 255 $ (42 ) $ (203 ) $ (211 ) $ (79 ) $ 424 $ (69 ) Noncurrent (4 ) (56 ) (52 ) 64 (48 ) (23 ) (37 ) (103 ) 65 (98 ) Total Liabilities $ (64 ) $ (239 ) $ (106 ) $ 319 $ (90 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,168 $ 500 $ 7 $ 18 $ 1,693 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 _______________________________________ (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 September 30, 2017 , available-for-sale securities of $19 million , included $8 million and $11 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2016 , available-for-sale securities of $17 million , included $7 million and $10 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. (c) At September 30, 2017 , the Nuclear Decommissioning Master Trust had outstanding commitments to invest in private equity investments of approximately $25 million . These commitments will be funded by existing nuclear decommissioning trust funds. (d) Excludes cash surrender value of life insurance investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis as of: September 30, 2017 December 31, 2016 Level 1 Level 2 Level 3 Net Balance Level 1 Level 2 Level 3 Net Balance (In millions) Assets: Cash equivalents (a) $ 8 $ 3 $ — $ 11 $ 8 $ 3 $ — $ 11 Nuclear decommissioning trusts (b) Equity securities 949 — — 949 887 — — 887 Fixed income securities 10 474 — 484 11 414 — 425 Cash equivalents 6 — — 6 8 — — 8 Other investments Equity securities 10 — — 10 9 — — 9 Derivative assets — FTRs — — 4 4 — — 2 2 Total $ 983 $ 477 $ 4 $ 1,464 $ 923 $ 417 $ 2 $ 1,342 Assets: Current $ 8 $ 3 $ 4 $ 15 $ 8 $ 3 $ 2 $ 13 Noncurrent 975 474 — 1,449 915 414 — 1,329 Total Assets $ 983 $ 477 $ 4 $ 1,464 $ 923 $ 417 $ 2 $ 1,342 _______________________________________ (a) At September 30, 2017 and December 31, 2016 , available-for-sale securities of $11 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. (b) At September 30, 2017 , the Nuclear Decommissioning Master Trust had outstanding commitments to invest in private equity investments of approximately $25 million . These commitments will be funded by existing nuclear decommissioning trust funds. 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 and commingled funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. Non-exchange-traded fixed income securities are valued based upon quotations available from brokers or pricing services. The institutional mutual funds hold exchange-traded equity or debt securities (exchange and non-exchange traded) and are valued based on publicly available NAVs. 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 tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Energy: Three Months Ended September 30, 2017 Three Months Ended September 30, 2016 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of June 30 $ (17 ) $ 6 $ 5 $ (6 ) $ (62 ) $ (6 ) $ (1 ) $ (69 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 — — — — (1 ) — — (1 ) Total gains (losses) Included in earnings (8 ) 33 1 26 (65 ) 24 — (41 ) Recorded in Regulatory liabilities — — 2 2 — — 2 2 Purchases, issuances, and settlements Settlements 23 (32 ) (6 ) (15 ) 28 (24 ) (2 ) 2 Net Assets (Liabilities) as of September 30 $ (2 ) $ 7 $ 2 $ 7 $ (100 ) $ (6 ) $ (1 ) $ (107 ) 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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ (8 ) $ 18 $ 1 $ 11 $ (50 ) $ 6 $ — $ (44 ) Nine Months Ended September 30, 2017 Nine Months Ended September 30, 2016 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of December 31 $ (96 ) $ 9 $ (1 ) $ (88 ) $ (5 ) $ 6 $ (5 ) $ (4 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 — — — — — — — — Total gains (losses) Included in earnings 38 45 1 84 (123 ) (22 ) 1 (144 ) Recorded in Regulatory liabilities — — 15 15 — — 6 6 Purchases, issuances, and settlements Issuances — — — — — 1 — 1 Settlements 56 (47 ) (13 ) (4 ) 28 9 (3 ) 34 Net Assets (Liabilities) as of September 30 $ (2 ) $ 7 $ 2 $ 7 $ (100 ) $ (6 ) $ (1 ) $ (107 ) 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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ 8 $ 35 $ — $ 43 $ (165 ) $ (1 ) $ 2 $ (164 ) 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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Net Assets as of beginning of period $ 8 $ 4 $ 2 $ 3 Change in fair value recorded in Regulatory liabilities 2 2 15 6 Purchases, issuances, and settlements Settlements (6 ) (3 ) (13 ) (6 ) Net Assets as of September 30 $ 4 $ 3 $ 4 $ 3 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets held at September 30, 2017 and 2016 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 1 $ 1 $ 4 $ 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 three and nine months ended September 30, 2017 and 2016 , 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: September 30, 2017 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 62 $ (64 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.92 ) — $ 6.36 /MMBtu $ (0.03 )/MMBtu Electricity $ 47 $ (40 ) Discounted Cash Flow Forward basis price (per MWh) $ (10 ) — $ 7 /MWh $ 1 /MWh December 31, 2016 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 53 $ (149 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.00 ) — $ 7.90 /MMBtu $ (0.05 )/MMBtu Electricity $ 39 $ (30 ) Discounted Cash Flow Forward basis price (per MWh) $ (6 ) — $ 12 /MWh $ 1 /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, and notes payable 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 and DTE Energy's Controller's Department which reports to DTE Energy's Vice President and Controller. The following table presents the carrying amount and fair value of financial instruments for DTE Energy: September 30, 2017 December 31, 2016 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 $ 36 $ — $ — $ 36 $ 36 $ — $ — $ 36 Dividends payable $ 148 $ 148 $ — $ — $ 148 $ 148 $ — $ — Short-term borrowings $ 659 $ — $ 659 $ — $ 499 $ — $ 499 $ — Notes payable — Other (a) $ 16 $ — $ — $ 16 $ 17 $ — $ — $ 17 Long-term debt (b) $ 11,897 $ 1,554 $ 10,522 $ 744 $ 11,270 $ 1,465 $ 9,384 $ 1,056 _______________________________________ (a) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Energy's Consolidated Statements of Financial Position. (b) Includes debt due within one year , unamortized debt discounts, premiums, and issuance costs. Excludes Capital lease obligations. The following table presents the carrying amount and fair value of financial instruments for DTE Electric: September 30, 2017 December 31, 2016 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 Short-term borrowings — affiliates $ 66 $ — $ — $ 66 $ 117 $ — $ — $ 117 Short-term borrowings — other $ 311 $ — $ 311 $ — $ 62 $ — $ 62 $ — Notes payable — Other (a) $ 5 $ — $ — $ 5 $ 6 $ — $ — $ 6 Long-term debt (b) $ 6,016 $ — $ 6,395 $ 163 $ 5,878 $ — $ 6,026 $ 264 _______________________________________ (a) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Electric's Consolidated Statements of Financial Position. (b) Includes debt due within one year , unamortized debt discounts, and issuance costs. Excludes Capital lease obligations. For further fair value information on financial and derivative instruments, see Note 8 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 Asset retirement obligation 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. The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: September 30, 2017 December 31, 2016 (In millions) Fermi 2 $ 1,423 $ 1,291 Fermi 1 3 3 Low-level radioactive waste 13 26 Total $ 1,439 $ 1,320 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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Realized gains $ 14 $ 13 $ 63 $ 59 Realized losses $ (7 ) $ (8 ) $ (23 ) $ (48 ) Proceeds from sale of securities $ 246 $ 394 $ 951 $ 1,135 Realized gains and losses from the sale of securities for Fermi 2 are recorded to the Regulatory asset and Nuclear decommissioning liability. Realized gains and losses from the sale of securities for low-level radioactive waste funds are recorded to the Nuclear decommissioning liability. The following table sets forth DTE Electric's fair value and unrealized gains and losses for the nuclear decommissioning trust funds: September 30, 2017 December 31, 2016 Fair Unrealized Unrealized Fair Unrealized Unrealized (In millions) Equity securities $ 949 $ 287 $ (34 ) $ 887 $ 222 $ (46 ) Fixed income securities 484 14 (2 ) 425 11 (5 ) Cash equivalents 6 — — 8 — — $ 1,439 $ 301 $ (36 ) $ 1,320 $ 233 $ (51 ) The following table summarizes the fair value of the fixed income securities held in nuclear decommissioning trust funds by contractual maturity: September 30, 2017 (In millions) Due within one year $ 15 Due after one through five years 100 Due after five through ten years 111 Due after ten years 258 $ 484 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 and Nuclear decommissioning liability. Unrealized losses on the low-level radioactive waste funds are recognized as a Nuclear decommissioning liability. Other Securities At September 30, 2017 and December 31, 2016 , 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 three and nine months ended September 30, 2017 and 2016 . For the three months ended September 30, 2017 and 2016 , gains related to trading securities held at September 30, 2017 and 2016 were $6 million and $5 million , respectively, for the Registrants. For the nine months ended September 30, 2017 and 2016 , gains related to trading securities held at September 30, 2017 and 2016 were $19 million and $15 million , respectively, for the Registrants. The trading gains or losses related to the Rabbi Trust assets, included in Other investments at DTE Energy, are allocated from DTE Energy to DTE Electric.

Financial and Other Derivative

Financial and Other Derivative Instruments	9 Months Ended
	Sep. 30, 2017
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 2020. 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 gathering, 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. Energy Trading 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 September 30, 2017 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 for DTE Energy: September 30, 2017 December 31, 2016 Derivative Derivative Liabilities Derivative Derivative Liabilities (In millions) Derivatives not designated as hedging instruments Commodity Contracts Natural Gas $ 230 $ (204 ) $ 348 $ (461 ) Electricity 202 (199 ) 193 (189 ) Other 4 (2 ) 2 (3 ) Foreign currency exchange contracts 3 (4 ) 6 (3 ) Total derivatives not designated as hedging instruments $ 439 $ (409 ) $ 549 $ (656 ) Current $ 301 $ (297 ) $ 447 $ (493 ) Noncurrent 138 (112 ) 102 (163 ) Total derivatives $ 439 $ (409 ) $ 549 $ (656 ) The following table presents the fair value of derivative instruments for DTE Electric: September 30, 2017 December 31, 2016 (In millions) FTRs — Other current assets $ 4 $ 2 Total derivatives not designated as hedging instrument $ 4 $ 2 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 $2 million outstanding at September 30, 2017 and December 31, 2016 , 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 $3 million and $2 million at September 30, 2017 and December 31, 2016 , 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. For DTE Energy, the total cash collateral posted, net of cash collateral received, was $42 million and $34 million as of September 30, 2017 and December 31, 2016 , respectively. DTE Energy had $12 million of cash collateral related to unrealized positions to net against Derivative assets while Derivative liabilities are shown net of cash collateral of $30 million as of September 30, 2017 . DTE Energy had $7 million of cash collateral related to unrealized positions to net against Derivative assets while Derivative liabilities are shown net of cash collateral of $28 million as of December 31, 2016 . DTE Energy recorded cash collateral paid of $25 million and cash collateral received of $1 million not related to unrealized derivative positions as of September 30, 2017 . DTE Energy recorded cash collateral paid of $18 million and cash collateral received of $5 million not related to unrealized derivative positions as of December 31, 2016 . 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: September 30, 2017 December 31, 2016 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 $ 230 $ (151 ) $ 79 $ 348 $ (306 ) $ 42 Electricity 202 (148 ) 54 193 (157 ) 36 Other 4 — 4 2 — 2 Foreign currency exchange contracts 3 (2 ) 1 6 (5 ) 1 Total derivative assets $ 439 $ (301 ) $ 138 $ 549 $ (468 ) $ 81 Derivative liabilities Commodity Contracts Natural Gas $ (204 ) $ 151 $ (53 ) $ (461 ) $ 321 $ (140 ) Electricity (199 ) 164 (35 ) (189 ) 163 (26 ) Other (2 ) 2 — (3 ) 2 (1 ) Foreign currency exchange contracts (4 ) 2 (2 ) (3 ) 3 — Total derivative liabilities $ (409 ) $ 319 $ (90 ) $ (656 ) $ 489 $ (167 ) 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: September 30, 2017 December 31, 2016 Derivative Assets Derivative Liabilities Derivative Assets Derivative Liabilities Current Noncurrent Current Noncurrent Current Noncurrent Current Noncurrent (In millions) Total fair value of derivatives $ 301 $ 138 $ (297 ) $ (112 ) $ 447 $ 102 $ (493 ) $ (163 ) Counterparty netting (225 ) (64 ) 225 64 (396 ) (65 ) 396 65 Collateral adjustment — (12 ) 30 — (4 ) (3 ) 28 — Total derivatives as reported $ 76 $ 62 $ (42 ) $ (48 ) $ 47 $ 34 $ (69 ) $ (98 ) The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations is as follows: Derivatives not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for the Three Months Ended September 30, Gain (Loss) Recognized in Income on Derivatives for the Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Commodity Contracts Natural Gas Operating Revenues — Non-utility operations $ (14 ) $ 16 $ 63 $ (70 ) Natural Gas Fuel, purchased power, and gas — non-utility 10 (59 ) 56 (27 ) Electricity Operating Revenues — Non-utility operations 33 23 39 18 Other Operating Revenues — Non-utility operations 2 1 1 (1 ) Foreign currency exchange contracts Operating Revenues — Non-utility operations (2 ) — (3 ) (4 ) Total $ 29 $ (19 ) $ 156 $ (84 ) 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 September 30, 2017 : Commodity Number of Units Natural Gas (MMBtu) 1,751,191,598 Electricity (MWh) 28,924,416 Foreign Currency Exchange (Canadian dollars) 89,049,511 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 September 30, 2017 , 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 $470 million . As of September 30, 2017 , DTE Energy had approximately $339 million of derivatives in net liability positions, for which hard triggers exist. There is no collateral that has been posted against such liabilities, including cash and letters of credit. Associated derivative net asset positions for which contractual offset exists were approximately $276 million . The net remaining amount of approximately $63 million is derived from the $470 million noted above.

Long-Term Debt

Long-Term Debt	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Long-Term Debt	LONG-TERM DEBT Debt Issuances In 2017 , the following debt was issued: Company Month Type Interest Rate Maturity Amount (In millions) DTE Energy March Senior Notes (a) 3.80% 2027 $ 500 DTE Electric August General and Refunding Mortgage Bonds (b) 3.75% 2047 440 DTE Gas September First Mortgage Bonds (a) 3.08% 2029 40 DTE Gas September First Mortgage Bonds (a) 3.75% 2047 40 $ 1,020 _______________________________________ (a) Proceeds were used for repayment of short-term borrowings and general corporate purposes. (b) Proceeds were used to repay $300 million of DTE Electric's 2008 series G 5.60% Senior Notes due on June 15, 2018, for the repayment of short-term borrowings and general corporate purposes. Debt Redemptions In 2017 , the following debt was redeemed: Company Month Type Interest Rate Maturity Amount (In millions) DTE Electric August Senior Notes 5.60% 2018 $ 300 DTE Energy September Secured Note (a) 7.29% 2029 77 DTE Energy Various Other Long-Term Debt Various 2017 8 $ 385 _______________________________________ (a) DTE Energy's Gas Storage and Pipelines segment recognized a $16 million net loss on extinguishment of debt associated with early repayment, consisting of $20 million of early redemption premiums and $4 million of unamortized debt premiums. The loss is reflected in Other (Income) and Deductions — Interest Expense on the Consolidated Statements of Operations.

Short-Term Credit Arrangements

Short-Term Credit Arrangements and Borrowings	9 Months Ended
	Sep. 30, 2017
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 revolvers 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 September 30, 2017 , the total funded debt to total capitalization ratios for DTE Energy, DTE Electric, and DTE Gas were 0.54 to 1, 0.51 to 1, and 0.48 to 1, respectively, and were in compliance with this financial covenant. The availability under the facilities in place at September 30, 2017 is shown in the following table: DTE Energy DTE Electric DTE Gas Total (In millions) Unsecured letter of credit facility, expiring in February 2019 $ 150 $ — $ — $ 150 Unsecured letter of credit facility, expiring in September 2019 (a) 70 — — 70 Unsecured revolving credit facility, expiring April 2022 1,200 400 300 1,900 1,420 400 300 2,120 Amounts outstanding at September 30, 2017 Commercial paper issuances 98 311 250 659 Letters of credit 132 — — 132 230 311 250 791 Net availability at September 30, 2017 $ 1,190 $ 89 $ 50 $ 1,329 _______________________________________ (a) In August 2017, DTE Energy amended its $70 million letter of credit facility. The facility's maturity date was extended from September 2017 to September 2019. DTE Energy has approximately $17 million of other outstanding letters of credit which are used for various corporate purposes and are not included in the facilities described above. 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 September 30, 2017 , the capacity under this facility was $100 million . The amount outstanding under this agreement was $32 million and $50 million at September 30, 2017 and December 31, 2016 , respectively, and was fully offset by the posted collateral.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2017
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 SO 2 and NOx. The EPA and the State of Michigan have also 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 NOx, SO 2 , mercury, and other emissions. Additional rulemakings may occur over the next few years which could require additional controls for SO 2 , NOx, and other hazardous air pollutants. The Cross State Air Pollution Rule (CSAPR), required further reductions of SO 2 and NOx emissions beginning in January 2015. On September 7, 2016, the EPA finalized an update to the CSAPR ozone season program by issuing the CSAPR Update Rule. This rule is expected to reduce summertime (May-September) NOx emissions from power plants in 22 states in the eastern half of the U.S., including DTE Electric 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 National Ambient Air Quality Standards implementing power sector emission budgets and NOx allowance trading programs. DTE Electric expects to meet its obligations under CSAPR. DTE Electric does not expect this rule to have a material effect on its compliance program. 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 recommended to the EPA in October 2016 which areas of the state are not attaining the new standard. The Registrants expect the EPA to designate areas as either attainment or non-attainment with the 2015 ozone standards in the fourth quarter of 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. 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 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 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 March 2014, the U.S. District Court judge again granted 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, and Trenton Channel Unit 9. In October 2014, the EPA and the U.S. Department of Justice filed a notice of appeal of the U.S. District Court judge's dismissal of the Monroe Unit 2 case. The amended New Source Review claims were all stayed pending resolution of the appeal by the Court of Appeals for the Sixth Circuit. Oral arguments before the Sixth Circuit occurred in December 2015. On January 10, 2017, a divided panel of the Court reversed the decision of the U.S. District Court. On February 24, 2017, DTE Energy and DTE Electric filed a petition with the Sixth Circuit Court for a rehearing and a rehearing en banc, which was denied on May 1, 2017. On May 8, 2017, DTE Energy and DTE Electric filed a motion to stay the mandate pending filing of a petition for writ of certiorari with the U.S. Supreme Court. The Sixth Circuit granted the motion on May 16, 2017, staying the claims in district court until the U.S. Supreme Court disposes of the case. DTE Electric and DTE Energy filed a petition for writ of certiorari on July 31, 2017. Responses to the petition are due November 1, 2017. 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 the litigation and further 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 has implemented 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 finalized performance standards for emissions of carbon dioxide from new and existing 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. In February 2016, the U.S. Supreme Court granted petitioners' requests for a stay of the carbon rules for existing EGUs (also known as the EPA Clean Power Plan) pending final review by the courts. The Clean Power Plan has no legal effect while the stay is in place. On March 28, 2017, a presidential executive order was issued on "Promoting Energy Independence and Economic Growth." The order instructs the EPA to review, and if appropriate, suspend, revise or rescind the Clean Power Plan rule. Additionally, federal agencies have been directed to conduct a review of all existing regulations that potentially burden the development and use of domestically produced energy resources. Following the issuance of this order, the federal government requested the U.S. Court of Appeals for the D.C. Circuit to hold all legal challenges in abeyance until the review of these regulations is completed. On October 10, 2017, the EPA proposed to rescind the Clean Power Plan and announced its intent to issue an ANPR seeking input as to whether it should replace the rule and, if so, what form it should take. It is not possible to determine the potential impact of 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 $2.4 billion through 2016 . DTE Electric does not anticipate additional capital expenditures through 2023 . Water — In response to an EPA regulation, DTE Electric was 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 September 30, 2017 and December 31, 2016 , DTE Electric had $8 million accrued for remediation. 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 CCR, commonly known as coal ash, became effective in October 2015, and was revised in October 2016. In September 2017, the EPA indicated that it intends to reconsider certain provisions of the CCR Rule, but the nature and timing of such a reconsideration is unknown. 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. CCR obligations vary based on plant life, but include the installation of monitoring wells, compliance with groundwater standards, and the closure of landfills and basins at the end of the useful life of the associated power plant or as a basin becomes inactive. In November 2015, the EPA finalized the ELG Rule for the steam electric power generating industry which may require additional controls to be installed between 2018 and 2023. Compliance schedules for individual facilities and individual waste streams are determined through issuance of new wastewater permits by the State of Michigan. The State of Michigan has issued a National Pollutant Discharge Elimination System permit for the Belle River Power Plant establishing a compliance deadline of December 31, 2021. No new permits have been issued for other facilities, consequently no compliance timelines have been established. Under the current rule, certain ELG requirements would be required to be performed in conjunction with the CCR. Over the next six years, to comply with the ELG requirements of the November 2015 rules and for CCR requirements, costs associated with the building of new facilities or installation of controls are estimated to be approximately $311 million . On April 12, 2017, the EPA granted a petition for reconsideration of the ELG Rule. The EPA also signed an administrative stay of the ELG Rule’s compliance deadlines for fly ash transport water, bottom ash transport water, and flue gas desulfurization (FGD) wastewater, among others. On June 6, 2017, the EPA published in the Federal Register a proposed rule to postpone certain applicable deadlines within the ELG rule. The final rule was published on September 18, 2017, which extended the earliest compliance deadlines for the FGD wastewater and bottom ash transport until November 1, 2020 in order for the EPA to propose and finalize a new ruling. The ELG compliance requirements, final deadlines, and compliance costs will not be known until the EPA completes its reconsideration of the ELG Rule. 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 six of the MGP sites is complete, and the sites are closed. DTE Gas has also completed partial closure of six 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 September 30, 2017 and December 31, 2016 , DTE Gas had $41 million and $43 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. Other In 2010, the EPA finalized a new one -hour SO 2 ambient air quality standard that requires states to submit plans and associated timelines for non-attainment areas that demonstrate attainment with the new SO 2 standard in phases. Phase 1 addresses non-attainment areas designated based on ambient monitoring data. Phase 2 addresses non-attainment areas with large sources of SO 2 and modeled concentrations exceeding the National Ambient Air Quality Standards for SO 2 . Phase 3 addresses smaller sources of SO 2 with modeled or monitored exceedances of the new SO 2 standard. Michigan's Phase 1 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 SO 2 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 the MDEQ to develop air permits reflecting significant SO 2 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. Michigan's Phase 2 non-attainment area includes DTE Electric facilities in St. Clair County. State implementation plans (SIPs) for Phase 2 areas describing the control strategy and timeline for demonstrating compliance with the new SO 2 standard are due to the EPA by April 2018. DTE Energy is currently working with the MDEQ to develop the required SIP. DTE Energy is unable to determine the full impact of the SIP strategy, as it is currently under development. 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 September 30, 2017 was approximately $620 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 September 30, 2017 was approximately $364 million . Payment under these guarantees is considered remote. NEXUS Guarantees NEXUS entered into certain 15 -year capacity lease agreements for the transportation of natural gas with DTE Gas and Texas Eastern Transmission, LP, an unrelated third party. Pursuant to the terms of those agreements, in December 2016, DTE Energy executed separate guarantee agreements with DTE Gas and Texas Eastern Transmission, LP, with maximum potential payments totaling $75 million and $9 million at September 30, 2017 , respectively; each representing 50% of all payment obligations due and payable by NEXUS. Should NEXUS fail to perform under the terms of those agreements, DTE Energy is required to perform on its behalf. Each guarantee terminates at the earlier of (i) such time as all of the guaranteed obligations have been fully performed, or (ii) two months following the end of the primary term of the capacity lease agreements. Subsequent to the NEXUS in-service date, the amount of each guarantee decreases annually as payments are made by NEXUS to each of the aforementioned counterparties. Payments under these guarantees are 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 $55 million at September 30, 2017 . 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 September 30, 2017 , DTE Energy had approximately $57 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 4,800 represented employees, including DTE Electric's approximately 2,600 represented employees. The majority of the represented employees are under contracts that expire in 2020 and 2021. Purchase Commitments Utility capital expenditures, expenditures for non-utility businesses, and contributions to equity method investees will be approximately $2.5 billion and $1.5 billion in 2017 for DTE Energy and DTE Electric, respectively. The Registrants have made certain commitments in connection with these estimated 2017 expenditures and contributions to equity method investees. 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 5 and 8 to the Consolidated Financial Statements, " Regulatory Matters ," and " Financial and Other Derivative Instruments ," respectively.

Retirement Benefits and Trustee

Retirement Benefits and Trusteed Assets	9 Months Ended
	Sep. 30, 2017
Defined Benefit Plan [Abstract]
Retirement Benefits and Trusteed Assets	RETIREMENT BENEFITS AND TRUSTEED ASSETS The following tables detail the components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits for DTE Energy: Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Three Months Ended September 30, (In millions) Service cost $ 22 $ 23 $ 7 $ 7 Interest cost 53 55 18 20 Expected return on plan assets (78 ) (77 ) (33 ) (33 ) Amortization of: Net actuarial loss 46 43 3 6 Prior service cost (credit) 1 — (3 ) (29 ) Net periodic benefit cost (credit) $ 44 $ 44 $ (8 ) $ (29 ) Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Nine Months Ended September 30, (In millions) Service cost $ 69 $ 69 $ 20 $ 20 Interest cost 160 164 55 60 Expected return on plan assets (233 ) (232 ) (98 ) (97 ) Amortization of: Net actuarial loss 132 124 10 22 Prior service cost (credit) 1 — (10 ) (88 ) Net periodic benefit cost (credit) $ 129 $ 125 $ (23 ) $ (83 ) The following tables detail the components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits for DTE Electric: Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Three Months Ended September 30, (In millions) Service cost $ 16 $ 18 $ 5 $ 5 Interest cost 40 42 14 15 Expected return on plan assets (56 ) (55 ) (23 ) (23 ) Amortization of: Net actuarial loss 32 31 2 4 Prior service cost ( credit) 1 — (2 ) (22 ) Net periodic benefit cost (credit) $ 33 $ 36 $ (4 ) $ (21 ) Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Nine Months Ended September 30, (In millions) Service cost $ 53 $ 53 $ 15 $ 15 Interest cost 121 125 42 46 Expected return on plan assets (167 ) (165 ) (68 ) (68 ) Amortization of: Net actuarial loss 94 88 6 15 Prior service cost (credit) 1 1 (7 ) (66 ) Net periodic benefit cost (credit) $ 102 $ 102 $ (12 ) $ (58 ) Pension and Other Postretirement Contributions During the first nine months of 2017 , DTE Energy made cash contributions of $220 million , including contributions from DTE Electric of $185 million , to its pension plans. At the discretion of management and depending upon financial market conditions, DTE Energy may make additional contributions up to $88 million , including additional contributions from DTE Electric of $85 million , to its pension plans in 2017 . DTE Energy does not anticipate making any contributions to the other postretirement benefit plans in 2017 .

Segment and Related Information

Segment and Related Information	9 Months Ended
	Sep. 30, 2017
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 1.3 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 holds 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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Electric $ 11 $ 15 $ 36 $ 32 Gas 1 5 6 8 Gas Storage and Pipelines 10 2 32 7 Power and Industrial Projects 138 178 462 476 Energy Trading 8 10 27 28 Corporate and Other 1 — 2 2 $ 169 $ 210 $ 565 $ 553 Financial data of DTE Energy's business segments follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Operating Revenues — Utility operations Electric $ 1,434 $ 1,608 $ 3,827 $ 3,976 Gas 152 160 929 911 Operating Revenues — Non-utility operations Gas Storage and Pipelines 115 63 333 199 Power and Industrial Projects 537 524 1,592 1,414 Energy Trading 1,174 782 3,217 1,807 Corporate and Other 2 1 3 2 Reconciliation and Eliminations (169 ) (210 ) (565 ) (553 ) Total $ 3,245 $ 2,928 $ 9,336 $ 7,756 Net Income (Loss) Attributable to DTE Energy by Segment: Electric $ 219 $ 285 $ 463 $ 547 Gas (15 ) (4 ) 93 96 Gas Storage and Pipelines 36 28 121 93 Power and Industrial Projects 44 34 104 66 Energy Trading 1 (4 ) 97 (34 ) Corporate and Other (15 ) (1 ) (31 ) (31 ) Net Income Attributable to DTE Energy Company $ 270 $ 338 $ 847 $ 737

Significant Accounting Polici22

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Consolidated Financial Statements should be read in conjunction with the Combined Notes to Consolidated Financial Statements included in the combined DTE Energy and DTE Electric 2016 Annual Report on Form 10-K. 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 Consolidated Financial Statements are unaudited but, in the Registrants' opinions include all adjustments necessary to present a fair statement of the results for the interim periods. All adjustments are of a normal recurring nature, except as otherwise disclosed in these Consolidated Financial Statements and Combined Notes to Consolidated Financial Statements. Financial results for this interim period are not necessarily indicative of results that may be expected for any other interim period or for the fiscal year ending December 31, 2017 . 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.
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 owns a 55% interest in SGG, which owns and operates midstream natural gas assets. SGG has contracts through which certain construction risk is designed to pass-through to the customers, with DTE Energy retaining operational and customer default risk. SGG is a VIE with DTE Energy as the primary beneficiary. See Note 4 to the Consolidated Financial Statements, " Acquisition ," for more information. The Registrants hold variable interests in NEXUS, including a 50% ownership interest. NEXUS is a joint venture which is in the process of constructing a 255-mile pipeline to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers. NEXUS is a VIE as it has insufficient equity at risk to finance its activities. The Registrants are not the primary beneficiaries, as the power to direct significant activities is shared between the owners of the equity interests. DTE Energy accounts for NEXUS under the equity method. The Registrants hold ownership interests in certain limited partnerships. The limited partnerships include investment funds which support regional development and economic growth, as well as, an operational business providing energy-related products. These entities are generally VIEs as a result of certain characteristics of the limited partnership voting rights. The ownership interests are accounted for under the equity method as the Registrants are not the primary beneficiaries. 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 September 30, 2017 , 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 September 30, 2017 , 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. The maximum risk exposure for consolidated VIEs is reflected on the Registrants' Consolidated Statements of Financial Position and in Note 11 to the Consolidated Financial Statements, " Commitments and Contingencies ," related to the REF guarantees and indemnities. For non-consolidated VIEs, the maximum risk exposure of the Registrants is generally limited to their investment, notes receivable, future funding commitments, and amounts which DTE Energy has guaranteed. See Note 11 to the Consolidated Financial Statements, " Commitments and Contingencies ," for further discussion of the NEXUS guarantee arrangements.
Changes in Accumulated Other Comprehensive Income (Loss)	Changes in Accumulated Other Comprehensive Income (Loss) For the three and nine months ended September 30, 2017 and 2016 , reclassifications out of Accumulated other comprehensive income (loss) for the Registrants were not material. Changes in Accumulated other comprehensive income (loss) are presented in DTE Energy's Consolidated Statements of Changes in Equity and DTE Electric's Consolidated Statements of Changes in Shareholder's Equity.
Recently Adopted and Recently Issued Pronouncements	Recently Adopted Pronouncements 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 was applied prospectively. The Registrants adopted this ASU at January 1, 2017. The adoption of the ASU did not have a significant impact on the Registrants' Consolidated Financial Statements. Recently Issued Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), as amended . 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. The standard is to be applied retrospectively. The Registrants will adopt the standard effective January 1, 2018 using the modified retrospective approach. The Registrants are finalizing the assessment of the impact of the ASU, as amended, on their Consolidated Financial Statements. The ASU is not expected to significantly affect the Registrants' results of operations. The Registrants will continue to evaluate the impact of the ASU on existing revenue recognition policies and procedures. Industry-related issues being vetted through the final stages of the American Institute of Certified Public Accountants' Power and Utilities Industry Task Force process will continue to be monitored. The ASU will result in additional disclosures for revenue compared to the current guidance. Accordingly, the Registrants are evaluating information that would be useful for users of the Consolidated Financial Statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), a replacement of Leases (Topic 840) . This guidance requires a lessee to account for leases as finance or operating leases. Both types of leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability on its balance sheet, with differing methodology for income statement recognition. For lessors, the standard modifies the classification criteria and the accounting for sales-type and direct financing leases. Entities will classify leases to determine how to recognize lease-related revenue and expense. This standard is effective for public entities for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. The Registrants do not plan to early adopt the standard. A modified retrospective approach is required for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements, with certain practical expedients permitted. The Registrants expect an increase in assets and liabilities, however, they are currently assessing the impact of this ASU on their Consolidated Financial Statements. This assessment includes monitoring unresolved utility industry implementation guidance. The Registrants have conducted outreach activities across their lines of business and have begun implementation of a third-party software tool that will assist with the initial adoption and ongoing compliance. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments . The amendments in this update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Entities will apply the new guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The ASU is effective for the Registrants beginning after December 15, 2019, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. In March 2017, the FASB issued ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments in this update require that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The standard will be applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. The ASU is effective for the Registrants for fiscal years, and interim periods within those years, beginning after December 15, 2017, and early adoption is permitted. The Registrants will adopt the standard effective January 1, 2018. The components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits are disclosed in Note 12 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets ." The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements.
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 September 30, 2017 and December 31, 2016 . 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 and commingled funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. Non-exchange-traded fixed income securities are valued based upon quotations available from brokers or pricing services. The institutional mutual funds hold exchange-traded equity or debt securities (exchange and non-exchange traded) and are valued based on publicly available NAVs. 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, and notes payable 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 and DTE Energy's Controller's Department which reports to DTE Energy's Vice President and Controller.
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. 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 2020. 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 gathering, 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. Energy Trading 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 September 30, 2017 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.
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 $2 million outstanding at September 30, 2017 and December 31, 2016 , 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 $3 million and $2 million at September 30, 2017 and December 31, 2016 , 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.
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.
Income Tax	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.

Organization and Basis of Pre23

Organization and Basis of Presentation (Tables)	9 Months Ended
	Sep. 30, 2017
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 September 30, 2017 and December 31, 2016 . 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. 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. September 30, 2017 December 31, 2016 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 31 $ 13 $ 44 $ 36 $ 27 $ 63 Restricted cash — 8 8 — 7 7 Accounts receivable 11 30 41 8 34 42 Inventories 3 84 87 3 112 115 Property, plant, and equipment, net 397 70 467 398 76 474 Goodwill 25 — 25 17 — 17 Intangible assets 576 — 576 586 — 586 Other current and long-term assets 1 — 1 1 1 2 $ 1,044 $ 205 $ 1,249 $ 1,049 $ 257 $ 1,306 LIABILITIES Accounts payable and accrued current liabilities $ 26 $ 29 $ 55 $ 19 $ 32 $ 51 Current portion long-term debt, including capital leases — 3 3 — 5 5 Mortgage bonds, notes, and other — 2 2 — 5 5 Other current and long-term liabilities 1 15 16 2 15 17 $ 27 $ 49 $ 76 $ 21 $ 57 $ 78 _____________________________________ (a) Amounts shown are 100% of SGG's assets and liabilities, of which DTE Energy owns 55% .
Summary of Amounts for Non-Consolidated Variable Interest Entities	Amounts for DTE Energy's non-consolidated VIEs are as follows: September 30, 2017 December 31, 2016 (In millions) Investments in equity method investees $ 716 $ 509 Notes receivable $ 17 $ 15 Future funding commitments $ 688 $ 692

Significant Accounting Polici24

Significant Accounting Policies (Tables)	9 Months Ended
	Sep. 30, 2017
Accounting Policies [Abstract]
Schedule of Other Income	The following is a summary of DTE Energy's Other income: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Equity earnings of equity method investees $ 26 $ 14 $ 77 $ 49 Income from REF entities 20 20 60 59 Gains from trading securities 6 5 19 15 Allowance for equity funds used during construction 5 5 17 15 Contract services 9 5 17 16 Other 8 2 14 6 $ 74 $ 51 $ 204 $ 160 The following is a summary of DTE Electric's Other income: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Gains from trading securities allocated from DTE Energy $ 6 $ 5 $ 19 $ 15 Contract services 9 5 18 16 Allowance for equity funds used during construction 4 4 14 13 Equity earnings of equity method investees — — 1 1 Other 2 1 5 3 $ 21 $ 15 $ 57 $ 48
Schedule of Effective Tax Rate	The effective tax rate of the Registrants are as follows: Effective Tax Rate Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 DTE Energy 22 % 25 % 22 % 25 % DTE Electric 35 % 35 % 35 % 36 %

Acquisition (Tables)

Acquisition (Tables)	9 Months Ended
	Sep. 30, 2017
Business Combinations [Abstract]
Schedule of Final Purchase Price Allocation	The components of the final purchase price allocation, inclusive of purchase accounting adjustments, are as follows: (In millions) Assets Cash $ 83 Accounts receivable 24 Inventory 6 Property, plant, and equipment, net 719 Goodwill 275 Customer relationship intangibles 770 Other current assets 1 $ 1,878 Liabilities Accounts payable $ 19 Other current liabilities 11 Long-term debt 204 Other long-term liabilities 20 $ 254 Less: Noncontrolling interest 392 Total cash consideration $ 1,232

Earnings Per Share (Tables)

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2017
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following is a reconciliation of DTE Energy's basic and diluted income per share calculation: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 270 $ 338 $ 847 $ 737 Less: Allocation of earnings to net restricted stock awards 1 — 2 1 Net income available to common shareholders — basic $ 269 $ 338 $ 845 $ 736 Average number of common shares outstanding 179 179 179 179 Basic Earnings per Common Share $ 1.51 $ 1.88 $ 4.72 $ 4.10 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 270 $ 338 $ 847 $ 737 Less: Allocation of earnings to net restricted stock awards 1 — 2 1 Net income available to common shareholders — diluted $ 269 $ 338 $ 845 $ 736 Average number of common shares outstanding 179 179 179 179 Incremental shares attributable to: Average dilutive performance share awards and stock options (a) — 1 — 1 Average number of common shares outstanding — diluted 179 180 179 180 Diluted Earnings per Common Share $ 1.51 $ 1.88 $ 4.72 $ 4.10 _______________________________________ (a) The 2016 equity units are potentially dilutive securities but were excluded from the calculation of diluted EPS for the three and nine months ended September 30, 2017 , as the dilutive stock price threshold was not met.

Fair Value (Tables)

Fair Value (Tables)	9 Months Ended
	Sep. 30, 2017
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured and 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: September 30, 2017 December 31, 2016 Level Level Level Netting (a) Net Balance Level Level Level Netting (a) Net Balance (In millions) Assets: Cash equivalents (b) $ 16 $ 3 $ — $ — $ 19 $ 14 $ 3 $ — $ — $ 17 Nuclear decommissioning trusts (c) Equity securities 949 — — — 949 887 — — — 887 Fixed income securities 10 474 — — 484 11 414 — — 425 Cash equivalents 6 — — — 6 8 — — — 8 Other investments (d) Equity securities 120 — — — 120 104 — — — 104 Fixed income securities 63 — — — 63 58 — — — 58 Cash equivalents 4 — — — 4 3 — — — 3 Derivative assets Commodity Contracts Natural Gas 64 104 62 (151 ) 79 216 79 53 (306 ) 42 Electricity — 155 47 (148 ) 54 — 154 39 (157 ) 36 Other — — 4 — 4 — — 2 — 2 Foreign currency exchange contracts — 3 — (2 ) 1 — 6 — (5 ) 1 Total derivative assets 64 262 113 (301 ) 138 216 239 94 (468 ) 81 Total $ 1,232 $ 739 $ 113 $ (301 ) $ 1,783 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Derivative liabilities Commodity Contracts Natural Gas $ (64 ) $ (76 ) $ (64 ) $ 151 $ (53 ) $ (226 ) $ (86 ) $ (149 ) $ 321 $ (140 ) Electricity — (159 ) (40 ) 164 (35 ) — (159 ) (30 ) 163 (26 ) Other — — (2 ) 2 — — — (3 ) 2 (1 ) Foreign currency exchange contracts — (4 ) — 2 (2 ) — (3 ) — 3 — Total derivative liabilities (64 ) (239 ) (106 ) 319 (90 ) (226 ) (248 ) (182 ) 489 (167 ) Total $ (64 ) $ (239 ) $ (106 ) $ 319 $ (90 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,168 $ 500 $ 7 $ 18 $ 1,693 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 Assets: Current $ 65 $ 194 $ 61 $ (225 ) $ 95 $ 205 $ 199 $ 60 $ (400 ) $ 64 Noncurrent 1,167 545 52 (76 ) 1,688 1,096 457 34 (68 ) 1,519 Total Assets $ 1,232 $ 739 $ 113 $ (301 ) $ 1,783 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Current $ (60 ) $ (183 ) $ (54 ) $ 255 $ (42 ) $ (203 ) $ (211 ) $ (79 ) $ 424 $ (69 ) Noncurrent (4 ) (56 ) (52 ) 64 (48 ) (23 ) (37 ) (103 ) 65 (98 ) Total Liabilities $ (64 ) $ (239 ) $ (106 ) $ 319 $ (90 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,168 $ 500 $ 7 $ 18 $ 1,693 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 _______________________________________ (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 September 30, 2017 , available-for-sale securities of $19 million , included $8 million and $11 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2016 , available-for-sale securities of $17 million , included $7 million and $10 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. (c) At September 30, 2017 , the Nuclear Decommissioning Master Trust had outstanding commitments to invest in private equity investments of approximately $25 million . These commitments will be funded by existing nuclear decommissioning trust funds. (d) Excludes cash surrender value of life insurance investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis as of: September 30, 2017 December 31, 2016 Level 1 Level 2 Level 3 Net Balance Level 1 Level 2 Level 3 Net Balance (In millions) Assets: Cash equivalents (a) $ 8 $ 3 $ — $ 11 $ 8 $ 3 $ — $ 11 Nuclear decommissioning trusts (b) Equity securities 949 — — 949 887 — — 887 Fixed income securities 10 474 — 484 11 414 — 425 Cash equivalents 6 — — 6 8 — — 8 Other investments Equity securities 10 — — 10 9 — — 9 Derivative assets — FTRs — — 4 4 — — 2 2 Total $ 983 $ 477 $ 4 $ 1,464 $ 923 $ 417 $ 2 $ 1,342 Assets: Current $ 8 $ 3 $ 4 $ 15 $ 8 $ 3 $ 2 $ 13 Noncurrent 975 474 — 1,449 915 414 — 1,329 Total Assets $ 983 $ 477 $ 4 $ 1,464 $ 923 $ 417 $ 2 $ 1,342 _______________________________________ (a) At September 30, 2017 and December 31, 2016 , available-for-sale securities of $11 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. (b) At September 30, 2017 , the Nuclear Decommissioning Master Trust had outstanding commitments to invest in private equity investments of approximately $25 million . These commitments will be funded by existing nuclear decommissioning trust funds.
Fair Value Reconciliation of Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following tables present the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Energy: Three Months Ended September 30, 2017 Three Months Ended September 30, 2016 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of June 30 $ (17 ) $ 6 $ 5 $ (6 ) $ (62 ) $ (6 ) $ (1 ) $ (69 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 — — — — (1 ) — — (1 ) Total gains (losses) Included in earnings (8 ) 33 1 26 (65 ) 24 — (41 ) Recorded in Regulatory liabilities — — 2 2 — — 2 2 Purchases, issuances, and settlements Settlements 23 (32 ) (6 ) (15 ) 28 (24 ) (2 ) 2 Net Assets (Liabilities) as of September 30 $ (2 ) $ 7 $ 2 $ 7 $ (100 ) $ (6 ) $ (1 ) $ (107 ) 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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ (8 ) $ 18 $ 1 $ 11 $ (50 ) $ 6 $ — $ (44 ) Nine Months Ended September 30, 2017 Nine Months Ended September 30, 2016 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of December 31 $ (96 ) $ 9 $ (1 ) $ (88 ) $ (5 ) $ 6 $ (5 ) $ (4 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 — — — — — — — — Total gains (losses) Included in earnings 38 45 1 84 (123 ) (22 ) 1 (144 ) Recorded in Regulatory liabilities — — 15 15 — — 6 6 Purchases, issuances, and settlements Issuances — — — — — 1 — 1 Settlements 56 (47 ) (13 ) (4 ) 28 9 (3 ) 34 Net Assets (Liabilities) as of September 30 $ (2 ) $ 7 $ 2 $ 7 $ (100 ) $ (6 ) $ (1 ) $ (107 ) 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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ 8 $ 35 $ — $ 43 $ (165 ) $ (1 ) $ 2 $ (164 ) 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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Net Assets as of beginning of period $ 8 $ 4 $ 2 $ 3 Change in fair value recorded in Regulatory liabilities 2 2 15 6 Purchases, issuances, and settlements Settlements (6 ) (3 ) (13 ) (6 ) Net Assets as of September 30 $ 4 $ 3 $ 4 $ 3 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets held at September 30, 2017 and 2016 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 1 $ 1 $ 4 $ 3
Unobservable Inputs Related to Level 3 Assets and Liabilities	The following tables present the unobservable inputs related to DTE Energy's Level 3 assets and liabilities: September 30, 2017 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 62 $ (64 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.92 ) — $ 6.36 /MMBtu $ (0.03 )/MMBtu Electricity $ 47 $ (40 ) Discounted Cash Flow Forward basis price (per MWh) $ (10 ) — $ 7 /MWh $ 1 /MWh December 31, 2016 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 53 $ (149 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.00 ) — $ 7.90 /MMBtu $ (0.05 )/MMBtu Electricity $ 39 $ (30 ) Discounted Cash Flow Forward basis price (per MWh) $ (6 ) — $ 12 /MWh $ 1 /MWh
Carrying Amount of Fair Value of Financial Instruments	The following table presents the carrying amount and fair value of financial instruments for DTE Energy: September 30, 2017 December 31, 2016 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 $ 36 $ — $ — $ 36 $ 36 $ — $ — $ 36 Dividends payable $ 148 $ 148 $ — $ — $ 148 $ 148 $ — $ — Short-term borrowings $ 659 $ — $ 659 $ — $ 499 $ — $ 499 $ — Notes payable — Other (a) $ 16 $ — $ — $ 16 $ 17 $ — $ — $ 17 Long-term debt (b) $ 11,897 $ 1,554 $ 10,522 $ 744 $ 11,270 $ 1,465 $ 9,384 $ 1,056 _______________________________________ (a) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Energy's Consolidated Statements of Financial Position. (b) Includes debt due within one year , unamortized debt discounts, premiums, and issuance costs. Excludes Capital lease obligations. The following table presents the carrying amount and fair value of financial instruments for DTE Electric: September 30, 2017 December 31, 2016 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 Short-term borrowings — affiliates $ 66 $ — $ — $ 66 $ 117 $ — $ — $ 117 Short-term borrowings — other $ 311 $ — $ 311 $ — $ 62 $ — $ 62 $ — Notes payable — Other (a) $ 5 $ — $ — $ 5 $ 6 $ — $ — $ 6 Long-term debt (b) $ 6,016 $ — $ 6,395 $ 163 $ 5,878 $ — $ 6,026 $ 264 _______________________________________ (a) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Electric's Consolidated Statements of Financial Position. (b) Includes debt due within one year , unamortized debt discounts, and issuance costs. Excludes Capital lease obligations.
Fair Value of Nuclear Decommissioning Trust Fund Assets	The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: September 30, 2017 December 31, 2016 (In millions) Fermi 2 $ 1,423 $ 1,291 Fermi 1 3 3 Low-level radioactive waste 13 26 Total $ 1,439 $ 1,320
Schedule of Realized Gains and Losses and Proceeds from Sale of Securities by Nuclear Decommissioning 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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Realized gains $ 14 $ 13 $ 63 $ 59 Realized losses $ (7 ) $ (8 ) $ (23 ) $ (48 ) Proceeds from sale of securities $ 246 $ 394 $ 951 $ 1,135
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: September 30, 2017 December 31, 2016 Fair Unrealized Unrealized Fair Unrealized Unrealized (In millions) Equity securities $ 949 $ 287 $ (34 ) $ 887 $ 222 $ (46 ) Fixed income securities 484 14 (2 ) 425 11 (5 ) Cash equivalents 6 — — 8 — — $ 1,439 $ 301 $ (36 ) $ 1,320 $ 233 $ (51 )
Fair Value of the Fixed Income Securities Held in Nuclear Decommissioning Trust Funds	The following table summarizes the fair value of the fixed income securities held in nuclear decommissioning trust funds by contractual maturity: September 30, 2017 (In millions) Due within one year $ 15 Due after one through five years 100 Due after five through ten years 111 Due after ten years 258 $ 484

Financial and Other Derivativ28

Financial and Other Derivative Instruments (Tables)	9 Months Ended
	Sep. 30, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following table presents the fair value of derivative instruments for DTE Energy: September 30, 2017 December 31, 2016 Derivative Derivative Liabilities Derivative Derivative Liabilities (In millions) Derivatives not designated as hedging instruments Commodity Contracts Natural Gas $ 230 $ (204 ) $ 348 $ (461 ) Electricity 202 (199 ) 193 (189 ) Other 4 (2 ) 2 (3 ) Foreign currency exchange contracts 3 (4 ) 6 (3 ) Total derivatives not designated as hedging instruments $ 439 $ (409 ) $ 549 $ (656 ) Current $ 301 $ (297 ) $ 447 $ (493 ) Noncurrent 138 (112 ) 102 (163 ) Total derivatives $ 439 $ (409 ) $ 549 $ (656 ) The following table presents the fair value of derivative instruments for DTE Electric: September 30, 2017 December 31, 2016 (In millions) FTRs — Other current assets $ 4 $ 2 Total derivatives not designated as hedging instrument $ 4 $ 2
Netting Offsets of Derivative Assets and Liabilities	The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy: September 30, 2017 December 31, 2016 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 $ 230 $ (151 ) $ 79 $ 348 $ (306 ) $ 42 Electricity 202 (148 ) 54 193 (157 ) 36 Other 4 — 4 2 — 2 Foreign currency exchange contracts 3 (2 ) 1 6 (5 ) 1 Total derivative assets $ 439 $ (301 ) $ 138 $ 549 $ (468 ) $ 81 Derivative liabilities Commodity Contracts Natural Gas $ (204 ) $ 151 $ (53 ) $ (461 ) $ 321 $ (140 ) Electricity (199 ) 164 (35 ) (189 ) 163 (26 ) Other (2 ) 2 — (3 ) 2 (1 ) Foreign currency exchange contracts (4 ) 2 (2 ) (3 ) 3 — Total derivative liabilities $ (409 ) $ 319 $ (90 ) $ (656 ) $ 489 $ (167 )
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: September 30, 2017 December 31, 2016 Derivative Assets Derivative Liabilities Derivative Assets Derivative Liabilities Current Noncurrent Current Noncurrent Current Noncurrent Current Noncurrent (In millions) Total fair value of derivatives $ 301 $ 138 $ (297 ) $ (112 ) $ 447 $ 102 $ (493 ) $ (163 ) Counterparty netting (225 ) (64 ) 225 64 (396 ) (65 ) 396 65 Collateral adjustment — (12 ) 30 — (4 ) (3 ) 28 — Total derivatives as reported $ 76 $ 62 $ (42 ) $ (48 ) $ 47 $ 34 $ (69 ) $ (98 )
Gain (Loss) Recognized in Income on Derivatives	The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations is as follows: Derivatives not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for the Three Months Ended September 30, Gain (Loss) Recognized in Income on Derivatives for the Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Commodity Contracts Natural Gas Operating Revenues — Non-utility operations $ (14 ) $ 16 $ 63 $ (70 ) Natural Gas Fuel, purchased power, and gas — non-utility 10 (59 ) 56 (27 ) Electricity Operating Revenues — Non-utility operations 33 23 39 18 Other Operating Revenues — Non-utility operations 2 1 1 (1 ) Foreign currency exchange contracts Operating Revenues — Non-utility operations (2 ) — (3 ) (4 ) Total $ 29 $ (19 ) $ 156 $ (84 )
Volume of Commodity Contracts	The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of September 30, 2017 : Commodity Number of Units Natural Gas (MMBtu) 1,751,191,598 Electricity (MWh) 28,924,416 Foreign Currency Exchange (Canadian dollars) 89,049,511

Long-Term Debt (Tables)

Long-Term Debt (Tables)	9 Months Ended
	Sep. 30, 2017
Debt Disclosure [Abstract]
Schedule of Issued Debt	In 2017 , the following debt was issued: Company Month Type Interest Rate Maturity Amount (In millions) DTE Energy March Senior Notes (a) 3.80% 2027 $ 500 DTE Electric August General and Refunding Mortgage Bonds (b) 3.75% 2047 440 DTE Gas September First Mortgage Bonds (a) 3.08% 2029 40 DTE Gas September First Mortgage Bonds (a) 3.75% 2047 40 $ 1,020 _______________________________________ (a) Proceeds were used for repayment of short-term borrowings and general corporate purposes. (b) Proceeds were used to repay $300 million of DTE Electric's 2008 series G 5.60% Senior Notes due on June 15, 2018, for the repayment of short-term borrowings and general corporate purposes.
Schedule of Debt Redemptions	In 2017 , the following debt was redeemed: Company Month Type Interest Rate Maturity Amount (In millions) DTE Electric August Senior Notes 5.60% 2018 $ 300 DTE Energy September Secured Note (a) 7.29% 2029 77 DTE Energy Various Other Long-Term Debt Various 2017 8 $ 385 _______________________________________ (a) DTE Energy's Gas Storage and Pipelines segment recognized a $16 million net loss on extinguishment of debt associated with early repayment, consisting of $20 million of early redemption premiums and $4 million of unamortized debt premiums. The loss is reflected in Other (Income) and Deductions — Interest Expense on the Consolidated Statements of Operations.

Short-Term Credit Arrangement30

Short-Term Credit Arrangements and Borrowings (Tables)	9 Months Ended
	Sep. 30, 2017
Short-term Debt [Abstract]
Schedule of Line of Credit Facilities	The availability under the facilities in place at September 30, 2017 is shown in the following table: DTE Energy DTE Electric DTE Gas Total (In millions) Unsecured letter of credit facility, expiring in February 2019 $ 150 $ — $ — $ 150 Unsecured letter of credit facility, expiring in September 2019 (a) 70 — — 70 Unsecured revolving credit facility, expiring April 2022 1,200 400 300 1,900 1,420 400 300 2,120 Amounts outstanding at September 30, 2017 Commercial paper issuances 98 311 250 659 Letters of credit 132 — — 132 230 311 250 791 Net availability at September 30, 2017 $ 1,190 $ 89 $ 50 $ 1,329 _______________________________________ (a) In August 2017, DTE Energy amended its $70 million letter of credit facility. The facility's maturity date was extended from September 2017 to September 2019.

Retirement Benefits and Trust31

Retirement Benefits and Trusteed Assets (Tables)	9 Months Ended
	Sep. 30, 2017
Defined Benefit Plan [Abstract]
Schedule of Net Periodic Benefit Costs (Credits)	The following tables detail the components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits for DTE Energy: Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Three Months Ended September 30, (In millions) Service cost $ 22 $ 23 $ 7 $ 7 Interest cost 53 55 18 20 Expected return on plan assets (78 ) (77 ) (33 ) (33 ) Amortization of: Net actuarial loss 46 43 3 6 Prior service cost (credit) 1 — (3 ) (29 ) Net periodic benefit cost (credit) $ 44 $ 44 $ (8 ) $ (29 ) Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Nine Months Ended September 30, (In millions) Service cost $ 69 $ 69 $ 20 $ 20 Interest cost 160 164 55 60 Expected return on plan assets (233 ) (232 ) (98 ) (97 ) Amortization of: Net actuarial loss 132 124 10 22 Prior service cost (credit) 1 — (10 ) (88 ) Net periodic benefit cost (credit) $ 129 $ 125 $ (23 ) $ (83 ) The following tables detail the components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits for DTE Electric: Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Three Months Ended September 30, (In millions) Service cost $ 16 $ 18 $ 5 $ 5 Interest cost 40 42 14 15 Expected return on plan assets (56 ) (55 ) (23 ) (23 ) Amortization of: Net actuarial loss 32 31 2 4 Prior service cost ( credit) 1 — (2 ) (22 ) Net periodic benefit cost (credit) $ 33 $ 36 $ (4 ) $ (21 ) Pension Benefits Other Postretirement Benefits 2017 2016 2017 2016 Nine Months Ended September 30, (In millions) Service cost $ 53 $ 53 $ 15 $ 15 Interest cost 121 125 42 46 Expected return on plan assets (167 ) (165 ) (68 ) (68 ) Amortization of: Net actuarial loss 94 88 6 15 Prior service cost (credit) 1 1 (7 ) (66 ) Net periodic benefit cost (credit) $ 102 $ 102 $ (12 ) $ (58 )

Segment and Related Informati32

Segment and Related Information (Tables)	9 Months Ended
	Sep. 30, 2017
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: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Electric $ 11 $ 15 $ 36 $ 32 Gas 1 5 6 8 Gas Storage and Pipelines 10 2 32 7 Power and Industrial Projects 138 178 462 476 Energy Trading 8 10 27 28 Corporate and Other 1 — 2 2 $ 169 $ 210 $ 565 $ 553 Financial data of DTE Energy's business segments follows: Three Months Ended September 30, Nine Months Ended September 30, 2017 2016 2017 2016 (In millions) Operating Revenues — Utility operations Electric $ 1,434 $ 1,608 $ 3,827 $ 3,976 Gas 152 160 929 911 Operating Revenues — Non-utility operations Gas Storage and Pipelines 115 63 333 199 Power and Industrial Projects 537 524 1,592 1,414 Energy Trading 1,174 782 3,217 1,807 Corporate and Other 2 1 3 2 Reconciliation and Eliminations (169 ) (210 ) (565 ) (553 ) Total $ 3,245 $ 2,928 $ 9,336 $ 7,756 Net Income (Loss) Attributable to DTE Energy by Segment: Electric $ 219 $ 285 $ 463 $ 547 Gas (15 ) (4 ) 93 96 Gas Storage and Pipelines 36 28 121 93 Power and Industrial Projects 44 34 104 66 Energy Trading 1 (4 ) 97 (34 ) Corporate and Other (15 ) (1 ) (31 ) (31 ) Net Income Attributable to DTE Energy Company $ 270 $ 338 $ 847 $ 737

Organization and Basis of Pre33

Organization and Basis of Presentation (Details Textuals) customer in Millions	Sep. 30, 2017USD ($)customer	Oct. 01, 2016
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Number of electric utility customers | customer	2.2
Number of gas utility customers | customer	1.3
Significant potential exposure | $	$ 0
DTE Electric
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Significant potential exposure | $	$ 0
NEXUS pipeline
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ownership interest	50.00%
West Virginia | Midstream Natural Gas Assets
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Percent of assets acquired	55.00%	55.00%

Organization and Basis of Pre34

Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
ASSETS
Cash and cash equivalents	$ 63	$ 92	$ 66	$ 37
Restricted cash	23	21
Accounts receivable	1,395	1,522
Property, plant, and equipment, net	20,307	19,730
Goodwill	2,293	2,286
Intangible assets	883	842
Total Assets	33,071	32,041
LIABILITIES
Current portion long-term debt, including capital leases	109	14
Mortgage bonds, notes, and other	11,038	10,506
Variable interest entity, primary beneficiary, restricted
ASSETS
Cash and cash equivalents	44	63
Restricted cash	8	7
Accounts receivable	41	42
Inventories	87	115
Property, plant, and equipment, net	467	474
Goodwill	25	17
Intangible assets	576	586
Other current and long-term assets	1	2
Total Assets	1,249	1,306
LIABILITIES
Accounts payable and accrued current liabilities	55	51
Current portion long-term debt, including capital leases	3	5
Mortgage bonds, notes, and other	2	5
Other current and long-term liabilities	16	17
Total liabilities	76	78
SGG
ASSETS
Cash and cash equivalents	31	36
Restricted cash	0	0
Accounts receivable	11	8
Inventories	3	3
Property, plant, and equipment, net	397	398
Goodwill	25	17
Intangible assets	576	586
Other current and long-term assets	1	1
Total Assets	1,044	1,049
LIABILITIES
Accounts payable and accrued current liabilities	26	19
Current portion long-term debt, including capital leases	0	0
Mortgage bonds, notes, and other	0	0
Other current and long-term liabilities	1	2
Total liabilities	$ 27	21
VIE ownership and non-ownership percentage	100.00%
VIE ownership percentage	55.00%
Other
ASSETS
Cash and cash equivalents	$ 13	27
Restricted cash	8	7
Accounts receivable	30	34
Inventories	84	112
Property, plant, and equipment, net	70	76
Goodwill	0	0
Intangible assets	0	0
Other current and long-term assets	0	1
Total Assets	205	257
LIABILITIES
Accounts payable and accrued current liabilities	29	32
Current portion long-term debt, including capital leases	3	5
Mortgage bonds, notes, and other	2	5
Other current and long-term liabilities	15	15
Total liabilities	$ 49	$ 57

Organization and Basis of Pre35

Organization and Basis of Presentation (Non-Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Investments in equity method investees	$ 971	$ 752
Notes receivable	74	73
Variable interest entity, non-consolidated
Variable Interest Entity [Line Items]
Investments in equity method investees	716	509
Notes receivable	17	15
Future funding commitments	$ 688	$ 692

Significant Accounting Polici36

Significant Accounting Policies Significant Accounting Policies (Other Income) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity earnings of equity method investees	$ 26	$ 14	$ 77	$ 49
Income from REF entities	20	20	60	59
Gains from trading securities	6	5	19	15
Allowance for equity funds used during construction	5	5	17	15
Contract services	9	5	17	16
Other	8	2	14	6
Total other income	74	51	204	160
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity earnings of equity method investees	0	0	1	1
Gains from trading securities	6	5	19	15
Allowance for equity funds used during construction	4	4	14	13
Contract services	9	5	18	16
Other	2	1	5	3
Total other income	$ 21	$ 15	$ 57	$ 48

Significant Accounting Polici37

Significant Accounting Policies (Income Taxes) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Income Taxes [Line Items]
Effective Tax Rate	22.00%	25.00%	22.00%	25.00%
DTE Electric
Schedule of Income Taxes [Line Items]
Effective Tax Rate	35.00%	35.00%	35.00%	36.00%

Significant Accounting Polici38

Significant Accounting Policies (Details Textuals) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Effective tax rate increase (decrease)	(3.00%)		(3.00%)
ASU 2016-09 excess tax benefit amount			$ 13
Unrecognized tax benefits	$ 10		10		$ 10
Unrecognized tax benefits that would impact effective tax rate	6		6		7
Unrecognized compensation cost	71		$ 71
Recognition period (in years)			1 year 4 months 6 days
DTE Electric
Significant Accounting Policies [Line Items]
Unrecognized tax benefits	13		$ 13		13
Unrecognized tax benefits that would impact effective tax rate	8		8		8
DTE Electric | DTE Energy
Significant Accounting Policies [Line Items]
Income tax receivable	9		9		$ 9
Allocated costs	$ 10	$ 7	$ 28	$ 26

Acquisition (Details)

Acquisition (Details) - Gas Storage and Pipelines Acquisition - USD ($) $ in Millions	Oct. 01, 2016	Dec. 31, 2016	Sep. 30, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Cash paid for gathering assets	$ 1,200
Assumed debt	204
Assumed debt, acquiree portion	$ 112
Noncontrolling interest percentage	45.00%
Assumed debt, noncontrolling interest portion	$ 92
Goodwill purchase accounting adjustments			$ 7
Useful life of acquired intangible assets	40 years
Pre-acquisition contingencies	$ 30
Direct transaction costs				$ 15
Operating revenues associated with acquired entities		$ 39
Net income (loss) associated with acquired entities		4
Transaction costs
Business Acquisition [Line Items]
Net income (loss) associated with acquired entities		$ (15)
Customer relationship intangibles
Business Acquisition [Line Items]
Intangible assets	$ 770
Useful life of acquired intangible assets	10 years
West Virginia
Business Acquisition [Line Items]
Percent of assets acquired	55.00%		55.00%
M3 Midstream | Pennsylvania and West Virginia
Business Acquisition [Line Items]
Percent of assets acquired	100.00%
M3 Midstream | West Virginia
Business Acquisition [Line Items]
Percent of assets acquired	40.00%
Vega Energy Partners | West Virginia
Business Acquisition [Line Items]
Percent of assets acquired	15.00%

Acquisition (Schedule of Purcha

Acquisition (Schedule of Purchase Price Allocation) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016	Oct. 01, 2016
Assets
Goodwill	$ 2,293	$ 2,286
Gas Storage and Pipelines Acquisition
Assets
Cash			$ 83
Accounts receivable			24
Inventory			6
Property, plant, and equipment, net			719
Goodwill			275
Other current assets			1
Total assets			1,878
Liabilities
Accounts payable			19
Other current liabilities			11
Long-term debt			204
Other long-term liabilities			20
Total liabilities			254
Less: Noncontrolling interest			392
Total cash consideration			1,232
Gas Storage and Pipelines Acquisition | Customer relationship intangibles
Assets
Intangible assets			$ 770

Regulatory Matters (Details Tex

Regulatory Matters (Details Textuals) - DTE Electric - MPSC $ in Millions	Sep. 08, 2017USD ($)	Jul. 31, 2017USD ($)certificateMW	Jul. 12, 2017USD ($)	Apr. 19, 2017USD ($)	Jan. 31, 2017USD ($)	Aug. 01, 2016USD ($)	Feb. 01, 2016USD ($)	Dec. 31, 2017USD ($)	Mar. 31, 2016USD ($)
Public Utilities, General Disclosures [Line Items]
Estimated recovery challenged amount									$ 13
Estimated recovery disallowed, including interest			$ 16
Amount of power associated with natural gas fueled combined cycle generation facility requesting to build | MW		1,100
Number of certificates of necessity requested to be issued | certificate		3
Estimated capital costs		$ 989
Period post filing with right to amend cost estimate		150 days
Electric Rate Case Filing 2016
Public Utilities, General Disclosures [Line Items]
Requested rate increase							$ 344
Self-implemented base rate						$ 245
Approved annual revenue change					$ 184
Return on equity percent					10.10%
Electric Rate Case Filing 2016 | Refundable self-implemented rates | Scenario, Forecast
Public Utilities, General Disclosures [Line Items]
Authorized amount to be refunded to customers								$ 38.5
Electric Rate Case Filing 2017
Public Utilities, General Disclosures [Line Items]
Requested rate increase	$ 125			$ 231
Return on equity percent				10.10%
Return on equity requested percent				10.50%

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Basic Earnings per Share
Net Income Attributable to DTE Energy Company	$ 270	$ 338	$ 847	$ 737
Less: Allocation of earnings to net restricted stock awards	1	0	2	1
Net income available to common shareholders — basic	$ 269	$ 338	$ 845	$ 736
Average number of common shares outstanding (in shares)	179	179	179	179
Basic Earnings per Common Share (in dollars per share)	$ 1.51	$ 1.88	$ 4.72	$ 4.10
Diluted Earnings per Share
Net Income Attributable to DTE Energy Company	$ 270	$ 338	$ 847	$ 737
Less: Allocation of earnings to net restricted stock awards	1	0	2	1
Net income available to common shareholders — diluted	$ 269	$ 338	$ 845	$ 736
Average number of common shares outstanding (in shares)	179	179	179	179
Incremental shares attributable to:
Average dilutive performance share awards and stock options (in shares)	0	1	0	1
Average number of common shares outstanding - diluted (in shares)	179	180	179	180
Diluted Earnings per Common Share (in dollars per share)	$ 1.51	$ 1.88	$ 4.72	$ 4.10

Fair Value (Assets and Liabilit

Fair Value (Assets and Liabilities Recorded at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivative assets
Derivative assets, gross	$ 439	$ 549
Derivative asset, netting	(301)	(468)
Derivative assets, net	138	81
Derivative liabilities
Derivative liabilities, gross	(409)	(656)
Derivative liability, netting	319	489
Derivative liabilities, net	(90)	(167)
Decommissioning fund outstanding commitments	25
DTE Electric
Derivative liabilities
Decommissioning fund outstanding commitments	25
Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(297)	(493)
Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(112)	(163)
Natural Gas
Derivative assets
Derivative assets, gross	230	348
Derivative asset, netting	(151)	(306)
Derivative assets, net	79	42
Derivative liabilities
Derivative liabilities, gross	(204)	(461)
Derivative liability, netting	151	321
Derivative liabilities, net	(53)	(140)
Electricity
Derivative assets
Derivative assets, gross	202	193
Derivative asset, netting	(148)	(157)
Derivative assets, net	54	36
Derivative liabilities
Derivative liabilities, gross	(199)	(189)
Derivative liability, netting	164	163
Derivative liabilities, net	(35)	(26)
Other
Derivative assets
Derivative assets, gross	4	2
Derivative asset, netting	0	0
Derivative assets, net	4	2
Derivative liabilities
Derivative liabilities, gross	(2)	(3)
Derivative liability, netting	2	2
Derivative liabilities, net	0	(1)
Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	3	6
Derivative asset, netting	(2)	(5)
Derivative assets, net	1	1
Derivative liabilities
Derivative liabilities, gross	(4)	(3)
Derivative liability, netting	2	3
Derivative liabilities, net	(2)	0
Recurring
Assets:
Cash equivalents	19	17
Derivative assets
Derivative asset, netting	(301)	(468)
Derivative assets, net	138	81
Total assets	1,783	1,583
Derivative liabilities
Derivative liability, netting	319	489
Derivative liabilities, net	(90)	(167)
Net Assets (Liabilities) at the end of the period	1,693	1,416
Net Assets (Liabilities) at the end of the period, netting	18	21
Recurring | DTE Electric
Assets:
Cash equivalents	11	11
Derivative assets
Total assets	1,464	1,342
Recurring | Current assets
Derivative assets
Derivative asset, netting	(225)	(400)
Total assets	95	64
Recurring | Current assets | DTE Electric
Derivative assets
Total assets	15	13
Recurring | Noncurrent assets
Derivative assets
Derivative asset, netting	(76)	(68)
Total assets	1,688	1,519
Recurring | Noncurrent assets | DTE Electric
Derivative assets
Total assets	1,449	1,329
Recurring | Current derivative liabilities
Derivative liabilities
Derivative liability, netting	255	424
Derivative liabilities, net	(42)	(69)
Recurring | Noncurrent derivative liabilities
Derivative liabilities
Derivative liability, netting	64	65
Derivative liabilities, net	(48)	(98)
Recurring | Restricted assets
Assets:
Cash equivalents	8	7
Recurring | Other
Assets:
Cash equivalents	11	10
Recurring | Other | DTE Electric
Assets:
Cash equivalents	11	11
Recurring | Natural Gas
Derivative assets
Derivative asset, netting	(151)	(306)
Derivative assets, net	79	42
Derivative liabilities
Derivative liability, netting	151	321
Derivative liabilities, net	(53)	(140)
Recurring | Electricity
Derivative assets
Derivative asset, netting	(148)	(157)
Derivative assets, net	54	36
Derivative liabilities
Derivative liability, netting	164	163
Derivative liabilities, net	(35)	(26)
Recurring | Other
Derivative assets
Derivative asset, netting	0	0
Derivative assets, net	4	2
Derivative liabilities
Derivative liability, netting	2	2
Derivative liabilities, net	0	(1)
Recurring | Foreign currency exchange contracts
Derivative assets
Derivative asset, netting	(2)	(5)
Derivative assets, net	1	1
Derivative liabilities
Derivative liability, netting	2	3
Derivative liabilities, net	(2)	0
Recurring | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	4	2
Recurring | Cash equivalents
Assets:
Nuclear decommissioning trusts	6	8
Other investments	4	3
Recurring | Cash equivalents | DTE Electric
Assets:
Nuclear decommissioning trusts	6	8
Recurring | Equity securities
Assets:
Nuclear decommissioning trusts	949	887
Other investments	120	104
Recurring | Equity securities | DTE Electric
Assets:
Nuclear decommissioning trusts	949	887
Other investments	10	9
Recurring | Fixed income securities
Assets:
Nuclear decommissioning trusts	484	425
Other investments	63	58
Recurring | Fixed income securities | DTE Electric
Assets:
Nuclear decommissioning trusts	484	425
Recurring | Level 1
Assets:
Cash equivalents	16	14
Derivative assets
Derivative assets, gross	64	216
Total assets	1,232	1,301
Derivative liabilities
Derivative liabilities, gross	(64)	(226)
Net Assets (Liabilities) at the end of the period	1,168	1,075
Recurring | Level 1 | DTE Electric
Assets:
Cash equivalents	8	8
Derivative assets
Total assets	983	923
Recurring | Level 1 | Current assets
Derivative assets
Total assets	65	205
Recurring | Level 1 | Current assets | DTE Electric
Derivative assets
Total assets	8	8
Recurring | Level 1 | Noncurrent assets
Derivative assets
Total assets	1,167	1,096
Recurring | Level 1 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	975	915
Recurring | Level 1 | Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(60)	(203)
Recurring | Level 1 | Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(4)	(23)
Recurring | Level 1 | Natural Gas
Derivative assets
Derivative assets, gross	64	216
Derivative liabilities
Derivative liabilities, gross	(64)	(226)
Recurring | Level 1 | Electricity
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Other
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	0	0
Recurring | Level 1 | Cash equivalents
Assets:
Nuclear decommissioning trusts	6	8
Other investments	4	3
Recurring | Level 1 | Cash equivalents | DTE Electric
Assets:
Nuclear decommissioning trusts	6	8
Recurring | Level 1 | Equity securities
Assets:
Nuclear decommissioning trusts	949	887
Other investments	120	104
Recurring | Level 1 | Equity securities | DTE Electric
Assets:
Nuclear decommissioning trusts	949	887
Other investments	10	9
Recurring | Level 1 | Fixed income securities
Assets:
Nuclear decommissioning trusts	10	11
Other investments	63	58
Recurring | Level 1 | Fixed income securities | DTE Electric
Assets:
Nuclear decommissioning trusts	10	11
Recurring | Level 2
Assets:
Cash equivalents	3	3
Derivative assets
Derivative assets, gross	262	239
Total assets	739	656
Derivative liabilities
Derivative liabilities, gross	(239)	(248)
Net Assets (Liabilities) at the end of the period	500	408
Recurring | Level 2 | DTE Electric
Assets:
Cash equivalents	3	3
Derivative assets
Total assets	477	417
Recurring | Level 2 | Current assets
Derivative assets
Total assets	194	199
Recurring | Level 2 | Current assets | DTE Electric
Derivative assets
Total assets	3	3
Recurring | Level 2 | Noncurrent assets
Derivative assets
Total assets	545	457
Recurring | Level 2 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	474	414
Recurring | Level 2 | Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(183)	(211)
Recurring | Level 2 | Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(56)	(37)
Recurring | Level 2 | Natural Gas
Derivative assets
Derivative assets, gross	104	79
Derivative liabilities
Derivative liabilities, gross	(76)	(86)
Recurring | Level 2 | Electricity
Derivative assets
Derivative assets, gross	155	154
Derivative liabilities
Derivative liabilities, gross	(159)	(159)
Recurring | Level 2 | Other
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 2 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	3	6
Derivative liabilities
Derivative liabilities, gross	(4)	(3)
Recurring | Level 2 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	0	0
Recurring | Level 2 | Cash equivalents
Assets:
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 2 | Cash equivalents | DTE Electric
Assets:
Nuclear decommissioning trusts	0	0
Recurring | Level 2 | Equity securities
Assets:
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 2 | Equity securities | DTE Electric
Assets:
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 2 | Fixed income securities
Assets:
Nuclear decommissioning trusts	474	414
Other investments	0	0
Recurring | Level 2 | Fixed income securities | DTE Electric
Assets:
Nuclear decommissioning trusts	474	414
Recurring | Level 3
Assets:
Cash equivalents	0	0
Derivative assets
Derivative assets, gross	113	94
Total assets	113	94
Derivative liabilities
Derivative liabilities, gross	(106)	(182)
Net Assets (Liabilities) at the end of the period	7	(88)
Recurring | Level 3 | DTE Electric
Assets:
Cash equivalents	0	0
Derivative assets
Total assets	4	2
Recurring | Level 3 | Current assets
Derivative assets
Total assets	61	60
Recurring | Level 3 | Current assets | DTE Electric
Derivative assets
Total assets	4	2
Recurring | Level 3 | Noncurrent assets
Derivative assets
Total assets	52	34
Recurring | Level 3 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	0	0
Recurring | Level 3 | Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(54)	(79)
Recurring | Level 3 | Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(52)	(103)
Recurring | Level 3 | Natural Gas
Derivative assets
Derivative assets, gross	62	53
Derivative liabilities
Derivative liabilities, gross	(64)	(149)
Recurring | Level 3 | Electricity
Derivative assets
Derivative assets, gross	47	39
Derivative liabilities
Derivative liabilities, gross	(40)	(30)
Recurring | Level 3 | Other
Derivative assets
Derivative assets, gross	4	2
Derivative liabilities
Derivative liabilities, gross	(2)	(3)
Recurring | Level 3 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 3 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	4	2
Recurring | Level 3 | Cash equivalents
Assets:
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Cash equivalents | DTE Electric
Assets:
Nuclear decommissioning trusts	0	0
Recurring | Level 3 | Equity securities
Assets:
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Equity securities | DTE Electric
Assets:
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Fixed income securities
Assets:
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Fixed income securities | DTE Electric
Assets:
Nuclear decommissioning trusts	$ 0	$ 0

Fair Value (Reconciliation of L

Fair Value (Reconciliation of Level 3 Assets and Liabilities at Fair Value on a Recurring Basis) (Details) - Recurring - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	$ (6)	$ (69)	$ (88)	$ (4)
Transfers into Level 3 from Level 2	0	0	0	0
Transfers from Level 3 into Level 2	0	(1)	0	0
Total gains (losses):
Included in earnings	26	(41)	84	(144)
Recorded in/Change in fair value recorded in Regulatory liabilities	2	2	15	6
Purchases, issuances, and settlements
Issuances			0	1
Settlements	(15)	2	(4)	34
Net Assets (Liabilities) as of end of period	7	(107)	7	(107)
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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	11	(44)	43	(164)
DTE Electric
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	8	4	2	3
Total gains (losses):
Recorded in/Change in fair value recorded in Regulatory liabilities	2	2	15	6
Purchases, issuances, and settlements
Settlements	(6)	(3)	(13)	(6)
Net Assets (Liabilities) as of end of period	4	3	4	3
The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets held at September 30, 2017 and 2016 and reflected in DTE Electric's Consolidated Statements of Financial Position	1	1	4	3
Natural Gas
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	(17)	(62)	(96)	(5)
Transfers into Level 3 from Level 2	0	0	0	0
Transfers from Level 3 into Level 2	0	(1)	0	0
Total gains (losses):
Included in earnings	(8)	(65)	38	(123)
Recorded in/Change in fair value recorded in Regulatory liabilities	0	0	0	0
Purchases, issuances, and settlements
Issuances			0	0
Settlements	23	28	56	28
Net Assets (Liabilities) as of end of period	(2)	(100)	(2)	(100)
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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(8)	(50)	8	(165)
Electricity
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	6	(6)	9	6
Transfers into Level 3 from Level 2	0	0	0	0
Transfers from Level 3 into Level 2	0	0	0	0
Total gains (losses):
Included in earnings	33	24	45	(22)
Recorded in/Change in fair value recorded in Regulatory liabilities	0	0	0	0
Purchases, issuances, and settlements
Issuances			0	1
Settlements	(32)	(24)	(47)	9
Net Assets (Liabilities) as of end of period	7	(6)	7	(6)
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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	18	6	35	(1)
Other
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	5	(1)	(1)	(5)
Transfers into Level 3 from Level 2	0	0	0	0
Transfers from Level 3 into Level 2	0	0	0	0
Total gains (losses):
Included in earnings	1	0	1	1
Recorded in/Change in fair value recorded in Regulatory liabilities	2	2	15	6
Purchases, issuances, and settlements
Issuances			0	0
Settlements	(6)	(2)	(13)	(3)
Net Assets (Liabilities) as of end of period	2	(1)	2	(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 September 30, 2017 and 2016 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	$ 1	$ 0	$ 0	$ 2

Fair Value (Unobservable Inputs

Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)$ / MMBTU$ / MWh	Dec. 31, 2016USD ($)$ / MMBTU$ / MWh
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	$ 439	$ 549
Derivative Liabilities	(409)	(656)
Recurring | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	113	94
Derivative Liabilities	(106)	(182)
Natural Gas
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	230	348
Derivative Liabilities	(204)	(461)
Natural Gas | Recurring | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	62	53
Derivative Liabilities	$ (64)	$ (149)
Natural Gas | Minimum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(1.92)	(1)
Natural Gas | Maximum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	6.36	7.90
Natural Gas | Weighted Average | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(0.03)	(0.05)
Electricity
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	$ 202	$ 193
Derivative Liabilities	(199)	(189)
Electricity | Recurring | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	47	39
Derivative Liabilities	$ (40)	$ (30)
Electricity | Minimum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(10)	(6)
Electricity | Maximum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MWh	7	12
Electricity | Weighted Average | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MWh	1	1

Fair Value (Fair Value of Finan

Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Carrying amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	$ 36	$ 36
Dividends payable	148	148
Short-term borrowings	659	499
Notes payable — Other	16	17
Long-term debt	11,897	11,270
Carrying amount | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	5
Short-term borrowings	311	62
Notes payable — Other	5	6
Long-term debt	6,016	5,878
Carrying amount | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	66	117
Fair value | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Dividends payable	148	148
Short-term borrowings	0	0
Notes payable — Other	0	0
Long-term debt	1,554	1,465
Fair value | Level 1 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	0	0
Notes payable — Other	0	0
Long-term debt	0	0
Fair value | Level 1 | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	0	0
Fair value | 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	659	499
Notes payable — Other	0	0
Long-term debt	10,522	9,384
Fair value | Level 2 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	311	62
Notes payable — Other	0	0
Long-term debt	6,395	6,026
Fair value | Level 2 | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	0	0
Fair value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	36	36
Dividends payable	0	0
Short-term borrowings	0	0
Notes payable — Other	16	17
Long-term debt	744	1,056
Fair value | Level 3 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	5
Short-term borrowings	0	0
Notes payable — Other	5	6
Long-term debt	163	264
Fair value | Level 3 | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	$ 66	$ 117

Fair Value (Fair Value of Nucle

Fair Value (Fair Value of Nuclear Decommissioning Trust Fund Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 1,439	$ 1,320
DTE Electric
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,439	1,320
DTE Electric | Nuclear decommissioning trust fund
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,439	1,320
DTE Electric | Nuclear decommissioning trust fund | Fermi 2
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,423	1,291
DTE Electric | Nuclear decommissioning trust fund | Fermi 1
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	3	3
DTE Electric | Nuclear decommissioning trust fund | Low-level radioactive waste
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 13	$ 26

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	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Available-for-sale Securities [Line Items]
Realized gains	$ 14	$ 13	$ 63	$ 59
Realized losses	(7)	(8)	(23)	(48)
Proceeds from sale of securities	$ 246	$ 394	$ 951	$ 1,135

Fair Value (Fair Value and Unre

Fair Value (Fair Value and Unrealized Gains and Losses for the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - Nuclear decommissioning trust fund - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Equity securities, fair value	$ 949	$ 887
Fixed income securities, fair value	484	425
Cash equivalents, fair value	6	8
Fair Value	1,439	1,320
Equity securities, unrealized gains	287	222
Fixed income securities, unrealized gains	14	11
Unrealized Gains	301	233
Equity securities, unrealized losses	(34)	(46)
Fixed income securities, unrealized losses	(2)	(5)
Unrealized Losses	$ (36)	$ (51)

Fair Value (Fair Value of Fixed

Fair Value (Fair Value of Fixed Income Securities Held in Nuclear Decommissioning Trust Funds (Details) - Fixed income securities - Nuclear decommissioning trust fund $ in Millions	Sep. 30, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 15
Due after one through five years	100
Due after five through ten years	111
Due after ten years	258
Available-for-sale securities total	$ 484

Fair Value (Details Textuals)

Fair Value (Details Textuals) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fair Value, Option, Quantitative Disclosures [Line Items]
Trading securities realized gain (loss)	$ 6,000,000	$ 5,000,000	$ 19,000,000	$ 15,000,000
DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Trading securities realized gain (loss)	6,000,000	5,000,000	19,000,000	15,000,000
Accumulated net unrealized investment gain (loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	0	0	0	0
Accumulated net unrealized investment gain (loss) | DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	$ 0	$ 0	$ 0	$ 0

Financial and Other Derivativ52

Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 439	$ 549
Derivative Liabilities	(409)	(656)
Current derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	301	447
Current derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(297)	(493)
Noncurrent derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	138	102
Noncurrent derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(112)	(163)
Natural Gas
Derivatives, Fair Value [Line Items]
Derivative Assets	230	348
Derivative Liabilities	(204)	(461)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	202	193
Derivative Liabilities	(199)	(189)
Other
Derivatives, Fair Value [Line Items]
Derivative Assets	4	2
Derivative Liabilities	(2)	(3)
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	3	6
Derivative Liabilities	(4)	(3)
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	439	549
Derivative Liabilities	(409)	(656)
Derivatives not designated as hedging instruments | DTE Electric
Derivatives, Fair Value [Line Items]
Derivative Assets	4	2
Derivatives not designated as hedging instruments | Natural Gas
Derivatives, Fair Value [Line Items]
Derivative Assets	230	348
Derivative Liabilities	(204)	(461)
Derivatives not designated as hedging instruments | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	202	193
Derivative Liabilities	(199)	(189)
Derivatives not designated as hedging instruments | Other
Derivatives, Fair Value [Line Items]
Derivative Assets	4	2
Derivative Liabilities	(2)	(3)
Derivatives not designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	3	6
Derivative Liabilities	(4)	(3)
Derivatives not designated as hedging instruments | FTRs — Other current assets | DTE Electric
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 4	$ 2

Financial and Other Derivativ53

Financial and Other Derivative Instruments (Details Textuals) - USD ($)	Sep. 30, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Letters of credit that could be used to offset net derivative liabilities	$ 2,000,000	$ 2,000,000
Letters of credit received that could be used to offset net derivative assets	3,000,000	2,000,000
Cash collateral posted, net of cash collateral received	42,000,000	34,000,000
Collateral adjustment on derivative assets	12,000,000	7,000,000
Collateral adjustment on derivative liabilities	30,000,000	28,000,000
Cash collateral paid	25,000,000	18,000,000
Cash collateral received	1,000,000	$ 5,000,000
Additional collateral, aggregate fair value	470,000,000
Derivative net liability position aggregate fair value	339,000,000
Collateral already posted fair value	0
Derivative net asset position, fair value	276,000,000
Remaining amount of offsets to derivative net liability positions for hard and soft trigger provisions	$ 63,000,000

Financial and Other Derivativ54

Financial and Other Derivative Instruments (Netting Offsets of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivative assets
Derivative assets	$ 439	$ 549
Gross Amounts Offset in the Consolidated Statements of Financial Position	(301)	(468)
Derivative assets, net	138	81
Derivative liabilities
Derivative liabilities	(409)	(656)
Gross Amounts Offset in the Consolidated Statements of Financial Position	319	489
Derivative liabilities, net	(90)	(167)
Natural Gas
Derivative assets
Derivative assets	230	348
Gross Amounts Offset in the Consolidated Statements of Financial Position	(151)	(306)
Derivative assets, net	79	42
Derivative liabilities
Derivative liabilities	(204)	(461)
Gross Amounts Offset in the Consolidated Statements of Financial Position	151	321
Derivative liabilities, net	(53)	(140)
Electricity
Derivative assets
Derivative assets	202	193
Gross Amounts Offset in the Consolidated Statements of Financial Position	(148)	(157)
Derivative assets, net	54	36
Derivative liabilities
Derivative liabilities	(199)	(189)
Gross Amounts Offset in the Consolidated Statements of Financial Position	164	163
Derivative liabilities, net	(35)	(26)
Other
Derivative assets
Derivative assets	4	2
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	0
Derivative assets, net	4	2
Derivative liabilities
Derivative liabilities	(2)	(3)
Gross Amounts Offset in the Consolidated Statements of Financial Position	2	2
Derivative liabilities, net	0	(1)
Foreign currency exchange contracts
Derivative assets
Derivative assets	3	6
Gross Amounts Offset in the Consolidated Statements of Financial Position	(2)	(5)
Derivative assets, net	1	1
Derivative liabilities
Derivative liabilities	(4)	(3)
Gross Amounts Offset in the Consolidated Statements of Financial Position	2	3
Derivative liabilities, net	$ (2)	$ 0

Financial and Other Derivativ55

Financial and Other Derivative Instruments (Netting Offsets Reconciliation to Balance Sheet) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Derivative Assets
Derivative assets	$ 439	$ 549
Collateral adjustment	(12)	(7)
Derivative assets, current	76	47
Derivative assets, noncurrent	62	34
Derivative Liabilities
Derivative liabilities	(409)	(656)
Collateral adjustment	30	28
Derivative liabilities, current	(42)	(69)
Derivative liabilities, noncurrent	(48)	(98)
Current derivative assets
Derivative Assets
Derivative assets	301	447
Counterparty netting	(225)	(396)
Collateral adjustment	0	(4)
Derivative assets, current	76	47
Noncurrent derivative assets
Derivative Assets
Derivative assets	138	102
Counterparty netting	(64)	(65)
Collateral adjustment	(12)	(3)
Derivative assets, noncurrent	62	34
Current derivative liabilities
Derivative Liabilities
Derivative liabilities	(297)	(493)
Counterparty netting	225	396
Collateral adjustment	30	28
Derivative liabilities, current	(42)	(69)
Noncurrent derivative liabilities
Derivative Liabilities
Derivative liabilities	(112)	(163)
Counterparty netting	64	65
Collateral adjustment	0	0
Derivative liabilities, noncurrent	$ (48)	$ (98)

Financial and Other Derivativ56

Financial and Other Derivative Instruments (Effect of Derivatives not Designated as Hedging Instruments on the Consolidated Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	$ 29	$ (19)	$ 156	$ (84)
Natural Gas | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	(14)	16	63	(70)
Natural Gas | Fuel, purchased power, and gas — non-utility
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	10	(59)	56	(27)
Electricity | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	33	23	39	18
Other | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	2	1	1	(1)
Foreign currency exchange contracts | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	$ (2)	$ 0	$ (3)	$ (4)

Financial and Other Derivativ57

Financial and Other Derivative Instruments (Cumulative Gross Volume of Derivative Contracts Outstanding) (Details)	9 Months Ended
	Sep. 30, 2017CADMWhMMBTU
Natural Gas (MMBtu)
Derivative [Line Items]
Commodity | MMBTU	1,751,191,598
Electricity (MWh)
Derivative [Line Items]
Commodity | MWh	28,924,416
Foreign Currency Exchange (Canadian dollars)
Derivative [Line Items]
Foreign Currency Exchange (Canadian dollars) | CAD	CAD 89,049,511

Long-Term Debt (Details)

Long-Term Debt (Details)	9 Months Ended
	Sep. 30, 2017USD ($)
Debt Instrument [Line Items]
Debt issued	$ 1,020,000,000
Debt redeemed	$ 385,000,000
DTE Electric | Senior Notes | 5.60% Senior Notes due 2018
Debt Instrument [Line Items]
Interest rate	5.60%
Debt redeemed	$ 300,000,000
DTE Electric | Mortgage Bonds | August 2017 3.75% General and Refunding Mortgage Bonds maturing in 2047
Debt Instrument [Line Items]
Interest rate	3.75%
Debt issued	$ 440,000,000
DTE Gas | Mortgage Bonds | September 2017 3.08% First Mortgage Bonds maturing in 2029
Debt Instrument [Line Items]
Interest rate	3.08%
Debt issued	$ 40,000,000
DTE Gas | Mortgage Bonds | September 2017 3.75% First Mortgage Bonds maturing in 2047
Debt Instrument [Line Items]
Interest rate	3.75%
Debt issued	$ 40,000,000
DTE Energy | Senior Notes | March 2017 3.80% Senior Notes due 2027
Debt Instrument [Line Items]
Interest rate	3.80%
Debt issued	$ 500,000,000
DTE Energy | Secured Note | 7.29% Secured Note due 2029
Debt Instrument [Line Items]
Interest rate	7.29%
Debt redeemed	$ 77,000,000
DTE Energy | Other Long-Term Debt
Debt Instrument [Line Items]
Debt redeemed	8,000,000
DTE Energy | Other Long-Term Debt | Gas Storage and Pipelines
Debt Instrument [Line Items]
Net loss on extinguishment of debt	16,000,000
Loss related to early redemption premiums	20,000,000
Unamortized debt premiums	$ 4,000,000

Short-Term Credit Arrangement59

Short-Term Credit Arrangements and Borrowings (Details Textuals)	Sep. 30, 2017USD ($)	Dec. 31, 2016USD ($)
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 791,000,000
Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 132,000,000
DTE Energy
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.54
Other outstanding letters of credit	$ 230,000,000
DTE Energy | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	132,000,000
DTE Energy | Demand financing agreement
Short-term Debt [Line Items]
Maximum borrowing capacity, financing agreement	100,000,000
Maximum additional margin financing	50,000,000
Amount outstanding	32,000,000	$ 50,000,000
DTE Energy | Demand financing agreement plus letter of credit
Short-term Debt [Line Items]
Maximum borrowing capacity, financing agreement	100,000,000
DTE Energy | Other outstanding letters of credit | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 17,000,000
DTE Electric
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.51
Other outstanding letters of credit	$ 311,000,000
DTE Electric | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
DTE Gas
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.48
Other outstanding letters of credit	$ 250,000,000
DTE Gas | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
Maximum
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.65

Short-Term Credit Arrangement60

Short-Term Credit Arrangements and Borrowings (Details)	Sep. 30, 2017USD ($)
Availability under combined facilities
Maximum borrowing capacity	$ 2,120,000,000
Amounts outstanding	791,000,000
Net availability	1,329,000,000
DTE Electric
Availability under combined facilities
Maximum borrowing capacity	400,000,000
Amounts outstanding	311,000,000
Net availability	89,000,000
DTE Gas
Availability under combined facilities
Maximum borrowing capacity	300,000,000
Amounts outstanding	250,000,000
Net availability	50,000,000
DTE Energy
Availability under combined facilities
Maximum borrowing capacity	1,420,000,000
Amounts outstanding	230,000,000
Net availability	1,190,000,000
Letter of credit
Availability under combined facilities
Amounts outstanding	132,000,000
Letter of credit | DTE Electric
Availability under combined facilities
Amounts outstanding	0
Letter of credit | DTE Gas
Availability under combined facilities
Amounts outstanding	0
Letter of credit | DTE Energy
Availability under combined facilities
Amounts outstanding	132,000,000
Letter of credit | Unsecured letter of credit facility, expiring in February 2019
Availability under combined facilities
Maximum borrowing capacity	150,000,000
Letter of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Electric
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Gas
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Energy
Availability under combined facilities
Maximum borrowing capacity	150,000,000
Letter of credit | Unsecured letter of credit facility, expiring in September 2019
Availability under combined facilities
Maximum borrowing capacity	70,000,000
Letter of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Electric
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Gas
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Energy
Availability under combined facilities
Maximum borrowing capacity	70,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022
Availability under combined facilities
Maximum borrowing capacity	1,900,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Electric
Availability under combined facilities
Maximum borrowing capacity	400,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Gas
Availability under combined facilities
Maximum borrowing capacity	300,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Energy
Availability under combined facilities
Maximum borrowing capacity	1,200,000,000
Commercial paper issuances
Availability under combined facilities
Amounts outstanding	659,000,000
Commercial paper issuances | DTE Electric
Availability under combined facilities
Amounts outstanding	311,000,000
Commercial paper issuances | DTE Gas
Availability under combined facilities
Amounts outstanding	250,000,000
Commercial paper issuances | DTE Energy
Availability under combined facilities
Amounts outstanding	$ 98,000,000

Commitments and Contingencies (

Commitments and Contingencies (Details Textuals) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2017USD ($)employeefacilityNOVsite	Dec. 31, 2016USD ($)	Sep. 07, 2016state	Jul. 31, 2009plant
Loss Contingencies [Line Items]
Unrecorded unconditional purchase obligation	$ 2,500
Workforce subject to collective bargaining arrangements | Labor force concentration risk
Loss Contingencies [Line Items]
Number of employees | employee	4,800
Synthetic fuel
Loss Contingencies [Line Items]
Number of days after expiration of statutes of limitations	90 days
Maximum potential liability	$ 620
Reduced emissions fuel guarantees
Loss Contingencies [Line Items]
Number of days after expiration of statutes of limitations	90 days
Maximum potential liability	$ 364
NEXUS pipeline
Loss Contingencies [Line Items]
Guarantee termination, minimum threshold, period following end of primary term of capacity lease agreements	2 months
Other guarantees
Loss Contingencies [Line Items]
Maximum potential liability	$ 55
Performance surety bonds
Loss Contingencies [Line Items]
Performance bonds outstanding	$ 57
DTE Electric
Loss Contingencies [Line Items]
Number of states with NOX emissions from power plants | state			22
Number of power plants in violation | plant				5
Number of NOVs/FOVs | NOV	2
Environmental capital expenditures through prior year end		$ 2,400
Number of former Mgp sites | site	3
Accrued for remediation	$ 8	8
Number of permitted engineered coal ash storage facilities owned | facility	3
Time period to comply with coal combustion residual requirements and effluent limitations guidelines	6 years
Unrecorded unconditional purchase obligation	$ 1,500
DTE Electric | Workforce subject to collective bargaining arrangements | Labor force concentration risk
Loss Contingencies [Line Items]
Number of employees | employee	2,600
DTE Electric | Coal combustion residual rule
Loss Contingencies [Line Items]
Estimated costs associated with building new facilities	$ 311
DTE Gas
Loss Contingencies [Line Items]
Number of former Mgp sites | site	14
Accrued for remediation	$ 41	$ 43
Amortization period (in years)	10 years
DTE Gas | NEXUS pipeline
Loss Contingencies [Line Items]
Maximum potential liability	$ 75
Lease agreement term	15 years
Percentage of payment obligations due	50.00%
DTE Gas | Clean up completed and site closed
Loss Contingencies [Line Items]
Number of former Mgp sites | site	6
DTE Gas | Partial closure complete
Loss Contingencies [Line Items]
Number of former Mgp sites | site	6
Texas Eastern Transmission, LP | NEXUS pipeline
Loss Contingencies [Line Items]
Maximum potential liability	$ 9
Lease agreement term	15 years
Percentage of payment obligations due	50.00%

Retirement Benefits and Trust62

Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	$ 22	$ 23	$ 69	$ 69
Interest cost	53	55	160	164
Expected return on plan assets	(78)	(77)	(233)	(232)
Amortization of net actuarial loss	46	43	132	124
Amortization of prior service cost (credit)	1	0	1	0
Net periodic benefit cost (credit)	44	44	129	125
Pension Benefits | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	16	18	53	53
Interest cost	40	42	121	125
Expected return on plan assets	(56)	(55)	(167)	(165)
Amortization of net actuarial loss	32	31	94	88
Amortization of prior service cost (credit)	1	0	1	1
Net periodic benefit cost (credit)	33	36	102	102
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	7	7	20	20
Interest cost	18	20	55	60
Expected return on plan assets	(33)	(33)	(98)	(97)
Amortization of net actuarial loss	3	6	10	22
Amortization of prior service cost (credit)	(3)	(29)	(10)	(88)
Net periodic benefit cost (credit)	(8)	(29)	(23)	(83)
Other Postretirement Benefits | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Service cost	5	5	15	15
Interest cost	14	15	42	46
Expected return on plan assets	(23)	(23)	(68)	(68)
Amortization of net actuarial loss	2	4	6	15
Amortization of prior service cost (credit)	(2)	(22)	(7)	(66)
Net periodic benefit cost (credit)	$ (4)	$ (21)	$ (12)	$ (58)

Retirement Benefits and Trust63

Retirement Benefits and Trusteed Assets (Details Textuals)	9 Months Ended
	Sep. 30, 2017USD ($)
Pension Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Contributions by employer	$ 220,000,000
Maximum contribution amount	88,000,000
Pension Benefits | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Contributions by employer	185,000,000
Maximum contribution amount	85,000,000
Other Postretirement Benefits
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Maximum contribution amount	$ 0

Segment and Related Informati64

Segment and Related Information (Details Textuals) customer in Millions	Sep. 30, 2017customer
Segment Reporting [Abstract]
Number of electric utility customers	2.2
Number of gas utility customers	1.3

Segment and Related Informati65

Segment and Related Information (Financial Data - Inter-segment Billing) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting Information [Line Items]
Revenues	$ (3,245)	$ (2,928)	$ (9,336)	$ (7,756)
Reconciliation and Eliminations
Segment Reporting Information [Line Items]
Revenues	169	210	565	553
Reconciliation and Eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	11	15	36	32
Reconciliation and Eliminations | Gas
Segment Reporting Information [Line Items]
Revenues	1	5	6	8
Reconciliation and Eliminations | Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Revenues	10	2	32	7
Reconciliation and Eliminations | Power and Industrial Projects
Segment Reporting Information [Line Items]
Revenues	138	178	462	476
Reconciliation and Eliminations | Energy Trading
Segment Reporting Information [Line Items]
Revenues	8	10	27	28
Reconciliation and Eliminations | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	$ 1	$ 0	$ 2	$ 2

Segment and Related Informati66

Segment and Related Information (Financial Data - Operating Revenues including Inter-segment Revenues) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Utility operations	$ 1,573	$ 1,748	$ 4,714	$ 4,847
Operating Revenues — Non-utility operations	1,672	1,180	4,622	2,909
Revenues	3,245	2,928	9,336	7,756
Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	(169)	(210)	(565)	(553)
Revenues	(169)	(210)	(565)	(553)
Electric | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Utility operations	1,434	1,608	3,827	3,976
Electric | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(11)	(15)	(36)	(32)
Gas | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Utility operations	152	160	929	911
Gas | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(1)	(5)	(6)	(8)
Gas Storage and Pipelines | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	115	63	333	199
Gas Storage and Pipelines | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(10)	(2)	(32)	(7)
Power and Industrial Projects | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	537	524	1,592	1,414
Power and Industrial Projects | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(138)	(178)	(462)	(476)
Energy Trading | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	1,174	782	3,217	1,807
Energy Trading | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(8)	(10)	(27)	(28)
Corporate and Other | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	2	1	3	2
Corporate and Other | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ (1)	$ 0	$ (2)	$ (2)

Segment and Related Informati67

Segment and Related Information (Financial Data - Net Income (Loss) Attributable to DTE Energy by Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	$ 270	$ 338	$ 847	$ 737
Electric
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	219	285	463	547
Gas
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	(15)	(4)	93	96
Gas Storage and Pipelines
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	36	28	121	93
Power and Industrial Projects
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	44	34	104	66
Energy Trading
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	1	(4)	97	(34)
Corporate and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	$ (15)	$ (1)	$ (31)	$ (31)