DTE Energy (DTE) 10-K 16 Feb 18 2017 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2017	Jan. 31, 2018	Jun. 30, 2017
Entity Information [Line Items]
Entity Registrant Name	DTE ENERGY CO
Entity Central Index Key	936,340
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		179,385,962
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 18,700,000,000
DTE Electric
Entity Information [Line Items]
Entity Registrant Name	DTE ELECTRIC CO
Entity Central Index Key	28,385
Current Fiscal Year End Date	--12-31
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2017
Document Fiscal Year Focus	2,017
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Common Stock, Shares Outstanding		138,632,324
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Revenues
Utility operations	$ 6,434	$ 6,497	$ 6,238
Non-utility operations	6,173	4,133	4,099
Operating Revenues	12,607	10,630	10,337
Operating Expenses
Fuel, purchased power, and gas — utility	1,881	1,968	2,081
Fuel, purchased power, and gas — non-utility	5,283	3,562	3,481
Operation and maintenance	2,335	2,302	2,214
Depreciation and amortization	1,030	976	852
Taxes other than income	391	370	364
Asset (gains) losses and impairments, net	(41)	(7)	(106)
Operating Expenses	10,961	9,185	9,098
Operating Income	1,646	1,445	1,239
Other (Income) and Deductions
Interest expense	536	472	450
Interest income	(12)	(20)	(13)
Other income	(268)	(207)	(209)
Other expenses	103	95	61
Other (Income) and Deductions	359	340	289
Income Before Income Taxes	1,287	1,105	950
Income Tax Expense	175	271	230
Net Income	1,112	834	720
Less: Net Loss Attributable to Noncontrolling Interests	(22)	(34)	(7)
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 1,134	$ 868	$ 727
Basic Earnings per Common Share
Net income attributable to DTE Energy Company (in dollars per share)	$ 6.32	$ 4.84	$ 4.05
Diluted Earnings per Common Share
Net income attributable to DTE Energy Company (in dollars per share)	$ 6.32	$ 4.83	$ 4.05
Weighted Average Common Shares Outstanding
Basic (in shares)	179	179	179
Diluted (in shares)	179	179	179
Dividends Declared per Common Share	$ 3.36	$ 3.06	$ 2.84
DTE Electric
Operating Revenues
Utility operations	$ 5,102	$ 5,225	$ 4,900
Operating Revenues	5,102	5,225
Operating Expenses
Fuel and purchased power — utility	1,454	1,532	1,574
Operation and maintenance	1,428	1,455	1,342
Depreciation and amortization	753	750	633
Taxes other than income	302	284	277
Operating Expenses	3,937	4,021	3,826
Operating Income	1,165	1,204	1,074
Other (Income) and Deductions
Interest expense	274	264	258
Interest income	0	(8)	0
Other income	(77)	(61)	(60)
Other expenses	40	34	40
Other (Income) and Deductions	237	229	238
Income Before Income Taxes	928	975	836
Income Tax Expense	327	353	292
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 601	$ 622	$ 544

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Sep. 30, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Net Income		$ 1,112	$ 834	$ 720
Net Income	$ 270	1,134	868	727
Other comprehensive income (loss), net of tax:
Benefit obligations, net of taxes		10	11	13
Net unrealized gains on derivatives during the period, net of taxes		1	0	0
Net unrealized gains on investments during the period, net of taxes		1	1	1
Foreign currency translation		1	0	(4)
Other comprehensive income		13	12	10
Comprehensive income		1,125	846	730
Less: Comprehensive loss attributable to noncontrolling interests		(22)	(34)	(7)
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company		1,147	880	737
DTE Electric
Net Income	219	601	622	544
Other comprehensive income (loss), net of tax:
Transfer of benefit obligations, net of taxes		0	0	27
Net unrealized gains on investments during the period, net of taxes		1	0	1
Other comprehensive income		1	0	28
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company		$ 602	$ 622	$ 572

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Tax effect on benefit obligation	$ 5	$ 6	$ 8
Tax effect, net unrealized gains on derivatives	0	0	0
Tax effect on net unrealized gains (losses) on investments during the period	1	1	0
DTE Electric
Tax effect on transfer of benefit obligations			18
Tax effect on net unrealized gains (losses) on investments during the period	$ 1	$ 0	$ 0

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Assets
Cash and cash equivalents	$ 66	$ 92
Restricted cash	23	21
Accounts receivable (less allowance for doubtful accounts)
Customer	1,758	1,522
Other	98	71
Inventories
Fuel and gas	399	416
Materials and supplies	380	356
Derivative assets	103	47
Regulatory assets	55	42
Other	199	195
Total Current Assets	3,081	2,762
Investments
Nuclear decommissioning trust funds	1,492	1,320
Investments in equity method investees	1,073	752
Other	232	201
Total Investments	2,797	2,273
Property
Property, plant, and equipment	31,424	30,029
Accumulated depreciation and amortization	(10,703)	(10,299)
Property, plant and equipment, net	20,721	19,730
Other Assets
Goodwill	2,293	2,286
Regulatory assets	3,723	3,871
Intangible assets	867	842
Notes receivable	73	73
Derivative assets	51	34
Other	161	170
Total Other Assets	7,168	7,276
Total Assets	33,767	32,041
Current Liabilities
Accounts payable	1,171	1,079
Accounts payable
Accrued interest	111	96
Dividends payable	158	148
Short-term borrowings	621	499
Current portion long-term debt, including capital leases	109	14
Derivative liabilities	99	69
Regulatory liabilities	18	34
Short-term borrowings
Other	525	498
Total Current Liabilities	2,812	2,437
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	11,039	10,506
Junior subordinated debentures	1,145	756
Capital lease obligations	1	7
Total Long-Term Debt (net of current portion)	12,185	11,269
Other Liabilities
Deferred income taxes	1,888	4,162
Regulatory liabilities	2,875	555
Asset retirement obligations	2,320	2,197
Unamortized investment tax credit	122	93
Derivative liabilities	47	98
Accrued pension liability	924	1,152
Accrued postretirement liability	61	36
Nuclear decommissioning	220	194
Other	323	349
Total Other Liabilities	8,780	8,836
Commitments and Contingencies
Equity
Common stock	3,989	4,030
Retained earnings	5,643	5,114
Accumulated other comprehensive (loss) income	(120)	(133)
Total DTE Energy Company/DTE Electric Company Equity	9,512	9,011
Noncontrolling interests	478	488
Total Equity	9,990	9,499
Total Liabilities and Equity	33,767	32,041
DTE Electric
Current Assets
Cash and cash equivalents	15	13
Accounts receivable (less allowance for doubtful accounts)
Customer	791	728
Affiliates	20	12
Other	37	29
Inventories
Fuel and gas	190	225
Materials and supplies	275	271
Regulatory assets	50	36
Other	68	63
Total Current Assets	1,446	1,377
Investments
Nuclear decommissioning trust funds	1,492	1,320
Other	36	36
Total Investments	1,528	1,356
Property
Property, plant, and equipment	22,972	22,094
Accumulated depreciation and amortization	(7,984)	(7,721)
Property, plant and equipment, net	14,988	14,373
Other Assets
Regulatory assets	3,005	3,113
Intangible assets	25	31
Prepaid postretirement costs — affiliates	113	114
Other	123	125
Total Other Assets	3,266	3,383
Total Assets	21,228	20,489
Accounts payable
Affiliates	52	58
Other	416	452
Accrued interest	72	65
Current portion long-term debt, including capital leases	5	6
Regulatory liabilities	17	27
Short-term borrowings
Affiliates	116	117
Other	238	62
Other	145	146
Total Current Liabilities	1,061	933
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	6,017	5,878
Capital lease obligations	1	7
Total Long-Term Debt (net of current portion)	6,018	5,885
Other Liabilities
Deferred income taxes	2,088	3,793
Regulatory liabilities	2,137	229
Asset retirement obligations	2,125	2,012
Unamortized investment tax credit	120	90
Nuclear decommissioning	220	194
Accrued pension liability — affiliates	811	1,008
Accrued postretirement liability — affiliates	311	269
Other	72	81
Total Other Liabilities	7,884	7,676
Commitments and Contingencies
Equity
Common stock	4,306	4,206
Retained earnings	1,956	1,787
Accumulated other comprehensive (loss) income	3	2
Total DTE Energy Company/DTE Electric Company Equity	6,265	5,995
Total Liabilities and Equity	$ 21,228	$ 20,489

Consolidated Statements of Fin6

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Current Assets:
Allowance for doubtful accounts	$ 49	$ 41
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 0	$ 0
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	179,386,967	179,432,581
Common stock, shares outstanding (in shares)	179,386,967	179,432,581
DTE Electric
Current Assets:
Allowance for doubtful accounts	$ 31	$ 25
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 10	$ 10
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	138,632,234	138,632,324
Common stock, shares outstanding (in shares)	138,632,234	138,632,324

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating Activities
Net Income	$ 1,112	$ 834	$ 720
Net Income	1,134	868	727
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	1,030	976	852
Nuclear fuel amortization	53	58	46
Allowance for equity funds used during construction	(23)	(21)	(21)
Deferred income taxes	196	265	237
Equity earnings of equity method investees	(102)	(68)	(66)
Dividends from equity method investees	74	68	64
Asset (gains) losses and impairments, net	38	8	107
Changes in assets and liabilities:
Accounts receivable, net	(252)	(226)	259
Inventories	(4)	37	1
Accounts payable	129	145	(158)
Accrued pension liability	(228)	19	(147)
Accrued postretirement liability	25	(192)	(287)
Derivative assets and liabilities	(94)	126	47
Regulatory assets and liabilities	217	(40)	85
Other current and noncurrent assets and liabilities	(54)	95	177
Net cash from operating activities	2,117	2,084	1,916
Investing Activities
Plant and equipment expenditures — utility	(2,037)	(1,898)	(1,817)
Plant and equipment expenditures — non-utility	(213)	(147)	(203)
Acquisition, net of cash acquired	0	(1,147)	(241)
Restricted cash for debt redemption, principally Securitization, net	(2)	1	97
Proceeds from sale of nuclear decommissioning trust fund assets	1,240	1,457	885
Investment in nuclear decommissioning trust funds	(1,226)	(1,463)	(898)
Distributions from equity method investees	10	11	19
Contributions to equity method investees	(299)	(239)	(98)
Other	(37)	37	52
Net cash used for investing activities	(2,564)	(3,388)	(2,204)
Financing Activities
Issuance of long-term debt, net of issuance costs	1,398	2,035	956
Redemption of long-term debt	(385)	(807)	(286)
Repurchase of long-term debt	0	(59)	0
Issuance of equity units, net of issuance costs	0	654	0
Short-term borrowings, net	122	0	101
Repurchase of common stock	(51)	(33)	0
Dividends on common stock	(592)	(531)	(501)
Contributions from noncontrolling interests	50	114	23
Distributions to noncontrolling interests	(40)	(5)	(8)
Other	(81)	(9)	(8)
Net cash from (used for) financing activities	421	1,359	277
Net Increase (Decrease) in Cash and Cash Equivalents	(26)	55	(11)
Cash and Cash Equivalents at Beginning of Period	92	37	48
Cash and Cash Equivalents at End of Period	66	92	37
Supplemental disclosure of cash information
Cash paid (received) for: Interest, net of interest capitalized	495	448	428
Cash paid (received) for: Income taxes	4	(1)	14
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Plant and equipment expenditures in accounts payable	295	312	207
Premium on equity units	0	98	0
DTE Electric
Operating Activities
Net Income	601	622	544
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	753	750	633
Nuclear fuel amortization	53	58	46
Allowance for equity funds used during construction	(18)	(18)	(20)
Deferred income taxes	345	342	320
Equity earnings of equity method investees	(1)	(2)	(2)
Changes in assets and liabilities:
Accounts receivable, net	(80)	(64)	33
Inventories	31	26	(22)
Prepaid postretirement benefit costs — affiliates	1	(90)	(24)
Accounts payable	(2)	59	(46)
Accrued pension liability — affiliates	(197)	32	(224)
Accrued postretirement liability — affiliates	42	(38)	(213)
Regulatory assets and liabilities	202	10	65
Other current and noncurrent assets and liabilities	(147)	(34)	58
Net cash from operating activities	1,584	1,655	1,150
Investing Activities
Plant and equipment expenditures	(1,574)	(1,503)	(1,545)
Acquisitions	0	0	(310)
Restricted cash for debt redemption, principally Securitization, net	0	0	96
Proceeds from sale of nuclear decommissioning trust fund assets	1,240	1,457	885
Investment in nuclear decommissioning trust funds	(1,226)	(1,463)	(898)
Transfer of Rabbi Trust assets to affiliate	0	0	137
Other	18	36	14
Net cash used for investing activities	(1,542)	(1,473)	(1,621)
Financing Activities
Issuance of long-term debt, net of issuance costs	435	355	495
Redemption of long-term debt	(300)	(10)	(135)
Repurchase of long-term debt	0	(59)	0
Capital contribution by parent company	100	120	300
Short-term borrowings, net — affiliate	(1)	41	(8)
Short-term borrowings, net — other	176	(210)	222
Dividends on common stock	(432)	(420)	(395)
Other	(18)	(1)	(7)
Net cash from (used for) financing activities	(40)	(184)	472
Net Increase (Decrease) in Cash and Cash Equivalents	2	(2)	1
Cash and Cash Equivalents at Beginning of Period	13	15	14
Cash and Cash Equivalents at End of Period	15	13	15
Supplemental disclosure of cash information
Cash paid (received) for: Interest, net of interest capitalized	252	252	244
Cash paid (received) for: Income taxes	(16)	6	(53)
Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract]
Plant and equipment expenditures in accounts payable	$ 191	$ 232	$ 150

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - 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, 2014		176,991,000					138,632,000
Beginning balance at Dec. 31, 2014	$ 8,342	$ 3,904	$ 4,578	$ (155)	$ 15
Beginning balance at Dec. 31, 2014						$ 5,196	$ 1,386	$ 2,400	$ 1,436	$ (26)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	720		727		(7)
Net Income	727					544			544
Dividends declared on common stock	(510)		(510)			(395)			(395)
Transfer of benefit obligations, net of tax						27				27
Issuance of common stock (in shares)		105,000
Issuance of common stock	9	$ 9
Contribution of common stock to pension plan/VEBA Trust (in shares)		1,428,000
Contribution of common stock to pension plan/VEBA Trust	117	$ 117
Benefit obligations, net of tax	13			13
Net change in unrealized gains on derivatives, net of tax	0
Net change in unrealized gains on investments, net of tax	1			1		1				1
Capital contribution by parent company						300		300
Foreign currency translation	(4)			(4)
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		946,000
Stock-based compensation, net contributions from noncontrolling interests, and other	107	$ 93	(1)		15
Ending balance (in shares) at Dec. 31, 2015		179,470,000					138,632,000
Ending balance at Dec. 31, 2015	8,795	$ 4,123	4,794	(145)	23
Ending balance at Dec. 31, 2015						5,673	$ 1,386	2,700	1,585	2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Implementation of ASU 2016-09	3		3
Net Income (Loss)	834		868		(34)
Net Income	868					622			622
Dividends declared on common stock	(548)		(548)			(420)			(420)
Transfer of benefit obligations, net of tax						0
Repurchase of common stock (in shares)		(394,000)
Repurchase of common stock	(33)	$ (33)
Premium on equity units	(98)	(98)
Issuance costs of equity units	(18)	$ (18)
Acquisition of SGG	390				390
Benefit obligations, net of tax	11			11
Net change in unrealized gains on derivatives, net of tax	0
Net change in unrealized gains on investments, net of tax	1			1		0
Capital contribution by parent company						$ 120		120
Foreign currency translation	0
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		357,000
Stock-based compensation, net contributions from noncontrolling interests, and other	$ 162	$ 56	(3)		109
Ending balance (in shares) at Dec. 31, 2016	179,432,581	179,433,000				138,632,324	138,632,000
Ending balance at Dec. 31, 2016	$ 9,499	$ 4,030	5,114	(133)	488
Ending 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)	1,112		1,134		(22)
Net Income	1,134					601			601
Dividends declared on common stock	(602)		(602)			(432)			(432)
Transfer of benefit obligations, net of tax						0
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 derivatives, net of tax	1			1
Net change in unrealized gains on investments, net of tax	1			1		1				1
Capital contribution by parent company						$ 100		100
Foreign currency translation	1			1
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		478,000
Stock-based compensation, net contributions from noncontrolling interests, and other	$ 19	$ 10	(3)		12
Ending balance (in shares) at Dec. 31, 2017	179,386,967	179,387,000				138,632,234	138,632,000
Ending balance at Dec. 31, 2017	$ 9,990	$ 3,989	$ 5,643	$ (120)	$ 478
Ending balance at Dec. 31, 2017	$ 9,512					$ 6,265	$ 1,386	$ 2,920	$ 1,956	$ 3

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 31, 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 accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The information in these combined notes relates to each of the Registrants as noted in the Index of Combined Notes to Consolidated Financial Statements. However, DTE Electric does not make any representation as to information related solely to DTE Energy or the subsidiaries of DTE Energy other than itself. Certain prior year balances for the Registrants were reclassified to match the current year's Consolidated Financial Statements presentation. 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, " Acquisitions and Exit Activities ," 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 December 31, 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 December 31, 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 18 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 18 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 December 31, 2017 and 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. December 31, 2017 December 31, 2016 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 23 $ 14 $ 37 $ 36 $ 27 $ 63 Restricted cash — 8 8 — 7 7 Accounts receivable 11 42 53 8 34 42 Inventories 3 114 117 3 112 115 Property, plant, and equipment, net 400 75 475 398 76 474 Goodwill 25 — 25 17 — 17 Intangible assets 572 — 572 586 — 586 Other current and long-term assets 4 — 4 1 1 2 $ 1,038 $ 253 $ 1,291 $ 1,049 $ 257 $ 1,306 LIABILITIES Accounts payable and accrued current liabilities $ 26 $ 47 $ 73 $ 19 $ 32 $ 51 Current portion long-term debt, including capital leases — 4 4 — 5 5 Mortgage bonds, notes, and other — 1 1 — 5 5 Other current and long-term liabilities 1 16 17 2 15 17 $ 27 $ 68 $ 95 $ 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: December 31, 2017 December 31, 2016 (In millions) Investments in equity method investees $ 811 $ 509 Notes receivable $ 17 $ 15 Future funding commitments $ 598 $ 692 Equity Method Investments Investments in non-consolidated affiliates that are not controlled by the Registrants, but over which they have significant influence, are accounted for using the equity method. Certain of the equity method investees are also considered VIEs and disclosed in the non-consolidated VIEs table above. At December 31, 2017 and 2016 , DTE Energy's share of the underlying equity in the net assets of the investees exceeded the carrying amounts of Investments in equity method investees by $72 million and $73 million , respectively. The difference is being amortized over the life of the underlying assets. DTE Energy equity method investees are described below: Investments % Owned Segment 2017 2016 2017 2016 Description (In millions) Significant Equity Method Investees Gas Storage and Pipelines NEXUS Pipeline $ 640 $ 322 50% 50% A 255-mile pipeline under construction to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers Vector Pipeline 115 100 40% 40% 348-mile pipeline connecting Chicago, Michigan, and Ontario market centers Millennium Pipeline 124 116 26% 26% 251-mile pipeline serving markets in the Northeast 879 538 Other Equity Method Investees Other Segments 194 214 $ 1,073 $ 752 The balances in Other Equity Method Investees are individually insignificant and are primarily from the Power and Industrial Projects segment. These investments are comprised of projects that deliver energy and utility-type products and services to an industrial customer, sell electricity from renewable energy projects under long-term power purchase agreements, and produce and sell metallurgical coke. For further information by segment, see Note 22 to the Consolidated Financial Statements, " Segment and Related Information ."

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Revenues The Registrants' revenues from the sale and delivery of electricity, and DTE Energy's revenues from the sale, delivery, and storage of natural gas are recognized as services are provided. DTE Electric and DTE Gas record revenues for electricity and gas provided but unbilled at the end of each month. Rates for DTE Electric and DTE Gas include provisions to adjust billings for fluctuations in fuel and purchased power costs, cost of natural gas, and certain other costs. Revenues are adjusted for differences between actual costs subject to reconciliation and the amounts billed in current rates. Under or over recovered revenues related to these cost recovery mechanisms are included in Regulatory assets or liabilities on the Registrants' Consolidated Statements of Financial Position and are recovered or returned to customers through adjustments to the billing factors. For further discussion of recovery mechanisms authorized by the MPSC, see Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." DTE Energy's non-utility businesses recognize revenues as services are provided and products are delivered. For discussion of derivative contracts, see Note 13 to the Consolidated Financial Statements, " Financial and Other Derivative Instruments ." Other Income Other income for the Registrants is recognized for non-operating income such as equity earnings of equity method investees, allowance for equity funds used during construction, contract services, and gains (losses) from trading securities. DTE Energy's Power and Industrial Projects segment also recognizes Other income in connection with the sale of membership interests in reduced emissions fuel facilities to investors. In exchange for the cash received, the investors will receive a portion of the economic attributes of the facilities, including income tax attributes. The transactions are not treated as a sale of membership interests for financial reporting purposes. Other income is considered earned when refined coal is produced and tax credits are generated. The following is a summary of DTE Energy's Other income: 2017 2016 2015 (In millions) Equity earnings of equity method investees $ 102 $ 68 $ 66 Income from REF entities 77 75 83 Gains from trading securities 26 15 1 Allowance for equity funds used during construction 23 21 21 Contract services 19 21 27 Other 21 7 11 $ 268 $ 207 $ 209 The following is a summary of DTE Electric's Other income: 2017 2016 2015 (In millions) Gains from trading securities allocated from DTE Energy $ 26 $ 15 $ 1 Contract services 21 20 27 Allowance for equity funds used during construction 18 18 20 Equity earnings of equity method investees 1 2 2 Other 11 6 10 $ 77 $ 61 $ 60 For information on equity earnings of equity method investees by segment, see Note 22 to the Consolidated Financial Statements, " Segment and Related Information ." Accounting for ISO Transactions DTE Electric participates in the energy market through MISO. MISO requires that DTE Electric submit hourly day-ahead, real-time, and FTR bids and offers for energy at locations across the MISO region. DTE Electric accounts for MISO transactions on a net hourly basis in each of the day-ahead, real-time, and FTR markets and net transactions across all MISO energy market locations. In any single hour DTE Electric records net purchases in Fuel, purchased power, and gas — utility and net sales in Operating Revenues — Utility operations on the Registrants' Consolidated Statements of Operations. The Energy Trading segment participates in the energy markets through various ISOs and RTOs. These markets require that Energy Trading submits hourly day-ahead, real-time bids and offers for energy at locations across each region. Energy Trading submits bids in the annual and monthly auction revenue rights and FTR auctions to the RTOs. Energy Trading accounts for these transactions on a net hourly basis for the day-ahead, real-time, and FTR markets. These transactions are related to trading contracts which, if derivatives, are presented on a net basis in Operating Revenues — Non-utility operations, and if non-derivatives, the realized gains and losses for sales are recorded in Operating Revenues — Non-utility operations and purchases are recorded in Fuel, purchased power, and gas — non-utility in the DTE Energy Consolidated Statements of Operations. DTE Electric and Energy Trading record accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual costs when invoices are received from MISO and other ISOs and RTOs. Changes in Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including Net Income. The amounts recorded to Accumulated other comprehensive income (loss) for the Registrants include unrealized gains and losses on available-for-sale securities and changes in benefit obligations, consisting of deferred actuarial losses and prior service costs. The amounts recorded to Accumulated other comprehensive income (loss) relating solely to DTE Energy also include unrealized gains and losses from derivatives accounted for as cash flow hedges, DTE Energy's interest in other comprehensive income of equity investees which comprise the net unrealized gains and losses on investments, and foreign currency translation adjustments. Refer to Note 20 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets ," regarding the transfer of a portion of DTE Electric benefit obligations in 2015. The following table summarizes the changes in DTE Energy's Accumulated other comprehensive income (loss) by component (a) for the years ended December 31, 2017 and 2016 : Net Unrealized Gain (Loss) on Deri vatives Net Unrealized Gain (Loss) on Investments Benefit Obligations (b) Foreign Currency Translation Total (In millions) Balance, December 31, 2015 $ (4 ) $ (4 ) $ (131 ) $ (6 ) $ (145 ) Other comprehensive loss before reclassifications — — (3 ) — (3 ) Amounts reclassified from Accumulated other comprehensive income — 1 14 — 15 Net current-period Other comprehensive income — 1 11 — 12 Balance, December 31, 2016 $ (4 ) $ (3 ) $ (120 ) $ (6 ) $ (133 ) Other comprehensive income (loss) before reclassi fications — 1 (3 ) 1 (1 ) Amounts reclassified from Accumulated other comprehensive income 1 — 13 — 14 Net current-period Other comprehensive income 1 1 10 1 13 Balance, December 31, 2017 $ (3 ) $ (2 ) $ (110 ) $ (5 ) $ (120 ) ______________________________________ (a) All amounts are net of tax, except for Foreign currency translation. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 20 to the Consolidated Financial Statements " Retirement Benefits and Trusteed Assets "). Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include cash on hand, cash in banks, and temporary investments purchased with remaining maturities of three months or less. Restricted cash consists of funds held to satisfy requirements of certain debt and DTE Energy partnership operating agreements. Restricted cash designated for interest and principal payments within one year is classified as a Current Asset. Receivables Accounts receivable are primarily composed of trade receivables and unbilled revenue. The Registrants' Accounts receivable are stated at net realizable value. The allowance for doubtful accounts for DTE Electric and DTE Gas is generally calculated using the aging approach that utilizes rates developed in reserve studies. DTE Electric and DTE Gas establish an allowance for uncollectible accounts based on historical losses and management’s assessment of existing economic conditions, customer trends, and other factors. Customer accounts are generally considered delinquent if the amount billed is not received by the due date, which is typically in 21 days, however, factors such as assistance programs may delay aggressive action. DTE Electric and DTE Gas assess late payment fees on trade receivables based on past-due terms with customers. Customer accounts are written off when collection efforts have been exhausted. The time period for write-off is 150 days after service has been terminated. The customer allowance for doubtful accounts for DTE Energy's other businesses is calculated based on specific review of probable future collections based on receivable balances generally in excess of 30 days. DTE Energy unbilled revenues of $1 billion and $814 million , including $290 million and $267 million of DTE Electric unbilled revenues, are included in Customer Accounts receivable at December 31, 2017 and 2016 , respectively. Notes Receivable Notes receivable, or financing receivables, for DTE Energy are primarily comprised of capital lease receivables and loans and are included in Notes receivable and Other current assets on DTE Energy’s Consolidated Statements of Financial Position. Notes receivable, or financing receivables, for DTE Electric are primarily comprised of loans. Notes receivable are typically considered delinquent when payment is not received for periods ranging from 60 to 120 days. The Registrants cease accruing interest (nonaccrual status), consider a note receivable impaired, and establish an allowance for credit loss when it is probable that all principal and interest amounts due will not be collected in accordance with the contractual terms of the note receivable. Cash payments received on nonaccrual status notes receivable, that do not bring the account contractually current, are first applied to contractually owed past due interest, with any remainder applied to principal. Accrual of interest is generally resumed when the note receivable becomes contractually current. In determining the allowance for credit losses for notes receivable, the Registrants consider the historical payment experience and other factors that are expected to have a specific impact on the counterparty’s ability to pay. In addition, the Registrants monitor the credit ratings of the counterparties from which they have notes receivable. Inventories Inventory related to utility operations is generally valued at average cost. Inventory related to non-utility operations is valued at the lower of cost or net realizable value. DTE Gas' natural gas inventory of $29 million and $45 million as of December 31, 2017 and 2016 , respectively, is determined using the last-in, first-out (LIFO) method. The replacement cost of gas in inventory exceeded the LIFO cost by $81 million and $132 million at December 31, 2017 and 2016 , respectively. Property, Retirement and Maintenance, and Depreciation and Amortization Property is stated at cost and includes construction-related labor, materials, overheads, and AFUDC for utility property. The cost of utility properties retired is charged to accumulated depreciation. Expenditures for maintenance and repairs are charged to expense when incurred, except for outage-related maintenance repairs for Fermi 2. Utility property at DTE Electric and DTE Gas is depreciated over its estimated useful life using straight-line rates approved by the MPSC. DTE Energy's non-utility property is depreciated over its estimated useful life using the straight-line method. Depreciation and amortization expense also includes the amortization of certain regulatory assets for the Registrants. Approximately $15 million and $27 million of expenses related to Fermi 2 refueling outages were accrued at December 31, 2017 and 2016 , respectively. Amounts are accrued on a pro-rata basis, generally over an 18 -month period, that coincides with scheduled refueling outages at Fermi 2. This accrual of outage costs matches the regulatory recovery of these costs in rates set by the MPSC. See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." The cost of nuclear fuel is capitalized. The amortization of nuclear fuel is included within Fuel, purchased power, and gas — utility in the DTE Energy Consolidated Statements of Operations, and Fuel and purchased power in the DTE Electric Consolidated Statements of Operations, and is recorded using the units-of-production method. See Note 6 to the Consolidated Financial Statements, " Property, Plant, and Equipment ." Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If the carrying amount of the asset exceeds the expected undiscounted future cash flows generated by the asset, an impairment loss is recognized resulting in the asset being written down to its estimated fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less costs to sell. Intangible Assets The Registrants have certain Intangible assets as shown below: December 31, 2017 December 31, 2016 Useful Lives Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (In millions) Intangible assets subject to amortization Customer relationships (a) 40 years (b) $ 770 $ (24 ) $ 746 $ 770 $ (5 ) $ 765 Contract intangibles 6 to 26 years 168 (72 ) 96 111 (65 ) 46 938 (96 ) 842 881 (70 ) 811 DTE Electric renewable energy credits (c) 24 — 24 30 — 30 DTE Electric emission allowances (c) 1 — 1 1 — 1 25 — 25 31 — 31 Long-term intangible assets DTE Electric $ 25 $ — $ 25 $ 31 $ — $ 31 DTE Energy $ 963 $ (96 ) $ 867 $ 912 $ (70 ) $ 842 ______________________________________ (a) In October 2016, DTE Energy acquired midstream natural gas assets that are part of the Gas Storage and Pipelines segment. The intangible assets recorded as a result of the acquisition pertain to existing customer relationships. See Note 4 to the Consolidated Financial Statements, " Acquisitions and Exit Activities ," for additional information. (b) The useful life of the customer relationship intangible assets is based on the number of years in which the assets are expected to economically contribute to the business. The expected economic benefit incorporates existing customer contracts and expected renewal rates based on the estimated volume and production lives of gas resources in the region. (c) Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the business. The following table summarizes DTE Energy's estimated customer relationship and contract intangible amortization expense expected to be recognized during each year through 2022 : 2018 2019 2020 2021 2022 (In millions) Estimated amortization expense $ 26 $ 26 $ 25 $ 25 $ 25 DTE Energy amortizes customer relationship and contract intangible assets on a straight-line basis over the expected period of benefit. DTE Energy's Intangible assets amortization expense was $29 million in 2017 , $16 million in 2016 , and $11 million in 2015 . Excise and Sales Taxes The Registrants record the billing of excise and sales taxes as a receivable with an offsetting payable to the applicable taxing authority, with no net impact on the Registrants’ Consolidated Statements of Operations. Deferred Debt Costs The costs related to the issuance of long-term debt are deferred and amortized over the life of each debt issue. The deferred amounts are included as a direct deduction from the carrying amount of each debt issue in Mortgage bonds, notes, and other and Junior subordinated debentures on DTE Energy's Consolidated Statements of Financial Position and in Mortgage bonds, notes, and other on DTE Electric's Consolidated Statements of Financial Position. In accordance with MPSC regulations applicable to DTE Energy’s electric and gas utilities, the unamortized discount, premium, and expense related to utility debt redeemed with a refinancing are amortized over the life of the replacement issue. Discount, premium, and expense on early redemptions of debt associated with DTE Energy's non-utility operations are charged to earnings. Investments in Debt and Equity Securities The Registrants generally classify investments in debt and equity securities as either trading or available-for-sale and have recorded such investments at market value with unrealized gains or losses included in earnings or in Other comprehensive income or loss, respectively. Changes in the fair value of Fermi 2 nuclear decommissioning investments are recorded as adjustments to Regulatory assets or liabilities, due to a recovery mechanism from customers. The Registrants' equity investments are reviewed for impairment each reporting period. If the assessment indicates that the impairment is other than temporary, a loss is recognized resulting in the equity investment being written down to its estimated fair value. See Note 12 of the Consolidated Financial Statements, " Fair Value ." Government Grants Grants are recognized when there is reasonable assurance that the grant will be received and that any conditions associated with the grant will be met. When grants are received related to Property, plant, and equipment, the Registrants reduce the cost of the assets on their Consolidated Statements of Financial Position, resulting in lower depreciation expense over the life of the associated asset. Grants received related to expenses are reflected as a reduction of the associated expense in the period in which the expense is incurred. DTE Energy Foundation DTE Energy's charitable contributions to the DTE Energy Foundation were $43 million , $26 million , and $12 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute to and assist charitable organizations. Other Accounting Policies See the following notes for other accounting policies impacting the Registrants’ Consolidated Financial Statements: Note Title 8 Asset Retirement Obligations 9 Regulatory Matters 10 Income Taxes 12 Fair Value 13 Financial and Other Derivative Instruments 20 Retirement Benefits and Trusteed Assets 21 Stock-Based Compensation

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 2017
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS 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 have substantially completed the assessment of the amended ASU's impact, on their Consolidated Financial Statements. The ASU will not significantly affect the Registrants' financial position or results of operations. The Registrants will continue to monitor the impact of the ASU on existing revenue recognition internal controls, 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, which are not expected to have a significant impact on the Registrants, 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, and include disclosure of key information about leasing arrangements. 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, as well as additional disclosures, 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 generally accepted accounting principles 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 20 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets ." The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . The amendments in this update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA. The amendments in this update also require entities to disclose their accounting policy for releasing income tax effects from accumulated other comprehensive income. The ASU is effective for the Registrants for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements.

Acquisitions and Exit Activitie

Acquisitions and Exit Activities	12 Months Ended
	Dec. 31, 2017
Business Acquisition, Integration, Restructuring and Other Related Costs [Abstract]
Acquisitions and Exit Activities	ACQUISITIONS AND EXIT ACTIVITIES 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 a result, the purchase accounting adjustments through September 30, 2017 contributed 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. Exit Activities On December 17, 2015, DTE Energy announced the closure of the Shenango coke battery plant in response to a sharp downturn in the North American steel industry. The plant, which was included in the Power and Industrial Projects segment, is located in Pittsburgh, PA. As a result of the closure, DTE Energy recorded a one-time pre-tax non-cash impairment charge of $111 million . The charge included $96 million to fully impair the long-lived assets, employee severance expenses related to the workforce reduction of approximately 170 employees for $3 million , and other expenses, including write downs of inventory, of $12 million . DTE Energy's coke production has been shifted to a larger, more efficient coke battery plant in the Power and Industrial Projects segment. Production of coke from the Shenango coke battery plant ceased in January 2016. A summary of the charges in the Consolidated Statements of Operations resulting from DTE Energy's exit activities is shown below: 2015 (In millions) Fuel, purchased power, and gas — non-utility $ 5 Operation and maintenance 10 Asset (gains) losses and impairments, net 96 Total exit activity charges $ 111 As of December 31, 2017 , DTE Energy had approximately $1 million accrued related to these exit activities and expects future cash payments of this remaining balance to be made in 2018 . DTE Energy does not anticipate incurring significant additional expenses, including required environmental remediation costs, in connection with the closure.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GOODWILL DTE Energy has goodwill resulting from business combinations. The following is the summary of change in the carrying amount of goodwill for the years ended December 31: 2017 2016 (In millions) Balance as of January 1 $ 2,286 $ 2,018 Goodwill attributable to Gas Storage and Pipelines acquisition 7 268 Balance at December 31 $ 2,293 $ 2,286 Refer to Note 4 to the Consolidated Financial Statements, " Acquisitions and Exit Activities ," for additional information related to the acquisition.

Property, Plant, and Equipment

Property, Plant, and Equipment	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Property, Plant, and Equipment	PROPERTY, PLANT, AND EQUIPMENT The following is a summary of Property, plant, and equipment by classification as of December 31: 2017 2016 Property, plant, and equipment (In millions) DTE Electric Generation $ 12,166 $ 11,990 Distribution 8,637 8,134 Other 2,169 1,970 Total DTE Electric 22,972 22,094 DTE Gas Distribution 3,523 3,382 Storage 533 503 Transmission and other 1,118 925 Total DTE Gas 5,174 4,810 Non-utility and other 3,278 3,125 Total DTE Energy 31,424 30,029 Accumulated depreciation and amortization DTE Electric Generation (4,403 ) (4,364 ) Distribution (2,914 ) (2,769 ) Other (667 ) (588 ) Total DTE Electric (7,984 ) (7,721 ) DTE Gas Distribution (1,238 ) (1,198 ) Storage (159 ) (152 ) Transmission and other (384 ) (370 ) Total DTE Gas (1,781 ) (1,720 ) Non-utility and other (938 ) (858 ) Total DTE Energy (10,703 ) (10,299 ) Net DTE Energy Property, plant, and equipment $ 20,721 $ 19,730 Net DTE Electric Property, plant, and equipment $ 14,988 $ 14,373 The following is a summary of the Registrants' AFUDC and interest capitalized for the years ended December 31: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Allowance for debt funds used during construction and interest capitalized $ 13 $ 10 $ 8 $ 8 Allowance for equity funds used during construction 23 21 18 18 Total $ 36 $ 31 $ 26 $ 26 The composite depreciation rate for DTE Electric was approximately 3.6% in 2017 and 3.5% in 2016 and 2015 . The composite depreciation rate for DTE Gas was 2.7% , 2.4% , and 2.6% in 2017 , 2016 , and 2015 , respectively. The average estimated useful life for each major class of utility Property, plant, and equipment as of December 31, 2017 follows: Estimated Useful Lives in Years Utility Generation Distribution Storage DTE Electric 40 41 N/A DTE Gas N/A 50 53 The estimated useful lives for DTE Electric's Other utility assets range from 4 to 62 years, while the estimated useful lives for DTE Gas' Transmission and other utility assets range from 5 to 70 years. The estimated useful lives for major classes of DTE Energy's non-utility assets and facilities range from 3 to 83 years. The following is a summary of Depreciation and amortization expense for DTE Energy: 2017 2016 2015 (In millions) Property, plant, and equipment $ 865 $ 783 $ 740 Regulatory assets and liabilities 165 193 150 Securitized regulatory assets (a) — — (38 ) $ 1,030 $ 976 $ 852 _______________________________________ (a) Securitization surcharges ended in December 2014 with remaining over recovery refunded to customers in 2015. Securitization bonds were paid and Securitization regulatory assets amortization was completed in 2015. The $38 million credit represents the final adjustments to close out the Securitization program. The following is a summary of Depreciation and amortization expense for DTE Electric: 2017 2016 2015 (In millions) Property, plant, and equipment $ 620 $ 582 $ 545 Regulatory assets and liabilities 133 168 126 Securitized regulatory assets (a) — — (38 ) $ 753 $ 750 $ 633 _______________________________________ (a) Securitization surcharges ended in December 2014 with remaining over recovery refunded to customers in 2015. Securitization bonds were paid and Securitization regulatory assets amortization was completed in 2015. The $38 million credit represents the final adjustments to close out the Securitization program. Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 3 to 15 years for DTE Energy and 4 to 15 years for DTE Electric. The following balances for capitalized software relate to DTE Energy: Year Ended December 31, 2017 2016 2015 (In millions) Amortization expense of capitalized software $ 101 $ 89 $ 98 Gross carrying value of capitalized software $ 890 $ 715 Accumulated amortization of capitalized software $ 500 $ 435 The following balances for capitalized software relate to DTE Electric: Year Ended December 31, 2017 2016 2015 (In millions) Amortization expense of capitalized software $ 93 $ 83 $ 80 Gross carrying value of capitalized software $ 774 $ 610 Accumulated amortization of capitalized software $ 423 $ 365 Property under capital leases for the Registrants is as follows: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Gross property under capital leases $ 44 $ 44 $ 18 $ 18 Accumulated amortization of property under capital leases $ 38 $ 32 $ 12 $ 6

Jointly-Owned Utility Plant

Jointly-Owned Utility Plant	12 Months Ended
	Dec. 31, 2017
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Jointly-Owned Utility Plant	JOINTLY-OWNED UTILITY PLANT DTE Electric has joint ownership interest in two power plants, Belle River and Ludington Hydroelectric Pumped Storage. DTE Electric’s share of direct expenses of the jointly-owned plants are included in Fuel, purchased power, and gas — utility and Operation and maintenance expenses in the DTE Energy Consolidated Statements of Operations and Fuel and purchased power — utility and Operation and maintenance expenses in the DTE Electric Consolidated Statements of Operations. Ownership information of the two utility plants as of December 31, 2017 was as follows: Belle River Ludington Hydroelectric Pumped Storage In-service date 1984-1985 1973 Total plant capacity 1,270 MW 2,080 MW Ownership interest (a) 49% Investment in Property, plant, and equipment (in millions) $ 1,814 $ 559 Accumulated depreciation (in millions) $ 1,060 $ 188 _______________________________________ (a) DTE Electric's ownership interest is 63% in Unit No. 1, 81% of the facilities applicable to Belle River used jointly by the Belle River and St. Clair Power Plants and 75% in common facilities used at Unit No. 2. Belle River The Michigan Public Power Agency (MPPA) has an ownership interest in Belle River Unit No. 1 and other related facilities. The MPPA is entitled to 19% of the total capacity and energy of the plant and is responsible for the same percentage of the plant’s operation, maintenance, and capital improvement costs. Ludington Hydroelectric Pumped Storage Consumers Energy Company has an ownership interest in the Ludington Hydroelectric Pumped Storage Plant. Consumers Energy is entitled to 51% of the total capacity and energy of the plant and is responsible for the same percentage of the plant’s operation, maintenance, and capital improvement costs.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2017
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS DTE Electric has a legal retirement obligation for the decommissioning costs for its Fermi 1 and Fermi 2 nuclear plants, dismantlement of facilities located on leased property, and various other operations. DTE Electric has conditional retirement obligations for asbestos and PCB removal at certain of its power plants and various distribution equipment. DTE Gas has conditional retirement obligations for gas pipelines, certain service centers, compressor and gate stations. The Registrants recognize such obligations as liabilities at fair market value when they are incurred, which generally is at the time the associated assets are placed in service. Fair value is measured using expected future cash outflows discounted at the Registrants' credit-adjusted risk-free rate. For its utility operations, the Registrants recognize in the Consolidated Statements of Operations removal costs in accordance with regulatory treatment. Any differences between costs recognized related to asset retirement and those reflected in rates are recognized as either a Regulatory asset or liability on the Consolidated Statements of Financial Position. If a reasonable estimate of fair value cannot be made in the period in which the retirement obligation is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. Natural gas storage system and certain other distribution assets for DTE Gas and substations, manholes, and certain other distribution assets for DTE Electric have an indeterminate life. Therefore, no liability has been recorded for these assets. A reconciliation of the asset retirement obligations for 2017 follows: DTE Energy DTE Electric (In millions) Asset retirement obligations at December 31, 2016 $ 2,197 $ 2,012 Accretion 131 120 Liabilities incurred 2 1 Liabilities settled (6 ) (2 ) Revision in estimated cash flows (4 ) (6 ) Asset retirement obligations at December 31, 2017 $ 2,320 $ 2,125 Approximately $1.9 billion of the asset retirement obligations represent nuclear decommissioning liabilities that are funded through a surcharge to electric customers over the life of the Fermi 2 nuclear plant. The NRC has jurisdiction over the decommissioning of nuclear power plants and requires minimum decommissioning funding based upon a formula. The MPSC and FERC regulate the recovery of costs of decommissioning nuclear power plants and both require the use of external trust funds to finance the decommissioning of Fermi 2. Rates approved by the MPSC provide for the recovery of decommissioning costs of Fermi 2 and the disposal of low-level radioactive waste. DTE Electric believes the MPSC collections will be adequate to fund the estimated cost of decommissioning. The decommissioning assets, anticipated earnings thereon, and future revenues from decommissioning collections will be used to decommission Fermi 2. DTE Electric expects the liabilities to be reduced to zero at the conclusion of the decommissioning activities. If amounts remain in the trust funds for Fermi 2 following the completion of the decommissioning activities, those amounts will be disbursed based on rulings by the MPSC and FERC. A portion of the funds recovered through the Fermi 2 decommissioning surcharge and deposited in external trust accounts is designated for the removal of non-radioactive assets and returning the site to greenfield. This removal and greenfielding is not considered a legal liability. Therefore, it is not included in the asset retirement obligation, but is reflected as the Nuclear decommissioning liability. The decommissioning of Fermi 1 is funded by DTE Electric. Contributions to the Fermi 1 trust are discretionary. For additional discussion of Nuclear decommissioning trust fund assets, see Note 12 to the Consolidated Financial Statements, " Fair Value ."

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2017
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	REGULATORY MATTERS Regulation DTE Electric and DTE Gas are subject to the regulatory jurisdiction of the MPSC, which issues orders pertaining to rates, recovery of certain costs, including the costs of generating facilities and regulatory assets, conditions of service, accounting, and operating-related matters. DTE Electric is also regulated by the FERC with respect to financing authorization and wholesale electric activities. Regulation results in differences in the application of generally accepted accounting principles between regulated and non-regulated businesses. The Registrants are unable to predict the outcome of the unresolved regulatory matters discussed herein. Resolution of these matters is dependent upon future MPSC orders and appeals, which may materially impact the Consolidated Financial Statements of the Registrants. Regulatory Assets and Liabilities DTE Electric and DTE Gas are required to record Regulatory assets and liabilities for certain transactions that would have been treated as revenue or expense in non-regulated businesses. Continued applicability of regulatory accounting treatment requires that rates be designed to recover specific costs of providing regulated services and be charged to and collected from customers. Future regulatory changes or changes in the competitive environment could result in the discontinuance of this accounting treatment for Regulatory assets and liabilities for some or all of the Registrants' businesses and may require the write-off of the portion of any Regulatory asset or liability that was no longer probable of recovery through regulated rates. Management believes that currently available facts support the continued use of Regulatory assets and liabilities and that all Regulatory assets and liabilities are recoverable or refundable in the current regulatory environment. The following are balances and a brief description of the Registrants' Regulatory assets and liabilities at December 31: DTE Energy DTE Electric 2017 2016 2017 2016 Assets (In millions) Recoverable pension and other postretirement costs Pension $ 2,000 $ 2,159 $ 1,502 $ 1,642 Other postretirement costs 278 286 211 207 Asset retirement obligation 569 613 569 613 Removal costs asset 299 193 299 193 Recoverable Michigan income taxes 213 231 171 187 Deferred environmental costs 75 78 — — Unamortized loss on reacquired debt 65 59 46 39 Transitional Reconciliation Mechanism 46 30 46 30 Customer360 deferred costs 45 33 45 33 Recoverable income taxes related to AFUDC equity 41 59 35 53 Other recoverable income taxes 26 57 26 57 Nuclear Performance Evaluation and Review Committee Tracker 22 — 22 — Accrued PSCR/GCR revenue 17 22 17 19 Other 82 93 66 76 3,778 3,913 3,055 3,149 Less amount included in Current Assets (55 ) (42 ) (50 ) (36 ) $ 3,723 $ 3,871 $ 3,005 $ 3,113 DTE Energy DTE Electric 2017 2016 2017 2016 Liabilities (In millions) Refundable federal income taxes $ 2,384 $ — $ 1,946 $ — Removal costs liability 265 266 — — Renewable energy 112 145 112 145 Negative other postretirement offset 80 56 67 55 Negative pension offset 21 36 — — Fermi 2 refueling outage 15 27 15 27 Refundable self-implemented rates 2 27 2 27 Other 14 32 12 2 2,893 589 2,154 256 Less amount included in Current Liabilities (18 ) (34 ) (17 ) (27 ) $ 2,875 $ 555 $ 2,137 $ 229 As noted below, certain Regulatory assets for which costs have been incurred have been included (or are expected to be included, for costs incurred subsequent to the most recently approved rate case) in DTE Electric's or DTE Gas' rate base, thereby providing a return on invested costs (except as noted). Certain other regulatory assets are not included in rate base but accrue recoverable carrying charges until surcharges to collect the assets are billed. Certain Regulatory assets do not result from cash expenditures and therefore do not represent investments included in rate base or have offsetting liabilities that reduce rate base. ASSETS • Recoverable pension and other postretirement costs — Accounting standards for pension and other postretirement benefit costs require, among other things, the recognition in Other comprehensive income of the actuarial gains or losses and the prior service costs that arise during the period but that are not immediately recognized as components of net periodic benefit costs. DTE Electric and DTE Gas record the impact of actuarial gains or losses and prior service costs as a Regulatory asset since the traditional rate setting process allows for the recovery of pension and other postretirement costs. The asset will reverse as the deferred items are amortized and recognized as components of net periodic benefit costs. (a) • Asset retirement obligation — This obligation is for Fermi 2 decommissioning costs. The asset captures the timing differences between expense recognition and current recovery in rates and will reverse over the remaining life of the related plant. (a) • Removal costs asset — Receivable for the recovery of asset removal expenditures in excess of amounts collected from customers. (a) • Recoverable Michigan income taxes — The State of Michigan enacted a corporate income tax resulting in the establishment of state deferred tax liabilities for DTE Energy's utilities. Offsetting Regulatory assets were also recorded as the impacts of the deferred tax liabilities will be reflected in rates as the related taxable temporary differences reverse and flow through current income tax expense. • Deferred environmental costs — The MPSC approved the deferral of investigation and remediation costs associated with DTE Gas' former MGP sites. Amortization of deferred costs is over a ten -year period beginning in the year after costs were incurred, with recovery (net of any insurance proceeds) through base rate filings. (a) • Unamortized loss on reacquired debt — The unamortized discount, premium, and expense related to debt redeemed with a refinancing are deferred, amortized, and recovered over the life of the replacement issue. • Transitional Reconciliation Mechanism — The MPSC approved the recovery of the deferred net incremental revenue requirement associated with the transition of PLD customers to DTE Electric's distribution system, effective July 1, 2014. Annual reconciliations will be filed and surcharges will be implemented to recover approved amounts. • Customer360 deferred costs — The MPSC approved the deferral and amortization of certain costs associated with implementing Customer360, which is an integrated software application that enables improved interface among customer service, billing, meter reading, credit and collections, device management, account management, and retail access. Amortization of deferred costs over a 15 -year amortization period began after the billing system was put into operation during the second quarter of 2017. • Recoverable income taxes related to AFUDC equity — Accounting standards for income taxes require recognition of a deferred tax liability for the equity component of AFUDC. A regulatory asset is required for the future increase in taxes payable related to the equity component of AFUDC that will be recovered from customers through future rates over the remaining life of the related plant. • Other recoverable income taxes — Income taxes receivable from DTE Electric's customers representing the difference in property-related deferred income taxes and amounts previously reflected in DTE Electric's rates. This asset will reverse over the remaining life of the related plant. • Nuclear Performance Evaluation and Review Committee Tracker — Deferral and amortization of certain costs associated with oversight and review of DTE Electric's nuclear power generation program, including safety and regulatory compliance, nuclear leadership, nuclear facilities, as well as operation and financial performance, pursuant to the MPSC authorization. The approved five -year amortization period began January 1, 2018, with recovery (net of carrying costs) through base rate filings. • Accrued PSCR/GCR revenue — Receivable for the temporary under-recovery of and carrying costs on fuel and purchased power costs incurred by DTE Electric which are recoverable through the PSCR mechanism and temporary under-recovery of and carrying costs on gas costs incurred by DTE Gas which are recoverable through the GCR mechanism. ________________________________________________ (a) Regulatory assets not earning a return or accruing carrying charges. LIABILITIES • Refundable federal income taxes — DTE Electric and DTE Gas' remeasurement of deferred taxes due to the enactment of the TCJA, which reflects the net impact of the tax rate change on cumulative temporary differences expected to reverse after the effective date of January 1, 2018. Refer to "2017 Tax Reform" section below for additional information. • Removal costs liability — The amount collected from customers for the funding of future asset removal activities. • Renewable energy — Amounts collected in rates in excess of renewable energy expenditures. • Negative other postretirement offset — DTE Electric and DTE Gas' negative other postretirement costs are not included as a reduction to their authorized rates; therefore, DTE Electric and DTE Gas are accruing a Regulatory liability to eliminate the impact on earnings of the negative other postretirement expense accrual. The Regulatory liabilities will reverse to the extent DTE Electric and DTE Gas' other postretirement expense is positive in future years. • Negative pension offset — DTE Gas' negative pension costs are not included as a reduction to its authorized rates; therefore, DTE Gas is accruing a Regulatory liability to eliminate the impact on earnings of the negative pension expense accrued. This Regulatory liability will reverse to the extent DTE Gas' pension expense is positive in future years. • Fermi 2 refueling outage — Accrued liability for refueling outage at Fermi 2 pursuant to MPSC authorization. • Refundable self-implemented rates — Amounts refundable to customers for base rates implemented from August 1, 2016 to December 31, 2016 in excess of amounts authorized in the January 2017 DTE Electric rate order from the MPSC. 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 Electric has refunded the majority of the settlement liability as of December 31, 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 November 1, 2017, DTE Electric self-implemented a base rate increase of $125 million . 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, NO x 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 expects an order in this proceeding from the MPSC by April 27, 2018. 2017 Gas Rate Case Filing DTE Gas filed a rate case with the MPSC on November 22, 2017 requesting an increase in base rates of $85.1 million based on a projected twelve-month period ending September 30, 2019. The requested increase in base rates is primarily due to an increase in net plant. The rate filing also includes projected changes in sales, operations, 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 Gas suggested regulatory accounting treatment for the pension and postretirement cost components previously included as capital overhead. If the MPSC adopts DTE Gas' 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 ." A final MPSC order in this case is expected by September 2018. 2017 Tax Reform On December 27, 2017, the MPSC issued an order to consider changes in the rates of all Michigan rate-regulated utilities to reflect the effects of the federal TCJA. On January 19, 2018, DTE Electric and DTE Gas filed information with the MPSC regarding the potential change in revenue requirements due to the TCJA effective January 1, 2018, and outlined our recommended method to flow the current and deferred tax benefits of those impacts to ratepayers.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Income Tax Summary DTE Energy files a consolidated federal income tax return. DTE Electric is a part of the consolidated federal income tax return of DTE Energy. DTE Energy and its subsidiaries file consolidated and/or separate company income tax returns in various states and localities, including a consolidated return in the State of Michigan. DTE Electric is part of the Michigan consolidated income tax return of DTE Energy. The federal, state and local income tax expense for DTE Electric is determined on an individual company basis with no allocation of tax expenses or benefits from other affiliates of DTE Energy. DTE Electric had income tax receivables with DTE Energy of $12 million and $9 million at December 31, 2017 and 2016 , respectively. The Registrants' total Income Tax Expense varied from the statutory federal income tax rate for the following reasons: 2017 2016 2015 DTE Energy (In millions) Income Before Income Taxes $ 1,287 $ 1,105 $ 950 Income tax expense at 35% statutory rate $ 450 $ 387 $ 333 Production tax credits (189 ) (145 ) (122 ) Investment tax credits (4 ) (5 ) (7 ) Depreciation (4 ) (4 ) (4 ) Noncontrolling interests 8 12 2 AFUDC equity (18 ) (10 ) (8 ) Employee Stock Ownership Plan dividends (5 ) (5 ) (5 ) Stock based compensation (14 ) — — Subsidiary stock loss — (10 ) — State and local income taxes, net of federal benefit 51 58 35 Enactment of the Tax Cuts and Jobs Act (105 ) — — Other, net 5 (7 ) 6 Income Tax Expense $ 175 $ 271 $ 230 Effective income tax rate 13.6 % 24.5 % 24.2 % 2017 2016 2015 DTE Electric (In millions) Income Before Income Taxes $ 928 $ 975 $ 836 Income tax expense at 35% statutory rate $ 325 $ 341 $ 293 Production tax credits (36 ) (30 ) (31 ) Investment tax credits (4 ) (4 ) (5 ) Depreciation 3 3 3 AFUDC equity (5 ) (6 ) (7 ) Employee Stock Ownership Plan dividends (3 ) (3 ) (3 ) State and local income taxes, net of federal benefit 48 56 43 Other, net (1 ) (4 ) (1 ) Income Tax Expense $ 327 $ 353 $ 292 Effective income tax rate 35.2 % 36.2 % 34.9 % Components of the Registrants' Income Tax Expense were as follows: 2017 2016 2015 DTE Energy (In millions) Current income tax expense (benefit) Federal $ (22 ) $ (1 ) $ (3 ) State and other income tax 1 7 (4 ) Total current income taxes (21 ) 6 (7 ) Deferred income tax expense Federal 118 184 178 State and other income tax 78 81 59 Total deferred income taxes 196 265 237 $ 175 $ 271 $ 230 2017 2016 2015 DTE Electric (In millions) Current income tax expense (benefit) Federal $ (17 ) $ — $ (26 ) State and other income tax (1 ) 11 (2 ) Total current income taxes (18 ) 11 (28 ) Deferred income tax expense Federal 270 268 252 State and other income tax 75 74 68 Total deferred income taxes 345 342 320 $ 327 $ 353 $ 292 Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts in the Consolidated Financial Statements. Consistent with the original establishment of these deferred tax liabilities (assets), no recognition of these non-cash transactions have been reflected in the Consolidated Statements of Cash Flows. The Registrants' deferred tax assets (liabilities) were comprised of the following at December 31: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Property, plant, and equipment $ (3,276 ) $ (4,880 ) $ (2,698 ) $ (3,819 ) Regulatory assets and liabilities (94 ) (879 ) (31 ) (778 ) Tax credit carry-forwards 947 643 193 116 Pension and benefits 334 643 302 518 Federal net operating loss carry-forward 83 190 47 42 State and local net operating loss carry-forwards 70 59 5 1 Investments in equity method investees (82 ) (119 ) — — Other 170 217 94 127 (1,848 ) (4,126 ) (2,088 ) (3,793 ) Less valuation allowance (40 ) (36 ) — — Long-term deferred income tax liabilities $ (1,888 ) $ (4,162 ) $ (2,088 ) $ (3,793 ) Deferred income tax assets $ 1,814 $ 1,463 $ 830 $ 569 Deferred income tax liabilities (3,702 ) (5,625 ) (2,918 ) (4,362 ) $ (1,888 ) $ (4,162 ) $ (2,088 ) $ (3,793 ) Tax credit carry-forwards for DTE Energy include $640 million of general business credits that expire from 2034 through 2037 and $307 million of alternative minimum tax credits that will be refundable over the next four years. The alternative minimum tax credits are production tax credits earned prior to 2006 but not utilized. The majority of these alternative minimum tax credits were generated from projects that had received a private letter ruling (PLR) from the IRS. These PLRs provide assurance as to the appropriateness of using these credits to offset taxable income, however, these tax credits are subject to IRS audit and adjustment. No valuation allowance is required for the tax credits carry-forward deferred tax asset. DTE Energy has a federal net operating loss carry-forward of $397 million as of December 31, 2017 , which will expire from 2035 through 2037 . No valuation allowance is required for the federal net operating loss deferred tax asset. DTE Energy has state and local deferred tax assets related to net operating loss carry-forwards of $70 million and $59 million at December 31, 2017 and 2016 , respectively. The state and local net operating loss carry-forwards expire from 2018 through 2037 . DTE Energy has recorded valuation allowances at December 31, 2017 and 2016 of approximately $40 million and $36 million , respectively, with respect to these deferred tax assets. In assessing the realizability of deferred tax assets, DTE Energy considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Tax credit carry-forwards for DTE Electric include $193 million of general business credits that expire from 2035 through 2037 . No valuation allowance is required for the tax credits carry-forward deferred tax asset. DTE Electric has a federal net operating loss carry-forward of $226 million as of December 31, 2017 , which will expire in 2035 . No valuation allowance is required for the federal net operating loss deferred tax asset. DTE Electric has state and local deferred tax assets related to net operating loss carry-forwards of $5 million at December 31, 2017 , while there was $1 million state and local deferred tax asset related to net operating loss carry-forwards at December 31, 2016 . No valuation allowance is required for DTE Electric's state and local net operating loss carry-forwards. The above tables exclude unamortized investment tax credits that are shown separately on the Registrants' Consolidated Statements of Financial Position. Investment tax credits are deferred and amortized to income over the average life of the related property. Tax Cuts and Jobs Act On December 22, 2017, the TCJA was enacted reducing the corporate income tax rate from 35% to 21% , effective January 1, 2018. As a result of the enactment, the deferred tax assets and liabilities were remeasured to reflect the impact of the TCJA on the cumulative temporary differences expected to reverse after the effective date. The net impact of this remeasurement was a decrease in deferred tax liabilities of $2.56 billion , of which $2.45 billion was attributable to regulated utilities and offset to regulatory assets and liabilities. This regulatory treatment is consistent with prior precedent set by the MPSC from previous tax law changes. The remaining $105 million was attributable to the non-utility entities and was recognized as a net reduction to income tax expense in 2017. On December 22, 2017, the SEC issued guidance under Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), directing taxpayers to consider the implications of the TCJA as provisional when it does not have the necessary information available, prepared, or analyzed in reasonable detail to complete its accounting for the change in the tax law. The amounts above represent our best estimate based on interpretations of the TCJA. In accordance with SAB 118, the amounts recorded are considered provisional and will continue to be analyzed throughout 2018, which may result in additional changes. Uncertain Tax Positions A reconciliation of the beginning and ending amount of unrecognized tax benefits for the Registrants is as follows: 2017 2016 2015 DTE Energy (In millions) Balance at January 1 $ 10 $ 3 $ 9 Additions for tax positions of prior years — 7 — Lapse of statute of limitations — — (6 ) Balance at December 31 $ 10 $ 10 $ 3 2017 2016 2015 DTE Electric (In millions) Balance at January 1 $ 13 $ 4 $ 4 Additions for tax positions of prior years — 9 — Balance at December 31 $ 13 $ 13 $ 4 DTE Energy had $8 million of unrecognized tax benefits at December 31, 2017 and 2016 that, if recognized, would favorably impact its effective tax rate. DTE Energy does not anticipate any material decrease in unrecognized tax benefits in the next twelve months. DTE Electric had $10 million of unrecognized tax benefits at December 31, 2017 and 2016 that, if recognized, would favorably impact its effective tax rate. DTE Electric does not anticipate any material decrease in unrecognized tax benefits in the next twelve months. The Registrants recognize interest and penalties pertaining to income taxes in Interest expense and Other expenses, respectively, on their Consolidated Statements of Operations. Accrued interest pertaining to income taxes for DTE Energy totaled $3 million at December 31, 2017 and 2016 . DTE Energy recognized interest expense related to income taxes of a nominal amount in 2017 , $2 million in 2016 , and a nominal amount in 2015 . DTE Energy had accrued no penalties pertaining to income taxes. Accrued interest pertaining to income taxes for DTE Electric totaled $4 million at December 31, 2017 and 2016 . DTE Electric recognized interest expense related to income taxes of a nominal amount in 2017 , $3 million in 2016 , and a nominal amount in 2015 . DTE Electric had accrued no penalties pertaining to income taxes. In 2017 , DTE Energy, including DTE Electric, settled a federal tax audit for the 2015 tax year. DTE Energy's federal income tax returns for 2016 and subsequent years remain subject to examination by the IRS. DTE Energy's Michigan Business Tax and Michigan Corporate Income Tax returns for the year 2008 and subsequent years remain subject to examination by the State of Michigan. DTE Energy also files tax returns in numerous state and local jurisdictions with varying statutes of limitation.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 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. For additional information, see Notes 14 and 21 to Consolidated Financial Statements, " Long-Term Debt " and " Stock-Based Compensation ," respectively. The following is a reconciliation of DTE Energy's basic and diluted income per share calculation for the years ended December 31 : 2017 2016 2015 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 1,134 $ 868 $ 727 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — basic $ 1,132 $ 866 $ 725 Average number of common shares outstanding 179 179 179 Basic Earnings per Common Share $ 6.32 $ 4.84 $ 4.05 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 1,134 $ 868 $ 727 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — diluted $ 1,132 $ 866 $ 725 Average number of common shares outstanding 179 179 179 Diluted Earnings per Common Share (a) $ 6.32 $ 4.83 $ 4.05 _______________________________________ (a) The 2016 Equity Units excluded from the calculation of diluted EPS were approximately 6 million and 7.1 million for the years ended December 31, 2017 and 2016 , respectively, as the dilutive stock price threshold was not met. For more information, see Note 14 to the Consolidated Financial Statements, " Long-Term Debt ."

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 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 December 31, 2017 and 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: December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Other (a) Netting (b) Net Balance Level 1 Level 2 Level 3 Netting (b) Net Balance (In millions) Assets: Cash equivalents (c) $ 16 $ 3 $ — $ — $ — $ 19 $ 14 $ 3 $ — $ — $ 17 Nuclear decommissioning trusts Equity securities 978 — — — — 978 887 — — — 887 Fixed income securities 18 477 — — — 495 11 414 — — 425 Private equity securities — — — 5 — 5 — — — — — Cash equivalents 14 — — — — 14 8 — — — 8 Other investments (d) Equity securities 118 — — — — 118 104 — — — 104 Fixed income securities 72 — — — — 72 58 — — — 58 Cash equivalents 4 — — — — 4 3 — — — 3 Derivative assets: Commodity Contracts: Natural Gas 148 112 97 — (256 ) 101 216 79 53 (306 ) 42 Electricity — 243 42 — (241 ) 44 — 154 39 (157 ) 36 Other — — 9 — — 9 — — 2 — 2 Foreign currency exchange contracts — 1 — — (1 ) — — 6 — (5 ) 1 Total derivative assets 148 356 148 — (498 ) 154 216 239 94 (468 ) 81 Total $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Derivative liabilities: Commodity Contracts: Natural Gas $ (141 ) $ (111 ) $ (126 ) $ — $ 263 $ (115 ) $ (226 ) $ (86 ) $ (149 ) $ 321 $ (140 ) Electricity — (245 ) (30 ) — 246 (29 ) — (159 ) (30 ) 163 (26 ) Other — — (1 ) — 1 — — — (3 ) 2 (1 ) Foreign currency exchange contracts — (3 ) — — 1 (2 ) — (3 ) — 3 — Total derivative liabilities (141 ) (359 ) (157 ) — 511 (146 ) (226 ) (248 ) (182 ) 489 (167 ) Total $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 Assets: Current $ 157 $ 298 $ 104 $ — $ (437 ) $ 122 $ 205 $ 199 $ 60 $ (400 ) $ 64 Noncurrent 1,211 538 44 5 (61 ) 1,737 1,096 457 34 (68 ) 1,519 Total Assets $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Current $ (137 ) $ (313 ) $ (108 ) $ — $ 459 $ (99 ) $ (203 ) $ (211 ) $ (79 ) $ 424 $ (69 ) Noncurrent (4 ) (46 ) (49 ) — 52 (47 ) (23 ) (37 ) (103 ) 65 (98 ) Total Liabilities $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) 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. (c) At December 31, 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. (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: December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Other (a) Net Balance Level 1 Level 2 Level 3 Net Balance (In millions) Assets: Cash equivalents (b) $ 8 $ 3 $ — $ — $ 11 $ 8 $ 3 $ — $ 11 Nuclear decommissioning trusts Equity securities 978 — — — 978 887 — — 887 Fixed income securities 18 477 — — 495 11 414 — 425 Private equity securities — — — 5 5 — — — — Cash equivalents 14 — — — 14 8 — — 8 Other investments Equity securities 11 — — — 11 9 — — 9 Derivative assets — FTRs — — 9 — 9 — — 2 2 Total $ 1,029 $ 480 $ 9 $ 5 $ 1,523 $ 923 $ 417 $ 2 $ 1,342 Assets: Current $ 8 $ 3 $ 9 $ — $ 20 $ 8 $ 3 $ 2 $ 13 Noncurrent 1,021 477 — 5 1,503 915 414 — 1,329 Total Assets $ 1,029 $ 480 $ 9 $ 5 $ 1,523 $ 923 $ 417 $ 2 $ 1,342 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) At December 31, 2017 , available-for-sale securities of $11 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. At 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. 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. Other assets such as private market investments are used to enhance long-term returns while improving portfolio diversification. All pricing for investments in this category are classified as NAV assets. 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 preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, the Registrants selectively corroborate the fair value of securities by comparison of market-based price sources. Investment policies and procedures are determined by DTE Energy's Trust Investments Department which reports to DTE Energy's Vice President and Treasurer. Derivative Assets and Liabilities Derivative assets and liabilities are comprised of physical and financial derivative contracts, including futures, forwards, options, and swaps that are both exchange-traded and over-the-counter traded contracts. Various inputs are used to value derivatives depending on the type of contract and availability of market data. Exchange-traded derivative contracts are valued using quoted prices in active markets. The Registrants consider the following criteria in determining whether a market is considered active: frequency in which pricing information is updated, variability in pricing between sources or over time, and the availability of public information. Other derivative contracts are valued based upon a variety of inputs including commodity market prices, broker quotes, interest rates, credit ratings, default rates, market-based seasonality, and basis differential factors. The Registrants monitor the prices that are supplied by brokers and pricing services and may use a supplemental price source or change the primary price source of an index if prices become unavailable or another price source is determined to be more representative of fair value. The Registrants have obtained an understanding of how these prices are derived. Additionally, the Registrants selectively corroborate the fair value of their transactions by comparison of market-based price sources. Mathematical valuation models are used for derivatives for which external market data is not readily observable, such as contracts which extend beyond the actively traded reporting period. The Registrants have established a Risk Management Committee whose responsibilities include directly or indirectly ensuring all valuation methods are applied in accordance with predefined policies. The development and maintenance of the Registrants' forward price curves has been assigned to DTE Energy's Risk Management Department, which is separate and distinct from the trading functions within DTE Energy. The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Energy for the years ended December 31, 2017 and 2016 : Year Ended December 31, 2017 Year Ended December 31, 2016 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of January 1 $ (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 (29 ) 109 2 82 (159 ) (2 ) 1 (160 ) Recorded in Regulatory liabilities — — 25 25 — — 6 6 Purchases, issuances, and settlements: Purchases — — — — — 1 — 1 Settlements 96 (106 ) (18 ) (28 ) 68 4 (3 ) 69 Net Assets (Liabilities) as of December 31 $ (29 ) $ 12 $ 8 $ (9 ) $ (96 ) $ 9 $ (1 ) $ (88 ) The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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 $ (30 ) $ 50 $ 1 $ 21 $ (166 ) $ 7 $ 2 $ (157 ) The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Electric for the years ended December 31, 2017 and 2016 : Year Ended December 31, 2017 2016 (In millions) Net Assets as of January 1 $ 2 $ 3 Change in fair value recorded in Regulatory liabilities 25 6 Purchases, issuances, and settlements: Settlements (18 ) (7 ) Net Assets as of December 31 $ 9 $ 2 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2017 and 2016 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 9 $ 2 Derivatives are transferred between levels primarily due to changes in the source data used to construct price curves as a result of changes in market liquidity. Transfers in and transfers out are reflected as if they had occurred at the beginning of the period. There were no transfers between Levels 1 and 2 for the Registrants during the years ended December 31, 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 as of December 31, 2017 and 2016 : December 31, 2017 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 97 $ (126 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.10 ) — $ 9.75 /MMBtu $ (0.03 )/MMBtu Electricity $ 42 $ (30 ) Discounted Cash Flow Forward basis price (per MWh) $ (5 ) — $ 15 /MWh $ 2 /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, Controller, and Chief Accounting Officer. The following table presents the carrying amount and fair value of financial instruments for DTE Energy as of December 31, 2017 and 2016 : December 31, 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 (a) , excluding capital leases $ 38 $ — $ — $ 38 $ 36 $ — $ — $ 36 Dividends payable $ 158 $ 158 $ — $ — $ 148 $ 148 $ — $ — Short-term borrowings $ 621 $ — $ 621 $ — $ 499 $ — $ 499 $ — Notes payable — Other (b) , excluding capital leases $ 12 $ — $ — $ 12 $ 17 $ — $ — $ 17 Long-term debt (c) $ 12,288 $ 1,939 $ 10,571 $ 764 $ 11,270 $ 1,465 $ 9,384 $ 1,056 _______________________________________ (a) Current portion included in Current Assets — Other on DTE Energy's Consolidated Statements of Financial Position. (b) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Energy's Consolidated Statements of Financial Position. (c) 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 as of December 31, 2017 and 2016 : December 31, 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 (a) , excluding capital leases $ — $ — $ — $ — $ 5 $ — $ — $ 5 Short-term borrowings — affiliates $ 116 $ — $ — $ 116 $ 117 $ — $ — $ 117 Short-term borrowings — other $ 238 $ — $ 238 $ — 62 $ — $ 62 $ — Notes payable — Other (b) , excluding capital leases $ 2 $ — $ — $ 2 $ 6 $ — $ — $ 6 Long-term debt (c) $ 6,017 $ — $ 6,441 $ 171 $ 5,878 $ — $ 6,026 $ 264 _______________________________________ (a) Current portion included in Current Assets — Other on DTE Electric's Consolidated Statements of Financial Position. (b) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Electric's Consolidated Statements of Financial Position. (c) 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 13 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. See Note 8 to the Consolidated Financial Statements, " Asset Retirement Obligations ." The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: December 31, 2017 December 31, 2016 (In millions) Fermi 2 $ 1,475 $ 1,291 Fermi 1 3 3 Low-level radioactive waste 14 26 $ 1,492 $ 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: Year Ended December 31, 2017 2016 2015 (In millions) Realized gains $ 83 $ 74 $ 39 Realized losses $ (29 ) $ (63 ) $ (33 ) Proceeds from sale of securities $ 1,240 $ 1,457 $ 885 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: December 31, 2017 December 31, 2016 Fair Unrealized Unrealized Losses Fair Unrealized Unrealized Losses (In millions) Equity securities $ 978 $ 320 $ (32 ) $ 887 $ 222 $ (46 ) Fixed income securities 495 13 (3 ) 425 11 (5 ) Private equity securities 5 — — — — — Cash equivalents 14 — — 8 — — $ 1,492 $ 333 $ (35 ) $ 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: December 31, 2017 (In millions) Due within one year $ 23 Due after one through five years 102 Due after five through ten years 115 Due after ten years 255 $ 495 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 December 31, 2017 and 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 years ended December 31, 2017 and 2016 . Gains related to trading securities held at December 31, 2017 , 2016 , and 2015 were $26 million , $15 million , and $1 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	12 Months Ended
	Dec. 31, 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 December 31, 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 as of December 31, 2017 and 2016 for DTE Energy: December 31, 2017 December 31, 2016 Derivative Derivative Derivative Derivative (In millions) Derivatives not designated as hedging instruments: Commodity Contracts: Natural Gas $ 357 $ (378 ) $ 348 $ (461 ) Electricity 285 (275 ) 193 (189 ) Other 9 (1 ) 2 (3 ) Foreign currency exchange contracts 1 (3 ) 6 (3 ) Total derivatives not designated as hedging instrument $ 652 $ (657 ) $ 549 $ (656 ) Current $ 540 $ (558 ) $ 447 $ (493 ) Noncurrent 112 (99 ) 102 (163 ) Total derivatives $ 652 $ (657 ) $ 549 $ (656 ) The following table presents the fair value of derivative instruments as of December 31, 2017 and 2016 for DTE Electric: December 31, 2017 2016 (In millions) FTRs — Other current assets $ 9 $ 2 Total derivatives not designated as hedging instruments $ 9 $ 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 $4 million and $2 million outstanding at December 31, 2017 and 2016 , respectively, 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 $4 million and $2 million at December 31, 2017 and 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 $28 million and $34 million as of December 31, 2017 and 2016 , respectively. DTE Energy had $9 million of cash collateral related to unrealized positions to net against Derivative assets while Derivative liabilities are shown net of cash collateral of $22 million as of December 31, 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 $18 million and cash collateral received of $3 million not related to unrealized derivative positions as of December 31, 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 at December 31, 2017 and 2016 : December 31, 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 $ 357 $ (256 ) $ 101 $ 348 $ (306 ) $ 42 Electricity 285 (241 ) 44 193 (157 ) 36 Other 9 — 9 2 — 2 Foreign currency exchange contracts 1 (1 ) — 6 (5 ) 1 Total derivative assets $ 652 $ (498 ) $ 154 $ 549 $ (468 ) $ 81 Derivative liabilities: Commodity Contracts: Natural Gas $ (378 ) $ 263 $ (115 ) $ (461 ) $ 321 $ (140 ) Electricity (275 ) 246 (29 ) (189 ) 163 (26 ) Other (1 ) 1 — (3 ) 2 (1 ) Foreign currency exchange contracts (3 ) 1 (2 ) (3 ) 3 — Total derivative liabilities $ (657 ) $ 511 $ (146 ) $ (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 at December 31, 2017 and 2016 : December 31, 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 $ 540 $ 112 $ (558 ) $ (99 ) $ 447 $ 102 $ (493 ) $ (163 ) Counterparty netting (437 ) (52 ) 437 52 (396 ) (65 ) 396 65 Collateral adjustment — (9 ) 22 — (4 ) (3 ) 28 — Total derivatives as reported $ 103 $ 51 $ (99 ) $ (47 ) $ 47 $ 34 $ (69 ) $ (98 ) The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations for years ended December 31, 2017 and 2016 is as follows: Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31, Derivatives not Designated as Hedging Instruments 2017 2016 (In millions) Commodity Contracts: Natural Gas Operating Revenues — Non-utility operations $ (74 ) $ (153 ) Natural Gas Fuel, purchased power, and gas — non-utility 97 (2 ) Electricity Operating Revenues — Non-utility operations 105 43 Other Operating Revenues — Non-utility operations 2 5 Foreign currency exchange contracts Operating Revenues — Non-utility operations (2 ) (2 ) Total $ 128 $ (109 ) Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility. The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of December 31, 2017 : Commodity Number of Units Natural Gas (MMBtu) 1,822,796,301 Electricity (MWh) 29,715,268 Foreign Currency Exchange (Canadian dollars) 108,023,948 Various subsidiaries of DTE Energy have entered into contracts which contain ratings triggers and are guaranteed by DTE Energy. These contracts contain provisions which allow the counterparties to require that DTE Energy post cash or letters of credit as collateral in the event that DTE Energy’s credit rating is downgraded below investment grade. Certain of these provisions (known as “hard triggers”) state specific circumstances under which DTE Energy can be required to post collateral upon the occurrence of a credit downgrade, while other provisions (known as “soft triggers”) are not as specific. For contracts with soft triggers, it is difficult to estimate the amount of collateral which may be requested by counterparties and/or which DTE Energy may ultimately be required to post. The amount of such collateral which could be requested fluctuates based on commodity prices (primarily natural gas, power, and coal) and the provisions and maturities of the underlying transactions. As of December 31, 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 $456 million . As of December 31, 2017 , DTE Energy had approximately $535 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 $468 million . The net remaining amount of approximately $67 million is derived from the $456 million noted above.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2017
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	LONG-TERM DEBT Long-Term Debt DTE Energy's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2017 2016 (In millions) Mortgage bonds, notes, and other DTE Energy Debt, Unsecured 3.1% 2019 — 2033 $ 3,825 $ 3,325 DTE Electric Taxable Debt, Principally Secured 4.3% 2020 — 2047 5,755 5,615 DTE Electric Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 DTE Gas Taxable Debt, Principally Secured 4.8% 2018 — 2047 1,330 1,250 Other Long-Term Debt, including Non-Recourse Debt 7 92 11,227 10,592 Unamortized debt discount and premium, net (15 ) (10 ) Unamortized debt issuance costs (69 ) (67 ) Long-term debt due within one year (104 ) (9 ) $ 11,039 $ 10,506 Junior Subordinated Debentures Subordinated Debentures 5.5% 2062 — 2077 $ 1,180 $ 780 Unamortized debt issuance costs (35 ) (24 ) $ 1,145 $ 756 _______________________________________ (a) Weighted average interest rate as of December 31, 2017 . (b) DTE Electric Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds. DTE Electric's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2017 2016 (In millions) Mortgage bonds, notes, and other Taxable Debt, Principally Secured 4.3% 2020 — 2047 $ 5,755 $ 5,615 Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 6,065 5,925 Unamortized debt discount (10 ) (10 ) Unamortized debt issuance costs (38 ) (37 ) $ 6,017 $ 5,878 _______________________________________ (a) Weighted average interest rate as of December 31, 2017 . (b) Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds. Debt Issuances In 2017 , the following debt was issued: Company Month Type Interest Rate Maturity Date 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 DTE Energy November Junior Subordinated Debentures (a) 5.25% 2077 400 $ 1,420 _______________________________________ (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 Date 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. The following table shows the Registrants' scheduled debt maturities, excluding any unamortized discount or premium on debt: 2018 2019 2020 2021 2022 2023 and Thereafter Total (In millions) DTE Energy (a) $ 104 $ 1,497 $ 683 $ 462 $ 616 $ 9,045 $ 12,407 DTE Electric $ — $ — $ 632 $ 462 $ 316 $ 4,655 $ 6,065 _______________________________________ (a) Amounts include DTE Electric's scheduled debt maturities. Junior Subordinated Debentures At December 31, 2017 , DTE Energy had the following Junior Subordinated Debentures: Interest Rate Maturity Date Amount (In millions) 2012 Series C 5.25% 2062 $ 200 2016 Series B 5.375% 2076 300 2016 Series F 6.00% 2076 280 2017 Series E 5.25% 2077 400 $ 1,180 DTE Energy has the right to defer interest payments on the debt securities. Should DTE Energy exercise this right, it cannot declare or pay dividends on, or redeem, purchase or acquire, any of its capital stock during the deferral period. Any deferred interest payments will bear additional interest at the rate associated with the related debt issue. As of December 31, 2017 , no interest payments have been deferred on the debt securities. Cross Default Provisions Substantially all of the net utility properties of DTE Electric and DTE Gas are subject to the lien of mortgages. Should DTE Electric or DTE Gas fail to timely pay their indebtedness under these mortgages, such failure may create cross defaults in the indebtedness of DTE Energy. Acquisition Financing Effective October 1, 2016 , DTE Energy closed on the purchase of midstream natural gas assets. The acquisition was financed through the issuance of Equity Units and Senior Notes. See Note 4 to the Consolidated Financial Statements, " Acquisitions and Exit Activities ," for more information on the acquisition. In October 2016, DTE issued $675 million of Equity Units. Each Equity Unit has a stated amount of $ 50 , initially in the form of a Corporate Unit, is comprised of (i) a forward purchase contract to buy DTE Energy common stock (stock purchase contract) and (ii) a 1/20 undivided beneficial ownership interest in $1,000 principal amount of DTE Energy’s 2016 Series C 1.5% RSNs due 2024 . The RSN debt instruments and the stock purchase contract equity instruments are deemed to be separate instruments as the investor may trade the RSNs separately from the stock purchase contracts and may also settle the stock purchase contracts separately. The Corporate Units are listed on the New York Stock Exchange under the symbol DTV. The stock purchase contract obligates the holder to purchase from DTE Energy on the settlement date, October 1, 2019, for a price of $ 50 per stock purchase contract, the following number of shares of DTE Energy’s common stock, subject to anti-dilution adjustments: • if the AMV of DTE Energy’s common stock, which is the average volume-weighted average price of DTE Energy’s common stock for the trading days during the 20 consecutive scheduled trading day period ending on the third scheduled trading day immediately preceding the stock purchase contract settlement date, is equal to or greater than $116.31 , 0.4299 shares of common stock; • if the AMV is less than $116.31 but greater than $ 93.05 , a number of shares of common stock equal to $50 divided by the AMV, rounded to the nearest 1/10,000th of a share; and • if the AMV is less than or equal to $93.05 , 0.5373 shares of common stock. The RSNs bear interest at a rate of 1.5% per year, payable quarterly, and mature on October 1, 2024 . The RSNs will be remarketed in 2019. If this remarketing is successful, the interest rate on the RSNs will be reset, and thereafter interest will be payable semi-annually at the reset rate. If there is no successful remarketing, the interest rate on the RSNs will not be reset, and the holders of the RSNs will have the right to put the RSNs to DTE Energy at a price equal to 100% of the principal amount, and the proceeds of the put right will be deemed to have been applied against the holders’ obligation under the stock purchase contracts. DTE Energy may also redeem, in whole or in part, the RSNs in the event of a failed final remarketing. On January 1, 2017, DTE Energy began paying the stock purchase contract holders quarterly contract adjustment payments at a rate of 5% per year of the stated amount of $50 per Equity Unit, or $2.50 per year. The present value of the future contract adjustment payments of $98 million was recorded as a reduction of shareholders’ equity, offset by the stock purchase contract liability. The stock purchase contract liability is included in Current Liabilities — Other and Other Liabilities — Other on DTE Energy’s Consolidated Statements of Financial Position. Interest payments on the RSNs are recorded as interest expense and stock purchase contract payments are charged against the liability. Accretion of the stock purchase contract liability is recorded as imputed interest expense. The treasury stock method is used to compute diluted EPS for the stock purchase contract. Under the treasury stock method, the stock purchase contract will only have a dilutive effect when the settlement rate is based on the market value of DTE’s common stock that is greater than $116.31 (the threshold appreciation price). At December 31, 2017 , the stock purchase price contract was anti-dilutive and, therefore, not included in the computation of diluted earnings per share. If payments for the stock purchase contract are deferred, DTE Energy may not make any cash distributions related to its capital stock, including dividends, redemptions, repurchases, liquidation payments or guarantee payments. Also, during the deferral period, DTE Energy may not make any payments on or redeem or repurchase any debt securities that are equal in right of payment with, or subordinated to, the RSNs. Until settlement of the stock purchase contracts, the shares of stock underlying each contract are not outstanding. Under the terms of the stock purchase contracts, assuming no anti-dilution or other adjustments, DTE Energy will issue between 5.8 million and 7.3 million shares of its common stock in October 2019. A total of 9 million shares of DTE Energy’s common stock have been reserved for issuance in connection with the stock purchase contracts. Selected information about DTE Energy’s 2016 Equity Units is presented below: Issuance Date Units Issued Total Net Proceeds Total Long-Term Debt RSN Annual Interest Rate Stock Purchase Contract Annual Rate Stock Purchase Settlement Date Stock Purchase Contract Liability (a) RSN Maturity Date (In millions, except interest rates) 10/5/2016 13.5 $ 654 $ 675 1.5% 5.0% 10/1/2019 $ 98 10/1/2024 _______________________________________ (a) Payments of $32 million were made in 2017. The stock purchase contract liability was $66 million and $98 million at December 31, 2017 and 2016 , respectively, exclusive of interest. In October 2016, DTE Energy issued $400 million of 2016 Series D 1.50% Senior Notes due 2019 and $600 million of Series E 2.85% Senior Notes due 2026. The proceeds from the Senior Notes were used for the acquisition and general corporate purposes.

Preferred and Preference Securi

Preferred and Preference Securities	12 Months Ended
	Dec. 31, 2017
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred and Preference Securities	PREFERRED AND PREFERENCE SECURITIES As of December 31, 2017 , the amount of authorized and unissued stock is as follows: Company Type of Stock Par Value Shares Authorized DTE Energy Preferred $ — 5,000,000 DTE Electric Preferred $ 100 6,747,484 DTE Electric Preference $ 1 30,000,000 DTE Gas Preferred $ 1 7,000,000 DTE Gas Preference $ 1 4,000,000

Short-Term Credit Arrangements

Short-Term Credit Arrangements and Borrowings	12 Months Ended
	Dec. 31, 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 December 31, 2017 , the total funded debt to total capitalization ratios for DTE Energy, DTE Electric, and DTE Gas were 0.54 to 1, 0.50 to 1, and 0.48 to 1, respectively, and were in compliance with this financial covenant. The availability under the facilities in place at December 31, 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 70 — — 70 Unsecured revolving credit facility, expiring April 2022 1,200 400 300 1,900 1,420 400 300 2,120 Amounts outstanding at December 31, 2017 Commercial paper issuances 83 238 300 621 Letters of credit 124 — — 124 207 238 300 745 Net availability at December 31, 2017 $ 1,213 $ 162 $ — $ 1,375 DTE Energy has approximately $9 million of other outstanding letters of credit which are used for various corporate purposes and are not included in the facilities described above. The weighted average interest rate for short-term borrowings was 1.9% and 0.9% at December 31, 2017 and 2016 , respectively, for DTE Energy. The weighted average interest rate for short-term borrowings was 1.5% and 0.8% at December 31, 2017 and 2016 , respectively, for DTE Electric. In conjunction with maintaining certain exchange traded risk management positions, DTE Energy may be required to post collateral with its clearing agent. DTE Energy has a demand financing agreement for up to $100 million with its clearing agent. The agreement, as amended, also allows for up to $50 million of additional margin financing provided that DTE Energy posts a letter of credit for the incremental amount and allows the right of setoff with posted collateral. At December 31, 2017 , the capacity under this facility was $100 million . The amount outstanding under this agreement was $56 million and $50 million at December 31, 2017 and 2016 , respectively, and was fully offset by the posted collateral. Dividend Restrictions Certain of DTE Energy’s credit facilities contain a provision requiring DTE Energy to maintain a total funded debt to capitalization ratio, as defined in the agreements, of no more than 0.65 to 1, which has the effect of limiting the amount of dividends DTE Energy can pay in order to maintain compliance with this provision. At December 31, 2017 , the effect of this provision was to restrict the payment of approximately $1.8 billion of Retained earnings totaling $5.6 billion . There are no other effective limitations with respect to DTE Energy’s ability to pay dividends.

Capital and Operating Leases

Capital and Operating Leases	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Capital and Operating Leases	CAPITAL AND OPERATING LEASES Lessee — Operating Lease — The Registrants lease various assets under operating leases, including coal railcars, office buildings, a warehouse, computers, vehicles, and other equipment. The lease arrangements expire at various dates through 2046 . The Registrants' future minimum lease payments under non-cancelable operating leases at December 31, 2017 were: DTE Energy DTE Electric (In millions) 2018 $ 40 $ 15 2019 34 14 2020 22 9 2021 13 9 2022 9 6 2022 and thereafter 48 38 Total minimum lease payments $ 166 $ 91 Rental expense for DTE Energy operating leases was $51 million in 2017 and $43 million in 2016 and 2015 , including rental expense for DTE Electric operating leases of $28 million in 2017 , $28 million in 2016 , and $32 million in 2015 . Lessor — Capital Lease — DTE Energy leases a portion of its pipeline system to the Vector Pipeline through a capital lease contract that expires in 2020, with renewal options extending for five years. DTE Energy owns a 40% interest in the Vector Pipeline. In addition, DTE Energy has two energy services agreements, for which a portion of are accounted for as capital leases. These agreements were extended during the year and expire in 2019 and 2026. The components of DTE Energy's net investment in capital leases at December 31, 2017 , were as follows: DTE Energy (In millions) 2018 $ 13 2019 10 2020 9 2021 — 2022 — 2023 and thereafter 1 Total minimum future lease receipts 33 Residual value of leased pipeline 40 Less unearned income (15 ) Net investment in capital lease 58 Less current portion (7 ) $ 51

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 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 NO x . 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 SO 2 , NO x , mercury, and other emissions. Additional rulemakings may occur over the next few years which could require additional controls for SO 2 , NO x , and other hazardous air pollutants. The Cross State Air Pollution Rule (CSAPR), required further reductions of SO 2 and NO x 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) NO x 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 NO x 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. In November 2017, the EPA completed the majority of the United States attainment/unclassifiable area designations. The Registrants expect the EPA to complete the remaining designations, including the non-attainment area designations with the 2015 ozone standards by the first quarter in 2018. 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. On January 10, 2017, a divided panel of the Court reversed the decision of the U.S. District Court. 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 the U.S. 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. On December 11, 2017, the U.S. Supreme Court denied certiorari. As a result of the Supreme Court electing not to review the matter, the case was sent back to the U.S. District Court for further proceedings. The Registrants are in discussion with the EPA regarding this matter. 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's repeal and possible replacement of the 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 2017 . DTE Electric does not anticipate additional capital expenditures through 2024 . 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 and submitted as part of the National Pollutant Discharge Elimination System (NPDES) permit application process to determine the type of technology needed to reduce impacts to fish. DTE Electric has initiated the process of completing the required studies. Final compliance for the installation of any required technology will be determined by each state on a case by case, site specific basis. DTE Electric is currently evaluating the compliance options and working with the State of Michigan on evaluating whether any controls are needed. These evaluations/studies may require modifications to some existing intake structures. It is not possible to quantify the impact of this rulemaking at this time. Contaminated and Other Sites — Prior to the construction of major interstate natural gas pipelines, gas for heating and other uses was manufactured locally from processes involving coal, coke, or oil. The facilities, which produced gas, have been designated as MGP sites. DTE Electric conducted remedial investigations at contaminated sites, including three former MGP sites. The investigations have revealed contamination related to the by-products of gas manufacturing at each MGP site. In addition to the MGP sites, DTE Electric is also in the process of cleaning up other contaminated sites, including the area surrounding an ash landfill, electrical distribution substations, electric generating power plants, and underground and aboveground storage tank locations. The findings of these investigations indicated that the estimated cost to remediate these sites is expected to be incurred over the next several years. At December 31, 2017 and 2016 , DTE Electric had $6 million and $8 million accrued for remediation, respectively. Any change in assumptions, such as remediation techniques, nature and extent of contamination, and regulatory requirements, could impact the estimate of remedial action costs for the sites and affect DTE Electric’s financial position and cash flows. DTE Electric believes the likelihood of a material change to the accrued amount is remote based on current knowledge of the conditions at each site. Coal Combustion Residuals and Effluent Limitations Guidelines — A final EPA rule for the disposal of coal combustion residuals, commonly known as coal ash, became effective in October 2015, 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 the CRR requirements, costs associated with the building of new facilities or installation of controls are estimated to be approximately $295 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 December 31, 2017 and 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 SO2 emission reductions that, in combination with other non-DTE Energy sources' emission reduction strategies, will help the state attain the standard and sustain its attainment. Since several non-DTE Energy sources are also part of the proposed compliance plan, DTE Energy is unable to determine the full impact of the final required emissions reductions at this time. 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 December 31, 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 December 31, 2017 was approximately $386 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 $80 million and $10 million at December 31, 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 December 31, 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 December 31, 2017 , DTE Energy had approximately $58 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 subsidiaries' approximate 5,000 represented employees, including DTE Electric's approximate 2,700 represented employees. The majority of the represented employees are under contracts that expire in 2020 and 2021 . Purchase Commitments As of December 31, 2017 , the Registrants were party to numerous long-term purchase commitments relating to a variety of goods and services required for their businesses. These agreements primarily consist of fuel supply commitments and renewable energy contracts for the Registrants, as well as energy trading contracts for DTE Energy. The Registrants estimate the following commitments from 2018 through 2051 for DTE Energy, and 2018 through 2033 for DTE Electric, as detailed in the following table: DTE Energy DTE Electric (In millions) 2018 $ 2,731 $ 930 2019 1,045 320 2020 638 192 2021 474 149 2022 371 88 2023 and thereafter 2,277 820 $ 7,536 $ 2,499 Utility capital expenditures, expenditures for non-utility businesses, and contributions to equity method investees will be approximately $3.6 billion and $1.9 billion in 2018 for DTE Energy and DTE Electric, respectively. The Registrants have made certain commitments in connection with the estimated 2018 annual capital 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 9 and 13 to the Consolidated Financial Statements, " Regulatory Matters " and " Financial and Other Derivative Instruments ," respectively.

Nuclear Operations

Nuclear Operations	12 Months Ended
	Dec. 31, 2017
Nuclear Operations [Abstract]
Nuclear Operations	NUCLEAR OPERATIONS Property Insurance DTE Electric maintains property insurance policies specifically for the Fermi 2 plant. These policies cover such items as replacement power and property damage. NEIL is the primary supplier of the insurance policies. DTE Electric maintains a policy for extra expenses, including replacement power costs necessitated by Fermi 2’s unavailability due to an insured event. This policy has a 12-week waiting period and provides an aggregate $490 million of coverage over a three -year period. DTE Electric has $1.5 billion in primary coverage and $1.25 billion of excess coverage for stabilization, decontamination, debris removal, repair and/or replacement of property, and decommissioning. The combined coverage limit for total property damage is $2.75 billion . The total limit for property damage for non-nuclear events is $2 billion and an aggregate of $328 million of coverage for extra expenses over a two -year period. On January 13, 2015, the Terrorism Risk Insurance Program Reauthorization Act of 2015 was signed, extending TRIA through December 31, 2020. For multiple terrorism losses caused by acts of terrorism not covered under the TRIA occurring within one year after the first loss from terrorism, the NEIL policies would make available to all insured entities up to $3.2 billion , plus any amounts recovered from reinsurance, government indemnity, or other sources to cover losses. Under NEIL policies, DTE Electric could be liable for maximum assessments of up to approximately $47 million per event if the loss associated with any one event at any nuclear plant should exceed the accumulated funds available to NEIL. Public Liability Insurance As required by federal law, DTE Electric maintains $450 million of public liability insurance for a nuclear incident. For liabilities arising from a terrorist act outside the scope of TRIA, the policy is subject to one industry aggregate limit of $300 million . Further, under the Price-Anderson Amendments Act of 2005, deferred premium charges up to $127 million could be levied against each licensed nuclear facility, but not more than $19 million per year per facility. Thus, deferred premium charges could be levied against all owners of licensed nuclear facilities in the event of a nuclear incident at any of these facilities. Nuclear Fuel Disposal Costs In accordance with the Federal Nuclear Waste Policy Act of 1982, DTE Electric has a contract with the DOE for the future storage and disposal of spent nuclear fuel from Fermi 2 that required DTE Electric to pay the DOE a fee of 1 mill per kWh of Fermi 2 electricity generated and sold. The fee was a component of nuclear fuel expense. The 1 mill per kWh DOE fee was reduced to zero effective May 16, 2014. The DOE's Yucca Mountain Nuclear Waste Repository program for the acceptance and disposal of spent nuclear fuel was terminated in 2011. DTE Electric is a party in the litigation against the DOE for both past and future costs associated with the DOE's failure to accept spent nuclear fuel under the timetable set forth in the Federal Nuclear Waste Policy Act of 1982. In July 2012, DTE Electric executed a settlement agreement with the federal government for costs associated with the DOE's delay in acceptance of spent nuclear fuel from Fermi 2 for permanent storage. The settlement agreement, including extensions, provides for a claims process and payment of delay-related costs experienced by DTE Electric through 2019. DTE Electric's claims are being settled and paid on a timely basis. The settlement proceeds reduce the cost of the dry cask storage facility assets and provide reimbursement for related operating expenses. DTE Electric currently employs a spent nuclear fuel storage strategy utilizing a fuel pool and a dry cask storage facility. The spent nuclear fuel storage strategy is expected to provide sufficient spent fuel storage capability for the life of the plant as defined by the original operating license. The federal government continues to maintain its legal obligation to accept spent nuclear fuel from Fermi 2 for permanent storage. Issues relating to long-term waste disposal policy and to the disposition of funds contributed by DTE Electric ratepayers to the federal waste fund await future governmental action.

Retirement Benefits and Trustee

Retirement Benefits and Trusteed Assets	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plan [Abstract]
Retirement Benefits and Trusteed Assets	RETIREMENT BENEFITS AND TRUSTEED ASSETS DTE Energy's subsidiary, DTE Energy Corporate Services, LLC (LLC), sponsors defined benefit pension plans and other postretirement plans covering substantially all employees of the Registrants. The table below represents the pension and other postretirement benefit plans which employees of each Registrant participated at December 31, 2017 : Registrants DTE Energy DTE Electric Qualified Pension Plans DTE Energy Company Retirement Plan X X DTE Gas Company Retirement Plan for Employees Covered by Collective Bargaining Agreements X Shenango Inc. Pension Plan X Nonqualified Pension Plans DTE Energy Company Supplemental Retirement Plan X X DTE Energy Company Executive Supplemental Retirement Plan (a) X X DTE Energy Company Supplemental Severance Benefit Plan X Other Postretirement Benefit Plans The DTE Energy Company Comprehensive Non-Health Welfare Plan X X The DTE Energy Company Comprehensive Retiree Group Health Care Plan X X DTE Supplemental Retiree Benefit Plan X X DTE Energy Company Retiree Reimbursement Arrangement Plan X X _____________________________________ (a) Sponsored by the DTE Energy subsidiary, DTE Energy Holding Company. DTE Electric participates in various plans that provide pension and other postretirement benefits for DTE Energy and its affiliates. The plans are sponsored by the LLC. DTE Electric accounts for its participation in DTE Energy's qualified and nonqualified pension plans by applying multiemployer accounting. DTE Electric accounts for its participation in other postretirement benefit plans by applying multiple-employer accounting. Within multiemployer and multiple-employer plans, participants pool plan assets for investment purposes and to reduce the cost of plan administration. The primary difference between plan types is assets contributed in multiemployer plans can be used to provide benefits for all participating employers, while assets contributed within a multiple-employer plan are restricted for use by the contributing employer. Plan participants of all plans are solely DTE Energy and affiliate employees. Pension Plan Benefits DTE Energy has qualified defined benefit retirement plans for eligible represented and non-represented employees. The plans are noncontributory and provide traditional retirement benefits based on the employee's years of benefit service, average final compensation, and age at retirement. In addition, certain represented and non-represented employees are covered under cash balance provisions that determine benefits on annual employer contributions and interest credits. DTE Energy also maintains supplemental nonqualified, noncontributory, retirement benefit plans for selected management employees. These plans provide for benefits that supplement those provided by DTE Energy’s other retirement plans. Net pension cost for DTE Energy includes the following components: 2017 2016 2015 (In millions) Service cost $ 92 $ 92 $ 100 Interest cost 214 219 210 Expected return on plan assets (311 ) (309 ) (296 ) Amortization of: Net actuarial loss 176 164 205 Prior service cost 1 1 — Other — — 2 Net pension cost $ 172 $ 167 $ 221 2017 2016 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial loss $ 27 $ 197 Amortization of net actuarial loss (176 ) (164 ) Prior service cost ( credit) (11 ) 7 Amortization of prior service cost (1 ) (1 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (161 ) $ 39 Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 11 $ 206 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 178 $ 172 Prior service cost $ — $ 1 The following table reconciles the obligations, assets, and funded status of the plans as well as the amounts recognized as prepaid pension cost or pension liability in DTE Energy's Consolidated Statements of Financial Position at December 31: DTE Energy 2017 2016 (In millions) Accumulated benefit obligation, end of year $ 5,149 $ 4,753 Change in projected benefit obligation Projected benefit obligation, beginning of year $ 5,171 $ 4,971 Service cost 92 92 Interest cost 214 219 Plan amendments (11 ) 7 Actuarial loss 391 141 Benefits paid (281 ) (259 ) Projected benefit obligation, end of year $ 5,576 $ 5,171 Change in plan assets Plan assets at fair value, beginning of year $ 4,012 $ 3,832 Actual return on plan assets 674 253 Company contributions 231 186 Benefits paid (281 ) (259 ) Plan assets at fair value, end of year $ 4,636 $ 4,012 Funded status $ (940 ) $ (1,159 ) Amount recorded as: Current liabilities $ (16 ) $ (7 ) Noncurrent liabilities (924 ) (1,152 ) $ (940 ) $ (1,159 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 163 $ 163 Prior service cost 6 8 $ 169 $ 171 Amounts recognized in Regulatory assets (a) Net actuarial loss $ 2,014 $ 2,163 Prior service credit (14 ) (4 ) $ 2,000 $ 2,159 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." The Registrants' policy is to fund pension costs by contributing amounts consistent with the provisions of the Pension Protection Act of 2006, and additional amounts when it deems appropriate. The following table provides cash contributions to the qualified pension plans as of December 31: 2017 2016 2015 (In millions) DTE Energy $ 223 $ 179 $ 177 DTE Electric 185 145 145 At the discretion of management, and depending upon financial market conditions, DTE Energy anticipates making up to $200 million in contributions, including $175 million of DTE Electric contributions, to the qualified pension plans in 2018 . DTE Energy's subsidiaries are responsible for their share of qualified and nonqualified pension benefit costs. DTE Electric's allocated portion of pension benefit costs included in capital expenditures and operating and maintenance expense were $136 million for the years ended December 31, 2017 and 2016 , and $176 million for the year ended December 31, 2015 . These amounts include recognized contractual termination benefit charges, curtailment gains, and settlement charges. At December 31, 2017 , the benefits related to DTE Energy's qualified and nonqualified pension plans expected to be paid in each of the next five years and in the aggregate for the five fiscal years thereafter are as follows: (In millions) 2018 $ 299 2019 301 2020 316 2021 317 2022 323 2023-2027 1,692 Total $ 3,248 Assumptions used in determining the projected benefit obligation and net pension costs of DTE Energy are: 2017 2016 2015 Projected benefit obligation Discount rate 3.70% 4.25% 4.50% Rate of compensation increase 4.98% 4.65% 4.65% Net pension costs Discount rate 4.25% 4.50% 4.12% Rate of compensation increase 4.65% 4.65% 4.65% Expected long-term rate of return on plan assets 7.50% 7.75% 7.75% DTE Energy employs a formal process in determining the long-term rate of return for various asset classes. Management reviews historic financial market risks and returns and long-term historic relationships between the asset classes of equities, fixed income, and other assets, consistent with the widely accepted capital market principle that asset classes with higher volatility generate a greater return over the long-term. Current market factors such as inflation, interest rates, asset class risks, and asset class returns are evaluated and considered before long-term capital market assumptions are determined. The long-term portfolio return is also established employing a consistent formal process, with due consideration of diversification, active investment management, and rebalancing. Peer data is reviewed to check for reasonableness. As a result of this process, the Registrants have long-term rate of return assumptions for the pension plans of 7.50% and other postretirement benefit plans of 7.75% for 2018 . The Registrants believe these rates are a reasonable assumption for the long-term rate of return on plan assets for 2018 given the current investment strategy. DTE Energy employs a total return investment approach whereby a mix of equities, fixed income, and other investments are used to maximize the long-term return on plan assets consistent with prudent levels of risk, with consideration given to the liquidity needs of the plan. Risk tolerance is established through consideration of future plan cash flows, plan funded status, and corporate financial considerations. The investment portfolio contains a diversified blend of equity, fixed income, and other investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks, growth and value stocks, and large and small market capitalizations. Fixed income securities generally include market duration bonds of companies from diversified industries, mortgage-backed securities, non-U.S. securities, bank loans, and U.S. Treasuries. Pension assets include long duration U.S. government and diversified corporate bonds intended to partially mitigate liability volatility caused by changes in discount rates. Other assets, such as private markets and hedge funds, are used to enhance long-term returns while improving portfolio diversification. Derivatives may be utilized in a risk controlled manner, to potentially increase the portfolio beyond the market value of invested assets and/or reduce portfolio investment risk. Investment risk is measured and monitored on an ongoing basis through annual liability measurements, periodic asset/liability studies, and quarterly investment portfolio reviews. Target allocations for DTE Energy's pension plan assets as of December 31, 2017 are listed below: U.S. Large Capitalization (Cap) Equity Securities 18 % U.S. Small Cap and Mid Cap Equity Securities 5 Non-U.S. Equity Securities 17 Fixed Income Securities 32 Hedge Funds and Similar Investments 20 Private Equity and Other 8 100 % The following tables provide the fair value measurement amounts for DTE Energy's pension plan assets at December 31, 2017 and 2016 (a) : December 31, 2017 December 31, 2016 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total (In millions) DTE Energy asset category: Short-term Investments (c) $ — $ 114 $ — $ 114 $ — $ 22 $ — $ 22 Equity Securities U.S. Large Cap (d) 821 5 — 826 875 5 — 880 U.S. Small Cap and Mid Cap (e) 229 5 — 234 229 3 — 232 Non-U.S. (f) 529 13 280 822 479 18 269 766 Fixed Income Securities (g) 1 1,453 — 1,454 1 1,037 52 1,090 Hedge Funds and Similar Investments (h) 265 — 593 858 231 — 578 809 Private Equity and Other (i) — — 328 328 — — 213 213 Securities Lending (j) (53 ) (13 ) — (66 ) (53 ) (25 ) — (78 ) Securities Lending Collateral (j) 53 13 — 66 53 25 — 78 DTE Energy Total $ 1,845 $ 1,590 $ 1,201 $ 4,636 $ 1,815 $ 1,085 $ 1,112 $ 4,012 _______________________________________ (a) For a description of levels within the fair value hierarchy, see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, and mortgage-backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as NAV assets. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds or limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. All pricing for investments in this category are classified as NAV assets. (j) DTE Energy has a securities lending program with a third-party agent. The program allows the agent to lend certain securities from DTE Energy's pension trusts to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. The pension trust holds debt and equity securities directly and indirectly through commingled funds and institutional mutual funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The commingled funds and institutional mutual funds hold exchange-traded equity or debt securities and are valued based on stated NAVs. Non-exchange traded fixed income securities are valued by the trustee based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee challenges an assigned price and determines that another price source is considered preferable. DTE Energy has obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, DTE Energy selectively corroborates the fair value of securities by comparison of market-based price sources. There were no significant transfers between Level 2 and Level 1 in the years ended December 31, 2017 and 2016 for DTE Energy. Other Postretirement Benefits The Registrants participate in defined benefit plans sponsored by the LLC that provide certain other postretirement health care and life insurance benefits for employees who are eligible for these benefits. The Registrants' policy is to fund certain trusts to meet its other postretirement benefit obligations. Separate qualified VEBA and other benefit trusts exist. DTE Energy did not make any contributions to these trusts during 2017 and does not anticipate making any contributions to the trusts in 2018 . DTE Energy and DTE Electric offer a defined contribution VEBA for eligible represented and non-represented employees, in lieu of defined benefit post-employment health care benefits. The Registrants allocate a fixed amount per year to an account in a defined contribution VEBA for each employee. These accounts are managed either by the Registrant (for non-represented and certain represented groups) or by the Utility Workers of America for Local 223 employees. DTE Energy contributions to the VEBA for these accounts were $8 million in 2017 , $6 million in 2016 , and $5 million in 2015 , including DTE Electric contributions of $3 million in 2017 , 2016 , and 2015 . The Registrants also contribute a fixed amount to a Retiree Reimbursement Account, for certain current and future non-represented and represented retirees, spouses, and surviving spouses when the youngest of the retiree's covered household becomes eligible for Medicare Part A based on age. The amount of the annual allocation to each participant is determined by the employee's retirement date, and increases each year for each eligible participant at the lower of the rate of medical inflation or 2% . Net other postretirement credit for DTE Energy includes the following components: 2017 2016 2015 (In millions) Service cost $ 27 $ 27 $ 34 Interest cost 73 80 81 Expected return on plan assets (130 ) (129 ) (131 ) Amortization of: Net actuarial loss 13 30 43 Prior service credit (14 ) (118 ) (126 ) Other — (1 ) — Net other postretirement credit $ (31 ) $ (111 ) $ (99 ) 2017 2016 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial gain $ (21 ) $ (68 ) Amortization of net actuarial loss (13 ) (30 ) Prior service credit (1 ) — Amortization of prior service credit 14 119 Total recognized in Regulatory assets and Other comprehensive income (loss) $ (21 ) $ 21 Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (52 ) $ (90 ) Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 11 $ 16 Prior service credit $ (1 ) $ (14 ) Net other postretirement credit for DTE Electric includes the following components: 2017 2016 2015 (In millions) Service cost $ 20 $ 20 $ 25 Interest cost 56 61 62 Expected return on plan assets (90 ) (90 ) (90 ) Amortization of: Net actuarial loss 8 21 31 Prior service credit (10 ) (89 ) (95 ) Net other postretirement credit $ (16 ) $ (77 ) $ (67 ) 2017 2016 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets Net actuarial (gai n) loss $ 2 $ (59 ) Amortization of net actuarial loss (8 ) (21 ) Amortization of prior service credit 10 89 Total recognized in Regulatory assets $ 4 $ 9 Total recognized in net periodic benefit cost and Regulatory assets $ (12 ) $ (68 ) Estimated amounts to be amortized from Regulatory assets into net periodic benefit cost during next fiscal year Net actuarial loss $ 8 $ 10 Prior service credit $ — $ (10 ) The following table reconciles the obligations, assets, and funded status of the plans including amounts recorded as Accrued postretirement liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Change in accumulated postretirement benefit obligation Accumulated postretirement benefit obligation, beginning of year $ 1,795 $ 1,846 $ 1,373 $ 1,414 Service cost 27 27 20 20 Interest cost 73 80 56 61 Actuarial (gai n) loss 101 (75 ) 84 (62 ) Benefits paid (86 ) (83 ) (63 ) (60 ) Accumulated postretirement benefit obligation, end of year $ 1,910 $ 1,795 $ 1,470 $ 1,373 Change in plan assets Plan assets at fair value, beginning of year $ 1,758 $ 1,617 $ 1,218 $ 1,131 Actual return on plan assets 252 122 172 87 Company contributions — 20 — — Benefits paid (162 ) (1 ) (118 ) — Plan assets at fair value, end of year $ 1,848 $ 1,758 $ 1,272 $ 1,218 Funded status $ (62 ) $ (37 ) $ (198 ) $ (155 ) Amount recorded as: Noncurrent assets $ — $ — $ 113 $ 114 Current liabilities (1 ) (1 ) — — Noncurrent liabilities (61 ) (36 ) (311 ) (269 ) $ (62 ) $ (37 ) $ (198 ) $ (155 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial (gain) loss $ (1 ) $ 12 $ — $ — $ (1 ) $ 12 $ — $ — Amounts recognized in Regulatory assets (a) Net actuarial loss $ 279 $ 300 $ 211 $ 217 Prior service credit (1 ) (14 ) — (10 ) $ 278 $ 286 $ 211 $ 207 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." At December 31, 2017 , the benefits expected to be paid, including prescription drug benefits, in each of the next five years and in the aggregate for the five fiscal years thereafter for the Registrants are as follows: DTE Energy DTE Electric (In millions) 2018 $ 94 $ 73 2019 99 77 2020 103 80 2021 105 82 2022 108 84 2023-2027 567 437 Total $ 1,076 $ 833 Assumptions used in determining the accumulated postretirement benefit obligation and net other postretirement benefit costs of the Registrants are: 2017 2016 2015 Accumulated postretirement benefit obligation Discount rate 3.70% 4.25% 4.50% Health care trend rate pre- and post- 65 6.75 / 7.25% 6.50 / 6.75% 6.25 / 6.75% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2030 2028 2027 Other postretirement benefit costs Discount rate 4.25% 4.50% 4.10% Expected long-term rate of return on plan assets 7.75% 8.00% 8.00% Health care trend rate pre- and post- 65 6.50 / 6.75% 6.25 / 6.75% 7.50 / 6.50% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2028 2027 2025 / 2024 A one percentage point increase in health care cost trend rates would have increased the total service cost and interest cost components of benefit costs for DTE Energy by $5 million , including $4 million for DTE Electric, in 2017 and would have increased the accumulated benefit obligation for DTE Energy by $97 million , including $72 million for DTE Electric, at December 31, 2017 . A one percentage point decrease in the health care cost trend rates would have decreased the total service and interest cost components of benefit costs for DTE Energy by $4 million , including $3 million for DTE Electric, in 2017 and would have decreased the accumulated benefit obligation for DTE Energy by $84 million , including $63 million for DTE Electric, at December 31, 2017 . The process used in determining the long-term rate of return for assets and the investment approach for the other postretirement benefit plans is similar to those previously described for the pension plans. Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2017 are listed below: U.S. Large Cap Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 20 Fixed Income Securities 26 Hedge Funds and Similar Investments 20 Private Equity and Other 14 100 % The following tables provide the fair value measurement amounts for the Registrants' other postretirement benefit plan assets at December 31, 2017 and 2016 (a) : December 31, 2017 December 31, 2016 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total DTE Energy asset category: (In millions) Short-term Investments (c) $ 13 $ 2 $ — $ 15 $ 39 $ 1 $ — $ 40 Equity Securities U.S. Large Cap (d) 284 — — 284 284 — — 284 U.S. Small Cap and Mid Cap (e) 131 — — 131 156 — — 156 Non-U.S. (f) 288 1 77 366 262 1 61 324 Fixed Income Securities (g) 29 324 130 483 15 299 125 439 Hedge Funds and Similar Investments (h) 116 — 219 335 114 — 224 338 Private Equity and Other (i) — — 234 234 — — 177 177 Securities Lending (j) (39 ) (1 ) — (40 ) (28 ) (3 ) — (31 ) Securities Lending Collateral (j) 39 1 — 40 28 3 — 31 DTE Energy Total $ 861 $ 327 $ 660 $ 1,848 $ 870 $ 301 $ 587 $ 1,758 DTE Electric asset category: Short-term Investments (c) $ 9 $ 1 $ — $ 10 $ 28 $ 1 $ — $ 29 Equity Securities U.S. Large Cap (d) 195 — — 195 195 — — 195 U.S. Small Cap and Mid Cap (e) 91 — — 91 109 — — 109 Non-U.S. (f) 200 1 52 253 182 1 41 224 Fixed Income Securities (g) 20 218 92 330 10 203 90 303 Hedge Funds and Similar Investments (h) 80 — 150 230 80 — 154 234 Private Equity and Other (i) — — 163 163 — — 124 124 Securities Lending (j) (27 ) (1 ) — (28 ) (20 ) (1 ) — (21 ) Securities Lending Collateral (j) 27 1 — 28 20 1 — 21 DTE Electric Total $ 595 $ 220 $ 457 $ 1,272 $ 604 $ 205 $ 409 $ 1,218 _______________________________________ (a) For a description of levels within the fair value hierarchy see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, bank loans, and mortgage backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as NAV assets. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds and limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. All investments in this category are classified as NAV assets. (j) The Registrants have a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' VEBA trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. The DTE Energy Company Master VEBA Trust holds debt and equity securities directly and indirectly through commingled funds and institutional mutual funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The commingled funds and institutional mutual funds hold exchange-traded equity or debt securities and are valued based on NAVs. Non-exchange traded fixed income securities are valued by the trustee based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee challenges an assigned price and determines that another price source is considered preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, the Registrants selectively corroborate the fair values of securities by comparison of market-based price sources. There were no significant transfers between Level 2 and Level 1 in the years ended December 31, 2017 and 2016 for either of the Registrants. Defined Contribution Plans The Registrants also sponsor defined contribution retirement savings plans. Participation in one of these plans is available to substantially all represented and non-represented employees. For substantially all employees, the Registrants match employee contributions up to certain predefined limits based upon eligible compensation and the employee’s contribution rate. Additionally, for eligible represented and non-represented employees who do not participate in the Pension Plans, the Registrants annually contribute an amount equivalent to 4% ( 8% for certain DTE Gas represented employees) of an employee's eligible pay to the employee's defined contribution retirement savings plan. For DTE Energy, the cost of these plans was $57 million , $51 million , and $49 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. For DTE Electric, the cost of these plans was $27 million for the year ended December 31, 2017 , and $23 million for the years ended December 31, 2016 and 2015 . Plan Changes In 2015, certain executive retirement benefit plans were amended to transfer the obligation for benefits as attributed to the LLC. The related plan liabilities were transferred from DTE Electric and DTE Gas to the LLC and DTE Energy. The related Rabbi Trust assets were also transferred to DTE Energy from DTE Electric.

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION DTE Energy’s stock incentive program permits the grant of incentive stock options, non-qualifying stock options, stock awards, performance shares, and performance units to employees and members of its Board of Directors. As a result of a stock award, a settlement of an award of performance shares, or by exercise of a participant’s stock option, DTE Energy may deliver common stock from its authorized but unissued common stock and/or from outstanding common stock acquired by or on behalf of DTE Energy in the name of the participant. Key provisions of the stock incentive program are: • Authorized limit is 14,500,000 shares of common stock; • Prohibits the grant of a stock option with an exercise price that is less than the fair market value of DTE Energy’s stock on the date of the grant; and • Imposes the following award limits to a single participant in a single calendar year, (1) options for more than 500,000 shares of common stock; (2) stock awards for more than 150,000 shares of common stock; (3) performance share awards for more than 300,000 shares of common stock (based on the maximum payout under the award); or (4) more than 1,000,000 performance units, which have a face amount of $1.00 each. DTE Energy records compensation expense at fair value over the vesting period for all awards it grants. The following table summarizes the components of stock-based compensation for DTE Energy: 2017 2016 2015 (In millions) Stock-based compensation expense $ 58 $ 61 $ 34 Tax benefit $ 23 $ 24 $ 13 Stock-based compensation cost capitalized in Property, plant, and equipment $ 9 $ 10 $ 5 Stock Options Options are exercisable according to the terms of the individual stock option award agreements and expire ten years after the date of the grant. The option exercise price equals the fair value of the stock on the date that the option was granted. Stock options vest ratably over a three -year period. The following table summarizes DTE Energy's stock option activity for the year ended December 31, 2017 : Number of Options Weighted Average Exercise Price Aggregate Intrinsic Options outstanding and exercisable at December 31, 2016 171,517 $ 41.59 Exercised (65,523 ) $ 39.37 Options outstanding and exercisable at December 31, 2017 105,994 $ 42.95 $ 7 As of December 31, 2017 , the weighted average remaining contractual life for the exercisable shares is 2.05 years. As of December 31, 2017 , all options were vested. No options vested during 2017 . There were no options granted during 2017 , 2016 , or 2015 . The intrinsic value of options exercised for the years ended December 31, 2017 and 2016 was $4 million . The intrinsic value of options for the year ended December 31, 2015 was $7 million . No option expense was recognized for 2017 , 2016 , or 2015 . The number, weighted average exercise price, and weighted average remaining contractual life of DTE Energy options outstanding as of December 31, 2017 were as follows: Range of Exercise Prices Number of Options Weighted Average Weighted Average $ 27.00 — $ 38.00 6,194 $ 27.70 1.16 $ 38.01 — $ 42.00 2,300 $ 41.79 0.15 $ 42.01 — $ 45.00 97,500 $ 43.95 2.15 105,994 $ 42.95 2.05 Restricted Stock Awards Stock awards granted under the plan are restricted for varying periods, generally for three years . Participants have all rights of a shareholder with respect to a stock award, including the right to receive dividends and vote the shares. Prior to vesting in stock awards, the participant: (i) may not sell, transfer, pledge, exchange, or otherwise dispose of shares; (ii) shall not retain custody of the share certificates; and (iii) will deliver to DTE Energy a stock power with respect to each stock award upon request. The stock awards are recorded at cost that approximates fair value on the date of grant. The cost is amortized to compensation expense over the vesting period. Stock award activity for DTE Energy for the years ended December 31 was: 2017 2016 2015 Fair value of awards vested (in millions) $ 10 $ 9 $ 9 Restricted common shares awarded 136,825 145,240 144,300 Weighted average market price of shares awarded $ 99.53 $ 87.28 $ 83.43 Compensation cost charged against income (in millions) $ 11 $ 11 $ 10 The following table summarizes DTE Energy’s restricted stock awards activity for the year ended December 31, 2017 : Restricted Weighted Average Balance at December 31, 2016 385,285 $ 80.10 Grants 136,825 $ 99.53 Forfeitures (11,745 ) $ 90.24 Vested and issued (144,601 ) $ 72.08 Balance at December 31, 2017 365,764 $ 90.26 Performance Share Awards Performance shares awarded under the plan are for a specified number of shares of DTE Energy common stock that entitle the holder to receive a cash payment, shares of DTE Energy common stock, or a combination thereof. The final value of the award is determined by the achievement of certain performance objectives and market conditions. The awards vest at the end of a specified period, usually three years . Awards granted in 2017 , 2016 , and 2015 were primarily deemed to be equity awards. The DTE Energy stock price and number of probable shares attributable to market conditions for such equity awards are fair valued only at the grant date. DTE Energy accounts for performance share awards by accruing compensation expense over the vesting period based on: (i) the number of shares expected to be paid which is based on the probable achievement of performance objectives; and (ii) the closing stock price market value. The settlement of the award is based on the closing price at the settlement date. DTE Energy recorded compensation expense for performance share awards as follows: 2017 2016 2015 (In millions) Compensation expense $ 47 $ 50 $ 24 Cash settlements (a) $ 15 $ 7 $ 13 Stock settlements (a) $ 66 $ 38 $ 71 _______________________________________ (a) Sum of cash and stock settlements approximates the intrinsic value of the awards. During the vesting period, the recipient of a performance share award has no shareholder rights. During the period beginning on the date the performance shares are awarded and ending on the certification date of the performance objectives, the number of performance shares awarded will be increased, assuming full dividend reinvestment at the fair market value on the dividend payment date. The cumulative number of performance shares will be adjusted to determine the final payment based on the performance objectives achieved. Performance share awards are nontransferable and are subject to risk of forfeiture. The following table summarizes DTE Energy’s performance share activity for the period ended December 31, 2017 : Performance Shares Weighted Average Balance at December 31, 2016 1,392,512 $ 79.97 Grants 494,688 $ 98.47 Forfeitures (49,547 ) $ 87.12 Payouts (513,252 ) $ 70.60 Balance at December 31, 2017 1,324,401 $ 90.31 Unrecognized Compensation Costs As of December 31, 2017 , DTE Energy's total unrecognized compensation cost related to non-vested stock incentive plan arrangements and the weighted average recognition period was as follows: Unrecognized Weighted Average (In millions) (In years) Stock awards $ 13 1.12 Performance shares 51 1.11 $ 64 1.11 Allocated Stock-Based Compensation DTE Electric received an allocation of costs from DTE Energy associated with stock-based compensation. DTE Electric's allocation for 2017 , 2016 , and 2015 for stock-based compensation expense was approximately $34 million , $38 million , and $21 million , respectively.

Segment and Related Information

Segment and Related Information	12 Months Ended
	Dec. 31, 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: Year Ended December 31, 2017 2016 2015 (In millions) Electric $ 48 $ 43 $ 36 Gas 8 9 3 Gas Storage and Pipelines 42 9 8 Power and Industrial Projects 569 602 785 Energy Trading 35 39 32 Corporate and Other 2 2 4 $ 704 $ 704 $ 868 Financial data of DTE Energy's business segments follows: Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2017 Operating Revenues — Utility operations $ 5,102 1,388 — — — — (56 ) $ 6,434 Operating Revenues — Non-utility operations $ — — 453 2,089 4,277 2 (648 ) $ 6,173 Depreciation and amortization $ 753 123 76 72 5 1 — $ 1,030 Interest expense $ 274 65 77 29 5 192 (106 ) $ 536 Interest income $ — (7 ) (14 ) (7 ) (2 ) (88 ) 106 $ (12 ) Equity in earnings of equity method investees $ 1 2 90 9 — — — $ 102 Income Tax Expense (Benefit) (a) $ 321 78 (30 ) (195 ) 49 (48 ) — $ 175 Net Income (Loss) Attributable to DTE Energy Company $ 606 146 275 138 72 (103 ) — $ 1,134 Investment in equity method investees $ 7 11 879 150 — 26 — $ 1,073 Capital expenditures and acquisitions $ 1,574 463 137 56 7 13 — $ 2,250 Goodwill $ 1,208 743 299 26 17 — — $ 2,293 Total Assets $ 21,163 5,072 2,594 593 725 5,324 (1,704 ) $ 33,767 _____________________________________ (a) Includes Income Tax Expense (Benefit) of $(5) million , $(115) million , $(21) million , $2 million , and $34 million for Electric — non-utility, Gas Storage and Pipelines, Power and Industrial Projects, Energy Trading, and Corporate and Other, respectively, related to the enactment of the TCJA. Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2016 Operating Revenues — Utility operations $ 5,225 1,324 — — — — (52 ) $ 6,497 Operating Revenues — Non-utility operations $ — — 302 1,906 2,575 2 (652 ) $ 4,133 Depreciation and amortization $ 750 106 45 72 3 — — $ 976 Interest expense $ 264 60 39 32 6 148 (77 ) $ 472 Interest income $ (8 ) (6 ) (9 ) (8 ) (1 ) (65 ) 77 $ (20 ) Equity in earnings of equity method investees $ 2 6 60 — — — — $ 68 Income Tax Expense (Benefit) $ 353 77 71 (140 ) (29 ) (61 ) — $ 271 Net Income (Loss) Attributable to DTE Energy Company $ 622 138 119 95 (45 ) (61 ) — $ 868 Investment in equity method investees $ 11 10 538 166 — 27 — $ 752 Capital expenditures and acquisitions $ 1,503 395 1,322 39 7 3 — $ 3,269 Goodwill $ 1,208 743 292 26 17 — — $ 2,286 Total Assets $ 20,417 4,729 2,417 683 660 4,648 (1,513 ) $ 32,041 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2015 Operating Revenues — Utility operations $ 4,901 1,376 — — — — (39 ) $ 6,238 Operating Revenues — Non-utility operations $ — — 243 2,224 2,459 2 (829 ) $ 4,099 Depreciation and amortization $ 637 104 30 78 2 1 — $ 852 Interest expense $ 258 62 24 32 6 132 (64 ) $ 450 Interest income $ — (7 ) (8 ) (8 ) (2 ) (52 ) 64 $ (13 ) Equity in earnings of equity method investees $ 2 6 47 8 — 3 — $ 66 Income Tax Expense (Benefit) $ 290 72 70 (140 ) (15 ) (47 ) — $ 230 Net Income (Loss) Attributable to DTE Energy Company $ 542 132 107 16 (22 ) (48 ) — $ 727 Investment in equity method investees $ 10 9 296 183 — 16 — $ 514 Capital expenditures and acquisitions $ 1,785 273 161 36 6 — — $ 2,261 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 19,503 4,294 1,047 860 590 3,496 (1,128 ) $ 28,662

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS DTE Electric has agreements with affiliated companies to sell energy for resale, purchase fuel and power, provide fuel supply services, and provide power plant operation and maintenance services. DTE Electric has agreements with certain DTE Energy affiliates where DTE Electric charges the affiliates for their use of the shared capital assets of DTE Electric. A shared services company accumulates various corporate support services expenses and charges various subsidiaries of DTE Energy, including DTE Electric. DTE Electric records federal, state, and local income taxes payable to or receivable from DTE Energy based on its federal, state, and local tax provisions. The following is a summary of DTE Electric's transactions with affiliated companies: 2017 2016 2015 (In millions) Revenues Energy sales $ 9 $ 10 $ 2 Other services $ (4 ) $ (1 ) $ 6 Shared capital assets $ 39 $ 33 $ 33 Costs Fuel and purchased power $ 6 $ 10 $ 9 Other services and interest $ (2 ) $ (1 ) $ 2 Corporate expenses, net $ 370 $ 370 $ 334 Other Dividends declared $ 432 $ 420 $ 395 Dividends paid $ 432 $ 420 $ 395 Capital contribution from DTE Energy $ 100 $ 120 $ 300 DTE Electric's Accounts receivable and Accounts payable related to Affiliates are payable upon demand and are generally settled in cash within a monthly business cycle. Notes receivable and Short-term borrowings related to Affiliates are subject to a credit agreement with DTE Energy whereby short-term excess cash or cash shortfalls are remitted to or funded by DTE Energy. This credit arrangement involves the charge and payment of interest at market-based rates. Refer to DTE Electric's Consolidated Statements of Financial Position for affiliate balances at December 31, 2017 and 2016 . DTE Electric's charitable contributions to the DTE Energy Foundation was $7 million for the the year ended December 31, 2017 . There were no contributions by DTE Electric to the DTE Energy Foundation for the years ended December 31, 2016 and 2015 . The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute and assist charitable organizations. See the following notes for other related party transactions impacting DTE Electric’s Consolidated Financial Statements: Note Title 20 Retirement Benefits and Trusteed Assets 21 Stock-Based Compensation

Supplementary Quarterly Financi

Supplementary Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Supplementary Quarterly Financial Information (Unaudited)	SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (UNAUDITED) DTE Energy Quarterly earnings per share may not equal full year totals, since quarterly computations are based on weighted average common shares outstanding during each quarter. First Second Third Fourth Year (In millions, except per share amounts) 2017 Operating Revenues $ 3,236 $ 2,855 $ 3,245 $ 3,271 $ 12,607 Operating Income $ 569 $ 303 $ 418 $ 356 $ 1,646 Net Income Attributable to DTE Energy Company (a) $ 400 $ 177 $ 270 $ 287 $ 1,134 Basic Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 Diluted Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 2016 Operating Revenues $ 2,566 $ 2,262 $ 2,928 $ 2,874 $ 10,630 Operating Income $ 381 $ 256 $ 507 $ 301 $ 1,445 Net Income Attributable to DTE Energy Company $ 247 $ 152 $ 338 $ 131 $ 868 Basic Earnings per Share $ 1.38 $ 0.84 $ 1.88 $ 0.73 $ 4.84 Diluted Earnings per Share $ 1.37 $ 0.84 $ 1.88 $ 0.73 $ 4.83 _____________________________________ (a) Includes a net Income Tax Benefit of $(105) million related to the enactment of the TCJA in the fourth quarter. DTE Electric First Second Third Fourth Year (In millions) 2017 Operating Revenues $ 1,175 $ 1,218 $ 1,434 $ 1,275 $ 5,102 Operating Income $ 217 $ 272 $ 395 $ 281 $ 1,165 Net Income $ 106 $ 138 $ 219 $ 138 $ 601 2016 Operating Revenues $ 1,153 $ 1,215 $ 1,608 $ 1,249 $ 5,225 Operating Income $ 245 $ 265 $ 501 $ 193 $ 1,204 Net Income $ 127 $ 135 $ 285 $ 75 $ 622

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2017
Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	DTE Energy Company Schedule II — Valuation and Qualifying Accounts Year Ending December 31, 2017 2016 2015 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 41 $ 49 $ 54 Additions: Charged to costs and expenses 80 78 93 Charged to other accounts (a) 26 18 14 Deductions (b) (98 ) (104 ) (112 ) Balance at End of Period $ 49 $ 41 $ 49 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off. DTE Electric Company Schedule II — Valuation and Qualifying Accounts Year Ending December 31, 2017 2016 2015 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Electric's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 25 $ 28 $ 29 Additions: Charged to costs and expenses 55 49 51 Charged to other accounts (a) 14 8 6 Deductions (b) (63 ) (60 ) (58 ) Balance at End of Period $ 31 $ 25 $ 28 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off.

Significant Accounting Polici34

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The information in these combined notes relates to each of the Registrants as noted in the Index of Combined Notes to Consolidated Financial Statements. However, DTE Electric does not make any representation as to information related solely to DTE Energy or the subsidiaries of DTE Energy other than itself.
Reclassification	Certain prior year balances for the Registrants were reclassified to match the current year's Consolidated Financial Statements presentation.
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, " Acquisitions and Exit Activities ," 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 December 31, 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 December 31, 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 18 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 18 to the Consolidated Financial Statements, " Commitments and Contingencies ," for further discussion of the NEXUS guarantee arrangements.
Revenues	Revenues The Registrants' revenues from the sale and delivery of electricity, and DTE Energy's revenues from the sale, delivery, and storage of natural gas are recognized as services are provided. DTE Electric and DTE Gas record revenues for electricity and gas provided but unbilled at the end of each month. Rates for DTE Electric and DTE Gas include provisions to adjust billings for fluctuations in fuel and purchased power costs, cost of natural gas, and certain other costs. Revenues are adjusted for differences between actual costs subject to reconciliation and the amounts billed in current rates. Under or over recovered revenues related to these cost recovery mechanisms are included in Regulatory assets or liabilities on the Registrants' Consolidated Statements of Financial Position and are recovered or returned to customers through adjustments to the billing factors. For further discussion of recovery mechanisms authorized by the MPSC, see Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." DTE Energy's non-utility businesses recognize revenues as services are provided and products are delivered.
Other Income	Other Income Other income for the Registrants is recognized for non-operating income such as equity earnings of equity method investees, allowance for equity funds used during construction, contract services, and gains (losses) from trading securities. DTE Energy's Power and Industrial Projects segment also recognizes Other income in connection with the sale of membership interests in reduced emissions fuel facilities to investors. In exchange for the cash received, the investors will receive a portion of the economic attributes of the facilities, including income tax attributes. The transactions are not treated as a sale of membership interests for financial reporting purposes. Other income is considered earned when refined coal is produced and tax credits are generated.
Accounting for ISO Transactions	Accounting for ISO Transactions DTE Electric participates in the energy market through MISO. MISO requires that DTE Electric submit hourly day-ahead, real-time, and FTR bids and offers for energy at locations across the MISO region. DTE Electric accounts for MISO transactions on a net hourly basis in each of the day-ahead, real-time, and FTR markets and net transactions across all MISO energy market locations. In any single hour DTE Electric records net purchases in Fuel, purchased power, and gas — utility and net sales in Operating Revenues — Utility operations on the Registrants' Consolidated Statements of Operations. The Energy Trading segment participates in the energy markets through various ISOs and RTOs. These markets require that Energy Trading submits hourly day-ahead, real-time bids and offers for energy at locations across each region. Energy Trading submits bids in the annual and monthly auction revenue rights and FTR auctions to the RTOs. Energy Trading accounts for these transactions on a net hourly basis for the day-ahead, real-time, and FTR markets. These transactions are related to trading contracts which, if derivatives, are presented on a net basis in Operating Revenues — Non-utility operations, and if non-derivatives, the realized gains and losses for sales are recorded in Operating Revenues — Non-utility operations and purchases are recorded in Fuel, purchased power, and gas — non-utility in the DTE Energy Consolidated Statements of Operations. DTE Electric and Energy Trading record accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual costs when invoices are received from MISO and other ISOs and RTOs.
Changes in Accumulated Other Comprehensive Income (Loss)	Changes in Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including Net Income. The amounts recorded to Accumulated other comprehensive income (loss) for the Registrants include unrealized gains and losses on available-for-sale securities and changes in benefit obligations, consisting of deferred actuarial losses and prior service costs. The amounts recorded to Accumulated other comprehensive income (loss) relating solely to DTE Energy also include unrealized gains and losses from derivatives accounted for as cash flow hedges, DTE Energy's interest in other comprehensive income of equity investees which comprise the net unrealized gains and losses on investments, and foreign currency translation adjustments.
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include cash on hand, cash in banks, and temporary investments purchased with remaining maturities of three months or less. Restricted cash consists of funds held to satisfy requirements of certain debt and DTE Energy partnership operating agreements. Restricted cash designated for interest and principal payments within one year is classified as a Current Asset.
Receivables and Notes Receivable	Receivables Accounts receivable are primarily composed of trade receivables and unbilled revenue. The Registrants' Accounts receivable are stated at net realizable value. The allowance for doubtful accounts for DTE Electric and DTE Gas is generally calculated using the aging approach that utilizes rates developed in reserve studies. DTE Electric and DTE Gas establish an allowance for uncollectible accounts based on historical losses and management’s assessment of existing economic conditions, customer trends, and other factors. Customer accounts are generally considered delinquent if the amount billed is not received by the due date, which is typically in 21 days, however, factors such as assistance programs may delay aggressive action. DTE Electric and DTE Gas assess late payment fees on trade receivables based on past-due terms with customers. Customer accounts are written off when collection efforts have been exhausted. The time period for write-off is 150 days after service has been terminated. The customer allowance for doubtful accounts for DTE Energy's other businesses is calculated based on specific review of probable future collections based on receivable balances generally in excess of 30 days. DTE Energy unbilled revenues of $1 billion and $814 million , including $290 million and $267 million of DTE Electric unbilled revenues, are included in Customer Accounts receivable at December 31, 2017 and 2016 , respectively. Notes Receivable Notes receivable, or financing receivables, for DTE Energy are primarily comprised of capital lease receivables and loans and are included in Notes receivable and Other current assets on DTE Energy’s Consolidated Statements of Financial Position. Notes receivable, or financing receivables, for DTE Electric are primarily comprised of loans. Notes receivable are typically considered delinquent when payment is not received for periods ranging from 60 to 120 days. The Registrants cease accruing interest (nonaccrual status), consider a note receivable impaired, and establish an allowance for credit loss when it is probable that all principal and interest amounts due will not be collected in accordance with the contractual terms of the note receivable. Cash payments received on nonaccrual status notes receivable, that do not bring the account contractually current, are first applied to contractually owed past due interest, with any remainder applied to principal. Accrual of interest is generally resumed when the note receivable becomes contractually current. In determining the allowance for credit losses for notes receivable, the Registrants consider the historical payment experience and other factors that are expected to have a specific impact on the counterparty’s ability to pay. In addition, the Registrants monitor the credit ratings of the counterparties from which they have notes receivable.
Inventories	Inventories Inventory related to utility operations is generally valued at average cost. Inventory related to non-utility operations is valued at the lower of cost or net realizable value.
Property, Retirement and Maintenance, and Depreciation and Amortization	Property, Retirement and Maintenance, and Depreciation and Amortization Property is stated at cost and includes construction-related labor, materials, overheads, and AFUDC for utility property. The cost of utility properties retired is charged to accumulated depreciation. Expenditures for maintenance and repairs are charged to expense when incurred, except for outage-related maintenance repairs for Fermi 2. Utility property at DTE Electric and DTE Gas is depreciated over its estimated useful life using straight-line rates approved by the MPSC. DTE Energy's non-utility property is depreciated over its estimated useful life using the straight-line method. Depreciation and amortization expense also includes the amortization of certain regulatory assets for the Registrants. Approximately $15 million and $27 million of expenses related to Fermi 2 refueling outages were accrued at December 31, 2017 and 2016 , respectively. Amounts are accrued on a pro-rata basis, generally over an 18 -month period, that coincides with scheduled refueling outages at Fermi 2. This accrual of outage costs matches the regulatory recovery of these costs in rates set by the MPSC. See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." The cost of nuclear fuel is capitalized. The amortization of nuclear fuel is included within Fuel, purchased power, and gas — utility in the DTE Energy Consolidated Statements of Operations, and Fuel and purchased power in the DTE Electric Consolidated Statements of Operations, and is recorded using the units-of-production method. Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 3 to 15 years for DTE Energy and 4 to 15 years for DTE Electric.
Long-Lived Assets	Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If the carrying amount of the asset exceeds the expected undiscounted future cash flows generated by the asset, an impairment loss is recognized resulting in the asset being written down to its estimated fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less costs to sell.
Intangible Assets	DTE Energy amortizes customer relationship and contract intangible assets on a straight-line basis over the expected period of benefit.
Excise and Sales Taxes and Income Taxes	Excise and Sales Taxes The Registrants record the billing of excise and sales taxes as a receivable with an offsetting payable to the applicable taxing authority, with no net impact on the Registrants’ Consolidated Statements of Operations. Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts in the Consolidated Financial Statements. Consistent with the original establishment of these deferred tax liabilities (assets), no recognition of these non-cash transactions have been reflected in the Consolidated Statements of Cash Flows. The federal income tax provisions or benefits of DTE Energy’s subsidiaries are determined on an individual company basis and recognize the tax benefit of tax credits and net operating losses, if applicable. The state and local income tax provisions of the utility subsidiaries are determined on an individual company basis and recognize the tax benefit of various tax credits and net operating losses, if applicable. The subsidiaries record federal, state, and local income taxes payable to or receivable from DTE Energy based on the federal, state, and local tax provisions of each company.
Deferred Debt Costs	Deferred Debt Costs The costs related to the issuance of long-term debt are deferred and amortized over the life of each debt issue. The deferred amounts are included as a direct deduction from the carrying amount of each debt issue in Mortgage bonds, notes, and other and Junior subordinated debentures on DTE Energy's Consolidated Statements of Financial Position and in Mortgage bonds, notes, and other on DTE Electric's Consolidated Statements of Financial Position. In accordance with MPSC regulations applicable to DTE Energy’s electric and gas utilities, the unamortized discount, premium, and expense related to utility debt redeemed with a refinancing are amortized over the life of the replacement issue. Discount, premium, and expense on early redemptions of debt associated with DTE Energy's non-utility operations are charged to earnings.
Investments in Debt and Equity Securities	Investments in Debt and Equity Securities The Registrants generally classify investments in debt and equity securities as either trading or available-for-sale and have recorded such investments at market value with unrealized gains or losses included in earnings or in Other comprehensive income or loss, respectively. Changes in the fair value of Fermi 2 nuclear decommissioning investments are recorded as adjustments to Regulatory assets or liabilities, due to a recovery mechanism from customers. The Registrants' equity investments are reviewed for impairment each reporting period. If the assessment indicates that the impairment is other than temporary, a loss is recognized resulting in the equity investment being written down to its estimated fair value.
Government Grants	Government Grants Grants are recognized when there is reasonable assurance that the grant will be received and that any conditions associated with the grant will be met. When grants are received related to Property, plant, and equipment, the Registrants reduce the cost of the assets on their Consolidated Statements of Financial Position, resulting in lower depreciation expense over the life of the associated asset. Grants received related to expenses are reflected as a reduction of the associated expense in the period in which the expense is incurred.
DTE Energy Foundation	DTE Energy Foundation DTE Energy's charitable contributions to the DTE Energy Foundation were $43 million , $26 million , and $12 million for the years ended December 31, 2017 , 2016 , and 2015 , respectively. The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute to and assist charitable organizations.
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS 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 have substantially completed the assessment of the amended ASU's impact, on their Consolidated Financial Statements. The ASU will not significantly affect the Registrants' financial position or results of operations. The Registrants will continue to monitor the impact of the ASU on existing revenue recognition internal controls, 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, which are not expected to have a significant impact on the Registrants, 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, and include disclosure of key information about leasing arrangements. 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, as well as additional disclosures, 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 generally accepted accounting principles 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 20 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets ." The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income . The amendments in this update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA. The amendments in this update also require entities to disclose their accounting policy for releasing income tax effects from accumulated other comprehensive income. The ASU is effective for the Registrants for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements.
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS DTE Electric has a legal retirement obligation for the decommissioning costs for its Fermi 1 and Fermi 2 nuclear plants, dismantlement of facilities located on leased property, and various other operations. DTE Electric has conditional retirement obligations for asbestos and PCB removal at certain of its power plants and various distribution equipment. DTE Gas has conditional retirement obligations for gas pipelines, certain service centers, compressor and gate stations. The Registrants recognize such obligations as liabilities at fair market value when they are incurred, which generally is at the time the associated assets are placed in service. Fair value is measured using expected future cash outflows discounted at the Registrants' credit-adjusted risk-free rate. For its utility operations, the Registrants recognize in the Consolidated Statements of Operations removal costs in accordance with regulatory treatment. Any differences between costs recognized related to asset retirement and those reflected in rates are recognized as either a Regulatory asset or liability on the Consolidated Statements of Financial Position. If a reasonable estimate of fair value cannot be made in the period in which the retirement obligation is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. Natural gas storage system and certain other distribution assets for DTE Gas and substations, manholes, and certain other distribution assets for DTE Electric have an indeterminate life. Therefore, no liability has been recorded for these assets.
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities DTE Electric and DTE Gas are required to record Regulatory assets and liabilities for certain transactions that would have been treated as revenue or expense in non-regulated businesses. Continued applicability of regulatory accounting treatment requires that rates be designed to recover specific costs of providing regulated services and be charged to and collected from customers. Future regulatory changes or changes in the competitive environment could result in the discontinuance of this accounting treatment for Regulatory assets and liabilities for some or all of the Registrants' businesses and may require the write-off of the portion of any Regulatory asset or liability that was no longer probable of recovery through regulated rates. Management believes that currently available facts support the continued use of Regulatory assets and liabilities and that all Regulatory assets and liabilities are recoverable or refundable in the current regulatory environment.
Fair Value Measurement	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, which refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable inputs. The Registrants make certain assumptions they believe that market participants would use in pricing assets or liabilities, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. Credit risk of the Registrants and their counterparties is incorporated in the valuation of assets and liabilities through the use of credit reserves, the impact of which was immaterial at December 31, 2017 and 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 Trust 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. Other assets such as private market investments are used to enhance long-term returns while improving portfolio diversification. All pricing for investments in this category are classified as NAV assets. 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 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, Controller, and Chief Accounting Officer.
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 December 31, 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 $4 million and $2 million outstanding at December 31, 2017 and 2016 , respectively, 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 $4 million and $2 million at December 31, 2017 and 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	Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility.
Stock-Based Compensation	DTE Energy records compensation expense at fair value over the vesting period for all awards it grants.

Organization and Basis of Pre35

Organization and Basis of Presentation (Tables)	12 Months Ended
	Dec. 31, 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 December 31, 2017 and 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. December 31, 2017 December 31, 2016 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 23 $ 14 $ 37 $ 36 $ 27 $ 63 Restricted cash — 8 8 — 7 7 Accounts receivable 11 42 53 8 34 42 Inventories 3 114 117 3 112 115 Property, plant, and equipment, net 400 75 475 398 76 474 Goodwill 25 — 25 17 — 17 Intangible assets 572 — 572 586 — 586 Other current and long-term assets 4 — 4 1 1 2 $ 1,038 $ 253 $ 1,291 $ 1,049 $ 257 $ 1,306 LIABILITIES Accounts payable and accrued current liabilities $ 26 $ 47 $ 73 $ 19 $ 32 $ 51 Current portion long-term debt, including capital leases — 4 4 — 5 5 Mortgage bonds, notes, and other — 1 1 — 5 5 Other current and long-term liabilities 1 16 17 2 15 17 $ 27 $ 68 $ 95 $ 21 $ 57 $ 78 _____________________________________ (a) Amounts shown are 100% of SGG's assets and liabilities, of which DTE Energy owns 55% .
Summary of Amounts For Nonconsolidated Variable Interest Entities	Amounts for DTE Energy's non-consolidated VIEs are as follows: December 31, 2017 December 31, 2016 (In millions) Investments in equity method investees $ 811 $ 509 Notes receivable $ 17 $ 15 Future funding commitments $ 598 $ 692
Equity Method Investments	DTE Energy equity method investees are described below: Investments % Owned Segment 2017 2016 2017 2016 Description (In millions) Significant Equity Method Investees Gas Storage and Pipelines NEXUS Pipeline $ 640 $ 322 50% 50% A 255-mile pipeline under construction to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers Vector Pipeline 115 100 40% 40% 348-mile pipeline connecting Chicago, Michigan, and Ontario market centers Millennium Pipeline 124 116 26% 26% 251-mile pipeline serving markets in the Northeast 879 538 Other Equity Method Investees Other Segments 194 214 $ 1,073 $ 752

Significant Accounting Polici36

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2017
Accounting Policies [Abstract]
Schedule of Other Income	The following is a summary of DTE Energy's Other income: 2017 2016 2015 (In millions) Equity earnings of equity method investees $ 102 $ 68 $ 66 Income from REF entities 77 75 83 Gains from trading securities 26 15 1 Allowance for equity funds used during construction 23 21 21 Contract services 19 21 27 Other 21 7 11 $ 268 $ 207 $ 209 The following is a summary of DTE Electric's Other income: 2017 2016 2015 (In millions) Gains from trading securities allocated from DTE Energy $ 26 $ 15 $ 1 Contract services 21 20 27 Allowance for equity funds used during construction 18 18 20 Equity earnings of equity method investees 1 2 2 Other 11 6 10 $ 77 $ 61 $ 60
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in DTE Energy's Accumulated other comprehensive income (loss) by component (a) for the years ended December 31, 2017 and 2016 : Net Unrealized Gain (Loss) on Deri vatives Net Unrealized Gain (Loss) on Investments Benefit Obligations (b) Foreign Currency Translation Total (In millions) Balance, December 31, 2015 $ (4 ) $ (4 ) $ (131 ) $ (6 ) $ (145 ) Other comprehensive loss before reclassifications — — (3 ) — (3 ) Amounts reclassified from Accumulated other comprehensive income — 1 14 — 15 Net current-period Other comprehensive income — 1 11 — 12 Balance, December 31, 2016 $ (4 ) $ (3 ) $ (120 ) $ (6 ) $ (133 ) Other comprehensive income (loss) before reclassi fications — 1 (3 ) 1 (1 ) Amounts reclassified from Accumulated other comprehensive income 1 — 13 — 14 Net current-period Other comprehensive income 1 1 10 1 13 Balance, December 31, 2017 $ (3 ) $ (2 ) $ (110 ) $ (5 ) $ (120 ) ______________________________________ (a) All amounts are net of tax, except for Foreign currency translation. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 20 to the Consolidated Financial Statements " Retirement Benefits and Trusteed Assets ").
Schedule of Finite-Lived Intangible Assets by Major Class	The Registrants have certain Intangible assets as shown below: December 31, 2017 December 31, 2016 Useful Lives Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (In millions) Intangible assets subject to amortization Customer relationships (a) 40 years (b) $ 770 $ (24 ) $ 746 $ 770 $ (5 ) $ 765 Contract intangibles 6 to 26 years 168 (72 ) 96 111 (65 ) 46 938 (96 ) 842 881 (70 ) 811 DTE Electric renewable energy credits (c) 24 — 24 30 — 30 DTE Electric emission allowances (c) 1 — 1 1 — 1 25 — 25 31 — 31 Long-term intangible assets DTE Electric $ 25 $ — $ 25 $ 31 $ — $ 31 DTE Energy $ 963 $ (96 ) $ 867 $ 912 $ (70 ) $ 842 ______________________________________ (a) In October 2016, DTE Energy acquired midstream natural gas assets that are part of the Gas Storage and Pipelines segment. The intangible assets recorded as a result of the acquisition pertain to existing customer relationships. See Note 4 to the Consolidated Financial Statements, " Acquisitions and Exit Activities ," for additional information. (b) The useful life of the customer relationship intangible assets is based on the number of years in which the assets are expected to economically contribute to the business. The expected economic benefit incorporates existing customer contracts and expected renewal rates based on the estimated volume and production lives of gas resources in the region. (c) Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the business.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The following table summarizes DTE Energy's estimated customer relationship and contract intangible amortization expense expected to be recognized during each year through 2022 : 2018 2019 2020 2021 2022 (In millions) Estimated amortization expense $ 26 $ 26 $ 25 $ 25 $ 25
Schedule Of Accounting Policies	See the following notes for other accounting policies impacting the Registrants’ Consolidated Financial Statements: Note Title 8 Asset Retirement Obligations 9 Regulatory Matters 10 Income Taxes 12 Fair Value 13 Financial and Other Derivative Instruments 20 Retirement Benefits and Trusteed Assets 21 Stock-Based Compensation

Acquisitions and Exit Activit37

Acquisitions and Exit Activities (Tables)	12 Months Ended
	Dec. 31, 2017
Business Acquisition, Integration, Restructuring and Other Related Costs [Abstract]
Schedule of Preliminary 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
Restructuring and Related Costs	A summary of the charges in the Consolidated Statements of Operations resulting from DTE Energy's exit activities is shown below: 2015 (In millions) Fuel, purchased power, and gas — non-utility $ 5 Operation and maintenance 10 Asset (gains) losses and impairments, net 96 Total exit activity charges $ 111

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2017
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following is the summary of change in the carrying amount of goodwill for the years ended December 31: 2017 2016 (In millions) Balance as of January 1 $ 2,286 $ 2,018 Goodwill attributable to Gas Storage and Pipelines acquisition 7 268 Balance at December 31 $ 2,293 $ 2,286

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
PP&E by Classification, Summary of Depreciation and Amortization	The following is a summary of Depreciation and amortization expense for DTE Energy: 2017 2016 2015 (In millions) Property, plant, and equipment $ 865 $ 783 $ 740 Regulatory assets and liabilities 165 193 150 Securitized regulatory assets (a) — — (38 ) $ 1,030 $ 976 $ 852 _______________________________________ (a) Securitization surcharges ended in December 2014 with remaining over recovery refunded to customers in 2015. Securitization bonds were paid and Securitization regulatory assets amortization was completed in 2015. The $38 million credit represents the final adjustments to close out the Securitization program. The following is a summary of Depreciation and amortization expense for DTE Electric: 2017 2016 2015 (In millions) Property, plant, and equipment $ 620 $ 582 $ 545 Regulatory assets and liabilities 133 168 126 Securitized regulatory assets (a) — — (38 ) $ 753 $ 750 $ 633 _______________________________________ (a) Securitization surcharges ended in December 2014 with remaining over recovery refunded to customers in 2015. Securitization bonds were paid and Securitization regulatory assets amortization was completed in 2015. The $38 million credit represents the final adjustments to close out the Securitization program. The following is a summary of Property, plant, and equipment by classification as of December 31: 2017 2016 Property, plant, and equipment (In millions) DTE Electric Generation $ 12,166 $ 11,990 Distribution 8,637 8,134 Other 2,169 1,970 Total DTE Electric 22,972 22,094 DTE Gas Distribution 3,523 3,382 Storage 533 503 Transmission and other 1,118 925 Total DTE Gas 5,174 4,810 Non-utility and other 3,278 3,125 Total DTE Energy 31,424 30,029 Accumulated depreciation and amortization DTE Electric Generation (4,403 ) (4,364 ) Distribution (2,914 ) (2,769 ) Other (667 ) (588 ) Total DTE Electric (7,984 ) (7,721 ) DTE Gas Distribution (1,238 ) (1,198 ) Storage (159 ) (152 ) Transmission and other (384 ) (370 ) Total DTE Gas (1,781 ) (1,720 ) Non-utility and other (938 ) (858 ) Total DTE Energy (10,703 ) (10,299 ) Net DTE Energy Property, plant, and equipment $ 20,721 $ 19,730 Net DTE Electric Property, plant, and equipment $ 14,988 $ 14,373
Schedule of AFUDC and Interest Capitalized	The following is a summary of the Registrants' AFUDC and interest capitalized for the years ended December 31: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Allowance for debt funds used during construction and interest capitalized $ 13 $ 10 $ 8 $ 8 Allowance for equity funds used during construction 23 21 18 18 Total $ 36 $ 31 $ 26 $ 26
Schedule of Utility Property, Plant, and Equipment	The average estimated useful life for each major class of utility Property, plant, and equipment as of December 31, 2017 follows: Estimated Useful Lives in Years Utility Generation Distribution Storage DTE Electric 40 41 N/A DTE Gas N/A 50 53
Schedule of Capitalized Software	The following balances for capitalized software relate to DTE Energy: Year Ended December 31, 2017 2016 2015 (In millions) Amortization expense of capitalized software $ 101 $ 89 $ 98 Gross carrying value of capitalized software $ 890 $ 715 Accumulated amortization of capitalized software $ 500 $ 435 The following balances for capitalized software relate to DTE Electric: Year Ended December 31, 2017 2016 2015 (In millions) Amortization expense of capitalized software $ 93 $ 83 $ 80 Gross carrying value of capitalized software $ 774 $ 610 Accumulated amortization of capitalized software $ 423 $ 365
Schedule of Capital Leased Assets	Property under capital leases for the Registrants is as follows: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Gross property under capital leases $ 44 $ 44 $ 18 $ 18 Accumulated amortization of property under capital leases $ 38 $ 32 $ 12 $ 6

Jointly-Owned Utility Plant (Ta

Jointly-Owned Utility Plant (Tables)	12 Months Ended
	Dec. 31, 2017
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Schedule of Jointly-Owned Utility Plants	Ownership information of the two utility plants as of December 31, 2017 was as follows: Belle River Ludington Hydroelectric Pumped Storage In-service date 1984-1985 1973 Total plant capacity 1,270 MW 2,080 MW Ownership interest (a) 49% Investment in Property, plant, and equipment (in millions) $ 1,814 $ 559 Accumulated depreciation (in millions) $ 1,060 $ 188 _______________________________________ (a) DTE Electric's ownership interest is 63% in Unit No. 1, 81% of the facilities applicable to Belle River used jointly by the Belle River and St. Clair Power Plants and 75% in common facilities used at Unit No. 2.

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2017
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligations	A reconciliation of the asset retirement obligations for 2017 follows: DTE Energy DTE Electric (In millions) Asset retirement obligations at December 31, 2016 $ 2,197 $ 2,012 Accretion 131 120 Liabilities incurred 2 1 Liabilities settled (6 ) (2 ) Revision in estimated cash flows (4 ) (6 ) Asset retirement obligations at December 31, 2017 $ 2,320 $ 2,125

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2017
Regulatory Assets and Liabilities Disclosure [Abstract]
Schedule of Regulatory Assets	The following are balances and a brief description of the Registrants' Regulatory assets and liabilities at December 31: DTE Energy DTE Electric 2017 2016 2017 2016 Assets (In millions) Recoverable pension and other postretirement costs Pension $ 2,000 $ 2,159 $ 1,502 $ 1,642 Other postretirement costs 278 286 211 207 Asset retirement obligation 569 613 569 613 Removal costs asset 299 193 299 193 Recoverable Michigan income taxes 213 231 171 187 Deferred environmental costs 75 78 — — Unamortized loss on reacquired debt 65 59 46 39 Transitional Reconciliation Mechanism 46 30 46 30 Customer360 deferred costs 45 33 45 33 Recoverable income taxes related to AFUDC equity 41 59 35 53 Other recoverable income taxes 26 57 26 57 Nuclear Performance Evaluation and Review Committee Tracker 22 — 22 — Accrued PSCR/GCR revenue 17 22 17 19 Other 82 93 66 76 3,778 3,913 3,055 3,149 Less amount included in Current Assets (55 ) (42 ) (50 ) (36 ) $ 3,723 $ 3,871 $ 3,005 $ 3,113
Schedule of Regulatory Liabilities	DTE Energy DTE Electric 2017 2016 2017 2016 Liabilities (In millions) Refundable federal income taxes $ 2,384 $ — $ 1,946 $ — Removal costs liability 265 266 — — Renewable energy 112 145 112 145 Negative other postretirement offset 80 56 67 55 Negative pension offset 21 36 — — Fermi 2 refueling outage 15 27 15 27 Refundable self-implemented rates 2 27 2 27 Other 14 32 12 2 2,893 589 2,154 256 Less amount included in Current Liabilities (18 ) (34 ) (17 ) (27 ) $ 2,875 $ 555 $ 2,137 $ 229

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The Registrants' total Income Tax Expense varied from the statutory federal income tax rate for the following reasons: 2017 2016 2015 DTE Energy (In millions) Income Before Income Taxes $ 1,287 $ 1,105 $ 950 Income tax expense at 35% statutory rate $ 450 $ 387 $ 333 Production tax credits (189 ) (145 ) (122 ) Investment tax credits (4 ) (5 ) (7 ) Depreciation (4 ) (4 ) (4 ) Noncontrolling interests 8 12 2 AFUDC equity (18 ) (10 ) (8 ) Employee Stock Ownership Plan dividends (5 ) (5 ) (5 ) Stock based compensation (14 ) — — Subsidiary stock loss — (10 ) — State and local income taxes, net of federal benefit 51 58 35 Enactment of the Tax Cuts and Jobs Act (105 ) — — Other, net 5 (7 ) 6 Income Tax Expense $ 175 $ 271 $ 230 Effective income tax rate 13.6 % 24.5 % 24.2 % 2017 2016 2015 DTE Electric (In millions) Income Before Income Taxes $ 928 $ 975 $ 836 Income tax expense at 35% statutory rate $ 325 $ 341 $ 293 Production tax credits (36 ) (30 ) (31 ) Investment tax credits (4 ) (4 ) (5 ) Depreciation 3 3 3 AFUDC equity (5 ) (6 ) (7 ) Employee Stock Ownership Plan dividends (3 ) (3 ) (3 ) State and local income taxes, net of federal benefit 48 56 43 Other, net (1 ) (4 ) (1 ) Income Tax Expense $ 327 $ 353 $ 292 Effective income tax rate 35.2 % 36.2 % 34.9 %
Schedule of Components of Income Tax Expense (Benefit)	Components of the Registrants' Income Tax Expense were as follows: 2017 2016 2015 DTE Energy (In millions) Current income tax expense (benefit) Federal $ (22 ) $ (1 ) $ (3 ) State and other income tax 1 7 (4 ) Total current income taxes (21 ) 6 (7 ) Deferred income tax expense Federal 118 184 178 State and other income tax 78 81 59 Total deferred income taxes 196 265 237 $ 175 $ 271 $ 230 2017 2016 2015 DTE Electric (In millions) Current income tax expense (benefit) Federal $ (17 ) $ — $ (26 ) State and other income tax (1 ) 11 (2 ) Total current income taxes (18 ) 11 (28 ) Deferred income tax expense Federal 270 268 252 State and other income tax 75 74 68 Total deferred income taxes 345 342 320 $ 327 $ 353 $ 292
Schedule of Deferred Tax Assets and Liabilities	The Registrants' deferred tax assets (liabilities) were comprised of the following at December 31: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Property, plant, and equipment $ (3,276 ) $ (4,880 ) $ (2,698 ) $ (3,819 ) Regulatory assets and liabilities (94 ) (879 ) (31 ) (778 ) Tax credit carry-forwards 947 643 193 116 Pension and benefits 334 643 302 518 Federal net operating loss carry-forward 83 190 47 42 State and local net operating loss carry-forwards 70 59 5 1 Investments in equity method investees (82 ) (119 ) — — Other 170 217 94 127 (1,848 ) (4,126 ) (2,088 ) (3,793 ) Less valuation allowance (40 ) (36 ) — — Long-term deferred income tax liabilities $ (1,888 ) $ (4,162 ) $ (2,088 ) $ (3,793 ) Deferred income tax assets $ 1,814 $ 1,463 $ 830 $ 569 Deferred income tax liabilities (3,702 ) (5,625 ) (2,918 ) (4,362 ) $ (1,888 ) $ (4,162 ) $ (2,088 ) $ (3,793 )
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the beginning and ending amount of unrecognized tax benefits for the Registrants is as follows: 2017 2016 2015 DTE Energy (In millions) Balance at January 1 $ 10 $ 3 $ 9 Additions for tax positions of prior years — 7 — Lapse of statute of limitations — — (6 ) Balance at December 31 $ 10 $ 10 $ 3 2017 2016 2015 DTE Electric (In millions) Balance at January 1 $ 13 $ 4 $ 4 Additions for tax positions of prior years — 9 — Balance at December 31 $ 13 $ 13 $ 4

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 31, 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 for the years ended December 31 : 2017 2016 2015 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 1,134 $ 868 $ 727 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — basic $ 1,132 $ 866 $ 725 Average number of common shares outstanding 179 179 179 Basic Earnings per Common Share $ 6.32 $ 4.84 $ 4.05 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 1,134 $ 868 $ 727 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — diluted $ 1,132 $ 866 $ 725 Average number of common shares outstanding 179 179 179 Diluted Earnings per Common Share (a) $ 6.32 $ 4.83 $ 4.05 _______________________________________ (a) The 2016 Equity Units excluded from the calculation of diluted EPS were approximately 6 million and 7.1 million for the years ended December 31, 2017 and 2016 , respectively, as the dilutive stock price threshold was not met.

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2017
Fair Value Disclosures [Abstract]
Assets and Liabilities Recorded at Fair Value on a Recurring Basis	The following table presents assets and liabilities for DTE Energy measured and recorded at fair value on a recurring basis: December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Other (a) Netting (b) Net Balance Level 1 Level 2 Level 3 Netting (b) Net Balance (In millions) Assets: Cash equivalents (c) $ 16 $ 3 $ — $ — $ — $ 19 $ 14 $ 3 $ — $ — $ 17 Nuclear decommissioning trusts Equity securities 978 — — — — 978 887 — — — 887 Fixed income securities 18 477 — — — 495 11 414 — — 425 Private equity securities — — — 5 — 5 — — — — — Cash equivalents 14 — — — — 14 8 — — — 8 Other investments (d) Equity securities 118 — — — — 118 104 — — — 104 Fixed income securities 72 — — — — 72 58 — — — 58 Cash equivalents 4 — — — — 4 3 — — — 3 Derivative assets: Commodity Contracts: Natural Gas 148 112 97 — (256 ) 101 216 79 53 (306 ) 42 Electricity — 243 42 — (241 ) 44 — 154 39 (157 ) 36 Other — — 9 — — 9 — — 2 — 2 Foreign currency exchange contracts — 1 — — (1 ) — — 6 — (5 ) 1 Total derivative assets 148 356 148 — (498 ) 154 216 239 94 (468 ) 81 Total $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Derivative liabilities: Commodity Contracts: Natural Gas $ (141 ) $ (111 ) $ (126 ) $ — $ 263 $ (115 ) $ (226 ) $ (86 ) $ (149 ) $ 321 $ (140 ) Electricity — (245 ) (30 ) — 246 (29 ) — (159 ) (30 ) 163 (26 ) Other — — (1 ) — 1 — — — (3 ) 2 (1 ) Foreign currency exchange contracts — (3 ) — — 1 (2 ) — (3 ) — 3 — Total derivative liabilities (141 ) (359 ) (157 ) — 511 (146 ) (226 ) (248 ) (182 ) 489 (167 ) Total $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 Assets: Current $ 157 $ 298 $ 104 $ — $ (437 ) $ 122 $ 205 $ 199 $ 60 $ (400 ) $ 64 Noncurrent 1,211 538 44 5 (61 ) 1,737 1,096 457 34 (68 ) 1,519 Total Assets $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 $ 1,301 $ 656 $ 94 $ (468 ) $ 1,583 Liabilities: Current $ (137 ) $ (313 ) $ (108 ) $ — $ 459 $ (99 ) $ (203 ) $ (211 ) $ (79 ) $ 424 $ (69 ) Noncurrent (4 ) (46 ) (49 ) — 52 (47 ) (23 ) (37 ) (103 ) 65 (98 ) Total Liabilities $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) $ (226 ) $ (248 ) $ (182 ) $ 489 $ (167 ) Net Assets (Liabilities) at end of period $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 $ 1,075 $ 408 $ (88 ) $ 21 $ 1,416 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) 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. (c) At December 31, 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. (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: December 31, 2017 December 31, 2016 Level 1 Level 2 Level 3 Other (a) Net Balance Level 1 Level 2 Level 3 Net Balance (In millions) Assets: Cash equivalents (b) $ 8 $ 3 $ — $ — $ 11 $ 8 $ 3 $ — $ 11 Nuclear decommissioning trusts Equity securities 978 — — — 978 887 — — 887 Fixed income securities 18 477 — — 495 11 414 — 425 Private equity securities — — — 5 5 — — — — Cash equivalents 14 — — — 14 8 — — 8 Other investments Equity securities 11 — — — 11 9 — — 9 Derivative assets — FTRs — — 9 — 9 — — 2 2 Total $ 1,029 $ 480 $ 9 $ 5 $ 1,523 $ 923 $ 417 $ 2 $ 1,342 Assets: Current $ 8 $ 3 $ 9 $ — $ 20 $ 8 $ 3 $ 2 $ 13 Noncurrent 1,021 477 — 5 1,503 915 414 — 1,329 Total Assets $ 1,029 $ 480 $ 9 $ 5 $ 1,523 $ 923 $ 417 $ 2 $ 1,342 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) At December 31, 2017 , available-for-sale securities of $11 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. At 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.
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis Level 3 Roll Forward	The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Energy for the years ended December 31, 2017 and 2016 : Year Ended December 31, 2017 Year Ended December 31, 2016 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of January 1 $ (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 (29 ) 109 2 82 (159 ) (2 ) 1 (160 ) Recorded in Regulatory liabilities — — 25 25 — — 6 6 Purchases, issuances, and settlements: Purchases — — — — — 1 — 1 Settlements 96 (106 ) (18 ) (28 ) 68 4 (3 ) 69 Net Assets (Liabilities) as of December 31 $ (29 ) $ 12 $ 8 $ (9 ) $ (96 ) $ 9 $ (1 ) $ (88 ) The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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 $ (30 ) $ 50 $ 1 $ 21 $ (166 ) $ 7 $ 2 $ (157 ) The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Electric for the years ended December 31, 2017 and 2016 : Year Ended December 31, 2017 2016 (In millions) Net Assets as of January 1 $ 2 $ 3 Change in fair value recorded in Regulatory liabilities 25 6 Purchases, issuances, and settlements: Settlements (18 ) (7 ) Net Assets as of December 31 $ 9 $ 2 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2017 and 2016 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 9 $ 2
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques	The following tables present the unobservable inputs related to DTE Energy's Level 3 assets and liabilities as of December 31, 2017 and 2016 : December 31, 2017 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 97 $ (126 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.10 ) — $ 9.75 /MMBtu $ (0.03 )/MMBtu Electricity $ 42 $ (30 ) Discounted Cash Flow Forward basis price (per MWh) $ (5 ) — $ 15 /MWh $ 2 /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
Fair Value of Financial Instruments	The following table presents the carrying amount and fair value of financial instruments for DTE Energy as of December 31, 2017 and 2016 : December 31, 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 (a) , excluding capital leases $ 38 $ — $ — $ 38 $ 36 $ — $ — $ 36 Dividends payable $ 158 $ 158 $ — $ — $ 148 $ 148 $ — $ — Short-term borrowings $ 621 $ — $ 621 $ — $ 499 $ — $ 499 $ — Notes payable — Other (b) , excluding capital leases $ 12 $ — $ — $ 12 $ 17 $ — $ — $ 17 Long-term debt (c) $ 12,288 $ 1,939 $ 10,571 $ 764 $ 11,270 $ 1,465 $ 9,384 $ 1,056 _______________________________________ (a) Current portion included in Current Assets — Other on DTE Energy's Consolidated Statements of Financial Position. (b) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Energy's Consolidated Statements of Financial Position. (c) 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 as of December 31, 2017 and 2016 : December 31, 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 (a) , excluding capital leases $ — $ — $ — $ — $ 5 $ — $ — $ 5 Short-term borrowings — affiliates $ 116 $ — $ — $ 116 $ 117 $ — $ — $ 117 Short-term borrowings — other $ 238 $ — $ 238 $ — 62 $ — $ 62 $ — Notes payable — Other (b) , excluding capital leases $ 2 $ — $ — $ 2 $ 6 $ — $ — $ 6 Long-term debt (c) $ 6,017 $ — $ 6,441 $ 171 $ 5,878 $ — $ 6,026 $ 264 _______________________________________ (a) Current portion included in Current Assets — Other on DTE Electric's Consolidated Statements of Financial Position. (b) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Electric's Consolidated Statements of Financial Position. (c) 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: December 31, 2017 December 31, 2016 (In millions) Fermi 2 $ 1,475 $ 1,291 Fermi 1 3 3 Low-level radioactive waste 14 26 $ 1,492 $ 1,320
Schedule of Realized Gain (Loss) for Nuclear Decomissioning Trust Funds	The following table sets forth DTE Electric's gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds: Year Ended December 31, 2017 2016 2015 (In millions) Realized gains $ 83 $ 74 $ 39 Realized losses $ (29 ) $ (63 ) $ (33 ) Proceeds from sale of securities $ 1,240 $ 1,457 $ 885
Fair Value and Unrealized Gains and Losses for Nuclear Decommissioning Trust Funds	The following table sets forth DTE Electric's fair value and unrealized gains and losses for the nuclear decommissioning trust funds: December 31, 2017 December 31, 2016 Fair Unrealized Unrealized Losses Fair Unrealized Unrealized Losses (In millions) Equity securities $ 978 $ 320 $ (32 ) $ 887 $ 222 $ (46 ) Fixed income securities 495 13 (3 ) 425 11 (5 ) Private equity securities 5 — — — — — Cash equivalents 14 — — 8 — — $ 1,492 $ 333 $ (35 ) $ 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: December 31, 2017 (In millions) Due within one year $ 23 Due after one through five years 102 Due after five through ten years 115 Due after ten years 255 $ 495

Financial and Other Derivativ46

Financial and Other Derivative Instruments (Tables)	12 Months Ended
	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following table presents the fair value of derivative instruments as of December 31, 2017 and 2016 for DTE Energy: December 31, 2017 December 31, 2016 Derivative Derivative Derivative Derivative (In millions) Derivatives not designated as hedging instruments: Commodity Contracts: Natural Gas $ 357 $ (378 ) $ 348 $ (461 ) Electricity 285 (275 ) 193 (189 ) Other 9 (1 ) 2 (3 ) Foreign currency exchange contracts 1 (3 ) 6 (3 ) Total derivatives not designated as hedging instrument $ 652 $ (657 ) $ 549 $ (656 ) Current $ 540 $ (558 ) $ 447 $ (493 ) Noncurrent 112 (99 ) 102 (163 ) Total derivatives $ 652 $ (657 ) $ 549 $ (656 ) The following table presents the fair value of derivative instruments as of December 31, 2017 and 2016 for DTE Electric: December 31, 2017 2016 (In millions) FTRs — Other current assets $ 9 $ 2 Total derivatives not designated as hedging instruments $ 9 $ 2
Offsetting Assets	The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy at December 31, 2017 and 2016 : December 31, 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 $ 357 $ (256 ) $ 101 $ 348 $ (306 ) $ 42 Electricity 285 (241 ) 44 193 (157 ) 36 Other 9 — 9 2 — 2 Foreign currency exchange contracts 1 (1 ) — 6 (5 ) 1 Total derivative assets $ 652 $ (498 ) $ 154 $ 549 $ (468 ) $ 81 Derivative liabilities: Commodity Contracts: Natural Gas $ (378 ) $ 263 $ (115 ) $ (461 ) $ 321 $ (140 ) Electricity (275 ) 246 (29 ) (189 ) 163 (26 ) Other (1 ) 1 — (3 ) 2 (1 ) Foreign currency exchange contracts (3 ) 1 (2 ) (3 ) 3 — Total derivative liabilities $ (657 ) $ 511 $ (146 ) $ (656 ) $ 489 $ (167 )
Offsetting Liabilities	The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy at December 31, 2017 and 2016 : December 31, 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 $ 357 $ (256 ) $ 101 $ 348 $ (306 ) $ 42 Electricity 285 (241 ) 44 193 (157 ) 36 Other 9 — 9 2 — 2 Foreign currency exchange contracts 1 (1 ) — 6 (5 ) 1 Total derivative assets $ 652 $ (498 ) $ 154 $ 549 $ (468 ) $ 81 Derivative liabilities: Commodity Contracts: Natural Gas $ (378 ) $ 263 $ (115 ) $ (461 ) $ 321 $ (140 ) Electricity (275 ) 246 (29 ) (189 ) 163 (26 ) Other (1 ) 1 — (3 ) 2 (1 ) Foreign currency exchange contracts (3 ) 1 (2 ) (3 ) 3 — Total derivative liabilities $ (657 ) $ 511 $ (146 ) $ (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 at December 31, 2017 and 2016 : December 31, 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 $ 540 $ 112 $ (558 ) $ (99 ) $ 447 $ 102 $ (493 ) $ (163 ) Counterparty netting (437 ) (52 ) 437 52 (396 ) (65 ) 396 65 Collateral adjustment — (9 ) 22 — (4 ) (3 ) 28 — Total derivatives as reported $ 103 $ 51 $ (99 ) $ (47 ) $ 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 for years ended December 31, 2017 and 2016 is as follows: Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31, Derivatives not Designated as Hedging Instruments 2017 2016 (In millions) Commodity Contracts: Natural Gas Operating Revenues — Non-utility operations $ (74 ) $ (153 ) Natural Gas Fuel, purchased power, and gas — non-utility 97 (2 ) Electricity Operating Revenues — Non-utility operations 105 43 Other Operating Revenues — Non-utility operations 2 5 Foreign currency exchange contracts Operating Revenues — Non-utility operations (2 ) (2 ) Total $ 128 $ (109 )
Volume of Commodity Contracts	The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of December 31, 2017 : Commodity Number of Units Natural Gas (MMBtu) 1,822,796,301 Electricity (MWh) 29,715,268 Foreign Currency Exchange (Canadian dollars) 108,023,948

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2017
Long-term Debt, Unclassified [Abstract]
Schedule of Long-term Debt Instruments	At December 31, 2017 , DTE Energy had the following Junior Subordinated Debentures: Interest Rate Maturity Date Amount (In millions) 2012 Series C 5.25% 2062 $ 200 2016 Series B 5.375% 2076 300 2016 Series F 6.00% 2076 280 2017 Series E 5.25% 2077 400 $ 1,180 Selected information about DTE Energy’s 2016 Equity Units is presented below: Issuance Date Units Issued Total Net Proceeds Total Long-Term Debt RSN Annual Interest Rate Stock Purchase Contract Annual Rate Stock Purchase Settlement Date Stock Purchase Contract Liability (a) RSN Maturity Date (In millions, except interest rates) 10/5/2016 13.5 $ 654 $ 675 1.5% 5.0% 10/1/2019 $ 98 10/1/2024 _______________________________________ (a) Payments of $32 million were made in 2017. The stock purchase contract liability was $66 million and $98 million at December 31, 2017 and 2016 , respectively, exclusive of interest. DTE Energy's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2017 2016 (In millions) Mortgage bonds, notes, and other DTE Energy Debt, Unsecured 3.1% 2019 — 2033 $ 3,825 $ 3,325 DTE Electric Taxable Debt, Principally Secured 4.3% 2020 — 2047 5,755 5,615 DTE Electric Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 DTE Gas Taxable Debt, Principally Secured 4.8% 2018 — 2047 1,330 1,250 Other Long-Term Debt, including Non-Recourse Debt 7 92 11,227 10,592 Unamortized debt discount and premium, net (15 ) (10 ) Unamortized debt issuance costs (69 ) (67 ) Long-term debt due within one year (104 ) (9 ) $ 11,039 $ 10,506 Junior Subordinated Debentures Subordinated Debentures 5.5% 2062 — 2077 $ 1,180 $ 780 Unamortized debt issuance costs (35 ) (24 ) $ 1,145 $ 756 _______________________________________ (a) Weighted average interest rate as of December 31, 2017 . (b) DTE Electric Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds. DTE Electric's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2017 2016 (In millions) Mortgage bonds, notes, and other Taxable Debt, Principally Secured 4.3% 2020 — 2047 $ 5,755 $ 5,615 Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 6,065 5,925 Unamortized debt discount (10 ) (10 ) Unamortized debt issuance costs (38 ) (37 ) $ 6,017 $ 5,878 _______________________________________ (a) Weighted average interest rate as of December 31, 2017 . (b) Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds.
Schedule of Issued Debt	In 2017 , the following debt was issued: Company Month Type Interest Rate Maturity Date 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 DTE Energy November Junior Subordinated Debentures (a) 5.25% 2077 400 $ 1,420 _______________________________________ (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 Redeemed	In 2017 , the following debt was redeemed: Company Month Type Interest Rate Maturity Date 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.
Schedule of Maturities of Long-term Debt	The following table shows the Registrants' scheduled debt maturities, excluding any unamortized discount or premium on debt: 2018 2019 2020 2021 2022 2023 and Thereafter Total (In millions) DTE Energy (a) $ 104 $ 1,497 $ 683 $ 462 $ 616 $ 9,045 $ 12,407 DTE Electric $ — $ — $ 632 $ 462 $ 316 $ 4,655 $ 6,065 _______________________________________ (a) Amounts include DTE Electric's scheduled debt maturities.

Preferred and Preference Secu48

Preferred and Preference Securities (Tables)	12 Months Ended
	Dec. 31, 2017
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Schedule of Preferred and Preference Securities	As of December 31, 2017 , the amount of authorized and unissued stock is as follows: Company Type of Stock Par Value Shares Authorized DTE Energy Preferred $ — 5,000,000 DTE Electric Preferred $ 100 6,747,484 DTE Electric Preference $ 1 30,000,000 DTE Gas Preferred $ 1 7,000,000 DTE Gas Preference $ 1 4,000,000

Short-Term Credit Arrangement49

Short-Term Credit Arrangements and Borrowings (Tables)	12 Months Ended
	Dec. 31, 2017
Short-term Debt [Abstract]
Schedule of Line of Credit Facilities	The availability under the facilities in place at December 31, 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 70 — — 70 Unsecured revolving credit facility, expiring April 2022 1,200 400 300 1,900 1,420 400 300 2,120 Amounts outstanding at December 31, 2017 Commercial paper issuances 83 238 300 621 Letters of credit 124 — — 124 207 238 300 745 Net availability at December 31, 2017 $ 1,213 $ 162 $ — $ 1,375

Capital and Operating Leases (T

Capital and Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2017
Leases [Abstract]
Schedule of Future Minimum Lease Payments for Operating Leases	The Registrants' future minimum lease payments under non-cancelable operating leases at December 31, 2017 were: DTE Energy DTE Electric (In millions) 2018 $ 40 $ 15 2019 34 14 2020 22 9 2021 13 9 2022 9 6 2022 and thereafter 48 38 Total minimum lease payments $ 166 $ 91
Schedule of Future Minimum Lease Receivables for Capital Leases	The components of DTE Energy's net investment in capital leases at December 31, 2017 , were as follows: DTE Energy (In millions) 2018 $ 13 2019 10 2020 9 2021 — 2022 — 2023 and thereafter 1 Total minimum future lease receipts 33 Residual value of leased pipeline 40 Less unearned income (15 ) Net investment in capital lease 58 Less current portion (7 ) $ 51

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2017
Commitments and Contingencies Disclosure [Abstract]
Schedule of Long-term Purchase Commitments	The Registrants estimate the following commitments from 2018 through 2051 for DTE Energy, and 2018 through 2033 for DTE Electric, as detailed in the following table: DTE Energy DTE Electric (In millions) 2018 $ 2,731 $ 930 2019 1,045 320 2020 638 192 2021 474 149 2022 371 88 2023 and thereafter 2,277 820 $ 7,536 $ 2,499

Retirement Benefits and Trust52

Retirement Benefits and Trusteed Assets (Tables)	12 Months Ended
	Dec. 31, 2017
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures	The following table provides cash contributions to the qualified pension plans as of December 31: 2017 2016 2015 (In millions) DTE Energy $ 223 $ 179 $ 177 DTE Electric 185 145 145 The table below represents the pension and other postretirement benefit plans which employees of each Registrant participated at December 31, 2017 : Registrants DTE Energy DTE Electric Qualified Pension Plans DTE Energy Company Retirement Plan X X DTE Gas Company Retirement Plan for Employees Covered by Collective Bargaining Agreements X Shenango Inc. Pension Plan X Nonqualified Pension Plans DTE Energy Company Supplemental Retirement Plan X X DTE Energy Company Executive Supplemental Retirement Plan (a) X X DTE Energy Company Supplemental Severance Benefit Plan X Other Postretirement Benefit Plans The DTE Energy Company Comprehensive Non-Health Welfare Plan X X The DTE Energy Company Comprehensive Retiree Group Health Care Plan X X DTE Supplemental Retiree Benefit Plan X X DTE Energy Company Retiree Reimbursement Arrangement Plan X X _____________________________________ (a) Sponsored by the DTE Energy subsidiary, DTE Energy Holding Company.
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures	The following table reconciles the obligations, assets, and funded status of the plans as well as the amounts recognized as prepaid pension cost or pension liability in DTE Energy's Consolidated Statements of Financial Position at December 31: DTE Energy 2017 2016 (In millions) Accumulated benefit obligation, end of year $ 5,149 $ 4,753 Change in projected benefit obligation Projected benefit obligation, beginning of year $ 5,171 $ 4,971 Service cost 92 92 Interest cost 214 219 Plan amendments (11 ) 7 Actuarial loss 391 141 Benefits paid (281 ) (259 ) Projected benefit obligation, end of year $ 5,576 $ 5,171 Change in plan assets Plan assets at fair value, beginning of year $ 4,012 $ 3,832 Actual return on plan assets 674 253 Company contributions 231 186 Benefits paid (281 ) (259 ) Plan assets at fair value, end of year $ 4,636 $ 4,012 Funded status $ (940 ) $ (1,159 ) Amount recorded as: Current liabilities $ (16 ) $ (7 ) Noncurrent liabilities (924 ) (1,152 ) $ (940 ) $ (1,159 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 163 $ 163 Prior service cost 6 8 $ 169 $ 171 Amounts recognized in Regulatory assets (a) Net actuarial loss $ 2,014 $ 2,163 Prior service credit (14 ) (4 ) $ 2,000 $ 2,159 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ."
Schedule of Net Benefit Costs	Net pension cost for DTE Energy includes the following components: 2017 2016 2015 (In millions) Service cost $ 92 $ 92 $ 100 Interest cost 214 219 210 Expected return on plan assets (311 ) (309 ) (296 ) Amortization of: Net actuarial loss 176 164 205 Prior service cost 1 1 — Other — — 2 Net pension cost $ 172 $ 167 $ 221
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	2017 2016 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial loss $ 27 $ 197 Amortization of net actuarial loss (176 ) (164 ) Prior service cost ( credit) (11 ) 7 Amortization of prior service cost (1 ) (1 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (161 ) $ 39 Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 11 $ 206 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 178 $ 172 Prior service cost $ — $ 1
Schedule of Expected Benefit Payments	At December 31, 2017 , the benefits related to DTE Energy's qualified and nonqualified pension plans expected to be paid in each of the next five years and in the aggregate for the five fiscal years thereafter are as follows: (In millions) 2018 $ 299 2019 301 2020 316 2021 317 2022 323 2023-2027 1,692 Total $ 3,248
Schedule of Assumptions Used	Assumptions used in determining the projected benefit obligation and net pension costs of DTE Energy are: 2017 2016 2015 Projected benefit obligation Discount rate 3.70% 4.25% 4.50% Rate of compensation increase 4.98% 4.65% 4.65% Net pension costs Discount rate 4.25% 4.50% 4.12% Rate of compensation increase 4.65% 4.65% 4.65% Expected long-term rate of return on plan assets 7.50% 7.75% 7.75%
Schedule of Allocation of Plan Assets	Target allocations for DTE Energy's pension plan assets as of December 31, 2017 are listed below: U.S. Large Capitalization (Cap) Equity Securities 18 % U.S. Small Cap and Mid Cap Equity Securities 5 Non-U.S. Equity Securities 17 Fixed Income Securities 32 Hedge Funds and Similar Investments 20 Private Equity and Other 8 100 % The following tables provide the fair value measurement amounts for DTE Energy's pension plan assets at December 31, 2017 and 2016 (a) : December 31, 2017 December 31, 2016 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total (In millions) DTE Energy asset category: Short-term Investments (c) $ — $ 114 $ — $ 114 $ — $ 22 $ — $ 22 Equity Securities U.S. Large Cap (d) 821 5 — 826 875 5 — 880 U.S. Small Cap and Mid Cap (e) 229 5 — 234 229 3 — 232 Non-U.S. (f) 529 13 280 822 479 18 269 766 Fixed Income Securities (g) 1 1,453 — 1,454 1 1,037 52 1,090 Hedge Funds and Similar Investments (h) 265 — 593 858 231 — 578 809 Private Equity and Other (i) — — 328 328 — — 213 213 Securities Lending (j) (53 ) (13 ) — (66 ) (53 ) (25 ) — (78 ) Securities Lending Collateral (j) 53 13 — 66 53 25 — 78 DTE Energy Total $ 1,845 $ 1,590 $ 1,201 $ 4,636 $ 1,815 $ 1,085 $ 1,112 $ 4,012 _______________________________________ (a) For a description of levels within the fair value hierarchy, see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, and mortgage-backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as NAV assets. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds or limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. All pricing for investments in this category are classified as NAV assets. (j) DTE Energy has a securities lending program with a third-party agent. The program allows the agent to lend certain securities from DTE Energy's pension trusts to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements.
Other postretirement benefit plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures	The following table reconciles the obligations, assets, and funded status of the plans including amounts recorded as Accrued postretirement liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2017 2016 2017 2016 (In millions) Change in accumulated postretirement benefit obligation Accumulated postretirement benefit obligation, beginning of year $ 1,795 $ 1,846 $ 1,373 $ 1,414 Service cost 27 27 20 20 Interest cost 73 80 56 61 Actuarial (gai n) loss 101 (75 ) 84 (62 ) Benefits paid (86 ) (83 ) (63 ) (60 ) Accumulated postretirement benefit obligation, end of year $ 1,910 $ 1,795 $ 1,470 $ 1,373 Change in plan assets Plan assets at fair value, beginning of year $ 1,758 $ 1,617 $ 1,218 $ 1,131 Actual return on plan assets 252 122 172 87 Company contributions — 20 — — Benefits paid (162 ) (1 ) (118 ) — Plan assets at fair value, end of year $ 1,848 $ 1,758 $ 1,272 $ 1,218 Funded status $ (62 ) $ (37 ) $ (198 ) $ (155 ) Amount recorded as: Noncurrent assets $ — $ — $ 113 $ 114 Current liabilities (1 ) (1 ) — — Noncurrent liabilities (61 ) (36 ) (311 ) (269 ) $ (62 ) $ (37 ) $ (198 ) $ (155 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial (gain) loss $ (1 ) $ 12 $ — $ — $ (1 ) $ 12 $ — $ — Amounts recognized in Regulatory assets (a) Net actuarial loss $ 279 $ 300 $ 211 $ 217 Prior service credit (1 ) (14 ) — (10 ) $ 278 $ 286 $ 211 $ 207 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ."
Schedule of Net Benefit Costs	Net other postretirement credit for DTE Electric includes the following components: 2017 2016 2015 (In millions) Service cost $ 20 $ 20 $ 25 Interest cost 56 61 62 Expected return on plan assets (90 ) (90 ) (90 ) Amortization of: Net actuarial loss 8 21 31 Prior service credit (10 ) (89 ) (95 ) Net other postretirement credit $ (16 ) $ (77 ) $ (67 ) Net other postretirement credit for DTE Energy includes the following components: 2017 2016 2015 (In millions) Service cost $ 27 $ 27 $ 34 Interest cost 73 80 81 Expected return on plan assets (130 ) (129 ) (131 ) Amortization of: Net actuarial loss 13 30 43 Prior service credit (14 ) (118 ) (126 ) Other — (1 ) — Net other postretirement credit $ (31 ) $ (111 ) $ (99 )
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	2017 2016 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial gain $ (21 ) $ (68 ) Amortization of net actuarial loss (13 ) (30 ) Prior service credit (1 ) — Amortization of prior service credit 14 119 Total recognized in Regulatory assets and Other comprehensive income (loss) $ (21 ) $ 21 Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (52 ) $ (90 ) Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 11 $ 16 Prior service credit $ (1 ) $ (14 ) 2017 2016 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets Net actuarial (gai n) loss $ 2 $ (59 ) Amortization of net actuarial loss (8 ) (21 ) Amortization of prior service credit 10 89 Total recognized in Regulatory assets $ 4 $ 9 Total recognized in net periodic benefit cost and Regulatory assets $ (12 ) $ (68 ) Estimated amounts to be amortized from Regulatory assets into net periodic benefit cost during next fiscal year Net actuarial loss $ 8 $ 10 Prior service credit $ — $ (10 )
Schedule of Expected Benefit Payments	At December 31, 2017 , the benefits expected to be paid, including prescription drug benefits, in each of the next five years and in the aggregate for the five fiscal years thereafter for the Registrants are as follows: DTE Energy DTE Electric (In millions) 2018 $ 94 $ 73 2019 99 77 2020 103 80 2021 105 82 2022 108 84 2023-2027 567 437 Total $ 1,076 $ 833
Schedule of Assumptions Used	Assumptions used in determining the accumulated postretirement benefit obligation and net other postretirement benefit costs of the Registrants are: 2017 2016 2015 Accumulated postretirement benefit obligation Discount rate 3.70% 4.25% 4.50% Health care trend rate pre- and post- 65 6.75 / 7.25% 6.50 / 6.75% 6.25 / 6.75% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2030 2028 2027 Other postretirement benefit costs Discount rate 4.25% 4.50% 4.10% Expected long-term rate of return on plan assets 7.75% 8.00% 8.00% Health care trend rate pre- and post- 65 6.50 / 6.75% 6.25 / 6.75% 7.50 / 6.50% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2028 2027 2025 / 2024
Schedule of Allocation of Plan Assets	Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2017 are listed below: U.S. Large Cap Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 20 Fixed Income Securities 26 Hedge Funds and Similar Investments 20 Private Equity and Other 14 100 % The following tables provide the fair value measurement amounts for the Registrants' other postretirement benefit plan assets at December 31, 2017 and 2016 (a) : December 31, 2017 December 31, 2016 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total DTE Energy asset category: (In millions) Short-term Investments (c) $ 13 $ 2 $ — $ 15 $ 39 $ 1 $ — $ 40 Equity Securities U.S. Large Cap (d) 284 — — 284 284 — — 284 U.S. Small Cap and Mid Cap (e) 131 — — 131 156 — — 156 Non-U.S. (f) 288 1 77 366 262 1 61 324 Fixed Income Securities (g) 29 324 130 483 15 299 125 439 Hedge Funds and Similar Investments (h) 116 — 219 335 114 — 224 338 Private Equity and Other (i) — — 234 234 — — 177 177 Securities Lending (j) (39 ) (1 ) — (40 ) (28 ) (3 ) — (31 ) Securities Lending Collateral (j) 39 1 — 40 28 3 — 31 DTE Energy Total $ 861 $ 327 $ 660 $ 1,848 $ 870 $ 301 $ 587 $ 1,758 DTE Electric asset category: Short-term Investments (c) $ 9 $ 1 $ — $ 10 $ 28 $ 1 $ — $ 29 Equity Securities U.S. Large Cap (d) 195 — — 195 195 — — 195 U.S. Small Cap and Mid Cap (e) 91 — — 91 109 — — 109 Non-U.S. (f) 200 1 52 253 182 1 41 224 Fixed Income Securities (g) 20 218 92 330 10 203 90 303 Hedge Funds and Similar Investments (h) 80 — 150 230 80 — 154 234 Private Equity and Other (i) — — 163 163 — — 124 124 Securities Lending (j) (27 ) (1 ) — (28 ) (20 ) (1 ) — (21 ) Securities Lending Collateral (j) 27 1 — 28 20 1 — 21 DTE Electric Total $ 595 $ 220 $ 457 $ 1,272 $ 604 $ 205 $ 409 $ 1,218 _______________________________________ (a) For a description of levels within the fair value hierarchy see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quote prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, bank loans, and mortgage backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as NAV assets. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds and limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in timber and private mezzanine debt. All investments in this category are classified as NAV assets. (j) The Registrants have a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' VEBA trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2017 are listed below: U.S. Large Cap Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 20 Fixed Income Securities 26 Hedge Funds and Similar Investments 20 Private Equity and Other 14 100 %

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2017
Share-based Compensation [Abstract]
Schedule of Components of Stock-Based Compensation	The following table summarizes the components of stock-based compensation for DTE Energy: 2017 2016 2015 (In millions) Stock-based compensation expense $ 58 $ 61 $ 34 Tax benefit $ 23 $ 24 $ 13 Stock-based compensation cost capitalized in Property, plant, and equipment $ 9 $ 10 $ 5
Schedule of Stock-based Compensation, Stock Options, Activity	The following table summarizes DTE Energy's stock option activity for the year ended December 31, 2017 : Number of Options Weighted Average Exercise Price Aggregate Intrinsic Options outstanding and exercisable at December 31, 2016 171,517 $ 41.59 Exercised (65,523 ) $ 39.37 Options outstanding and exercisable at December 31, 2017 105,994 $ 42.95 $ 7
Schedule of Stock-based Compensation, Shares Authorized Under Stock Option Plans, by Exercise Price Range	The number, weighted average exercise price, and weighted average remaining contractual life of DTE Energy options outstanding as of December 31, 2017 were as follows: Range of Exercise Prices Number of Options Weighted Average Weighted Average $ 27.00 — $ 38.00 6,194 $ 27.70 1.16 $ 38.01 — $ 42.00 2,300 $ 41.79 0.15 $ 42.01 — $ 45.00 97,500 $ 43.95 2.15 105,994 $ 42.95 2.05
Schedule of Stock-based Compensation, Stock Award Activity	Stock award activity for DTE Energy for the years ended December 31 was: 2017 2016 2015 Fair value of awards vested (in millions) $ 10 $ 9 $ 9 Restricted common shares awarded 136,825 145,240 144,300 Weighted average market price of shares awarded $ 99.53 $ 87.28 $ 83.43 Compensation cost charged against income (in millions) $ 11 $ 11 $ 10
Schedule of Stock-based Compensation, Restricted Stock Activity Rollforward	The following table summarizes DTE Energy’s restricted stock awards activity for the year ended December 31, 2017 : Restricted Weighted Average Balance at December 31, 2016 385,285 $ 80.10 Grants 136,825 $ 99.53 Forfeitures (11,745 ) $ 90.24 Vested and issued (144,601 ) $ 72.08 Balance at December 31, 2017 365,764 $ 90.26
Stock-based Compensation Expense	DTE Energy recorded compensation expense for performance share awards as follows: 2017 2016 2015 (In millions) Compensation expense $ 47 $ 50 $ 24 Cash settlements (a) $ 15 $ 7 $ 13 Stock settlements (a) $ 66 $ 38 $ 71 _______________________________________ (a) Sum of cash and stock settlements approximates the intrinsic value of the awards.
Schedule of Stock-based Compensation, Performance Shares Activity Rollforward	The following table summarizes DTE Energy’s performance share activity for the period ended December 31, 2017 : Performance Shares Weighted Average Balance at December 31, 2016 1,392,512 $ 79.97 Grants 494,688 $ 98.47 Forfeitures (49,547 ) $ 87.12 Payouts (513,252 ) $ 70.60 Balance at December 31, 2017 1,324,401 $ 90.31
Schedule of Unrecognized Compensation Cost, Non-Vested Awards	As of December 31, 2017 , DTE Energy's total unrecognized compensation cost related to non-vested stock incentive plan arrangements and the weighted average recognition period was as follows: Unrecognized Weighted Average (In millions) (In years) Stock awards $ 13 1.12 Performance shares 51 1.11 $ 64 1.11

Segment and Related Informati54

Segment and Related Information (Tables)	12 Months Ended
	Dec. 31, 2017
Segment Reporting [Abstract]
Financial Data of Business Segments	Inter-segment billing for goods and services exchanged between segments is based upon tariffed or market-based prices of the provider and primarily consists of the sale of reduced emissions fuel, power sales, and natural gas sales in the following segments: Year Ended December 31, 2017 2016 2015 (In millions) Electric $ 48 $ 43 $ 36 Gas 8 9 3 Gas Storage and Pipelines 42 9 8 Power and Industrial Projects 569 602 785 Energy Trading 35 39 32 Corporate and Other 2 2 4 $ 704 $ 704 $ 868 Financial data of DTE Energy's business segments follows: Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2017 Operating Revenues — Utility operations $ 5,102 1,388 — — — — (56 ) $ 6,434 Operating Revenues — Non-utility operations $ — — 453 2,089 4,277 2 (648 ) $ 6,173 Depreciation and amortization $ 753 123 76 72 5 1 — $ 1,030 Interest expense $ 274 65 77 29 5 192 (106 ) $ 536 Interest income $ — (7 ) (14 ) (7 ) (2 ) (88 ) 106 $ (12 ) Equity in earnings of equity method investees $ 1 2 90 9 — — — $ 102 Income Tax Expense (Benefit) (a) $ 321 78 (30 ) (195 ) 49 (48 ) — $ 175 Net Income (Loss) Attributable to DTE Energy Company $ 606 146 275 138 72 (103 ) — $ 1,134 Investment in equity method investees $ 7 11 879 150 — 26 — $ 1,073 Capital expenditures and acquisitions $ 1,574 463 137 56 7 13 — $ 2,250 Goodwill $ 1,208 743 299 26 17 — — $ 2,293 Total Assets $ 21,163 5,072 2,594 593 725 5,324 (1,704 ) $ 33,767 _____________________________________ (a) Includes Income Tax Expense (Benefit) of $(5) million , $(115) million , $(21) million , $2 million , and $34 million for Electric — non-utility, Gas Storage and Pipelines, Power and Industrial Projects, Energy Trading, and Corporate and Other, respectively, related to the enactment of the TCJA. Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2016 Operating Revenues — Utility operations $ 5,225 1,324 — — — — (52 ) $ 6,497 Operating Revenues — Non-utility operations $ — — 302 1,906 2,575 2 (652 ) $ 4,133 Depreciation and amortization $ 750 106 45 72 3 — — $ 976 Interest expense $ 264 60 39 32 6 148 (77 ) $ 472 Interest income $ (8 ) (6 ) (9 ) (8 ) (1 ) (65 ) 77 $ (20 ) Equity in earnings of equity method investees $ 2 6 60 — — — — $ 68 Income Tax Expense (Benefit) $ 353 77 71 (140 ) (29 ) (61 ) — $ 271 Net Income (Loss) Attributable to DTE Energy Company $ 622 138 119 95 (45 ) (61 ) — $ 868 Investment in equity method investees $ 11 10 538 166 — 27 — $ 752 Capital expenditures and acquisitions $ 1,503 395 1,322 39 7 3 — $ 3,269 Goodwill $ 1,208 743 292 26 17 — — $ 2,286 Total Assets $ 20,417 4,729 2,417 683 660 4,648 (1,513 ) $ 32,041 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2015 Operating Revenues — Utility operations $ 4,901 1,376 — — — — (39 ) $ 6,238 Operating Revenues — Non-utility operations $ — — 243 2,224 2,459 2 (829 ) $ 4,099 Depreciation and amortization $ 637 104 30 78 2 1 — $ 852 Interest expense $ 258 62 24 32 6 132 (64 ) $ 450 Interest income $ — (7 ) (8 ) (8 ) (2 ) (52 ) 64 $ (13 ) Equity in earnings of equity method investees $ 2 6 47 8 — 3 — $ 66 Income Tax Expense (Benefit) $ 290 72 70 (140 ) (15 ) (47 ) — $ 230 Net Income (Loss) Attributable to DTE Energy Company $ 542 132 107 16 (22 ) (48 ) — $ 727 Investment in equity method investees $ 10 9 296 183 — 16 — $ 514 Capital expenditures and acquisitions $ 1,785 273 161 36 6 — — $ 2,261 Goodwill $ 1,208 743 24 26 17 — — $ 2,018 Total Assets $ 19,503 4,294 1,047 860 590 3,496 (1,128 ) $ 28,662

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2017
Related Party Transactions [Abstract]
Transactions With Affiliated Companies	The following is a summary of DTE Electric's transactions with affiliated companies: 2017 2016 2015 (In millions) Revenues Energy sales $ 9 $ 10 $ 2 Other services $ (4 ) $ (1 ) $ 6 Shared capital assets $ 39 $ 33 $ 33 Costs Fuel and purchased power $ 6 $ 10 $ 9 Other services and interest $ (2 ) $ (1 ) $ 2 Corporate expenses, net $ 370 $ 370 $ 334 Other Dividends declared $ 432 $ 420 $ 395 Dividends paid $ 432 $ 420 $ 395 Capital contribution from DTE Energy $ 100 $ 120 $ 300

Supplementary Quarterly Finan56

Supplementary Quarterly Financial Information (Unaudited ) (Tables)	12 Months Ended
	Dec. 31, 2017
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	DTE Energy Quarterly earnings per share may not equal full year totals, since quarterly computations are based on weighted average common shares outstanding during each quarter. First Second Third Fourth Year (In millions, except per share amounts) 2017 Operating Revenues $ 3,236 $ 2,855 $ 3,245 $ 3,271 $ 12,607 Operating Income $ 569 $ 303 $ 418 $ 356 $ 1,646 Net Income Attributable to DTE Energy Company (a) $ 400 $ 177 $ 270 $ 287 $ 1,134 Basic Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 Diluted Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 2016 Operating Revenues $ 2,566 $ 2,262 $ 2,928 $ 2,874 $ 10,630 Operating Income $ 381 $ 256 $ 507 $ 301 $ 1,445 Net Income Attributable to DTE Energy Company $ 247 $ 152 $ 338 $ 131 $ 868 Basic Earnings per Share $ 1.38 $ 0.84 $ 1.88 $ 0.73 $ 4.84 Diluted Earnings per Share $ 1.37 $ 0.84 $ 1.88 $ 0.73 $ 4.83 _____________________________________ (a) Includes a net Income Tax Benefit of $(105) million related to the enactment of the TCJA in the fourth quarter. DTE Electric First Second Third Fourth Year (In millions) 2017 Operating Revenues $ 1,175 $ 1,218 $ 1,434 $ 1,275 $ 5,102 Operating Income $ 217 $ 272 $ 395 $ 281 $ 1,165 Net Income $ 106 $ 138 $ 219 $ 138 $ 601 2016 Operating Revenues $ 1,153 $ 1,215 $ 1,608 $ 1,249 $ 5,225 Operating Income $ 245 $ 265 $ 501 $ 193 $ 1,204 Net Income $ 127 $ 135 $ 285 $ 75 $ 622

Organization and Basis of Pre57

Organization and Basis of Presentation (Details) customer in Millions	Dec. 31, 2017USD ($)customer	Dec. 31, 2016USD ($)	Oct. 01, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of electric utility customers | customer	2.2
Number of gas utility customers | customer	1.3
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Significant potential exposure	$ 0
Amount in excess of carrying amount	72,000,000	$ 73,000,000
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 gathering assets
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Percentage of voting interests acquired	55.00%		55.00%

Organization and Basis of Pre58

Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
ASSETS
Cash and cash equivalents	$ 66	$ 92	$ 37	$ 48
Restricted cash	23	21
Accounts receivable	1,758	1,522
Property, plant, and equipment, net	20,721	19,730
Goodwill	2,293	2,286	2,018
Total Assets	33,767	32,041	$ 28,662
LIABILITIES
Current portion long-term debt, including capital leases	109	14
Mortgage bonds, notes, and other	11,039	10,506
Variable interest entity, primary beneficiary, restricted
ASSETS
Cash and cash equivalents	37	63
Restricted cash	8	7
Accounts receivable	53	42
Inventories	117	115
Property, plant, and equipment, net	475	474
Goodwill	25	17
Intangible assets	572	586
Other current and long-term assets	4	2
Total Assets	1,291	1,306
LIABILITIES
Accounts payable and accrued current liabilities	73	51
Current portion long-term debt, including capital leases	4	5
Mortgage bonds, notes, and other	1	5
Other current and long-term liabilities	17	17
Total liabilities	95	78
SGG
ASSETS
Cash and cash equivalents	23	36
Restricted cash	0	0
Accounts receivable	11	8
Inventories	3	3
Property, plant, and equipment, net	400	398
Goodwill	25	17
Intangible assets	572	586
Other current and long-term assets	4	1
Total Assets	1,038	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 percentage	100.00%
VIE ownership percentage	55.00%
Other
ASSETS
Cash and cash equivalents	$ 14	27
Restricted cash	8	7
Accounts receivable	42	34
Inventories	114	112
Property, plant, and equipment, net	75	76
Goodwill	0	0
Intangible assets	0	0
Other current and long-term assets	0	1
Total Assets	253	257
LIABILITIES
Accounts payable and accrued current liabilities	47	32
Current portion long-term debt, including capital leases	4	5
Mortgage bonds, notes, and other	1	5
Other current and long-term liabilities	16	15
Total liabilities	$ 68	$ 57

Organization and Basis of Pre59

Organization and Basis of Presentation (Non Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Variable Interest Entity [Line Items]
Investments in equity method investees	$ 1,073	$ 752	$ 514
Notes receivable	73	73
Variable interest entity, nonconsolidated
Variable Interest Entity [Line Items]
Investments in equity method investees	811	509
Notes receivable	17	15
Future funding commitments	$ 598	$ 692

Organization and Basis of Pre60

Organization and Basis of Presentation (Equity Method Investees) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Equity Method Investments [Line Items]
Investments	$ 1,073	$ 752	$ 514
NEXUS Pipeline
Schedule of Equity Method Investments [Line Items]
Percent Owned	50.00%
Gas Storage and Pipelines
Schedule of Equity Method Investments [Line Items]
Investments	$ 879	538
Gas Storage and Pipelines | NEXUS Pipeline
Schedule of Equity Method Investments [Line Items]
Investments	$ 640	$ 322
Percent Owned	50.00%	50.00%
Gas Storage and Pipelines | Vector Pipeline
Schedule of Equity Method Investments [Line Items]
Investments	$ 115	$ 100
Percent Owned	40.00%	40.00%
Gas Storage and Pipelines | Millennium Pipeline
Schedule of Equity Method Investments [Line Items]
Investments	$ 124	$ 116
Percent Owned	26.00%	26.00%
Other Segments
Schedule of Equity Method Investments [Line Items]
Investments	$ 194	$ 214

Significant Accounting Polici61

Significant Accounting Policies (Schedule of Other Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity in earnings of equity method investees	$ 102	$ 68	$ 66
Income from REF entities	77	75	83
Gains from trading securities	26	15	1
Allowance for equity funds used during construction	23	21	21
Contract services	19	21	27
Other	21	7	11
Other income	268	207	209
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity in earnings of equity method investees	1	2	2
Gains from trading securities	26	15	1
Allowance for equity funds used during construction	18	18	20
Contract services	21	20	27
Other	11	6	10
Other income	$ 77	$ 61	$ 60

Significant Accounting Polici62

Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 9,990,000,000	$ 9,499,000,000	$ 8,795,000,000	$ 8,342,000,000
Beginning balance	9,011,000,000
Other comprehensive income	13,000,000	12,000,000	10,000,000
Ending balance	9,990,000,000	9,499,000,000	8,795,000,000
Ending balance	9,512,000,000	9,011,000,000
AOCI including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(120,000,000)	(133,000,000)	(145,000,000)
Other comprehensive income (loss) before reclassifications	(1,000,000)	(3,000,000)
Amounts reclassified from Accumulated other comprehensive income	14,000,000	15,000,000
Other comprehensive income	13,000,000	12,000,000
Ending balance	(120,000,000)	(133,000,000)	(145,000,000)
Net Unrealized Gain (Loss) on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(3,000,000)	(4,000,000)	(4,000,000)
Other comprehensive income (loss) before reclassifications	0	0
Amounts reclassified from Accumulated other comprehensive income	1,000,000	0
Other comprehensive income	1,000,000	0
Ending balance	(3,000,000)	(4,000,000)	(4,000,000)
Net Unrealized Gain (Loss) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(2,000,000)	(3,000,000)	(4,000,000)
Other comprehensive income (loss) before reclassifications	1,000,000	0
Amounts reclassified from Accumulated other comprehensive income	0	1,000,000
Other comprehensive income	1,000,000	1,000,000
Ending balance	(2,000,000)	(3,000,000)	(4,000,000)
Benefit Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(110,000,000)	(120,000,000)	(131,000,000)
Other comprehensive income (loss) before reclassifications	(3,000,000)	(3,000,000)
Amounts reclassified from Accumulated other comprehensive income	13,000,000	14,000,000
Other comprehensive income	10,000,000	11,000,000
Ending balance	(110,000,000)	(120,000,000)	(131,000,000)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5,000,000)	(6,000,000)	(6,000,000)
Other comprehensive income (loss) before reclassifications	1,000,000	0
Amounts reclassified from Accumulated other comprehensive income	0	0
Other comprehensive income	1,000,000	0
Ending balance	(5,000,000)	(6,000,000)	(6,000,000)
AOCI attributable to parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(120,000,000)	(133,000,000)	(145,000,000)	$ (155,000,000)
Ending balance	(120,000,000)	(133,000,000)	(145,000,000)
Net Unrealized Gain on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive income	0	0
DTE Electric
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	5,995,000,000	5,673,000,000	5,196,000,000
Other comprehensive income	1,000,000	0	28,000,000
Ending balance	6,265,000,000	5,995,000,000	5,673,000,000
DTE Electric | AOCI attributable to parent
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	2,000,000	2,000,000	(26,000,000)
Ending balance	3,000,000	2,000,000	$ 2,000,000
DTE Electric | Net Unrealized Gain on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Amounts reclassified from Accumulated other comprehensive income	$ 0	$ 0

Significant Accounting Polici63

Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Significant Accounting Policies [Line Items]
Specific review of probable future collections based on receivable balances in excess of 90 days	30 days
Unbilled revenues	$ 1,758,000,000	$ 1,522,000,000
Regulatory liabilities	$ 2,893,000,000	589,000,000
Property maintenance accrual period	18 months
Amortization of intangible assets	$ 29,000,000	16,000,000	$ 11,000,000
Excise and sales taxes net impact on statement of operations	0
Charitable contributions	43,000,000	26,000,000	$ 12,000,000
Fermi 2 refueling outage
Significant Accounting Policies [Line Items]
Regulatory liabilities	15,000,000	27,000,000
Natural gas inventory
Significant Accounting Policies [Line Items]
LIFO inventory amount	29,000,000	45,000,000
Excess of replacement costs over stated LIFO value	$ 81,000,000	132,000,000
Minimum
Significant Accounting Policies [Line Items]
Notes receivable considered delinquent period	60 days
Maximum
Significant Accounting Policies [Line Items]
Notes receivable considered delinquent period	120 days
DTE Electric and DTE Gas
Significant Accounting Policies [Line Items]
Receivables due date	21 days
Threshold period past due for write-off of trade accounts receivable	150 days
DTE Electric
Significant Accounting Policies [Line Items]
Unbilled revenues	$ 791,000,000	728,000,000
Regulatory liabilities	2,154,000,000	256,000,000
DTE Electric | Fermi 2 refueling outage
Significant Accounting Policies [Line Items]
Regulatory liabilities	15,000,000	27,000,000
Unbilled revenues
Significant Accounting Policies [Line Items]
Unbilled revenues	1,000,000,000	814,000,000
Unbilled revenues | DTE Electric
Significant Accounting Policies [Line Items]
Unbilled revenues	$ 290,000,000	$ 267,000,000

Significant Accounting Polici64

Significant Accounting Policies (Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Finite-Lived Intangible Assets [Line Items]
Intangible assets, gross	$ 963	$ 912
Accumulated Amortization	(96)	(70)
Intangible assets, net carrying value	$ 867	842
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Useful Lives	40 years
DTE Electric
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	$ 25	31
Intangible assets, gross	25	31
Accumulated Amortization	0	0
Intangible assets, net carrying value	25	31
DTE Electric | DTE Electric renewable energy credits
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	24	30
DTE Electric | DTE Electric emission allowances
Finite-Lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	1	1
DTE Energy
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	938	881
Accumulated Amortization	(96)	(70)
Finite-lived intangible assets, net carrying value	842	811
DTE Energy | Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	770	770
Accumulated Amortization	(24)	(5)
Finite-lived intangible assets, net carrying value	746	765
DTE Energy | Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	168	111
Accumulated Amortization	(72)	(65)
Finite-lived intangible assets, net carrying value	$ 96	$ 46
Minimum | Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Useful Lives	6 years
Maximum | Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Useful Lives	26 years

Significant Accounting Polici65

Significant Accounting Policies (Future Amortization Expense Intangible Assets) (Details) $ in Millions	Dec. 31, 2017USD ($)
Finite-Lived Intangible Assets, Net, Amortization Expense, Fiscal Year Maturity [Abstract]
2,018	$ 26
2,019	26
2,020	25
2,021	25
2,022	$ 25

Acquisitions and Exit Activit66

Acquisitions and Exit Activities (Acquisition) (Details) - Gas Storage and Pipelines Acquisition - USD ($) $ in Millions	Oct. 01, 2016	Sep. 30, 2017	Dec. 31, 2016	Dec. 31, 2017
Business Acquisition [Line Items]
Payments to acquire businesses	$ 1,200
Assumed debt	204
Assumed debt, acquiree portion	$ 112
Noncontrolling interest percentage	45.00%
Assumed debt, noncontrolling interest portion	$ 92
Purchase accounting adjustment, additional goodwill		$ 7
Useful life of acquired intangible assets	40 years
Pre-acquisition contingencies	$ 30
Direct transaction costs			$ 15
Operating revenues			39
Net income			4
Transaction Costs
Business Acquisition [Line Items]
Net income			$ 15
Customer relationships
Business Acquisition [Line Items]
Customer relationship intangibles	$ 770
Useful life of acquired intangible assets	10 years
West Virginia
Business Acquisition [Line Items]
Percentage of voting interests acquired	55.00%			55.00%
M3 Midstream | Pennsylvania and West Virginia
Business Acquisition [Line Items]
Percentage of voting interests acquired	100.00%
M3 Midstream | West Virginia
Business Acquisition [Line Items]
Percentage of voting interests acquired	40.00%
Vega Energy Partners | West Virginia
Business Acquisition [Line Items]
Percentage of voting interests acquired	15.00%

Acquisitions and Exit Activit67

Acquisitions and Exit Activities (Schedule of Purchase Price Allocation) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2015
Assets
Goodwill	$ 2,293	$ 2,286		$ 2,018
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

Acquisitions and Exit Activit68

Acquisitions and Exit Activities (Exit Activities) (Details) - Facility Closing $ in Millions	Dec. 17, 2015USD ($)employee	Dec. 31, 2017USD ($)	Dec. 31, 2015USD ($)
Restructuring Cost and Reserve [Line Items]
Pre-tax non-cash impairment charge	$ 111		$ 111
Charge to fully impair long-lived assets	$ 96
Number of employees related to workforce reduction | employee	170
Severance expense	$ 3
Other expenses, including write downs of inventory	$ 12
Accrual related to exit activities		$ 1
Expected future cash payments on exit activities		$ 4

Acquisitions and Exit Activit69

Acquisitions and Exit Activities (Restructuring and Related Costs) (Details) - Facility Closing - USD ($) $ in Millions	Dec. 17, 2015	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Total exit activity charges	$ 111	$ 111
Fuel, purchased power, and gas — non-utility
Restructuring Cost and Reserve [Line Items]
Total exit activity charges		5
Operation and maintenance
Restructuring Cost and Reserve [Line Items]
Total exit activity charges		10
Asset (gains) losses and impairments, net
Restructuring Cost and Reserve [Line Items]
Total exit activity charges		$ 96

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Goodwill [Roll Forward]
Balance as of January 1	$ 2,286	$ 2,018
Goodwill attributable to Gas Storage and Pipelines acquisition	7	268
Balance at December 31	$ 2,293	$ 2,286

Property, Plant, and Equipmen71

Property, Plant, and Equipment (Summary of Property by Classification) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	$ 31,424	$ 30,029
Accumulated depreciation and amortization	(10,703)	(10,299)
Net property, plant, and equipment	20,721	19,730
Non-utility and other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	3,278	3,125
Accumulated depreciation and amortization	(938)	(858)
DTE Electric
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	22,972	22,094
Accumulated depreciation and amortization	(7,984)	(7,721)
Net property, plant, and equipment	14,988	14,373
DTE Electric | Generation
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	12,166	11,990
Accumulated depreciation and amortization	(4,403)	(4,364)
DTE Electric | Distribution
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	8,637	8,134
Accumulated depreciation and amortization	(2,914)	(2,769)
DTE Electric | Other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	2,169	1,970
Accumulated depreciation and amortization	(667)	(588)
DTE Gas
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	5,174	4,810
Accumulated depreciation and amortization	(1,781)	(1,720)
DTE Gas | Distribution
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	3,523	3,382
Accumulated depreciation and amortization	(1,238)	(1,198)
DTE Gas | Storage
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	533	503
Accumulated depreciation and amortization	(159)	(152)
DTE Gas | Transmission and other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	1,118	925
Accumulated depreciation and amortization	$ (384)	$ (370)

Property, Plant, and Equipmen72

Property, Plant, and Equipment (Schedule of Interest Costs Capitalized) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Property, Plant, and Equipment [Line Items]
Allowance for debt funds used during construction and interest capitalized	$ 13	$ 10
Allowance for equity funds used during construction	23	21
Total	36	31
DTE Electric
Property, Plant, and Equipment [Line Items]
Allowance for debt funds used during construction and interest capitalized	8	8
Allowance for equity funds used during construction	18	18
Total	$ 26	$ 26

Property, Plant, and Equipmen73

Property, Plant, and Equipment (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Minimum | Non-utility
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	3 years
Minimum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	3 years
Maximum | Non-utility
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	83 years
Maximum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	15 years
DTE Electric | Minimum | Other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	4 years
DTE Electric | Minimum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	4 years
DTE Electric | Maximum | Other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	62 years
DTE Electric | Maximum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	15 years
DTE Gas | Minimum | Transmission and other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	5 years
DTE Gas | Maximum | Transmission and other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	70 years
DTE Electric
Public Utility Property, Plant, and Equipment [Line Items]
Composite depreciation rate for plants in service	3.60%	3.50%	3.50%
DTE Gas
Public Utility Property, Plant, and Equipment [Line Items]
Composite depreciation rate for plants in service	2.70%	2.40%	2.60%

Property, Plant, and Equipmen74

Property, Plant, and Equipment (Average Estimated Useful Life of Each Major Class) (Details)	12 Months Ended
	Dec. 31, 2017
DTE Electric
Public Utility Property, Plant, and Equipment [Line Items]
Useful Life - Generation	40 years
Useful Life - Distribution	41 years
DTE Gas
Public Utility Property, Plant, and Equipment [Line Items]
Useful Life - Distribution	50 years
Useful Life - Storage	53 years

Property, Plant, and Equipmen75

Property, Plant, and Equipment (Depreciation and Amortization) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	$ 865	$ 783	$ 740
Regulatory assets and liabilities	165	193	150
Securitized regulatory assets	0	0	(38)
Depreciation and amortization	1,030	976	852
DTE Electric
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	620	582	545
Regulatory assets and liabilities	133	168	126
Securitized regulatory assets	0	0	(38)
Depreciation and amortization	$ 753	$ 750	$ 633

Property, Plant, and Equipmen76

Property, Plant, and Equipment (Capitalized Software) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Property, Plant, and Equipment [Line Items]
Amortization expense of capitalized software	$ 101	$ 89	$ 98
Gross carrying value of capitalized software	890	715
Accumulated amortization of capitalized software	500	435
DTE Electric
Property, Plant, and Equipment [Line Items]
Amortization expense of capitalized software	93	83	$ 80
Gross carrying value of capitalized software	774	610
Accumulated amortization of capitalized software	$ 423	$ 365

Property, Plant, and Equipmen77

Property, Plant, and Equipment (Capital Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Capital Leased Assets [Line Items]
Gross property under capital leases	$ 44	$ 44
Accumulated amortization of property under capital leases	38	32
DTE Electric
Capital Leased Assets [Line Items]
Gross property under capital leases	18	18
Accumulated amortization of property under capital leases	$ 12	$ 6

Jointly-Owned Utility Plant (De

Jointly-Owned Utility Plant (Details)	Dec. 31, 2017plant
Jointly-Owned Utility Plant Interests [Line Items]
Number of power plants owned	2
Belle River Unit 1
Jointly-Owned Utility Plant Interests [Line Items]
Percent of the total capacity and energy of the plant	19.00%
Ludington Hydroelectric Pumped Storage
Jointly-Owned Utility Plant Interests [Line Items]
Percent of the total capacity and energy of the plant	51.00%

Jointly-Owned Utility Plant (Ow

Jointly-Owned Utility Plant (Ownership Information) (Details) $ in Millions	Dec. 31, 2017USD ($)MW
Belle River facilities used jointly by Belle River and St. Clair Power plants
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	81.00%
Belle River
Jointly-Owned Utility Plant Interests [Line Items]
Total plant capacity | MW	1,270
Investment in Property, plant, and equipment (in millions)	$ 1,814
Accumulated depreciation (in millions)	$ 1,060
Belle River Unit 1
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	63.00%
Belle River Unit 2
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	75.00%
Ludington Hydroelectric Pumped Storage
Jointly-Owned Utility Plant Interests [Line Items]
Total plant capacity | MW	2,080
Ownership interest	49.00%
Investment in Property, plant, and equipment (in millions)	$ 559
Accumulated depreciation (in millions)	$ 188

Asset Retirement Obligations (R

Asset Retirement Obligations (Rollforward) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at December 31, 2016	$ 2,197
Accretion	131
Liabilities incurred	2
Liabilities settled	(6)
Revision in estimated cash flows	(4)
Asset retirement obligations at December 31, 2017	2,320
DTE Electric
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at December 31, 2016	2,012
Accretion	120
Liabilities incurred	1
Liabilities settled	(2)
Revision in estimated cash flows	(6)
Asset retirement obligations at December 31, 2017	$ 2,125

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - Fermi 2	Dec. 31, 2017USD ($)
Asset Retirement Obligations [Line Items]
Nuclear decommissioning liabilities funded through surcharge and included in ARO balance	$ 1,900,000,000
Liabilities balance upon completion of decommissioning	$ 0

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Regulatory Assets [Line Items]
Regulatory assets	$ 3,778	$ 3,913
Less amount included in Current Assets	(55)	(42)
Regulatory assets, noncurrent	3,723	3,871
Pension
Regulatory Assets [Line Items]
Regulatory assets	2,000	2,159
Other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets	278	286
Asset retirement obligation
Regulatory Assets [Line Items]
Regulatory assets	569	613
Removal costs asset
Regulatory Assets [Line Items]
Regulatory assets	299	193
Recoverable Michigan income taxes
Regulatory Assets [Line Items]
Regulatory assets	213	231
Deferred environmental costs
Regulatory Assets [Line Items]
Regulatory assets	75	78
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	65	59
Transitional Reconciliation Mechanism
Regulatory Assets [Line Items]
Regulatory assets	46	30
Customer360 deferred costs
Regulatory Assets [Line Items]
Regulatory assets	45	33
Recoverable income taxes related to AFUDC equity
Regulatory Assets [Line Items]
Regulatory assets	41	59
Other recoverable income taxes
Regulatory Assets [Line Items]
Regulatory assets	26	57
Nuclear Performance Evaluation and Review Committee Tracker
Regulatory Assets [Line Items]
Regulatory assets	22	0
Accrued PSCR/GCR revenue
Regulatory Assets [Line Items]
Regulatory assets	17	22
Other
Regulatory Assets [Line Items]
Regulatory assets	82	93
DTE Electric
Regulatory Assets [Line Items]
Regulatory assets	3,055	3,149
Less amount included in Current Assets	(50)	(36)
Regulatory assets, noncurrent	3,005	3,113
DTE Electric | Pension
Regulatory Assets [Line Items]
Regulatory assets	1,502	1,642
DTE Electric | Other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets	211	207
DTE Electric | Asset retirement obligation
Regulatory Assets [Line Items]
Regulatory assets	569	613
DTE Electric | Removal costs asset
Regulatory Assets [Line Items]
Regulatory assets	299	193
DTE Electric | Recoverable Michigan income taxes
Regulatory Assets [Line Items]
Regulatory assets	171	187
DTE Electric | Deferred environmental costs
Regulatory Assets [Line Items]
Regulatory assets	0	0
DTE Electric | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	46	39
DTE Electric | Transitional Reconciliation Mechanism
Regulatory Assets [Line Items]
Regulatory assets	46	30
DTE Electric | Customer360 deferred costs
Regulatory Assets [Line Items]
Regulatory assets	45	33
DTE Electric | Recoverable income taxes related to AFUDC equity
Regulatory Assets [Line Items]
Regulatory assets	35	53
DTE Electric | Other recoverable income taxes
Regulatory Assets [Line Items]
Regulatory assets	26	57
DTE Electric | Nuclear Performance Evaluation and Review Committee Tracker
Regulatory Assets [Line Items]
Regulatory assets	22	0
DTE Electric | Accrued PSCR/GCR revenue
Regulatory Assets [Line Items]
Regulatory assets	17	19
DTE Electric | Other
Regulatory Assets [Line Items]
Regulatory assets	$ 66	$ 76

Regulatory Matters Regulatory M

Regulatory Matters Regulatory Matters (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 2,893	$ 589
Less amount included in Current Liabilities	(18)	(34)
Regulatory liabilities, noncurrent	2,875	555
Refundable federal income taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	2,384	0
Removal costs liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	265	266
Renewable energy
Regulatory Liabilities [Line Items]
Regulatory liabilities	112	145
Negative other postretirement offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	80	56
Negative pension offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	21	36
Fermi 2 refueling outage
Regulatory Liabilities [Line Items]
Regulatory liabilities	15	27
Refundable self-implemented rates
Regulatory Liabilities [Line Items]
Regulatory liabilities	2	27
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	14	32
DTE Electric
Regulatory Liabilities [Line Items]
Regulatory liabilities	2,154	256
Less amount included in Current Liabilities	(17)	(27)
Regulatory liabilities, noncurrent	2,137	229
DTE Electric | Refundable federal income taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	1,946	0
DTE Electric | Removal costs liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	0
DTE Electric | Renewable energy
Regulatory Liabilities [Line Items]
Regulatory liabilities	112	145
DTE Electric | Negative other postretirement offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	67	55
DTE Electric | Negative pension offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	0
DTE Electric | Fermi 2 refueling outage
Regulatory Liabilities [Line Items]
Regulatory liabilities	15	27
DTE Electric | Refundable self-implemented rates
Regulatory Liabilities [Line Items]
Regulatory liabilities	2	27
DTE Electric | Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 12	$ 2

Regulatory Matters (Details)

Regulatory Matters (Details) $ in Millions	Nov. 22, 2017USD ($)	Sep. 08, 2017USD ($)	Jul. 12, 2017USD ($)	Apr. 19, 2017USD ($)	Jan. 31, 2017USD ($)	Aug. 01, 2016USD ($)	Feb. 01, 2016USD ($)	Dec. 31, 2017USD ($)	Dec. 31, 2017	Jul. 31, 2017USD ($)certificateMW	Mar. 31, 2016USD ($)
Regulatory Assets [Line Items]
Deferral of investigation and remediation of costs associated with gas utilities former MGP sites									10 years
DTE Electric | MPSC
Regulatory Assets [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 | MW										1,100
Number of certificates of necessity requested to be issued | certificate										3
Estimated capital costs										$ 989
DTE Electric | MPSC | Electric Rate Case Filing 2016
Regulatory Assets [Line Items]
Requested rate increase							$ 344
Self-implemented base rate increase						$ 245
Approved annual revenue increase					$ 184
Return on equity, percent					10.10%
DTE Electric | MPSC | Electric Rate Case Filing 2017
Regulatory Assets [Line Items]
Requested rate increase		$ 125		$ 231
Return on equity, percent				10.10%
Return on equity, requested percent				10.50%
DTE Gas | MPSC | DTE Gas Rate Case Filing 2017
Regulatory Assets [Line Items]
Requested rate increase	$ 85.1
Return on equity, percent	10.10%
Return on equity, requested percent	10.50%
Refundable Self-Implemented Rates | DTE Electric | MPSC | Electric Rate Case Filing 2016
Regulatory Assets [Line Items]
Authorized amount to be refunded to customers								$ 38.5
Customer360 deferred costs
Regulatory Assets [Line Items]
Approved amortization period									15 years
Nuclear Performance Evaluation and Review Committee Tracker
Regulatory Assets [Line Items]
Approved amortization period									5 years

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Entity Information [Line Items]
Deferred tax asset, general business tax credit carryforwards	$ 640
Deferred tax asset, alternative minimum tax credit carryforwards	$ 307
Tax credit carry forwards refundable period	4 years
State and local net operating loss carry-forwards	$ 70	$ 59
Valuation allowance	$ 40	$ 36
Statutory rate	35.00%	35.00%	35.00%
Adjustment to deferred tax liabilities related to Tax Cuts and Jobs Act of 2017	$ 2,560
Unrecognized tax benefits that would impact effective tax rate	8	$ 8
Interest on income taxes accrued	3	3
Interest on income taxes expense	0	2	$ 0
Federal
Entity Information [Line Items]
Operating loss carryforward	397
DTE Electric
Entity Information [Line Items]
Income tax receivable from related party	12	9
State and local net operating loss carry-forwards	5	1
Valuation allowance	$ 0	$ 0
Statutory rate	35.00%	35.00%	35.00%
Unrecognized tax benefits that would impact effective tax rate	$ 10	$ 10
Interest on income taxes accrued	4	4
Interest on income taxes expense	0	$ 3	$ 0
DTE Electric | General Business Credits
Entity Information [Line Items]
Tax credit carry-forward	193
DTE Electric | Federal
Entity Information [Line Items]
Operating loss carryforward	226
Refundable federal income taxes
Entity Information [Line Items]
Adjustment to deferred tax liabilities related to Tax Cuts and Jobs Act of 2017	2,450
Unregulated Operation
Entity Information [Line Items]
Adjustment to deferred tax liabilities related to Tax Cuts and Jobs Act of 2017	$ 105

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Income Tax Expense to the Statutory Federal Income Tax Rate) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Entity Information [Line Items]
Statutory rate		35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Before Income Taxes		$ 1,287	$ 1,105	$ 950
Income tax expense at 35% statutory rate		450	387	333
Production tax credits		(189)	(145)	(122)
Investment tax credits		(4)	(5)	(7)
Depreciation		(4)	(4)	(4)
Noncontrolling interests		8	12	2
AFUDC equity		(18)	(10)	(8)
Employee Stock Ownership Plan dividends		(5)	(5)	(5)
Stock based compensation		(14)	0	0
Subsidiary stock loss		0	(10)	0
State and local income taxes, net of federal benefit		51	58	35
Enactment of the Tax Cuts and Jobs Act	$ (105)	(105)	0	0
Other, net		5	(7)	6
Income Tax Expense		$ 175	$ 271	$ 230
Effective income tax rate		13.60%	24.50%	24.20%
DTE Electric
Entity Information [Line Items]
Statutory rate		35.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Before Income Taxes		$ 928	$ 975	$ 836
Income tax expense at 35% statutory rate		325	341	293
Production tax credits		(36)	(30)	(31)
Investment tax credits		(4)	(4)	(5)
Depreciation		3	3	3
AFUDC equity		(5)	(6)	(7)
Employee Stock Ownership Plan dividends		(3)	(3)	(3)
State and local income taxes, net of federal benefit		48	56	43
Other, net		(1)	(4)	(1)
Income Tax Expense		$ 327	$ 353	$ 292
Effective income tax rate		35.20%	36.20%	34.90%

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current income tax expense (benefit)
Federal	$ (22)	$ (1)	$ (3)
State and other income tax	1	7	(4)
Total current income taxes	(21)	6	(7)
Deferred income tax expense
Federal	118	184	178
State and other income tax	78	81	59
Total deferred income taxes	196	265	237
Total	175	271	230
DTE Electric
Current income tax expense (benefit)
Federal	(17)	0	(26)
State and other income tax	(1)	11	(2)
Total current income taxes	(18)	11	(28)
Deferred income tax expense
Federal	270	268	252
State and other income tax	75	74	68
Total deferred income taxes	345	342	320
Total	$ 327	$ 353	$ 292

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets (Liabilities)) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Components of Deferred Tax Assets and Liabilities [Abstract]
Property, plant, and equipment	$ (3,276)	$ (4,880)
Regulatory assets and liabilities	(94)	(879)
Tax credit carry-forwards	947	643
Pension and benefits	334	643
Federal net operating loss carry-forward	83	190
State and local net operating loss carry-forwards	70	59
Investments in equity method investees	(82)	(119)
Other	170	217
Deferred tax liabilities, gross	(1,848)	(4,126)
Less valuation allowance	(40)	(36)
Deferred income tax liabilities	(1,888)	(4,162)
Deferred income tax assets	1,814	1,463
Deferred income tax liabilities	(3,702)	(5,625)
DTE Electric
Components of Deferred Tax Assets and Liabilities [Abstract]
Property, plant, and equipment	(2,698)	(3,819)
Regulatory assets and liabilities	(31)	(778)
Tax credit carry-forwards	193	116
Pension and benefits	302	518
Federal net operating loss carry-forward	47	42
State and local net operating loss carry-forwards	5	1
Investments in equity method investees	0	0
Other	94	127
Deferred tax liabilities, gross	(2,088)	(3,793)
Less valuation allowance	0	0
Deferred income tax liabilities	(2,088)	(3,793)
Deferred income tax assets	830	569
Deferred income tax liabilities	$ (2,918)	$ (4,362)

Income Taxes (Reconciliation 89

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	$ 10	$ 3	$ 9
Additions for tax positions of prior years	0	7	0
Lapse of statute of limitations	0	0	(6)
Unrecognized tax benefits, ending balance	10	10	3
DTE Electric
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	13	4	4
Additions for tax positions of prior years	0	9	0
Unrecognized tax benefits, ending balance	$ 13	$ 13	$ 4

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Basic Earnings per Share
Net Income Attributable to DTE Energy Company	$ 287	$ 270	$ 177	$ 400	$ 131	$ 338	$ 152	$ 247	$ 1,134	$ 868	$ 727
Less: Allocation of earnings to net restricted stock awards									(2)	(2)	(2)
Net income available to common shareholders — basic									$ 1,132	$ 866	$ 725
Average number of common shares outstanding (in shares)									179	179	179
Basic Earnings per Common Share (in dollars per share)	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 0.73	$ 1.88	$ 0.84	$ 1.38	$ 6.32	$ 4.84	$ 4.05
Diluted Earnings per Share
Net Income Attributable to DTE Energy Company	$ 287	$ 270	$ 177	$ 400	$ 131	$ 338	$ 152	$ 247	$ 1,134	$ 868	$ 727
Less: Allocation of earnings to net restricted stock awards									(2)	(2)	(2)
Net income available to common shareholders — diluted									$ 1,132	$ 866	$ 725
Average number of common shares outstanding (in shares)									179	179	179
Diluted Earnings per Common Share (in dollars per share)	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 0.73	$ 1.88	$ 0.84	$ 1.37	$ 6.32	$ 4.83	$ 4.05
Incremental common shares attributable to dilutive effect of equity units (in shares)									6	7.1

Fair Value (Assets and Liabilit

Fair Value (Assets and Liabilities Recorded at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivative assets
Derivative assets, gross	$ 652	$ 549
Derivative assets, netting	(498)	(468)
Derivative assets, net	154	81
LIABILITIES
Derivative liabilities, gross	(657)	(656)
Derivative liabilities, netting	511	489
Derivative liabilities, net	(146)	(167)
Current liabilities
LIABILITIES
Derivative liabilities, gross	(558)	(493)
Noncurrent liabilities
LIABILITIES
Derivative liabilities, gross	(99)	(163)
Natural Gas
Derivative assets
Derivative assets, gross	357	348
Derivative assets, netting	(256)	(306)
Derivative assets, net	101	42
LIABILITIES
Derivative liabilities, gross	(378)	(461)
Derivative liabilities, netting	263	321
Derivative liabilities, net	(115)	(140)
Electricity
Derivative assets
Derivative assets, gross	285	193
Derivative assets, netting	(241)	(157)
Derivative assets, net	44	36
LIABILITIES
Derivative liabilities, gross	(275)	(189)
Derivative liabilities, netting	246	163
Derivative liabilities, net	(29)	(26)
Other
Derivative assets
Derivative assets, gross	9	2
Derivative assets, netting	0	0
Derivative assets, net	9	2
LIABILITIES
Derivative liabilities, gross	(1)	(3)
Derivative liabilities, netting	1	2
Derivative liabilities, net	0	(1)
Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	1	6
Derivative assets, netting	(1)	(5)
Derivative assets, net	0	1
LIABILITIES
Derivative liabilities, gross	(3)	(3)
Derivative liabilities, netting	1	3
Derivative liabilities, net	(2)	0
Recurring
ASSETS
Cash and cash equivalents	19	17
Derivative assets
Derivative assets, netting	(498)	(468)
Derivative assets, net	154	81
Total assets	1,859	1,583
Private equity securities	5
LIABILITIES
Derivative liabilities, netting	511	489
Derivative liabilities, net	(146)	(167)
Net Assets (Liabilities) at end of period	1,713	1,416
Net Assets (Liabilities) at the end of the period, netting	13	21
Recurring | DTE Electric
ASSETS
Cash and cash equivalents	11	11
Derivative assets
Total assets	1,523	1,342
Private equity securities	5
Recurring | Current asset
Derivative assets
Derivative assets, netting	(437)	(400)
Total assets	122	64
Recurring | Current asset | DTE Electric
Derivative assets
Total assets	20	13
Recurring | Noncurrent asset
Derivative assets
Derivative assets, netting	(61)	(68)
Total assets	1,737	1,519
Private equity securities	5
Recurring | Noncurrent asset | DTE Electric
Derivative assets
Total assets	1,503	1,329
Private equity securities	5
Recurring | Current liabilities
LIABILITIES
Derivative liabilities, netting	459	424
Derivative liabilities, net	(99)	(69)
Recurring | Noncurrent liabilities
LIABILITIES
Derivative liabilities, netting	52	65
Derivative liabilities, net	(47)	(98)
Recurring | Restricted assets
ASSETS
Cash and cash equivalents	8	7
Recurring | Other
ASSETS
Cash and cash equivalents	11	10
Recurring | Other | DTE Electric
ASSETS
Cash and cash equivalents	11	11
Recurring | Natural Gas
Derivative assets
Derivative assets, netting	(256)	(306)
Derivative assets, net	101	42
LIABILITIES
Derivative liabilities, netting	263	321
Derivative liabilities, net	(115)	(140)
Recurring | Electricity
Derivative assets
Derivative assets, netting	(241)	(157)
Derivative assets, net	44	36
LIABILITIES
Derivative liabilities, netting	246	163
Derivative liabilities, net	(29)	(26)
Recurring | Other
Derivative assets
Derivative assets, netting	0	0
Derivative assets, net	9	2
LIABILITIES
Derivative liabilities, netting	1	2
Derivative liabilities, net	0	(1)
Recurring | Foreign currency exchange contracts
Derivative assets
Derivative assets, netting	(1)	(5)
Derivative assets, net	0	1
LIABILITIES
Derivative liabilities, netting	1	3
Derivative liabilities, net	(2)	0
Recurring | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	9	2
Recurring | Cash equivalents
ASSETS
Nuclear decommissioning trusts	14	8
Other investments	4	3
Recurring | Cash equivalents | DTE Electric
ASSETS
Nuclear decommissioning trusts	14	8
Recurring | Private equity securities
ASSETS
Nuclear decommissioning trusts	5	0
Derivative assets
Private equity securities	5
Recurring | Private equity securities | DTE Electric
ASSETS
Nuclear decommissioning trusts	5	0
Derivative assets
Private equity securities	5
Recurring | Equity securities
ASSETS
Nuclear decommissioning trusts	978	887
Other investments	118	104
Recurring | Equity securities | DTE Electric
ASSETS
Nuclear decommissioning trusts	978	887
Other investments	11	9
Recurring | Fixed Income Securities
ASSETS
Nuclear decommissioning trusts	495	425
Other investments	72	58
Recurring | Fixed Income Securities | DTE Electric
ASSETS
Nuclear decommissioning trusts	495	425
Recurring | Level 1
ASSETS
Cash and cash equivalents	16	14
Derivative assets
Derivative assets, gross	148	216
Total assets	1,368	1,301
LIABILITIES
Derivative liabilities, gross	(141)	(226)
Net Assets (Liabilities) at end of period	1,227	1,075
Recurring | Level 1 | DTE Electric
ASSETS
Cash and cash equivalents	8	8
Derivative assets
Total assets	1,029	923
Recurring | Level 1 | Current asset
Derivative assets
Total assets	157	205
Recurring | Level 1 | Current asset | DTE Electric
Derivative assets
Total assets	8	8
Recurring | Level 1 | Noncurrent asset
Derivative assets
Total assets	1,211	1,096
Recurring | Level 1 | Noncurrent asset | DTE Electric
Derivative assets
Total assets	1,021	915
Recurring | Level 1 | Current liabilities
LIABILITIES
Derivative liabilities, gross	(137)	(203)
Recurring | Level 1 | Noncurrent liabilities
LIABILITIES
Derivative liabilities, gross	(4)	(23)
Recurring | Level 1 | Natural Gas
Derivative assets
Derivative assets, gross	148	216
LIABILITIES
Derivative liabilities, gross	(141)	(226)
Recurring | Level 1 | Electricity
Derivative assets
Derivative assets, gross	0	0
LIABILITIES
Derivative liabilities, gross	0	0
Recurring | Level 1 | Other
Derivative assets
Derivative assets, gross	0	0
LIABILITIES
Derivative liabilities, gross	0	0
Recurring | Level 1 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
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	14	8
Other investments	4	3
Recurring | Level 1 | Cash equivalents | DTE Electric
ASSETS
Nuclear decommissioning trusts	14	8
Recurring | Level 1 | Private equity securities
ASSETS
Nuclear decommissioning trusts	0	0
Recurring | Level 1 | Private equity securities | DTE Electric
ASSETS
Nuclear decommissioning trusts	0	0
Recurring | Level 1 | Equity securities
ASSETS
Nuclear decommissioning trusts	978	887
Other investments	118	104
Recurring | Level 1 | Equity securities | DTE Electric
ASSETS
Nuclear decommissioning trusts	978	887
Other investments	11	9
Recurring | Level 1 | Fixed Income Securities
ASSETS
Nuclear decommissioning trusts	18	11
Other investments	72	58
Recurring | Level 1 | Fixed Income Securities | DTE Electric
ASSETS
Nuclear decommissioning trusts	18	11
Recurring | Level 2
ASSETS
Cash and cash equivalents	3	3
Derivative assets
Derivative assets, gross	356	239
Total assets	836	656
LIABILITIES
Derivative liabilities, gross	(359)	(248)
Net Assets (Liabilities) at end of period	477	408
Recurring | Level 2 | DTE Electric
ASSETS
Cash and cash equivalents	3	3
Derivative assets
Total assets	480	417
Recurring | Level 2 | Current asset
Derivative assets
Total assets	298	199
Recurring | Level 2 | Current asset | DTE Electric
Derivative assets
Total assets	3	3
Recurring | Level 2 | Noncurrent asset
Derivative assets
Total assets	538	457
Recurring | Level 2 | Noncurrent asset | DTE Electric
Derivative assets
Total assets	477	414
Recurring | Level 2 | Current liabilities
LIABILITIES
Derivative liabilities, gross	(313)	(211)
Recurring | Level 2 | Noncurrent liabilities
LIABILITIES
Derivative liabilities, gross	(46)	(37)
Recurring | Level 2 | Natural Gas
Derivative assets
Derivative assets, gross	112	79
LIABILITIES
Derivative liabilities, gross	(111)	(86)
Recurring | Level 2 | Electricity
Derivative assets
Derivative assets, gross	243	154
LIABILITIES
Derivative liabilities, gross	(245)	(159)
Recurring | Level 2 | Other
Derivative assets
Derivative assets, gross	0	0
LIABILITIES
Derivative liabilities, gross	0	0
Recurring | Level 2 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	1	6
LIABILITIES
Derivative liabilities, gross	(3)	(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 | Private equity securities
ASSETS
Nuclear decommissioning trusts	0	0
Recurring | Level 2 | Private equity securities | 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	477	414
Other investments	0	0
Recurring | Level 2 | Fixed Income Securities | DTE Electric
ASSETS
Nuclear decommissioning trusts	477	414
Recurring | Level 3
ASSETS
Cash and cash equivalents	0	0
Derivative assets
Derivative assets, gross	148	94
Total assets	148	94
LIABILITIES
Derivative liabilities, gross	(157)	(182)
Net Assets (Liabilities) at end of period	(9)	(88)
Recurring | Level 3 | DTE Electric
ASSETS
Cash and cash equivalents	0	0
Derivative assets
Total assets	9	2
Recurring | Level 3 | Current asset
Derivative assets
Total assets	104	60
Recurring | Level 3 | Current asset | DTE Electric
Derivative assets
Total assets	9	2
Recurring | Level 3 | Noncurrent asset
Derivative assets
Total assets	44	34
Recurring | Level 3 | Noncurrent asset | DTE Electric
Derivative assets
Total assets	0	0
Recurring | Level 3 | Current liabilities
LIABILITIES
Derivative liabilities, gross	(108)	(79)
Recurring | Level 3 | Noncurrent liabilities
LIABILITIES
Derivative liabilities, gross	(49)	(103)
Recurring | Level 3 | Natural Gas
Derivative assets
Derivative assets, gross	97	53
LIABILITIES
Derivative liabilities, gross	(126)	(149)
Recurring | Level 3 | Electricity
Derivative assets
Derivative assets, gross	42	39
LIABILITIES
Derivative liabilities, gross	(30)	(30)
Recurring | Level 3 | Other
Derivative assets
Derivative assets, gross	9	2
LIABILITIES
Derivative liabilities, gross	(1)	(3)
Recurring | Level 3 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
LIABILITIES
Derivative liabilities, gross	0	0
Recurring | Level 3 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	9	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 | Private equity securities
ASSETS
Nuclear decommissioning trusts	0	0
Recurring | Level 3 | Private equity securities | 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	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	$ (88)	$ (4)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses)
Included in earnings	82	(160)
Recorded in Regulatory liabilities	25	6
Purchases, issuances, and settlements:
Purchases	0	1
Settlements	(28)	69
Net Assets (Liabilities) as of December 31	(9)	(88)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	21	(157)
Natural Gas
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	(96)	(5)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses)
Included in earnings	(29)	(159)
Recorded in Regulatory liabilities	0	0
Purchases, issuances, and settlements:
Purchases	0	0
Settlements	96	68
Net Assets (Liabilities) as of December 31	(29)	(96)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	(30)	(166)
Electricity
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	9	6
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses)
Included in earnings	109	(2)
Recorded in Regulatory liabilities	0	0
Purchases, issuances, and settlements:
Purchases	0	1
Settlements	(106)	4
Net Assets (Liabilities) as of December 31	12	9
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	50	7
Other
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	(1)	(5)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses)
Included in earnings	2	1
Recorded in Regulatory liabilities	25	6
Purchases, issuances, and settlements:
Purchases	0	0
Settlements	(18)	(3)
Net Assets (Liabilities) as of December 31	8	(1)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	2
DTE Electric
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	2	3
Total gains (losses)
Recorded in Regulatory liabilities	25	6
Purchases, issuances, and settlements:
Settlements	(18)	(7)
Net Assets (Liabilities) as of December 31	9	2
The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2017 and 2016 and reflected in DTE Electric's Consolidated Statements of Financial Position	$ 9	$ 2

Fair Value (Unobservable Inputs

Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)$ / MMBTU$ / MWh	Dec. 31, 2016USD ($)$ / MMBTU$ / MWh
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 652	$ 549
Derivative Liabilities	(657)	(656)
Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	357	348
Derivative Liabilities	(378)	(461)
Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	285	193
Derivative Liabilities	$ (275)	$ (189)
Level 3 | Discounted Cash Flow | Natural Gas | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(1.10)	(1)
Level 3 | Discounted Cash Flow | Natural Gas | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	9.75	7.90
Level 3 | Discounted Cash Flow | Natural Gas | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(0.03)	(0.05)
Level 3 | Discounted Cash Flow | Electricity | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(5)	(6)
Level 3 | Discounted Cash Flow | Electricity | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	15	12
Level 3 | Discounted Cash Flow | Electricity | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	2	1
Recurring | Level 3
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 148	$ 94
Derivative Liabilities	(157)	(182)
Recurring | Level 3 | Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	97	53
Derivative Liabilities	(126)	(149)
Recurring | Level 3 | Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	42	39
Derivative Liabilities	$ (30)	$ (30)

Fair Value (Fair Value of Finan

Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable(a), excluding capital leases	$ 38	$ 36
Dividends payable	158	148
Short-term borrowings	621	499
Notes payable — Other	12	17
Long-term debt	12,288	11,270
Carrying Amount | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable(a), excluding capital leases	0	5
Short-term borrowings	238	62
Notes payable — Other	2	6
Long-term debt	6,017	5,878
Carrying Amount | DTE Electric | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	116	117
Fair Value | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable(a), excluding capital leases	0	0
Dividends payable	158	148
Short-term borrowings	0	0
Notes payable — Other	0	0
Long-term debt	1,939	1,465
Fair Value | Level 1 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable(a), 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 | Affiliated entity
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(a), excluding capital leases	0	0
Dividends payable	0	0
Short-term borrowings	621	499
Notes payable — Other	0	0
Long-term debt	10,571	9,384
Fair Value | Level 2 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable(a), excluding capital leases	0	0
Short-term borrowings	238	62
Notes payable — Other	0	0
Long-term debt	6,441	6,026
Fair Value | Level 2 | DTE Electric | Affiliated entity
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(a), excluding capital leases	38	36
Dividends payable	0	0
Short-term borrowings	0	0
Notes payable — Other	12	17
Long-term debt	764	1,056
Fair Value | Level 3 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable(a), excluding capital leases	0	5
Short-term borrowings	0	0
Notes payable — Other	2	6
Long-term debt	171	264
Fair Value | Level 3 | DTE Electric | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	$ 116	$ 117

Fair Value (Fair Value of Nucle

Fair Value (Fair Value of Nuclear Decommissioning Trust Fund Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 1,492	$ 1,320
DTE Electric
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,492	1,320
DTE Electric | Nuclear decommissioning trusts
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,492	1,320
DTE Electric | Nuclear decommissioning trusts | Fermi 2
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,475	1,291
DTE Electric | Nuclear decommissioning trusts | Fermi 1
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	3	3
DTE Electric | Nuclear decommissioning trusts | Low-level radioactive waste
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 14	$ 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 trusts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items]
Realized gains	$ 83	$ 74	$ 39
Realized losses	(29)	(63)	(33)
Proceeds from sale of securities	$ 1,240	$ 1,457	$ 885

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 trusts - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Equity securities, fair value	$ 978	$ 887
Fixed income securities, fair value	495	425
Private equity securities	5	0
Cash equivalents, fair value	14	8
Fair Value	1,492	1,320
Equity securities, unrealized gain	320	222
Fixed income securities, unrealized gain	13	11
Unrealized Gains	333	233
Equity securities, unrealized loss	(32)	(46)
Fixed income securities, unrealized loss	(3)	(5)
Unrealized Losses	$ (35)	$ (51)

Fair Value (Fair Value of Fixed

Fair Value (Fair Value of Fixed Income Securities Held in Nuclear Decommissioning Trust Funds (Details) - Nuclear decommissioning trusts - Fixed Income Securities $ in Millions	Dec. 31, 2017USD ($)
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 23
Due after one through five years	102
Due after five through ten years	115
Due after ten years	255
Fixed income securities total	$ 495

Fair Value (Details)

Fair Value (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Fair Value, Option, Quantitative Disclosures [Line Items]
Gains from trading securities	$ 26,000,000	$ 15,000,000	$ 1,000,000
Accumulated net unrealized investment gain (loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available-for-sale securities reclassified out of other comprehensive income (loss)	0	0
DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Gains from trading securities	26,000,000	15,000,000	$ 1,000,000
DTE Electric | Accumulated net unrealized investment gain (loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available-for-sale securities reclassified out of other comprehensive income (loss)	$ 0	$ 0

Financial and Other Derivati100

Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 652	$ 549
Derivative Liabilities	(657)	(656)
Natural Gas
Derivatives, Fair Value [Line Items]
Derivative Assets	357	348
Derivative Liabilities	(378)	(461)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	285	193
Derivative Liabilities	(275)	(189)
Other
Derivatives, Fair Value [Line Items]
Derivative Assets	9	2
Derivative Liabilities	(1)	(3)
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	1	6
Derivative Liabilities	(3)	(3)
Not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	652	549
Derivative Liabilities	(657)	(656)
Not designated as hedging instruments | Natural Gas
Derivatives, Fair Value [Line Items]
Derivative Assets	357	348
Derivative Liabilities	(378)	(461)
Not designated as hedging instruments | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	285	193
Derivative Liabilities	(275)	(189)
Not designated as hedging instruments | Other
Derivatives, Fair Value [Line Items]
Derivative Assets	9	2
Derivative Liabilities	(1)	(3)
Not designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	1	6
Derivative Liabilities	(3)	(3)
Current derivative asset
Derivatives, Fair Value [Line Items]
Derivative Assets	540	447
Noncurrent derivative asset
Derivatives, Fair Value [Line Items]
Derivative Assets	112	102
Current derivative liability
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(558)	(493)
Noncurrent derivative liability
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(99)	(163)
DTE Electric | Not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	9	2
DTE Electric | Not designated as hedging instruments | FTRs — Other current assets
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 9	$ 2

Financial and Other Derivati101

Financial and Other Derivative Instruments (Details) - USD ($)	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Letters of credit that could be used to offset net derivative liabilities	$ 4,000,000	$ 2,000,000
Letters of credit that could be used to offset net derivative assets	4,000,000	2,000,000
Cash collateral posted, net of cash collateral received	28,000,000	34,000,000
Collateral adjustment on derivative assets	9,000,000	7,000,000
Collateral adjustment on derivative liabilities	22,000,000	28,000,000
Cash collateral paid	18,000,000	18,000,000
Cash collateral received	3,000,000	$ 5,000,000
Additional collateral, aggregate fair value	456,000,000
Derivative net liability position aggregate fair value	535,000,000
Collateral already posted fair value	0
Derivative, net asset position, fair value	468,000,000
Remaining amount of offsets to derivative net liability positions for hard and soft trigger provisions	$ 67,000,000

Financial and Other Derivati102

Financial and Other Derivative Instruments (Netting Offsets of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets (Liabilities)	$ 652	$ 549
Gross Amounts Offset in the Consolidated Statements of Financial Position	(498)	(468)
Derivative assets, net	154	81
Gross Amounts of Recognized Assets (Liabilities)	(657)	(656)
Gross Amounts Offset in the Consolidated Statements of Financial Position	511	489
Derivative liabilities, net	(146)	(167)
Natural Gas
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets (Liabilities)	357	348
Gross Amounts Offset in the Consolidated Statements of Financial Position	(256)	(306)
Derivative assets, net	101	42
Gross Amounts of Recognized Assets (Liabilities)	(378)	(461)
Gross Amounts Offset in the Consolidated Statements of Financial Position	263	321
Derivative liabilities, net	(115)	(140)
Electricity
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets (Liabilities)	285	193
Gross Amounts Offset in the Consolidated Statements of Financial Position	(241)	(157)
Derivative assets, net	44	36
Gross Amounts of Recognized Assets (Liabilities)	(275)	(189)
Gross Amounts Offset in the Consolidated Statements of Financial Position	246	163
Derivative liabilities, net	(29)	(26)
Other
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets (Liabilities)	9	2
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	0
Derivative assets, net	9	2
Gross Amounts of Recognized Assets (Liabilities)	(1)	(3)
Gross Amounts Offset in the Consolidated Statements of Financial Position	1	2
Derivative liabilities, net	0	(1)
Foreign currency exchange contracts
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets (Liabilities)	1	6
Gross Amounts Offset in the Consolidated Statements of Financial Position	(1)	(5)
Derivative assets, net	0	1
Gross Amounts of Recognized Assets (Liabilities)	(3)	(3)
Gross Amounts Offset in the Consolidated Statements of Financial Position	1	3
Derivative liabilities, net	$ (2)	$ 0

Financial and Other Derivati103

Financial and Other Derivative Instruments (Netting Offsets Reconciliation to Balance Sheet) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Derivative Assets:
Derivative Assets	$ 652	$ 549
Collateral adjustment	(9)	(7)
Derivative asset, current	103	47
Derivative assets, noncurrent	51	34
Derivative Liabilities:
Derivative Liabilities	(657)	(656)
Counterparty netting	22	28
Derivative liabilities, current	(99)	(69)
Derivative liabilities, noncurrent	(47)	(98)
Current derivative asset
Derivative Assets:
Derivative Assets	540	447
Counterparty netting	(437)	(396)
Collateral adjustment	0	(4)
Derivative asset, current	103	47
Noncurrent derivative asset
Derivative Assets:
Derivative Assets	112	102
Counterparty netting	(52)	(65)
Collateral adjustment	(9)	(3)
Derivative assets, noncurrent	51	34
Current derivative liability
Derivative Liabilities:
Derivative Liabilities	(558)	(493)
Collateral adjustment	437	396
Counterparty netting	22	28
Derivative liabilities, current	(99)	(69)
Noncurrent derivative liability
Derivative Liabilities:
Derivative Liabilities	(99)	(163)
Collateral adjustment	52	65
Counterparty netting	0	0
Derivative liabilities, noncurrent	$ (47)	$ (98)

Financial and Other Derivati104

Financial and Other Derivative Instruments (Effect of Derivatives not Designated as Hedging Instruments on the Consolidated Statement of Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	$ 128	$ (109)
Natural Gas | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	(74)	(153)
Natural Gas | Fuel, purchased power, and gas — non-utility
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	97	(2)
Electricity | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	105	43
Other | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	2	5
Foreign currency exchange contracts | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31,	$ (2)	$ (2)

Financial and Other Derivati105

Financial and Other Derivative Instruments (Cumulative Gross Volume of Derivative Contracts Outstanding) (Details)	12 Months Ended
	Dec. 31, 2017CADMWhMMBTU
Natural Gas (MMBtu)
Derivative [Line Items]
Commodity | MMBTU	1,822,796,301
Electricity (MWh)
Derivative [Line Items]
Commodity | MWh	29,715,268
Foreign Currency Exchange (Canadian dollars)
Derivative [Line Items]
Foreign Currency Exchange (Canadian dollars) | CAD	CAD 108,023,948

Long-Term Debt (Long Term Debt

Long-Term Debt (Long Term Debt Outstanding and Weighted Average Interest Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Long-term debt, excluding current maturities	$ 11,039	$ 10,506
Long-term debt, total	12,407
Other long-term debt
Debt Instrument [Line Items]
Long-term debt, gross	7	92
Secured debt, unsecured debt, mortgage notes and other debt
Debt Instrument [Line Items]
Long-term debt, gross	11,227	10,592
Unamortized debt discount and premium, net	(15)	(10)
Unamortized debt issuance costs	(69)	(67)
Long-term debt due within one year	(104)	(9)
Long-term debt, excluding current maturities	$ 11,039	10,506
Junior subordinated debentures
Debt Instrument [Line Items]
Interest rate	5.50%
Long-term debt, gross	$ 1,180	780
Unamortized debt issuance costs	(35)	(24)
Long-term debt, total	1,145	756
DTE Electric
Debt Instrument [Line Items]
Long-term debt, gross	6,065	5,925
Long-term debt, excluding current maturities	6,017	5,878
Long-term debt, total	$ 6,065
DTE Electric | Secured debt
Debt Instrument [Line Items]
Interest rate	4.30%
Long-term debt, gross	$ 5,755	5,615
DTE Electric | Tax-exempt revenue bonds
Debt Instrument [Line Items]
Interest rate	4.30%
Long-term debt, gross	$ 310	310
DTE Electric | Secured debt, unsecured debt, mortgage notes and other debt
Debt Instrument [Line Items]
Unamortized debt discount and premium, net	(10)	(10)
Unamortized debt issuance costs	$ (38)	(37)
DTE Gas | Secured debt
Debt Instrument [Line Items]
Interest rate	4.80%
Long-term debt, gross	$ 1,330	1,250
DTE Energy | Unsecured debt
Debt Instrument [Line Items]
Interest rate	3.10%
Long-term debt, gross	$ 3,825	$ 3,325

Long-Term Debt (Debt Issuances)

Long-Term Debt (Debt Issuances) (Details)	12 Months Ended
	Dec. 31, 2017USD ($)
Debt Instrument [Line Items]
Amount	$ 1,420,000,000
Debt redeemed	$ 385,000,000
Junior subordinated debentures | 5.25% junior subordinated debentures due 2077
Debt Instrument [Line Items]
Interest Rate	5.25%
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%
Amount	$ 440,000,000
DTE Gas | Mortgage Bonds | September 2017 3.08% First Mortgage Bonds maturing 2029
Debt Instrument [Line Items]
Interest Rate	3.08%
Amount	$ 40,000,000
DTE Gas | Mortgage Bonds | September 2017 3.75% First Mortgage Bonds maturing 2047
Debt Instrument [Line Items]
Interest Rate	3.75%
Amount	$ 40,000,000
DTE Energy | Senior Notes | March 2017 3.80% Senior Notes due 2027
Debt Instrument [Line Items]
Interest Rate	3.80%
Amount	$ 500,000,000
DTE Energy | Junior subordinated debentures | 5.25% junior subordinated debentures due 2077
Debt Instrument [Line Items]
Interest Rate	5.25%
Amount	$ 400,000,000

Long-Term Debt (Debt Redemption

Long-Term Debt (Debt Redemptions) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Debt Instrument, Redemption [Line Items]
Amount	$ 385
DTE Energy | Secured Note | 7.29% Secured Note due 2029
Debt Instrument, Redemption [Line Items]
Interest Rate	7.29%
Amount	$ 77
DTE Energy | Other Long-Term Debt
Debt Instrument, Redemption [Line Items]
Amount	8
DTE Energy | Other Long-Term Debt | Gas Storage and Pipelines
Debt Instrument, Redemption [Line Items]
Net loss on extinguishment of debt	16
Loss related to early redemption premiums	20
Unamortized debt premiums	$ 4
DTE Electric | Senior Notes | 5.60% Senior Notes Due 2018
Debt Instrument, Redemption [Line Items]
Interest Rate	5.60%
Amount	$ 300

Long-Term Debt (Scheduled Debt

Long-Term Debt (Scheduled Debt Maturities) (Details) $ in Millions	Dec. 31, 2017USD ($)
Maturities of Long-term Debt [Abstract]
2,018	$ 104
2,019	1,497
2,020	683
2,021	462
2,022	616
2023 and Thereafter	9,045
Long-term debt, total	12,407
DTE Electric
Maturities of Long-term Debt [Abstract]
2,018	0
2,019	0
2,020	632
2,021	462
2,022	316
2023 and Thereafter	4,655
Long-term debt, total	$ 6,065

Long-Term Debt Long Term Debt (

Long-Term Debt Long Term Debt (Junior Subordinated Debt and Interest Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Junior subordinated debentures	$ 1,145	$ 756
Junior subordinated debentures
Debt Instrument [Line Items]
Junior subordinated debentures	$ 1,180
Junior subordinated debentures | 5.25% junior subordinated debentures due 2062
Debt Instrument [Line Items]
Interest Rate	5.25%
Junior subordinated debentures	$ 200
Junior subordinated debentures | May 5.375% junior subordinated debentures maturing in 2076
Debt Instrument [Line Items]
Interest Rate	5.375%
Junior subordinated debentures	$ 300
Junior subordinated debentures | 6% junior subordinated debentures maturing 2076
Debt Instrument [Line Items]
Interest Rate	6.00%
Junior subordinated debentures	$ 280
Junior subordinated debentures | 5.25% junior subordinated debentures due 2077
Debt Instrument [Line Items]
Interest Rate	5.25%
Junior subordinated debentures	$ 400

Long-Term Debt (Details)

Long-Term Debt (Details) $ / shares in Units, shares in Millions	Jan. 01, 2017$ / shares	Oct. 05, 2016USD ($)	Oct. 31, 2016USD ($)day$ / shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)	Oct. 31, 2019shares
Debt Instrument [Line Items]
Face amount				$ 1,420,000,000
Junior subordinated debentures				1,145,000,000	$ 756,000,000
Equity units, percentage interest in attached debt instrument			0.005%
Financial instruments subject to mandatory redemption, settlement terms, share value, amount					$ 98,000,000
Junior subordinated debentures
Debt Instrument [Line Items]
Junior subordinated debentures				$ 1,180,000,000
Interest rate				5.50%
5.25% junior subordinated debentures due 2062 | Junior subordinated debentures
Debt Instrument [Line Items]
Interest rate				5.25%
Junior subordinated debentures				$ 200,000,000
May 5.375% junior subordinated debentures maturing in 2076 | Junior subordinated debentures
Debt Instrument [Line Items]
Interest rate				5.375%
Junior subordinated debentures				$ 300,000,000
6% junior subordinated debentures maturing 2076 | Junior subordinated debentures
Debt Instrument [Line Items]
Interest rate				6.00%
Junior subordinated debentures				$ 280,000,000
5.25% junior subordinated debentures due 2077 | Junior subordinated debentures
Debt Instrument [Line Items]
Interest rate				5.25%
Junior subordinated debentures				$ 400,000,000
October series C 1.5% RSNs maturing 2024 | Other long-term debt
Debt Instrument [Line Items]
Interest rate		1.50%	1.50%
Face amount		$ 675,000,000	$ 675,000,000
October series D 1.50% senior notes maturing 2019 | Other long-term debt
Debt Instrument [Line Items]
Interest rate			1.50%
Face amount			$ 400,000,000
October series E 2.85% senior notes maturing 2026 | Other long-term debt
Debt Instrument [Line Items]
Interest rate			2.85%
Face amount			$ 600,000,000
Unsuccessful remarketing | October series C 1.5% RSNs maturing 2024 | Other long-term debt
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage			100.00%
Equity units subject to mandatory redemption
Debt Instrument [Line Items]
Forward contract indexed to issuer's equity, forward rate per share (in dollars per share) | $ / shares	$ 50
Financial instruments subject to mandatory redemption, contract adjustment rate	5.00%	5.00%
Financial instruments subject to mandatory redemption, contract adjustment rate, annual amount (in dollars per share) | $ / shares	$ 2.50
Financial instruments subject to mandatory redemption, settlement terms, share value, amount				$ 98,000,000
Financial instruments subject to mandatory redemption, settlement terms, maximum number of shares (in shares) | shares				9
Equity units subject to mandatory redemption | Equal to or greater than $116.31, 0.4299 shares of common stock
Debt Instrument [Line Items]
Number of consecutive scheduled trading days | day			20
Financial instruments subject to mandatory redemption, anti-dilution provision, conversion ratio			0.4299
Equity units subject to mandatory redemption | Equal to or greater than $116.31, 0.4299 shares of common stock | Minimum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share) | $ / shares			$ 116.31
Equity units subject to mandatory redemption | Less than $116.31, but greater than $93.05, number of shares of common stock equal to $50 divided by the AMV rounded to the nearest 1/10,000th of a share | Minimum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share) | $ / shares			93.05
Equity units subject to mandatory redemption | Less than $116.31, but greater than $93.05, number of shares of common stock equal to $50 divided by the AMV rounded to the nearest 1/10,000th of a share | Maximum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share) | $ / shares			$ 116.31
Equity units subject to mandatory redemption | Less than or equal to $93.05, 0.5373 shares of common stock
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, conversion ratio			0.5373
Equity units subject to mandatory redemption | Less than or equal to $93.05, 0.5373 shares of common stock | Maximum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share) | $ / shares			$ 93.05
DTE Electric | Tax-exempt revenue bonds
Debt Instrument [Line Items]
Interest rate				4.30%
Scenario, Forecast | Equity units subject to mandatory redemption | Minimum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, settlement terms, number of shares (in shares) | shares						5.8
Scenario, Forecast | Equity units subject to mandatory redemption | Maximum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, settlement terms, number of shares (in shares) | shares						7.3

Long-Term Debt (Equity Units an

Long-Term Debt (Equity Units and RSNs) (Details) - USD ($) shares in Millions	Jan. 01, 2017	Oct. 05, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Oct. 31, 2016
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Total Net Proceeds		$ 654,000,000	$ 0	$ 654,000,000	$ 0
Total Long-Term Debt			1,420,000,000
Equity units subject to mandatory redemption
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Units Issued (in shares)		13.5
Stock Purchase Contract Annual Rate	5.00%	5.00%
Stock Purchase Contract Liability(a)		$ 98,000,000	66,000,000	$ 98,000,000
Redemption of long-term debt			$ 32,000,000
October series C 1.5% RSNs maturing 2024 | Other long-term debt
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Total Long-Term Debt		$ 675,000,000				$ 675,000,000
RSN Annual Interest Rate		1.50%				1.50%

Preferred and Preference Sec113

Preferred and Preference Securities (Details)	Dec. 31, 2017$ / sharesshares
DTE Electric
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 100
Preferred stock, shares authorized (in shares) | shares	6,747,484
Preference stock, par value (in dollars per share) | $ / shares	$ 1
Preference stock shares authorized (in shares) | shares	30,000,000
DTE Gas
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 1
Preferred stock, shares authorized (in shares) | shares	7,000,000
Preference stock, par value (in dollars per share) | $ / shares	$ 1
Preference stock shares authorized (in shares) | shares	4,000,000
DTE Energy
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 0
Preferred stock, shares authorized (in shares) | shares	5,000,000

Short-Term Credit Arrangemen114

Short-Term Credit Arrangements and Borrowings (Schedule of Borrowings) (Details)	Dec. 31, 2017USD ($)
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 2,120,000,000
Amounts outstanding	745,000,000
Net availability	1,375,000,000
DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	400,000,000
Amounts outstanding	238,000,000
Net availability	162,000,000
DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	300,000,000
Amounts outstanding	300,000,000
Net availability	0
DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,420,000,000
Amounts outstanding	207,000,000
Net availability	1,213,000,000
Letters of credit
Line Of Credit Facility [Line Items]
Amounts outstanding	124,000,000
Letters of credit | DTE Electric
Line Of Credit Facility [Line Items]
Amounts outstanding	0
Letters of credit | DTE Gas
Line Of Credit Facility [Line Items]
Amounts outstanding	0
Letters of credit | DTE Energy
Line Of Credit Facility [Line Items]
Amounts outstanding	124,000,000
Letters of credit | Unsecured letter of credit facility, expiring in February 2019
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	150,000,000
Letters of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	150,000,000
Letters of credit | Unsecured letter of credit facility, expiring in September 2019
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	70,000,000
Letters of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	70,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,900,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	400,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	300,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,200,000,000
Commercial paper issuances
Line Of Credit Facility [Line Items]
Amounts outstanding	621,000,000
Commercial paper issuances | DTE Electric
Line Of Credit Facility [Line Items]
Amounts outstanding	238,000,000
Commercial paper issuances | DTE Gas
Line Of Credit Facility [Line Items]
Amounts outstanding	300,000,000
Commercial paper issuances | DTE Energy
Line Of Credit Facility [Line Items]
Amounts outstanding	$ 83,000,000

Short-Term Credit Arrangemen115

Short-Term Credit Arrangements and Borrowings (Details)	Dec. 31, 2017USD ($)	Dec. 31, 2016USD ($)
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 745,000,000
Weighted average interest rate	1.90%	0.90%
Dividend restriction	$ 1,800,000,000
Retained earnings	5,643,000,000	$ 5,114,000,000
Effective limitations	$ 0
Maximum
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.65
Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 124,000,000
DTE Electric
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.50
Other outstanding letters of credit	$ 238,000,000
Weighted average interest rate	1.50%	0.80%
Retained earnings	$ 1,956,000,000	$ 1,787,000,000
DTE Electric | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
DTE Gas
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.48
Other outstanding letters of credit	$ 300,000,000
DTE Gas | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
DTE Energy
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.54
Other outstanding letters of credit	$ 207,000,000
DTE Energy | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	124,000,000
DTE Energy | Demand financing agreement
Short-term Debt [Line Items]
Maximum borrowing capacity	100,000,000
Additional margin financing	50,000,000
Amount outstanding	56,000,000	$ 50,000,000
DTE Energy | Demand financing agreement plus letter of credit
Short-term Debt [Line Items]
Maximum borrowing capacity	100,000,000
DTE Energy | Other outstanding letters of credit | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 9,000,000

Capital and Operating Leases (F

Capital and Operating Leases (Future Minimum Lease Payments under Non-Cancelable Leases) (Details) $ in Millions	Dec. 31, 2017USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,018	$ 40
2,019	34
2,020	22
2,021	13
2,022	9
2022 and thereafter	48
Total minimum lease payments	166
DTE Electric
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,018	15
2,019	14
2,020	9
2,021	9
2,022	6
2022 and thereafter	38
Total minimum lease payments	$ 91

Capital and Operating Leases (D

Capital and Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Schedule of Lessor Capital Leases [Line Items]
Rent expense	$ 51	$ 43	$ 43
Pipeline System Lease
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	5 years
Percent ownership in pipeline	40.00%
DTE Electric
Schedule of Lessor Capital Leases [Line Items]
Rent expense	$ 28	$ 28	$ 32

Capital and Operating Leases (C

Capital and Operating Leases (Components of the Net Investment in the Capital Leases) (Details) $ in Millions	Dec. 31, 2017USD ($)
Capital Leases of Lessor [Abstract]
2,018	$ 13
2,019	10
2,020	9
2,021	0
2,022	0
2023 and thereafter	1
Total minimum future lease receipts	33
Residual value of leased pipeline	40
Less unearned income	(15)
Net investment in capital lease	58
Less current portion	(7)
Capital lease, noncurrent	$ 51

Commitments and Contingencie119

Commitments and Contingencies (Details)	12 Months Ended
	Dec. 31, 2017USD ($)employeefacilityNOVsite	Dec. 31, 2010	Dec. 31, 2016USD ($)	Sep. 07, 2016state	Jul. 31, 2009plant
Loss Contingencies [Line Items]
Sulfur dioxide ambient air quality standard finalized		1 hour
Estimated Future Capital Expenditures For Next Year	$ 3,600,000,000
Labor force concentration risk | Workforce subject to collective bargaining arrangements
Loss Contingencies [Line Items]
Approximate number of employees | employee	5,000
Synthetic fuel
Loss Contingencies [Line Items]
Number of days after expiration of statutes of limitations	90 days
Maximum potential liability	$ 620,000,000
Reduced emissions fuel guarantees
Loss Contingencies [Line Items]
Number of days after expiration of statutes of limitations	90 days
Maximum potential liability	$ 386,000,000
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	$ 55,000,000
Performance surety bonds
Loss Contingencies [Line Items]
Performance bonds outstanding	$ 58,000,000
DTE Electric
Loss Contingencies [Line Items]
Number of states with NOX emissions from power plants | state				22
Number of power plants allegedly in violation | plant					5
Number of NOVs/FOVs currently being discussed with the EPA | NOV	2
Amount spent to comply with air pollution requirements	$ 2,400,000,000
Estimated capital expenditures	$ 0
Number of former MGP sites | site	3
Accrued for remediation related to the sites	$ 6,000,000		$ 8,000,000
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
Estimated Future Capital Expenditures For Next Year	$ 1,900,000,000
DTE Electric | Labor force concentration risk | Workforce subject to collective bargaining arrangements
Loss Contingencies [Line Items]
Approximate number of employees | employee	2,700
DTE Electric | Coal combustion residual rule
Loss Contingencies [Line Items]
Estimated cost associated with building new facilities	$ 295,000,000
DTE Gas
Loss Contingencies [Line Items]
Number of former MGP sites | site	14
Accrued for remediation related to the sites	$ 41,000,000		$ 43,000,000
Amortization period for MGP costs (in years)	10 years
DTE Gas | NEXUS Pipeline
Loss Contingencies [Line Items]
Maximum potential liability	$ 80,000,000
Capacity lease agreement term	15 years
Percentage of all payment obligations due and payable	50.00%
DTE Gas | Cleanup completed and site closed
Loss Contingencies [Line Items]
Number of former MGP sites | site	6
DTE Gas | Partial closure completed
Loss Contingencies [Line Items]
Number of former MGP sites | site	6
Texas Eastern Transmission, LP | NEXUS Pipeline
Loss Contingencies [Line Items]
Maximum potential liability	$ 10,000,000
Capacity lease agreement term	15 years
Percentage of all payment obligations due and payable	50.00%

Commitments and Contingencie120

Commitments and Contingencies (Purchase Commitments) (Details) $ in Millions	Dec. 31, 2017USD ($)
Purchase Obligation, Fiscal Year Maturity [Abstract]
2,018	$ 2,731
2,019	1,045
2,020	638
2,021	474
2,022	371
2023 and thereafter	2,277
Total purchase commitments	7,536
DTE Electric
Purchase Obligation, Fiscal Year Maturity [Abstract]
2,018	930
2,019	320
2,020	192
2,021	149
2,022	88
2023 and thereafter	820
Total purchase commitments	$ 2,499

Nuclear Operations (Details)

Nuclear Operations (Details) - DTE Electric $ in Millions	May 16, 2014kWh	May 15, 2014$ / MWh	Dec. 31, 2017USD ($)
Entity Information [Line Items]
Policy waiting period			84 days
Insurance coverage for extra expense when power plant unavailable			$ 490
Period of coverage of policy for extra expenses			3 years
Primary coverage for stabilization, decontamination, debris removal, repair and/or replacement of property, and decommissioning			$ 1,500
Excess coverage for stabilization, decontamination, debris removal, repair and/or replacement of property, and decommissioning			1,250
Combined coverage limit for total property damage			2,750
Total limit for property damage for non-nuclear events			2,000
Limit of coverage for aggregate extra expenses for non-nuclear events			$ 328
Period of coverage for extra expenses			2 years
Time period for TRIA after the first loss from terrorism			1 year
NEIL policies against terrorism loss, amount made available to all insured entities (up to)			$ 3,200
Maximum assessment if loss amount exceeds funds available			47
Public liability insurance for a nuclear incident			450
One industry aggregate limit of coverage arising from terrorist act outside scope of TRIA			300
Maximum deferred premium charges that could be levied against each licensed nuclear facility			127
Limit of deferred premium charges per year per facility			$ 19
Company obligated to pay DOE fee of Fermi 2 electricity generated and sold | $ / MWh		1
New DOE fee for Fermi 2 electricity generated and sold | kWh	0

Retirement Benefits and Trus122

Retirement Benefits and Trusteed Assets (Pension Plan - Pension Cost Inclusions) (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 92	$ 92	$ 100
Interest cost	214	219	210
Expected return on plan assets	(311)	(309)	(296)
Amortization of:
Net actuarial loss	176	164	205
Prior service cost	1	1	0
Other	0	0	2
Net pension cost	$ 172	$ 167	$ 221

Retirement Benefits and Trus123

Retirement Benefits and Trusteed Assets (Pension Plan - Other Changes in Plan Assets and Benefit Obligations recognized in Reg Assets and OCI) (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial loss	$ 27	$ 197
Amortization of net actuarial loss	(176)	(164)
Prior service cost (credit)	(11)	7
Amortization of prior service cost	(1)	(1)
Total recognized in Regulatory assets and Other comprehensive income (loss)	(161)	39
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	11	206
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	178	172
Prior service cost	$ 0	$ 1

Retirement Benefits and Trus124

Retirement Benefits and Trusteed Assets (Pension Plan - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized in Regulatory assets
Regulatory assets	$ 3,778	$ 3,913
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Accumulated benefit obligation, end of year	5,149	4,753
Change in projected benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	5,171	4,971
Service cost	92	92	$ 100
Interest cost	214	219	210
Plan amendments	(11)	7
Actuarial loss	391	141
Benefits paid	(281)	(259)
Projected/Accumulated postretirement benefit obligation, end of year	5,576	5,171	4,971
Change in plan assets
Plan assets at fair value, beginning of year	4,012	3,832
Actual return on plan assets	674	253
Company contributions	231	186
Benefits paid	(281)	(259)
Plan assets at fair value, end of year	4,636	4,012	$ 3,832
Funded status	(940)	(1,159)
Amount recorded as:
Current liabilities	(16)	(7)
Noncurrent liabilities	(924)	(1,152)
Defined benefit plans liabilities	(940)	(1,159)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	163	163
Prior service cost	6	8
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	169	171
Amounts recognized in Regulatory assets
Net actuarial loss	2,014	2,163
Prior service credit	(14)	(4)
Regulatory assets	$ 2,000	$ 2,159

Retirement Benefits and Trus125

Retirement Benefits and Trusteed Assets (Pension Plan - Cash Contributions) (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	$ 231	$ 186
Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	223	179	$ 177
Qualified Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	$ 185	$ 145	$ 145

Retirement Benefits and Trus126

Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized	$ 57	$ 51	$ 49
Annual contributions per employee, percentage	4.00%
DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized	$ 27	23	23
DTE Gas
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Annual contributions per employee, percentage	8.00%
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected return on plan assets	7.50%
Company contributions	$ 231	186
Pension plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Allocated pension benefit costs	136	136	176
Pension plan | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions in next fiscal year	200
Pension plan | Maximum | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions in next fiscal year	$ 175
Other postretirement benefit plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected return on plan assets	7.75%
Company contributions	$ 0	20
Retiree health care allowance will increase at lower of the rate of medical inflation or a set percentage	2.00%
Defined benefit plan, effect of one percentage point increase on service and interest cost components	$ 5
Defined benefit plan, effect of one percentage point increase on accumulated postretirement benefit obligation	97
Defined benefit plan, effect of one percentage point decrease on service and interest cost components	4
Defined benefit plan, effect of one percentage point decrease on accumulated postretirement benefit obligation	84
Other postretirement benefit plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Company contributions	0	0
Defined benefit plan, effect of one percentage point increase on service and interest cost components	4
Defined benefit plan, effect of one percentage point increase on accumulated postretirement benefit obligation	72
Defined benefit plan, effect of one percentage point decrease on service and interest cost components	3
Defined benefit plan, effect of one percentage point decrease on accumulated postretirement benefit obligation	63
Retiree healthcare plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized	8	6	5
Retiree healthcare plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized	$ 3	$ 3	$ 3

Retirement Benefits and Trus127

Retirement Benefits and Trusteed Assets (Pension Plan - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) - Pension plan $ in Millions	Dec. 31, 2017USD ($)
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,018	$ 299
2,019	301
2,020	316
2,021	317
2,022	323
2023-2027	1,692
Total	$ 3,248

Retirement Benefits and Trus128

Retirement Benefits and Trusteed Assets (Pension Plan - Assumptions used in Determining the PBO and Net Pension Costs) (Details) - Pension plan	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Projected benefit obligation
Discount rate	3.70%	4.25%	4.50%
Rate of compensation increase	4.98%	4.65%	4.65%
Net pension costs
Discount rate	4.25%	4.50%	4.12%
Rate of compensation increase	4.65%	4.65%	4.65%
Expected long-term rate of return on plan assets	7.50%	7.75%	7.75%

Retirement Benefits and Trus129

Retirement Benefits and Trusteed Assets (Pension Plan - Target Allocations of Plan Assets) (Details) - Pension plan	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	100.00%
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	18.00%
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	5.00%
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	17.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	32.00%
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	20.00%
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	8.00%

Retirement Benefits and Trus130

Retirement Benefits and Trusteed Assets (Pension Plan - Fair Value Measurements) (Details) - Pension Plan - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 4,636	$ 4,012	$ 3,832
Assets valued at NAV	1,201	1,112
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	114	22
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	826	880
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	234	232
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	822	766
Assets valued at NAV	280	269
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,454	1,090
Assets valued at NAV	0	52
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	858	809
Assets valued at NAV	593	578
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	328	213
Assets valued at NAV	328	213
Securities lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(66)	(78)
Securities lending collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	66	78
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,845	1,815
Level 1 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	821	875
Level 1 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	229	229
Level 1 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	529	479
Level 1 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	1
Level 1 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	265	231
Level 1 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Securities lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(53)	(53)
Level 1 | Securities lending collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	53	53
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,590	1,085
Level 2 | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	114	22
Level 2 | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	5	5
Level 2 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	5	3
Level 2 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	13	18
Level 2 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,453	1,037
Level 2 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Securities lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(13)	(25)
Level 2 | Securities lending collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 13	$ 25

Retirement Benefits and Trus131

Retirement Benefits and Trusteed Assets (OPEB - Postretirement Cost Inclusions) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 27	$ 27	$ 34
Interest cost	73	80	81
Expected return on plan assets	(130)	(129)	(131)
Amortization of:
Net actuarial loss	13	30	43
Prior service cost	(14)	(118)	(126)
Other	0	(1)	0
Net pension cost	(31)	(111)	(99)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	20	25
Interest cost	56	61	62
Expected return on plan assets	(90)	(90)	(90)
Amortization of:
Net actuarial loss	8	21	31
Prior service cost	(10)	(89)	(95)
Net pension cost	$ (16)	$ (77)	$ (67)

Retirement Benefits and Trus132

Retirement Benefits and Trusteed Assets (OPEB - Other Changes in Plan Assets and APBO Recognized in Regulatory Assets and OCI) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial gain	$ (21)	$ (68)
Amortization of net actuarial loss	(13)	(30)
Prior service credit	(1)	0
Amortization of prior service credit	14	119
Total recognized in Regulatory assets and Other comprehensive income (loss)	(21)	21
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(52)	(90)
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	11	16
Prior service credit	(1)	(14)
DTE Electric
Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial gain	2	(59)
Amortization of net actuarial loss	(8)	(21)
Amortization of prior service credit	10	89
Total recognized in Regulatory assets and Other comprehensive income (loss)	4	9
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(12)	(68)
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	8	10
Prior service credit	$ 0	$ (10)

Retirement Benefits and Trus133

Retirement Benefits and Trusteed Assets (OPEB - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Amounts recognized in Regulatory assets
Regulatory assets	$ 3,778	$ 3,913
Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,795	1,846
Service cost	27	27	$ 34
Interest cost	73	80	81
Actuarial (gain) loss	101	(75)
Benefits paid	(86)	(83)
Projected/Accumulated postretirement benefit obligation, end of year	1,910	1,795	1,846
Change in plan assets
Plan assets at fair value, beginning of year	1,758	1,617
Actual return on plan assets	252	122
Company contributions	0	20
Benefits paid	(162)	(1)
Plan assets at fair value, end of year	1,848	1,758	1,617
Funded status	(62)	(37)
Amount recorded as:
Noncurrent assets	0	0
Current liabilities	(1)	(1)
Noncurrent liabilities	(61)	(36)
Defined benefit plans liabilities	(62)	(37)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	(1)	12
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	(1)	12
Amounts recognized in Regulatory assets
Net actuarial loss	279	300
Prior service credit	(1)	(14)
Regulatory assets	278	286
DTE Electric
Amounts recognized in Regulatory assets
Regulatory assets	3,055	3,149
DTE Electric | Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,373	1,414
Service cost	20	20	25
Interest cost	56	61	62
Actuarial (gain) loss	84	(62)
Benefits paid	(63)	(60)
Projected/Accumulated postretirement benefit obligation, end of year	1,470	1,373	1,414
Change in plan assets
Plan assets at fair value, beginning of year	1,218	1,131
Actual return on plan assets	172	87
Company contributions	0	0
Benefits paid	(118)	0
Plan assets at fair value, end of year	1,272	1,218	$ 1,131
Funded status	(198)	(155)
Amount recorded as:
Noncurrent assets	113	114
Current liabilities	0	0
Noncurrent liabilities	(311)	(269)
Defined benefit plans liabilities	(198)	(155)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	0	0
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	0	0
Amounts recognized in Regulatory assets
Net actuarial loss	211	217
Prior service credit	0	(10)
Regulatory assets	$ 211	$ 207

Retirement Benefits and Trus134

Retirement Benefits and Trusteed Assets (OPEB - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) - Other postretirement benefit plan $ in Millions	Dec. 31, 2017USD ($)
Defined Benefit Plan Disclosure [Line Items]
2,018	$ 94
2,019	99
2,020	103
2,021	105
2,022	108
2023-2027	567
Total	1,076
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
2,018	73
2,019	77
2,020	80
2,021	82
2,022	84
2023-2027	437
Total	$ 833

Retirement Benefits and Trus135

Retirement Benefits and Trusteed Assets (OPEB - Assumptions used in Determining the PBO and Net Pension Costs) (Details)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated postretirement benefit obligation
Ultimate health care trend rate			4.50%
Other postretirement benefit costs
Ultimate health care trend rate			4.50%
Other postretirement benefit plan
Accumulated postretirement benefit obligation
Discount rate	3.70%	4.25%	4.50%
Health care trend rate pre- 65	6.75%	6.50%	6.25%
Health care trend post- 65	7.25%	6.75%	6.75%
Ultimate health care trend rate	4.50%	4.50%	4.50%
Other postretirement benefit costs
Discount rate	4.25%	4.50%	4.10%
Expected long-term rate of return on plan assets	7.75%	8.00%	8.00%
Health care trend rate pre- 65	6.50%	6.25%	7.50%
Health care trend post- 65	6.75%	6.75%	6.50%
Ultimate health care trend rate	4.50%	4.50%	4.50%

Retirement Benefits and Trus136

Retirement Benefits and Trusteed Assets (OPEB - Target Allocations of Plan Assets) (Details) - Other postretirement benefit plan	Dec. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	100.00%
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	16.00%
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	4.00%
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	20.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	26.00%
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	20.00%
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	14.00%

Retirement Benefits and Trus137

Retirement Benefits and Trusteed Assets (OPEB - Fair Value Measurements) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1,848	$ 1,758	$ 1,617
Assets valued at NAV	660	587
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	861	870
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	327	301
Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	15	40
Short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	13	39
Short-term investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	2	1
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	284	284
U.S. Large Capitalization (Cap) Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	284	284
U.S. Large Capitalization (Cap) Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	131	156
U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	131	156
U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	366	324
Assets valued at NAV	77	61
Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	288	262
Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	1
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	483	439
Assets valued at NAV	130	125
Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	29	15
Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	324	299
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	335	338
Assets valued at NAV	219	224
Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	116	114
Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	234	177
Assets valued at NAV	234	177
Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Securities lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(40)	(31)
Securities lending | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(39)	(28)
Securities lending | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(1)	(3)
Securities lending collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	40	31
Securities lending collateral | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	39	28
Securities lending collateral | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	3
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,272	1,218	$ 1,131
Assets valued at NAV	457	409
DTE Electric | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	595	604
DTE Electric | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	220	205
DTE Electric | Short-term investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	10	29
DTE Electric | Short-term investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	9	28
DTE Electric | Short-term investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	1
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	195	195
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	195	195
DTE Electric | U.S. Large Capitalization (Cap) Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	91	109
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	91	109
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	253	224
Assets valued at NAV	52	41
DTE Electric | Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	200	182
DTE Electric | Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	1
DTE Electric | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	330	303
Assets valued at NAV	92	90
DTE Electric | Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	20	10
DTE Electric | Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	218	203
DTE Electric | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	230	234
Assets valued at NAV	150	154
DTE Electric | Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	80	80
DTE Electric | Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	163	124
Assets valued at NAV	163	124
DTE Electric | Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Securities lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(28)	(21)
DTE Electric | Securities lending | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(27)	(20)
DTE Electric | Securities lending | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(1)	(1)
DTE Electric | Securities lending collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	28	21
DTE Electric | Securities lending collateral | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	27	20
DTE Electric | Securities lending collateral | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1	$ 1

Stock-Based Compensation (Detai

Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares	Dec. 31, 2015USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized limit of common stock shares (in shares)	14,500,000
Performance units price per unit (in dollars per share)	1
Remaining contractual term (in years)	2 years 18 days
Options vested (in shares)	0
Options grants in period (in shares)	0	0
Options, exercises, intrinsic value | $	$ 4,000,000	$ 4,000,000	$ 7,000,000
Stock option expense | $	0	0	0
DTE Electric | DTE Energy
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost charged against income (in millions) | $	$ 34,000,000	38,000,000	21,000,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	500,000
Award expiration period	10 years
Award vesting period	3 years
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	150,000
Award vesting period	3 years
Compensation cost charged against income (in millions) | $	$ 11,000,000	$ 11,000,000	$ 10,000,000
Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	300,000
Award vesting period	3 years
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	1,000,000

Stock-Based Compensation (Compo

Stock-Based Compensation (Components of Stock Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of stock based-compensation [Abstract]
Stock-based compensation expense	$ 58	$ 61	$ 34
Tax benefit	23	24	13
Stock-based compensation cost capitalized in Property, plant, and equipment	$ 9	$ 10	$ 5

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock Option Activity) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)$ / sharesshares
Number of Options
Options outstanding beginning of the year (in shares) | shares	171,517
Exercised (in shares) | shares	(65,523)
Options outstanding end of the year (in shares) | shares	105,994
Weighted Average Exercise Price
Options outstanding beginning of the year (in dollars per share) | $ / shares	$ 41.59
Exercised (in dollars per share) | $ / shares	39.37
Options outstanding end of the year (in dollars per share) | $ / shares	$ 42.95
Options outstanding, Aggregate Intrinsic Value | $	$ 7

Stock-Based Compensation (Numbe

Stock-Based Compensation (Number, Weighted Average Exercise Price and Weighted Average Remaining Contractual Life of Options Outstanding) (Details)	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options (in shares) | shares	105,994
Weighted Average Exercise Price (in dollars per share)	$ 42.95
Weighted Average Remaining Contractual Life (Years)	2 years 18 days
$27.00 - $38.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 27
Range of Exercise Prices Upper Limit (in dollars per share)	$ 38
Number of Options (in shares) | shares	6,194
Weighted Average Exercise Price (in dollars per share)	$ 27.70
Weighted Average Remaining Contractual Life (Years)	1 year 1 month 28 days
$38.01 - $42.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 38.01
Range of Exercise Prices Upper Limit (in dollars per share)	$ 42
Number of Options (in shares) | shares	2,300
Weighted Average Exercise Price (in dollars per share)	$ 41.79
Weighted Average Remaining Contractual Life (Years)	1 month 24 days
$42.01 - $45.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 42.01
Range of Exercise Prices Upper Limit (in dollars per share)	$ 45
Number of Options (in shares) | shares	97,500
Weighted Average Exercise Price (in dollars per share)	$ 43.95
Weighted Average Remaining Contractual Life (Years)	2 years 1 month 24 days

Stock-Based Compensation (Restr

Stock-Based Compensation (Restricted Stock Award Activity) (Details) - Restricted Stock Awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	$ 10	$ 9	$ 9
Restricted common shares awarded (in shares)	136,825	145,240	144,300
Weighted average market price of shares awarded (in dollars per share)	$ 99.53	$ 87.28	$ 83.43
Compensation cost charged against income	$ 11	$ 11	$ 10

Stock Based-Compensation (Stock

Stock Based-Compensation (Stock Awards Activity Rollforward) (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restricted Stock
Balance at beginning of the period (in shares)	385,285
Grants (in shares)	136,825	145,240	144,300
Forfeitures (in shares)	(11,745)
Vested and issued (in shares)	(144,601)
Balance at end of period (in shares)	365,764	385,285
Weighted Average Grant Date Fair Value
Balance at beginning of period (in dollars per share)	$ 80.10
Grants (in dollars per share)	99.53	$ 87.28	$ 83.43
Forfeitures (in dollars per share)	90.24
Vested and issued (in dollars per share)	72.08
Balance at end of period (in dollars per share)	$ 90.26	$ 80.10

Stock-Based Compensation (Perfo

Stock-Based Compensation (Performance Share Awards Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Compensation Expense Recorded [Line Items]
Compensation expense	$ 58	$ 61	$ 34
Performance Share Awards
Compensation Expense Recorded [Line Items]
Compensation expense	47	50	24
Cash settlements	15	7	13
Stock settlements	$ 66	$ 38	$ 71

Stock-Based Compensation (Pe145

Stock-Based Compensation (Performance Share Awards Activity) (Details) - Performance shares	12 Months Ended
	Dec. 31, 2017$ / sharesshares
Performance Shares
Balance at beginning of period (in shares) | shares	1,392,512
Grants (in shares) | shares	494,688
Forfeitures (in shares) | shares	(49,547)
Payouts (in shares) | shares	(513,252)
Balance at end of period (in shares) | shares	1,324,401
Weighted Average Grant Date Fair Value
Balance at beginning of period (in dollars per share) | $ / shares	$ 79.97
Grants (in dollars per share) | $ / shares	98.47
Forfeitures (in dollars per share) | $ / shares	87.12
Payouts (in dollars per share) | $ / shares	70.60
Balance at end of period (in dollars per share) | $ / shares	$ 90.31

Stock-Based Compensation (Unrec

Stock-Based Compensation (Unrecognized Compensation Costs) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2017USD ($)
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 64
Weighted Average to be Recognized	1 year 1 month 10 days
Stock awards
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 13
Weighted Average to be Recognized	1 year 1 month 13 days
Performance shares
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 51
Weighted Average to be Recognized	1 year 1 month 10 days

Segment and Related Informat147

Segment and Related Information (Details) customer in Millions	Dec. 31, 2017customer
Segment Reporting [Abstract]
Number of electric utility customers	2.2
Number of gas utility customers	1.3

Segment and Related Informat148

Segment and Related Information (Financial Data - Inter-Segment Billing) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ (3,271)	$ (3,245)	$ (2,855)	$ (3,236)	$ (2,874)	$ (2,928)	$ (2,262)	$ (2,566)	$ (12,607)	$ (10,630)	$ (10,337)
Reclassifications and Eliminations
Segment Reporting Information [Line Items]
Revenues									704	704	868
Reclassifications and Eliminations | Electric
Segment Reporting Information [Line Items]
Revenues									48	43	36
Reclassifications and Eliminations | Gas
Segment Reporting Information [Line Items]
Revenues									8	9	3
Reclassifications and Eliminations | Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Revenues									42	9	8
Reclassifications and Eliminations | Power and Industrial Projects
Segment Reporting Information [Line Items]
Revenues									569	602	785
Reclassifications and Eliminations | Energy Trading
Segment Reporting Information [Line Items]
Revenues									35	39	32
Reclassifications and Eliminations | Corporate and Other
Segment Reporting Information [Line Items]
Revenues									$ 2	$ 2	$ 4

Segment and Related Informat149

Segment and Related Information (Financial Data - Operating Revenues Including Inter-Segment Revenues) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									$ 6,434	$ 6,497	$ 6,238
Operating Revenues — Non-utility operations									6,173	4,133	4,099
Depreciation and amortization									1,030	976	852
Interest expense									536	472	450
Interest income									(12)	(20)	(13)
Equity in earnings of equity method investees									102	68	66
Income Tax Expense (Benefit)									175	271	230
Net Income (Loss) Attributable to DTE Energy Company	$ 287	$ 270	$ 177	$ 400	$ 131	$ 338	$ 152	$ 247	1,134	868	727
Investments in equity method investees	1,073				752				1,073	752	514
Capital expenditures and acquisitions									2,250	3,269	2,261
Goodwill	2,293				2,286				2,293	2,286	2,018
Total Assets	33,767				32,041				33,767	32,041	28,662
Effect of the Tax Cuts and Jobs Act of 2017	(105)								(105)	0	0
Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Investments in equity method investees	879				538				879	538
Operating Segments | Electric
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									5,102	5,225	4,901
Operating Revenues — Non-utility operations									0	0	0
Depreciation and amortization									753	750	637
Interest expense									274	264	258
Interest income									0	(8)	0
Equity in earnings of equity method investees									1	2	2
Income Tax Expense (Benefit)									321	353	290
Net Income (Loss) Attributable to DTE Energy Company									606	622	542
Investments in equity method investees	7				11				7	11	10
Capital expenditures and acquisitions									1,574	1,503	1,785
Goodwill	1,208				1,208				1,208	1,208	1,208
Total Assets	21,163				20,417				21,163	20,417	19,503
Operating Segments | Gas
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									1,388	1,324	1,376
Operating Revenues — Non-utility operations									0	0	0
Depreciation and amortization									123	106	104
Interest expense									65	60	62
Interest income									(7)	(6)	(7)
Equity in earnings of equity method investees									2	6	6
Income Tax Expense (Benefit)									78	77	72
Net Income (Loss) Attributable to DTE Energy Company									146	138	132
Investments in equity method investees	11				10				11	10	9
Capital expenditures and acquisitions									463	395	273
Goodwill	743				743				743	743	743
Total Assets	5,072				4,729				5,072	4,729	4,294
Operating Segments | Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									453	302	243
Depreciation and amortization									76	45	30
Interest expense									77	39	24
Interest income									(14)	(9)	(8)
Equity in earnings of equity method investees									90	60	47
Income Tax Expense (Benefit)									(30)	71	70
Net Income (Loss) Attributable to DTE Energy Company									275	119	107
Investments in equity method investees	879				538				879	538	296
Capital expenditures and acquisitions									137	1,322	161
Goodwill	299				292				299	292	24
Total Assets	2,594				2,417				2,594	2,417	1,047
Effect of the Tax Cuts and Jobs Act of 2017									(115)
Operating Segments | Power and Industrial Projects
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									2,089	1,906	2,224
Depreciation and amortization									72	72	78
Interest expense									29	32	32
Interest income									(7)	(8)	(8)
Equity in earnings of equity method investees									9	0	8
Income Tax Expense (Benefit)									(195)	(140)	(140)
Net Income (Loss) Attributable to DTE Energy Company									138	95	16
Investments in equity method investees	150				166				150	166	183
Capital expenditures and acquisitions									56	39	36
Goodwill	26				26				26	26	26
Total Assets	593				683				593	683	860
Effect of the Tax Cuts and Jobs Act of 2017									(21)
Operating Segments | Energy Trading
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									4,277	2,575	2,459
Depreciation and amortization									5	3	2
Interest expense									5	6	6
Interest income									(2)	(1)	(2)
Equity in earnings of equity method investees									0	0	0
Income Tax Expense (Benefit)									49	(29)	(15)
Net Income (Loss) Attributable to DTE Energy Company									72	(45)	(22)
Investments in equity method investees	0				0				0	0	0
Capital expenditures and acquisitions									7	7	6
Goodwill	17				17				17	17	17
Total Assets	725				660				725	660	590
Effect of the Tax Cuts and Jobs Act of 2017									2
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									2	2	2
Depreciation and amortization									1	0	1
Interest expense									192	148	132
Interest income									(88)	(65)	(52)
Equity in earnings of equity method investees									0	0	3
Income Tax Expense (Benefit)									(48)	(61)	(47)
Net Income (Loss) Attributable to DTE Energy Company									(103)	(61)	(48)
Investments in equity method investees	26				27				26	27	16
Capital expenditures and acquisitions									13	3	0
Goodwill	0				0				0	0	0
Total Assets	5,324				4,648				5,324	4,648	3,496
Effect of the Tax Cuts and Jobs Act of 2017									34
Reclassifications and Eliminations
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									(56)	(52)	(39)
Operating Revenues — Non-utility operations									(648)	(652)	(829)
Depreciation and amortization									0	0	0
Interest expense									(106)	(77)	(64)
Interest income									106	77	64
Equity in earnings of equity method investees									0	0	0
Income Tax Expense (Benefit)									0	0	0
Net Income (Loss) Attributable to DTE Energy Company									0	0	0
Investments in equity method investees	0				0				0	0	0
Capital expenditures and acquisitions									0	0	0
Goodwill	0				0				0	0	0
Total Assets	$ (1,704)				$ (1,513)				(1,704)	$ (1,513)	$ (1,128)
Non-utility Entities | Operating Segments | Electric
Segment Reporting Information [Line Items]
Effect of the Tax Cuts and Jobs Act of 2017									$ (5)

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Dividends declared	$ 602,000,000	$ 548,000,000	$ 510,000,000
Dividends paid	592,000,000	531,000,000	501,000,000
DTE Electric
Related Party Transaction [Line Items]
Other services	(4,000,000)	(1,000,000)	6,000,000
Dividends declared	432,000,000	420,000,000	395,000,000
Dividends paid	432,000,000	420,000,000	395,000,000
DTE Electric | Energy sales
Related Party Transaction [Line Items]
Revenues	9,000,000	10,000,000	2,000,000
DTE Electric | Shared capital assets
Related Party Transaction [Line Items]
Revenues	39,000,000	33,000,000	33,000,000
DTE Electric | Fuel and purchased power
Related Party Transaction [Line Items]
Costs	6,000,000	10,000,000	9,000,000
DTE Electric | Other services and interest
Related Party Transaction [Line Items]
Costs	(2,000,000)	(1,000,000)	2,000,000
DTE Electric | Corporate expenses, net
Related Party Transaction [Line Items]
Costs	370,000,000	370,000,000	334,000,000
DTE Electric | DTE Energy
Related Party Transaction [Line Items]
Dividends declared	432,000,000	420,000,000	395,000,000
Dividends paid	432,000,000	420,000,000	395,000,000
Capital contribution from DTE Energy	100,000,000	120,000,000	300,000,000
DTE Electric | DTE Energy Foundation
Related Party Transaction [Line Items]
Charitable contributions to foundation	$ 7,000,000	$ 0	$ 0

Supplementary Quarterly Fina151

Supplementary Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Entity Information [Line Items]
Operating Revenues	$ 3,271	$ 3,245	$ 2,855	$ 3,236	$ 2,874	$ 2,928	$ 2,262	$ 2,566	$ 12,607	$ 10,630	$ 10,337
Operating Income	356	418	303	569	301	507	256	381	1,646	1,445	1,239
Net Income	$ 287	$ 270	$ 177	$ 400	$ 131	$ 338	$ 152	$ 247	$ 1,134	$ 868	$ 727
Basic Earnings per Share (in dollars per share)	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 0.73	$ 1.88	$ 0.84	$ 1.38	$ 6.32	$ 4.84	$ 4.05
Diluted Earnings per Share (in dollars per share)	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 0.73	$ 1.88	$ 0.84	$ 1.37	$ 6.32	$ 4.83	$ 4.05
Effect of the Tax Cuts and Jobs Act of 2017	$ (105)								$ (105)	$ 0	$ 0
DTE Electric
Entity Information [Line Items]
Operating Revenues	1,275	$ 1,434	$ 1,218	$ 1,175	$ 1,249	$ 1,608	$ 1,215	$ 1,153	5,102	5,225
Operating Income	281	395	272	217	193	501	265	245	1,165	1,204	1,074
Net Income	$ 138	$ 219	$ 138	$ 106	$ 75	$ 285	$ 135	$ 127	$ 601	$ 622	$ 544

Schedule II - Valuation and 152

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	$ 41
Additions:
Balance at End of Period	49	$ 41
DTE Electric
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	25
Additions:
Balance at End of Period	31	25
Allowance for Doubtful Accounts
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	41	49	$ 54
Additions:
Charged to costs and expenses	80	78	93
Charged to other accounts	26	18	14
Deductions	(98)	(104)	(112)
Balance at End of Period	49	41	49
Allowance for Doubtful Accounts | DTE Electric
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	25	28	29
Additions:
Charged to costs and expenses	55	49	51
Charged to other accounts	14	8	6
Deductions	(63)	(60)	(58)
Balance at End of Period	$ 31	$ 25	$ 28