DTE Energy (DTE) 10-Q 25 Apr 18 2018 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information	3 Months Ended
	Mar. 31, 2018shares
Entity Registrant Name	DTE ENERGY CO
Entity Central Index Key	936,340
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	Mar. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding	181,483,163
DTE Electric
Entity Registrant Name	DTE ELECTRIC CO
Entity Central Index Key	28,385
Entity Filer Category	Non-accelerated Filer
Document Type	10-Q
Document Fiscal Period Focus	Q1
Amendment Flag	false
Entity Common Stock, Shares Outstanding	138,632,324

Consolidated Statements of Oper

Consolidated Statements of Operations (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Revenues
Utility operations	$ 1,740	$ 1,718
Non-utility operations	2,013	1,518
Operating Revenues	3,753	3,236
Operating Expenses
Fuel, purchased power, and gas — utility	553	529
Fuel, purchased power, and gas — non-utility	1,773	1,180
Operation and maintenance	534	584
Depreciation and amortization	281	249
Taxes other than income	111	109
Asset (gains) losses and impairments, net	(3)	0
Operating Expenses	3,249	2,651
Operating Income	504	585
Other (Income) and Deductions
Interest expense	135	125
Interest income	(3)	(3)
Non-operating retirement benefits, net	9	16
Other income	(81)	(64)
Other expenses	25	7
Total Other (Income) and Deductions	85	81
Income Before Income Taxes	419	504
Income Tax Expense	68	110
Net Income	351	394
Less: Net Loss Attributable to Noncontrolling Interests	(10)	(6)
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 361	$ 400
Basic Earnings per Common Share
Net Income Attributable to DTE Energy Company (in dollars per share)	$ 2.01	$ 2.23
Diluted Earnings per Common Share
Net Income Attributable to DTE Energy Company (in dollars per share)	$ 2	$ 2.23
Weighted Average Common Shares Outstanding
Basic (in shares)	180	179
Diluted (in shares)	180	179
Dividends Declared per Common Share (in dollars per share)	$ 0.8825	$ 0.825
DTE Electric
Operating Revenues
Utility operations	$ 1,205	$ 1,175
Operating Expenses
Fuel and purchased power — utility	339	314
Operation and maintenance	320	383
Depreciation and amortization	212	181
Taxes other than income	81	80
Operating Expenses	952	958
Operating Income	253	217
Other (Income) and Deductions
Interest expense	68	66
Other income	(27)	(19)
Other expenses	25	7
Total Other (Income) and Deductions	66	54
Income Before Income Taxes	187	163
Income Tax Expense	47	57
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 140	$ 106

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Net Income	$ 351	$ 394
Net Income	361	400
Other comprehensive income (loss), net of tax:
Implementation of ASU 2016-01	(5)	0
Benefit obligations, net of taxes of $1, and $2, respectively	2	4
Other comprehensive income (loss)	(3)	4
Comprehensive income	348	398
Less: Comprehensive loss attributable to noncontrolling interests	(10)	(6)
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company	358	404
DTE Electric
Net Income	140	106
Other comprehensive income (loss), net of tax:
Implementation of ASU 2016-01	3	0
Other comprehensive income (loss)	3	0
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company	$ 143	$ 106

Consolidated Statements of Com4

Consolidated Statements of Comprehensive Income (Unaudited) (Parentheticals) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Statement of Comprehensive Income [Abstract]
Tax effect on benefit obligation	$ 1	$ 2

Consolidated Statements of Fina

Consolidated Statements of Financial Position (Unaudited) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 164	$ 66
Restricted cash	22	23
Accounts receivable (less allowance for doubtful accounts)
Customer	1,709	1,758
Other	116	98
Inventories
Fuel and gas	237	399
Materials and supplies	360	380
Derivative assets	84	103
Regulatory assets	44	55
Other	221	199
Total Current Assets	2,957	3,081
Investments
Nuclear decommissioning trust funds	1,481	1,492
Investments in equity method investees	1,141	1,073
Other	230	232
Total Investments	2,852	2,797
Property
Property, plant, and equipment	31,656	31,424
Accumulated depreciation and amortization	(10,786)	(10,703)
Property, plant, and equipment, net	20,870	20,721
Other Assets
Goodwill	2,293	2,293
Regulatory assets	3,715	3,723
Intangible assets	867	867
Notes receivable	70	73
Derivative assets	58	51
Other	159	161
Total Other Assets	7,162	7,168
Total Assets	33,841	33,767
Accounts payable
Accounts payable	920	1,171
Accrued interest	132	111
Dividends payable	160	158
Short-term borrowings	635	621
Current portion long-term debt, including capital leases	106	109
Derivative liabilities	69	99
Gas inventory equalization	85	0
Regulatory liabilities	23	18
Short-term borrowings
Other	411	525
Total Current Liabilities	2,541	2,812
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	11,040	11,039
Junior subordinated debentures	1,145	1,145
Capital lease obligations	0	1
Total Long-Term Debt (net of current portion)	12,185	12,185
Other Liabilities
Deferred income taxes	1,936	1,888
Regulatory liabilities	3,001	2,875
Asset retirement obligations	2,361	2,320
Unamortized investment tax credit	122	122
Derivative liabilities	58	47
Accrued pension liability	737	924
Accrued postretirement liability	25	61
Nuclear decommissioning	219	220
Other	293	323
Total Other Liabilities	8,752	8,780
Commitments and Contingencies (Notes 5 and 10)
Equity
Common stock	4,163	3,989
Retained earnings	5,848	5,643
Accumulated other comprehensive income (loss)	(123)	(120)
Total DTE Energy/DTE Electric Company Equity	9,888	9,512
Noncontrolling interests	475	478
Total Equity	10,363	9,990
Total Liabilities and Equity	33,841	33,767
DTE Electric
Current Assets
Cash and cash equivalents	16	15
Accounts receivable (less allowance for doubtful accounts)
Customer	754	791
Affiliates	14	20
Other	39	37
Inventories
Fuel and gas	138	190
Materials and supplies	277	275
Regulatory assets	40	50
Prepaid property tax	91	48
Other	18	20
Total Current Assets	1,387	1,446
Investments
Nuclear decommissioning trust funds	1,481	1,492
Other	36	36
Total Investments	1,517	1,528
Property
Property, plant, and equipment	23,098	22,972
Accumulated depreciation and amortization	(8,023)	(7,984)
Property, plant, and equipment, net	15,075	14,988
Other Assets
Regulatory assets	3,009	3,005
Intangible assets	31	25
Prepaid postretirement costs — affiliates	113	113
Other	123	123
Total Other Assets	3,276	3,266
Total Assets	21,255	21,228
Accounts payable
Affiliates	61	52
Other	295	416
Accrued interest	70	72
Current portion long-term debt, including capital leases	2	5
Regulatory liabilities	21	17
Short-term borrowings
Affiliates	142	116
Other	380	238
Other	133	145
Total Current Liabilities	1,104	1,061
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	6,018	6,017
Capital lease obligations	0	1
Total Long-Term Debt (net of current portion)	6,018	6,018
Other Liabilities
Deferred income taxes	2,127	2,088
Regulatory liabilities	2,218	2,137
Asset retirement obligations	2,165	2,125
Unamortized investment tax credit	120	120
Nuclear decommissioning	219	220
Accrued pension liability — affiliates	633	811
Accrued postretirement liability — affiliates	287	311
Other	74	72
Total Other Liabilities	7,843	7,884
Commitments and Contingencies (Notes 5 and 10)
Equity
Common stock	4,306	4,306
Retained earnings	1,984	1,956
Accumulated other comprehensive income (loss)	0	3
Total DTE Energy/DTE Electric Company Equity	6,290	6,265
Total Liabilities and Equity	$ 21,255	$ 21,228

Consolidated Statements of Fin6

Consolidated Statements of Financial Position (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Allowance for doubtful accounts	$ 54	$ 49
Shareholder’s Equity
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	181,483,163	179,386,967
Common stock, shares outstanding (in shares)	181,483,163	179,386,967
DTE Electric
Allowance for doubtful accounts	$ 31	$ 31
Shareholder’s Equity
Par value (in dollars per share)	$ 10	$ 10
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	138,632,324	138,632,324
Common stock, shares outstanding (in shares)	138,632,324	138,632,324

Consolidated Statements of Cash

Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities
Net Income	$ 351	$ 394
Net Income	361	400
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	281	249
Nuclear fuel amortization	15	12
Allowance for equity funds used during construction	(7)	(7)
Deferred income taxes	60	100
Equity earnings of equity method investees	(21)	(26)
Dividends from equity method investees	15	18
Changes in assets and liabilities:
Accounts receivable, net	33	84
Inventories	182	135
Accounts payable	(136)	(33)
Gas inventory equalization	85	86
Accrued pension liability	(187)	(130)
Accrued postretirement liability	(36)	27
Derivative assets and liabilities	(7)	(100)
Regulatory assets and liabilities	148	128
Other current and noncurrent assets and liabilities	62	(150)
Net cash from operating activities	838	787
Investing Activities
Plant and equipment expenditures — utility	(466)	(533)
Plant and equipment expenditures — non-utility	(61)	(22)
Proceeds from sale of nuclear decommissioning trust fund assets	336	394
Investment in nuclear decommissioning trust funds	(337)	(378)
Distributions from equity method investees	4	6
Contributions to equity method investees	(64)	(112)
Other	2	3
Net cash used for investing activities	(586)	(642)
Financing Activities
Issuance of long-term debt, net of issuance costs	0	496
Short-term borrowings, net	14	(440)
Repurchase of common stock	0	(51)
Dividends on common stock	(158)	(148)
REF contributions from noncontrolling interests	12	11
Other	(23)	(24)
Net cash used for financing activities	(155)	(156)
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	97	(11)
Cash and Cash Equivalents at Beginning of Period	66
Cash and Cash Equivalents at End of Period	164	82
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	89	113
Cash, Cash Equivalents, and Restricted Cash at End of Period	186	102
Supplemental disclosure of non-cash investing and financing activities
Plant and equipment expenditures in accounts payable	179	196
DTE Electric
Operating Activities
Net Income	140	106
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	212	181
Nuclear fuel amortization	15	12
Allowance for equity funds used during construction	(5)	(6)
Deferred income taxes	48	57
Changes in assets and liabilities:
Accounts receivable, net	39	58
Inventories	50	44
Accounts payable	(30)	26
Accrued pension liability — affiliates	(178)	(123)
Accrued postretirement liability — affiliates	(24)	21
Regulatory assets and liabilities	97	122
Other current and noncurrent assets and liabilities	(41)	(87)
Net cash from operating activities	323	411
Investing Activities
Plant and equipment expenditures	(370)	(408)
Proceeds from sale of nuclear decommissioning trust fund assets	336	394
Investment in nuclear decommissioning trust funds	(337)	(378)
Other	0	5
Net cash used for investing activities	(371)	(387)
Financing Activities
Short-term borrowings, net — affiliate	26	88
Short-term borrowings, net — other	142	(3)
Dividends on common stock	(115)	(108)
Other	(4)	(3)
Net cash used for financing activities	49	(26)
Net Increase (Decrease) in Cash and Cash Equivalents	1	(2)
Cash and Cash Equivalents at Beginning of Period	15	13
Cash and Cash Equivalents at End of Period	16	11
Supplemental disclosure of non-cash investing and financing activities
Plant and equipment expenditures in accounts payable	$ 109	$ 134

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity (Unaudited) - 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)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Implementation of ASU 2016-01	$ 0		$ 5	$ (5)		$ 0			$ 3	$ (3)
Beginning Balance (in shares) at Dec. 31, 2017	179,386,967	179,387,000				138,632,324	138,632,000
Beginning Balance at Dec. 31, 2017	$ 9,990	$ 3,989	5,643	(120)	$ 478
Beginning Balance at Dec. 31, 2017	9,512					$ 6,265	$ 1,386	$ 2,920	1,956	3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	351		361		(10)
Net Income	361					140			140
Dividends declared on common stock	(160)		(160)			$ (115)			(115)
Contribution of common stock to pension plan (in shares)		1,751,000
Contribution of common stock to pension plan	175	$ 175
Benefit obligations, net of tax	2			2
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		345,000
Stock-based compensation, net contributions from noncontrolling interests, and other	$ 5	$ (1)	(1)		7
Ending Balance (in shares) at Mar. 31, 2018	181,483,163	181,483,000				138,632,324	138,632,000
Ending Balance at Mar. 31, 2018	$ 10,363	$ 4,163	$ 5,848	$ (123)	$ 475
Ending Balance at Mar. 31, 2018	$ 9,888					$ 6,290	$ 1,386	$ 2,920	$ 1,984	$ 0

Organization and Basis of Prese

Organization and Basis of Presentation	3 Months Ended
	Mar. 31, 2018
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) services related to the gathering, transportation, and storage of natural gas; 2) power and industrial projects; and 3) energy marketing and trading operations. DTE Electric and DTE Gas are regulated by the MPSC. Certain activities of DTE Electric and DTE Gas, as well as various other aspects of businesses under DTE Energy, are regulated by the FERC. In addition, the Registrants are regulated by other federal and state regulatory agencies including the NRC, the EPA, the MDEQ, and for DTE Energy, the CFTC. Basis of Presentation The Consolidated Financial Statements should be read in conjunction with the Combined Notes to Consolidated Financial Statements included in the combined DTE Energy and DTE Electric 2017 Annual Report on Form 10-K. The accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The Consolidated Financial Statements are unaudited but, in the Registrants' opinions include all adjustments necessary to present a fair statement of the results for the interim periods. All adjustments are of a normal recurring nature, except as otherwise disclosed in these Consolidated Financial Statements and Combined Notes to Consolidated Financial Statements. Financial results for this interim period are not necessarily indicative of results that may be expected for any other interim period or for the fiscal year ending December 31, 2018 . 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 DTE Energy were reclassified to match the current year's Consolidated Financial Statements presentation. Due to the implementation of ASU 2017-07, amounts previously included in Operation and maintenance were reclassified to Non-operating retirement benefits, net on the Consolidated Statements of Operations. See Note 3 to the Consolidated Financial Statements, " New Accounting Pronouncements ." Principles of Consolidation The Registrants consolidate all majority-owned subsidiaries and investments in entities in which they have controlling influence. Non-majority owned investments are accounted for using the equity method when the Registrants are able to significantly influence the operating policies of the investee. When the Registrants do not influence the operating policies of an investee, the cost method is used. These Consolidated Financial Statements also reflect the Registrants' proportionate interests in certain jointly-owned utility plants. The Registrants eliminate all intercompany balances and transactions. The Registrants evaluate whether an entity is a VIE whenever reconsideration events occur. The Registrants consolidate VIEs for which they are the primary beneficiary. If a Registrant is not the primary beneficiary and an ownership interest is held, the VIE is accounted for under the equity method of accounting. When assessing the determination of the primary beneficiary, a Registrant considers all relevant facts and circumstances, including: the power, through voting or similar rights, to direct the activities of the VIE that most significantly impact the VIE's economic performance and the obligation to absorb the expected losses and/or the right to receive the expected returns of the VIE. The Registrants perform ongoing reassessments of all VIEs to determine if the primary beneficiary status has changed. Legal entities within DTE Energy's Power and Industrial Projects segment enter into long-term contractual arrangements with customers to supply energy-related products or services. The entities are generally designed to pass-through the commodity risk associated with these contracts to the customers, with DTE Energy retaining operational and customer default risk. These entities generally are VIEs and consolidated when DTE Energy is the primary beneficiary. In addition, DTE Energy has interests in certain VIEs through which control of all significant activities is shared with partners, and therefore are accounted for under the equity method. DTE Energy 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. The Registrants have variable interests in NEXUS, which include DTE Energy's 50% ownership interest and DTE Electric's transportation services contract. 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 its ownership interest in 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 March 31, 2018 , 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 March 31, 2018 , 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 10 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 10 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 March 31, 2018 and December 31, 2017 . 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. March 31, 2018 December 31, 2017 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 29 $ 12 $ 41 $ 23 $ 14 $ 37 Restricted cash — 8 8 — 8 8 Accounts receivable 11 37 48 11 42 53 Inventories 3 66 69 3 114 117 Property, plant, and equipment, net 386 73 459 400 75 475 Goodwill 25 — 25 25 — 25 Intangible assets 568 — 568 572 — 572 Other current and long-term assets 2 — 2 4 — 4 $ 1,024 $ 196 $ 1,220 $ 1,038 $ 253 $ 1,291 LIABILITIES Accounts payable and accrued current liabilities $ 2 $ 35 $ 37 $ 26 $ 47 $ 73 Current portion long-term debt, including capital leases — 4 4 — 4 4 Mortgage bonds, notes, and other — — — — 1 1 Other current and long-term liabilities 2 15 17 1 16 17 $ 4 $ 54 $ 58 $ 27 $ 68 $ 95 _____________________________________ (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: March 31, 2018 December 31, 2017 (In millions) Investments in equity method investees $ 866 $ 811 Notes receivable $ 17 $ 17 Future funding commitments $ 551 $ 598

Significant Accounting Policies

Significant Accounting Policies	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Other Income The following is a summary of DTE Energy's Other income: Three Months Ended March 31, 2018 2017 (In millions) Income from REF entities $ 23 $ 18 Equity earnings of equity method investees 21 26 Contract services 20 4 Allowance for equity funds used during construction 7 7 Gains from equity securities — 8 Other 10 1 $ 81 $ 64 The following is a summary of DTE Electric's Other income: Three Months Ended March 31, 2018 2017 (In millions) Contract services $ 20 $ 4 Allowance for equity funds used during construction 5 6 Gains from equity securities allocated from DTE Energy — 8 Other 2 1 $ 27 $ 19 Changes in Accumulated Other Comprehensive Income (Loss) For the three months ended March 31, 2018 and 2017 , reclassifications out of Accumulated other comprehensive income (loss) for the Registrants were not material. Changes in Accumulated other comprehensive income (loss) are presented in DTE Energy's Consolidated Statements of Changes in Equity and DTE Electric's Consolidated Statements of Changes in Shareholder's Equity. For further discussion regarding changes in Accumulated other comprehensive income (loss), see Note 3 to the Consolidated Financial Statements, " New Accounting Pronouncements ." Income Taxes The 2018 estimated annual effective tax rates for DTE Energy and DTE Electric are 13% and 22% , respectively. These tax rates are affected by estimated annual permanent items, including AFUDC equity, production tax credits, and other flow-through items, as well as discrete items that may occur in any given period, but are not consistent from period to period. The interim effective tax rate of the Registrants are as follows: Effective Tax Rate Three Months Ended March 31, 2018 2017 DTE Energy 16 % 22 % DTE Electric 25 % 35 % The 6% decrease in DTE Energy's effective tax rate for the three months ended March 31, 2018 was primarily due to the reduction of the corporate tax rate from 35% to 21%, which became effective in 2018. The decrease in the effective tax rate was partially offset by true-up adjustments to the remeasurement of deferred taxes in 2018 of $21 million , which increased the effective tax rate by 5% , and the reduction of excess tax benefits on stock-based compensation of $10 million , which increased the effective tax rate by 2% . For further discussion regarding the true-up adjustments, see Note 3 to the Consolidated Financial Statements, " New Accounting Pronouncements ." The 10% decrease in DTE Electric's effective tax rate for the three months ended March 31, 2018 was primarily due to the reduction of the corporate tax rate from 35% to 21%, which became effective in 2018, partially offset by true-up adjustments to the remeasurement of deferred taxes in 2018 of $8 million , which increased the effective tax rate by 4% . DTE Energy's total amount of unrecognized tax benefits as of March 31, 2018 was $8 million , of which $8 million , if recognized, would favorably impact its effective tax rate. DTE Electric's total amount of unrecognized tax benefits as of March 31, 2018 was $10 million , of which $10 million , if recognized, would favorably impact its effective tax rate. The Registrants do not anticipate any material changes to the unrecognized tax benefits in the next twelve months. DTE Electric had income tax receivables with DTE Energy of $13 million and $12 million at March 31, 2018 and December 31, 2017 , respectively. Unrecognized Compensation Costs As of March 31, 2018 , DTE Energy had $111 million of total unrecognized compensation cost related to non-vested stock incentive plan arrangements. That cost is expected to be recognized over a weighted-average period of 1.75 years . Allocated Stock-Based Compensation DTE Electric received an allocation of costs from DTE Energy associated with stock-based compensation of $9 million and $8 million for the three months ended March 31, 2018 and 2017, respectively . 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. The following is a table that provides a reconciliation of DTE Energy's Cash and cash equivalents as well as Restricted cash reported within the Consolidated Statements of Financial Position that sum to the total of the same such amounts shown in the Consolidated Statements of Cash Flows: Three Months Ended March 31, 2018 2017 (In millions) Cash and cash equivalents $ 164 $ 82 Restricted cash 22 20 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 186 $ 102

New Accounting Pronouncements

New Accounting Pronouncements	3 Months Ended
	Mar. 31, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS Recently Adopted 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 required 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 adopted the standard effective January 1, 2018 using the modified retrospective approach. Under the modified retrospective approach, the information for periods prior to the adoption date has not been restated and continues to be reported under the accounting standards in effect for those periods. As permitted under the standard, the Registrants have elected to apply the guidance only to those contracts that were not completed at January 1, 2018, and have elected not to restate the impacts of any contract modifications made prior to the earliest period presented. The adoption of the ASU did not have a significant impact on the Registrants' financial position or results of operations, but required additional disclosures for revenue. See Note 4 to the Consolidated Financial Statements, " Revenue ." 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 required 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 of income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The Registrants adopted the standard effective January 1, 2018. The standard has been 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. As permitted by the standard, the Registrants have used benefit cost amounts disclosed for prior periods as the basis for retrospective application in the income statement. As a result of regulatory mechanisms, the impact to the Consolidated Financial Statements was not material for the first quarter of 2018. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments — Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , as amended. The new guidance is intended to improve the recognition and measurement of financial instruments. The guidance primarily impacts accounting for equity investments in unconsolidated entities (other than those accounted for using the equity method of accounting) and financial liabilities under the fair value option. The guidance requires equity investments to be generally measured at fair value, with subsequent changes in fair value recognized in net income. The guidance requires entities to make a cumulative-effect adjustment to the Statements of Financial Position as of the beginning of the first reporting period in which the guidance is effective. The Registrants adopted the standard effective January 1, 2018. Upon adoption, DTE Energy and DTE Electric recorded a cumulative-effect adjustment to reclassify $5 million and $3 million of unrealized gains from Accumulated other comprehensive income (loss) to Retained earnings, respectively. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC paragraphs pursuant to SEC Staff Accounting Bulletin No. 118 . The Amendments in this update add various SEC paragraphs pursuant to the issuance of SEC Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118) . SAB 118 directs 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. As described in Note 10 to the Consolidated Financial Statements, "Income Taxes," within the combined DTE Energy and DTE Electric 2017 Annual Report on Form 10-K and in accordance with SAB 118, the Registrants recorded amounts that were considered provisional. In first quarter of 2018, DTE Energy and DTE Electric recorded true-up adjustments to the remeasurement of deferred taxes of $21 million and $8 million , respectively. The impact of the true-up adjustments was an increase in Income Tax Expense, of which $16 million was attributable to the regulated utilities and offset to Regulatory liabilities. The true-up adjustments were a result of further analysis for items subject to further consideration at December 31, 2017 under SAB 118 and primarily related to timing differences not recoverable from DTE Electric and DTE Gas customers. The Registrants will continue to analyze the amounts throughout 2018, which may result in additional changes. Recently Issued Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), as amended. This guidance requires a lessee to account for leases as finance or operating leases, and disclose 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, depending on the lease classification. The Registrants will adopt the standard on January 1, 2019. As originally issued, the standard requires a modified retrospective approach for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements. The Registrants are evaluating the transition practical expedients available under the guidance, such as retaining the current lease assessment and classifications for existing leases at the effective date, and not applying the new guidance to land easements that exist or expire before the effective date. A third-party software tool is being implemented that will assist with the initial adoption and ongoing compliance of the standard. The Registrants are evaluating contracts for leases and abstracting the required data, as well as evaluating new business processes, internal controls, and accounting policies. In addition, the Registrants are monitoring utility industry implementation issues for purchase power agreements, pipeline laterals, and other industry specific arrangements. While the Registrants expect an increase in assets and liabilities, as well as additional disclosures, they are still assessing the impact of this ASU on their Consolidated Financial Statements. 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 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.

Revenue

Revenue	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Revenue	REVENUE Significant Accounting Policy Upon the adoption of Topic 606, revenue is measured based upon the consideration specified in a contract with a customer at the time when performance obligations are satisfied. Under Topic 606, a performance obligation is a promise in a contract to transfer a distinct good or service or a series of distinct goods or services to the customer. The Registrants recognize revenue when performance obligations are satisfied by transferring control over a product or service to a customer. The Registrants have determined control to be transferred when the product is delivered or the service is provided to the customer. For the three months ended March 31, 2018 , recognition of revenue for the Registrants subsequent to the adoption of Topic 606 is substantially similar in amount and approach to that prior to adoption. 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 discussion of derivative contracts, see Note 8 to the Consolidated Financial Statements, " Financial and Other Derivative Instruments ." Disaggregation of Revenue The following is a summary of revenues disaggregated by segment for DTE Energy: Three Months Ended March 31, 2018 (In millions) Electric (a) Residential $ 586 Commercial 429 Industrial 176 Other (b) 14 Total Electric operating revenues (c) $ 1,205 Gas Gas sales $ 457 End User Transportation 85 Intermediate Transportation 18 Other (d) (10 ) Total Gas operating revenues (e) $ 550 Other segment operating revenues (f) Gas Storage and Pipelines $ 119 Power and Industrial Projects $ 567 Energy Trading $ 1,498 _______________________________________ (a) Revenues under the Electric segment generally represent those of DTE Electric. (b) Includes a reduction of $39 million in revenues related to TCJA rate reduction reserve. (c) Includes $5 million of other revenues which are outside the scope of Topic 606. (d) Includes a reduction of $32 million in revenues related to TCJA rate reduction reserve. (e) Includes a reduction of $3 million under Alternative Revenue Programs and $2 million of other revenues which are both outside the scope of Topic 606. (f) Includes revenues outside the scope of Topic 606 primarily related to $445 million of contracts accounted for as leases at the Power and Industrial Projects segment and $1.2 billion related to derivatives at the Energy Trading segment. Nature of Goods and Services The following is a description of principal activities, separated by reportable segments, from which DTE Energy generates revenue. For more detailed information about reportable segments, see Note 12 to the Consolidated Financial Statements, “ Segment and Related Information .” The Registrants have contracts with customers which may contain more than one performance obligation. When more than one performance obligation exists in a contract, the consideration under the contract is allocated to the performance obligations based on the relative standalone selling price. DTE Energy generally determines stand alone selling prices based on the prices charged to customers or the use of the adjusted market assessment approach. The adjusted market assessment approach involves the evaluation of the market in which DTE Energy sells goods or services and estimating the price that a customer in that market would be willing to pay. Under Topic 606, when a customer simultaneously receives and consumes the product or service provided, revenue is considered to be recognized over time. Alternatively, if it is determined that the criteria for recognition of revenue over time is not met, the revenue is considered to be recognized at a point in time. Electric Electric consists principally of DTE Electric. Electric revenues are primarily comprised of the supply and delivery of electricity, and related capacity. Revenues are primarily associated with cancelable contracts, with the exception of certain long-term contracts with commercial and industrial customers. Revenues, including estimated unbilled amounts, are generally recognized over time based upon volumes delivered or through the passage of time ratably based upon providing a stand-ready service. The Registrants have determined that the above methods represent a faithful depiction of the transfer of control to the customer. Unbilled revenues are typically determined utilizing approved tariff rates and estimated meter volumes. Estimated unbilled amounts recognized in revenue are subject to adjustment in the following reporting period as actual volumes by customer class are known. Revenues are typically subject to tariff rates based upon customer class and type of service, and are billed and received monthly. Tariff rates are determined by the MPSC on a per kWh or monthly basis. Gas Gas revenues are primarily comprised of the supply and delivery of natural gas, and other services including storage, transportation, and appliance maintenance. Revenues are primarily associated with cancelable contracts with the exception of certain long-term contracts with commercial and industrial customers. Revenues, including estimated unbilled amounts, are generally recognized over time based upon volumes delivered or through the passage of time ratably based upon providing a stand-ready service. DTE Energy has determined that the above methods represent a faithful depiction of the transfer of control to the customer. Unbilled revenues are typically determined using both estimated meter volumes and estimated usage based upon the number of unbilled days and historical temperatures. Estimated unbilled amounts recognized in revenue are subject to adjustment in the following reporting period as actual volumes by customer class and service type are known. Revenues are typically subject to tariff rates or other rates subject to regulatory oversight and are billed and received monthly. Tariff rates are determined by the MPSC on a per unit or monthly basis. Gas Storage and Pipelines Gas Storage and Pipelines revenues generally consist of services related to the gathering, transportation, and storage of natural gas. Contracts are primarily long-term in nature. Revenues, including estimated unbilled amounts, are generally recognized over time based upon services provided or through the passage of time ratably based upon providing a stand-ready service. DTE Energy has determined that the above methods represent a faithful depiction of the transfer of control to the customer. Revenues are typically billed and received monthly. Pricing for such revenues may consist of demand rates, commodity rates, transportation rates, and other associated fees. Consideration may consist of both fixed and variable components. Generally, uncertainties in the variable consideration components are resolved and revenues are known at the time of recognition. Power and Industrial Projects Power and Industrial Projects revenues consist primarily of contracts accounted for as leases which are outside of the scope of Topic 606. For performance obligations within the scope of Topic 606, the timing of revenue recognition is dependent upon when control over the associated product or service is transferred. Revenues at Power and Industrial Projects, within the scope of Topic 606, generally consist of sales of blast furnace coke and coke oven gas, electricity, equipment maintenance services, and other energy related products and services. Revenues, including estimated unbilled amounts, for the sale of blast furnace coke are generally recognized at a point in time when the product is delivered, which represents the transfer of control to the customer. Other revenues are generally recognized over time based upon services provided or through the passage of time ratably based upon providing a stand-ready service. DTE Energy has determined that the above methods represent a faithful depiction of the transfer of control to the customer. Market based pricing structures exist in such contracts including adjustments for consumer price or other indices. Consideration may consist of both fixed and variable components. Generally, uncertainties in the variable consideration components are resolved and revenues are known at the time of recognition. Billing terms vary and are generally monthly with payment terms typically within 30 days following billing. Energy Trading Energy Trading revenues consist primarily of derivative contracts outside of the scope of Topic 606. For performance obligations within the scope of Topic 606, the timing of revenue recognition is dependent upon when control over the associated product or service is transferred. Revenues, including estimated unbilled amounts, within the scope of Topic 606 arising from the sale of natural gas, electricity, power capacity, and other energy related products are generally recognized over time based upon volumes delivered or through the passage of time ratably based upon providing a stand-ready service. DTE Energy has determined that the above methods represent a faithful depiction of the transfer of control to the customer. Revenues are known at the time of recognition. Payment for the aforementioned revenues is generally due from customers in the month following delivery. Revenues associated with RECs are recognized at a point in time when control of the RECs are transferred to the customer which is deemed to be when the subject RECs are entered for transfer to the customer in the applicable regulatory tracking system. Revenues associated with RECs under a wholesale full requirements power contract are deferred until control has been transferred. The deferred revenues represent a contract liability for which payment has been received and the amounts have been estimated using the adjusted market assessment approach. With the exception of RECs, generally all other performance obligations associated with wholesale full requirements power contracts are satisfied over time in conjunction with the delivery of power. At the time power is delivered, DTE Energy may not have control over the RECs as the RECs are not self-generated and may not yet have been procured resulting in deferred revenues. Deferred Revenue The following is a summary of deferred revenue activity: DTE Energy (In millions) Beginning Balance, January 1, 2018 $ 56 Increases due to cash received or receivable, excluding amounts recognized as revenue during the period 14 Revenue recognized that was included in the deferred revenue balance at the beginning of the period (16 ) Ending Balance, March 31, 2018 $ 54 The deferred revenues at DTE Energy generally represent amounts paid by or receivable from customers for which the associated performance obligation has not yet been satisfied. Deferred revenues include amounts associated with REC performance obligations under certain wholesale full requirements power contracts. Deferred revenues associated with RECs are recognized as revenue when control of the RECs has transferred. Other performance obligations associated with deferred revenues include providing products and services related to customer prepayments. Deferred revenues associated with these products and services are recognized when control has transferred to the customer. The following table represents deferred revenue amounts for DTE Energy that are expected to be recognized as revenue in future periods: DTE Energy (In millions) 2018 $ 23 2019 9 2020 1 2021 5 2022 6 2023 and thereafter 10 $ 54 Transaction Price Allocated to the Remaining Performance Obligations In accordance with optional exemptions available under Topic 606, the Registrants did not disclose the value of unsatisfied performance obligations for (1) contracts with an original expected length of one year or less, (2) with the exception of fixed consideration, contracts for which revenue is recognized at the amount to which the Registrants have the right to invoice for goods provided and services performed, and (3) contracts for which variable consideration relates entirely to an unsatisfied performance obligation. Such contracts consist of varying types of performance obligations across the segments, including the supply and delivery of energy related products and services. Contracts with variable volumes and/or variable pricing, including those with pricing provisions tied to a consumer price or other index, have also been excluded as the related consideration under the contract is variable at inception of the contract. Contract lengths vary from cancelable to multi-year. The Registrants expect to recognize revenue for the following amounts related to fixed consideration associated with remaining performance obligations in each of the future periods noted: DTE Energy DTE Electric (In millions) 2018 $ 159 $ 6 2019 238 8 2020 168 — 2021 128 — 2022 103 — 2023 and thereafter 351 — Total $ 1,147 $ 14 Other Matters DTE Energy has recognized charges of $25 million related to expense recognized for estimated uncollectible accounts receivable for the three months ended March 31, 2018 . DTE Electric has recognized charges of $14 million related to expense recognized for estimated uncollectible accounts receivable for the three months ended March 31, 2018 .

Regulatory Matters

Regulatory Matters	3 Months Ended
	Mar. 31, 2018
Public Utilities, General Disclosures [Abstract]
Regulatory Matters	REGULATORY MATTERS 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 implemented regulatory accounting treatment. As such, beginning January 1, 2018, pension and postretirement cost components previously included as capital overhead are being deferred. 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 . On April 18, 2018, the MPSC issued an order approving an annual revenue increase of $65.2 million for service rendered on or after May 1, 2018. The MPSC authorized a return on equity of 10.0% . DTE Electric has recorded a refund liability of $25 million , representing the total estimated refund due to customers, inclusive of interest, at March 31, 2018 . 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 requests an increase in return on equity from 10.1% to 10.5% and includes projected changes in sales, operations, maintenance expenses, and working capital. To mitigate the impact to its customers resulting from ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715), DTE Gas suggested regulatory accounting treatment, consistent with the methodology approved by the MPSC in the 2017 DTE Electric Rate Case order. As such, beginning January 1, 2018, pension and postretirement cost components previously included as capital overhead are being deferred. 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 their recommended method to flow the current and deferred tax benefits of those impacts to ratepayers. On February 22, 2018, the MPSC issued an order in this case requiring utilities, including DTE Electric and DTE Gas, to follow a 3-step approach of credits and calculations. The first step is to establish Credit A, through contested cases. Credit A is a going-forward tax credit to reflect the reduction of the corporate tax rate from 35% to 21%. DTE Gas submitted its Credit A filing on March 28, 2018, reflecting a reduction in revenues of $38.2 million . The proposed new rates are expected to be effective July 1, 2018. DTE Electric is required to file its Credit A application by May 18, 2018. The second step is to establish Credit B, through contested cases. Credit B is a backward-looking tax credit to reflect the reduction of the corporate rate of 35% to 21%, for the period January 1, 2018 through the date Credit A is established. The Credit B filing is required within sixty days after Credit A is implemented. DTE Electric and DTE Gas have been deferring the impact of the reduction to the corporate tax rate since January 1, 2018. The third step is to perform Calculation C, through contested cases. Calculation C will address all remaining issues relative to the new tax law, which is primarily the remeasurement of deferred taxes and how the amounts deferred as Regulatory liabilities will flow to ratepayers. DTE Electric and DTE Gas are required to file Calculation C no later than October 1, 2018, unless they file a new general rate case prior to October 1, 2018, and address Calculation C within that filing.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Earnings Per Share	EARNINGS PER SHARE Basic earnings per share is calculated by dividing the net income, adjusted for income allocated to participating securities, by the weighted average number of common shares outstanding during the period. Diluted earnings per share reflect the dilution that would occur if any potentially dilutive instruments were exercised or converted into common shares. DTE Energy’s participating securities are restricted shares under the stock incentive program that contain rights to receive non-forfeitable dividends. Equity units, performance shares, and stock options do not receive cash dividends; as such, these awards are not considered participating securities. The following is a reconciliation of DTE Energy's basic and diluted income per share calculation: Three Months Ended March 31, 2018 2017 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 361 $ 400 Less: Allocation of earnings to net restricted stock awards 1 1 Net income available to common shareholders — basic $ 360 $ 399 Average number of common shares outstanding 180 179 Basic Earnings per Common Share $ 2.01 $ 2.23 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 361 $ 400 Less: Allocation of earnings to net restricted stock awards 1 1 Net income available to common shareholders — diluted $ 360 $ 399 Average number of common shares outstanding 180 179 Diluted Earnings per Common Share (a) $ 2.00 $ 2.23 _______________________________________ (a) The 2016 Equity Units excluded from the calculation of diluted EPS were approximately 6.6 million and 6.8 million for the three months ended March 31, 2018 and 2017 , respectively, as the dilutive stock price threshold was not met.

Fair Value

Fair Value	3 Months Ended
	Mar. 31, 2018
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 March 31, 2018 and December 31, 2017 . 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: March 31, 2018 December 31, 2017 Level Level Level Other (a) Netting (b) Net Balance Level Level Level Other (a) Netting (b) Net Balance (In millions) Assets Cash equivalents (c) $ 16 $ — $ — $ — $ — $ 16 $ 16 $ 3 $ — $ — $ — $ 19 Nuclear decommissioning trusts Equity securities 933 — — — — 933 978 — — — — 978 Fixed income securities 14 516 — — — 530 18 477 — — — 495 Private equity securities — — — 5 — 5 — — — 5 — 5 Cash equivalents 13 — — — — 13 14 — — — — 14 Other investments (d) Equity securities 117 — — — — 117 118 — — — — 118 Fixed income securities 70 — — — — 70 72 — — — — 72 Cash equivalents 4 — — — — 4 4 — — — — 4 Derivative assets Commodity contracts Natural gas 49 92 66 — (118 ) 89 148 112 97 — (256 ) 101 Electricity — 162 21 — (135 ) 48 — 243 42 — (241 ) 44 Other — — 5 — — 5 — — 9 — — 9 Foreign currency exchange contracts — 2 — — (2 ) — — 1 — — (1 ) — Total derivative assets 49 256 92 — (255 ) 142 148 356 148 — (498 ) 154 Total $ 1,216 $ 772 $ 92 $ 5 $ (255 ) $ 1,830 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Derivative liabilities Commodity contracts Natural gas $ (58 ) $ (62 ) $ (76 ) $ — $ 126 $ (70 ) $ (141 ) $ (111 ) $ (126 ) $ — $ 263 $ (115 ) Electricity — (164 ) (34 ) — 142 (56 ) — (245 ) (30 ) — 246 (29 ) Other — — (1 ) — — (1 ) — — (1 ) — 1 — Foreign currency exchange contracts — (2 ) — — 2 — — (3 ) — — 1 (2 ) Total derivative liabilities (58 ) (228 ) (111 ) — 270 (127 ) (141 ) (359 ) (157 ) — 511 (146 ) Total $ (58 ) $ (228 ) $ (111 ) $ — $ 270 $ (127 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,158 $ 544 $ (19 ) $ 5 $ 15 $ 1,703 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 Assets Current $ 65 $ 194 $ 51 $ — $ (210 ) $ 100 $ 157 $ 298 $ 104 $ — $ (437 ) $ 122 Noncurrent 1,151 578 41 5 (45 ) 1,730 1,211 538 44 5 (61 ) 1,737 Total Assets $ 1,216 $ 772 $ 92 $ 5 $ (255 ) $ 1,830 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Current $ (53 ) $ (183 ) $ (53 ) $ — $ 220 $ (69 ) $ (137 ) $ (313 ) $ (108 ) $ — $ 459 $ (99 ) Noncurrent (5 ) (45 ) (58 ) — 50 (58 ) (4 ) (46 ) (49 ) — 52 (47 ) Total Liabilities $ (58 ) $ (228 ) $ (111 ) $ — $ 270 $ (127 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,158 $ 544 $ (19 ) $ 5 $ 15 $ 1,703 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 _______________________________________ (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 March 31, 2018 , equity securities of $16 million consisted of $8 million and $8 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2017 , equity securities of $19 million consisted of $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. (d) Excludes cash surrender value of life insurance investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis as of: March 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Other (a) Net Balance Level 1 Level 2 Level 3 Other (a) Net Balance (In millions) Assets Cash equivalents (b) $ 8 $ — $ — $ — $ 8 $ 8 $ 3 $ — $ — $ 11 Nuclear decommissioning trusts Equity securities 933 — — — 933 978 — — — 978 Fixed income securities 14 516 — — 530 18 477 — — 495 Private equity securities — — — 5 5 — — — 5 5 Cash equivalents 13 — — — 13 14 — — — 14 Other investments Equity securities 11 — — — 11 11 — — — 11 Derivative assets — FTRs — — 5 — 5 — — 9 — 9 Total $ 979 $ 516 $ 5 $ 5 $ 1,505 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 Assets Current $ 8 $ — $ 5 $ — $ 13 $ 8 $ 3 $ 9 $ — $ 20 Noncurrent 971 516 — 5 1,492 1,021 477 — 5 1,503 Total Assets $ 979 $ 516 $ 5 $ 5 $ 1,505 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) At March 31, 2018 , equity securities of $8 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. At December 31, 2017 , equity 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: Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of January 1 $ (29 ) $ 12 $ 8 $ (9 ) $ (96 ) $ 9 $ (1 ) $ (88 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 (3 ) — — (3 ) — — — — Total gains (losses) Included in earnings (70 ) 131 — 61 52 (9 ) 1 44 Recorded in Regulatory liabilities — — — — — — 2 2 Purchases, issuances, and settlements Settlements 92 (156 ) (4 ) (68 ) 29 (6 ) (4 ) 19 Net Assets (Liabilities) as of March 31 $ (10 ) $ (13 ) $ 4 $ (19 ) $ (15 ) $ (6 ) $ (2 ) $ (23 ) 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 March 31, 2018 and 2017 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ (58 ) $ (10 ) $ — $ (68 ) $ 35 $ (3 ) $ — $ 32 The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Electric: Three Months Ended March 31, 2018 2017 (In millions) Net Assets as of beginning of period $ 9 $ 2 Change in fair value recorded in Regulatory liabilities — 2 Purchases, issuances, and settlements Settlements (4 ) (3 ) Net Assets as of March 31 $ 5 $ 1 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets held at March 31, 2018 and 2017 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 3 $ — Derivatives are transferred between levels primarily due to changes in the source data used to construct price curves as a result of changes in market liquidity. Transfers in and transfers out are reflected as if they had occurred at the beginning of the period. There were no transfers between Levels 1 and 2 for the Registrants during the three months ended March 31, 2018 and 2017 , 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: March 31, 2018 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 66 $ (76 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.37 ) — $ 4.10 /MMBtu $ (0.08 )/MMBtu Electricity $ 21 $ (34 ) Discounted Cash Flow Forward basis price (per MWh) $ (6 ) — $ 8 /MWh $ — 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 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 following table presents the carrying amount and fair value of financial instruments for DTE Energy: March 31, 2018 December 31, 2017 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 $ 37 $ — $ — $ 37 $ 38 $ — $ — $ 38 Dividends payable $ 160 $ 160 $ — $ — $ 158 $ 158 $ — $ — Short-term borrowings $ 635 $ — $ 635 $ — $ 621 $ — $ 621 $ — Notes payable — Other (b) , excluding capital leases $ 12 $ — $ — $ 12 $ 12 $ — $ — $ 12 Long-term debt (c) $ 12,289 $ 1,874 $ 10,136 $ 813 $ 12,288 $ 1,939 $ 10,571 $ 764 _______________________________________ (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, and issuance costs. Excludes Capital lease obligations. The following table presents the carrying amount and fair value of financial instruments for DTE Electric: March 31, 2018 December 31, 2017 Carrying Fair Value Carrying Fair Value Amount Level 1 Level 2 Level 3 Amount Level 1 Level 2 Level 3 (In millions) Short-term borrowings — affiliates $ 142 $ — $ — $ 142 $ 116 $ — $ — $ 116 Short-term borrowings — other $ 380 $ — $ 380 $ — $ 238 $ — $ 238 $ — Notes payable — Other (b) , excluding capital leases $ 2 $ — $ — $ 2 $ 2 $ — $ — $ 2 Long-term debt (c) $ 6,018 $ — $ 6,194 $ 171 $ 6,017 $ — $ 6,441 $ 171 _______________________________________ (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 8 to the Consolidated Financial Statements, " Financial and Other Derivative Instruments ." Nuclear Decommissioning Trust Funds DTE Electric has a legal obligation to decommission its nuclear power plants following the expiration of its operating licenses. This obligation is reflected as an Asset retirement obligation on DTE Electric's Consolidated Statements of Financial Position. Rates approved by the MPSC provide for the recovery of decommissioning costs of Fermi 2 and the disposal of low-level radioactive waste. The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: March 31, 2018 December 31, 2017 (In millions) Fermi 2 $ 1,463 $ 1,475 Fermi 1 3 3 Low-level radioactive waste 15 14 $ 1,481 $ 1,492 The costs of securities sold are determined on the basis of specific identification. The following table sets forth DTE Electric's gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds: Three Months Ended March 31, 2018 2017 (In millions) Realized gains $ 23 $ 23 Realized losses $ (9 ) $ (8 ) Proceeds from sale of securities $ 336 $ 394 Realized gains and losses from the sale of securities and unrealized gains and losses incurred by the Fermi 2 trust are recorded to the Regulatory asset and Nuclear decommissioning liability. Realized gains and losses from the sale of securities and unrealized gains and losses on the 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: March 31, 2018 December 31, 2017 Fair Unrealized Unrealized Fair Unrealized Unrealized (In millions) Equity securities $ 933 $ 302 $ (38 ) $ 978 $ 320 $ (32 ) Fixed income securities 530 8 (7 ) 495 13 (3 ) Private equity securities 5 — — 5 — — Cash equivalents 13 — — 14 — — $ 1,481 $ 310 $ (45 ) $ 1,492 $ 333 $ (35 ) The following table summarizes the fair value of the fixed income securities held in nuclear decommissioning trust funds by contractual maturity: March 31, 2018 (In millions) Due within one year $ 25 Due after one through five years 108 Due after five through ten years 117 Due after ten years 280 $ 530 Other Securities At March 31, 2018 and December 31, 2017 , the Registrants' securities were comprised primarily of money market and equity securities. Losses related to equity securities held at March 31, 2018 were $3 million and gains related to equity securities held at March 31, 2017 were $8 million for the Registrants. The 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	3 Months Ended
	Mar. 31, 2018
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 2021. 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 March 31, 2018 provision for credit losses, DTE Energy’s exposure to counterparty nonperformance is not expected to have a material adverse effect on DTE Energy's Consolidated Financial Statements. Derivative Activities DTE Energy manages its MTM risk on a portfolio basis based upon the delivery period of its contracts and the individual components of the risks within each contract. Accordingly, it records and manages the energy purchase and sale obligations under its contracts in separate components based on the commodity (e.g. electricity or natural gas), the product (e.g. electricity for delivery during peak or off-peak hours), the delivery location (e.g. by region), the risk profile (e.g. forward or option), and the delivery period (e.g. by month and year). The following describes the categories of activities represented by their operating characteristics and key risks: • Asset Optimization — Represents derivative activity associated with assets owned and contracted by DTE Energy, including forward natural gas purchases and sales, natural gas transportation, and storage capacity. Changes in the value of derivatives in this category typically economically offset changes in the value of underlying non-derivative positions, which do not qualify for fair value accounting. The difference in accounting treatment of derivatives in this category and the underlying non-derivative positions can result in significant earnings volatility. • Marketing and Origination — Represents derivative activity transacted by originating substantially hedged positions with wholesale energy marketers, producers, end-users, utilities, retail aggregators, and alternative energy suppliers. • Fundamentals Based Trading — Represents derivative activity transacted with the intent of taking a view, capturing market price changes, or putting capital at risk. This activity is speculative in nature as opposed to hedging an existing exposure. • Other — Includes derivative activity at DTE Electric related to FTRs. Changes in the value of derivative contracts at DTE Electric are recorded as Derivative assets or liabilities, with an offset to Regulatory assets or liabilities as the settlement value of these contracts will be included in the PSCR mechanism when realized. The following table presents the fair value of derivative instruments for DTE Energy: March 31, 2018 December 31, 2017 Derivative Derivative Liabilities Derivative Derivative Liabilities (In millions) Derivatives not designated as hedging instruments Commodity contracts Natural gas $ 207 $ (196 ) $ 357 $ (378 ) Electricity 183 (198 ) 285 (275 ) Other 5 (1 ) 9 (1 ) Foreign currency exchange contracts 2 (2 ) 1 (3 ) Total derivatives not designated as hedging instruments $ 397 $ (397 ) $ 652 $ (657 ) Current $ 294 $ (289 ) $ 540 $ (558 ) Noncurrent 103 (108 ) 112 (99 ) Total derivatives $ 397 $ (397 ) $ 652 $ (657 ) The following table presents the fair value of derivative instruments for DTE Electric: March 31, 2018 December 31, 2017 (In millions) FTRs — Other current assets $ 5 $ 9 Total derivatives not designated as hedging instruments $ 5 $ 9 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 $1 million and $4 million outstanding at March 31, 2018 and December 31, 2017 , 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 $5 million and $4 million at March 31, 2018 and December 31, 2017 , 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 $18 million and $28 million as of March 31, 2018 and December 31, 2017 , respectively. 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 $22 million as of March 31, 2018 . 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 recorded cash collateral paid of $15 million and cash collateral received of $12 million not related to unrealized derivative positions as of March 31, 2018 . 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 . 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: March 31, 2018 December 31, 2017 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 $ 207 $ (118 ) $ 89 $ 357 $ (256 ) $ 101 Electricity 183 (135 ) 48 285 (241 ) 44 Other 5 — 5 9 — 9 Foreign currency exchange contracts 2 (2 ) — 1 (1 ) — Total derivative assets $ 397 $ (255 ) $ 142 $ 652 $ (498 ) $ 154 Derivative liabilities Commodity contracts Natural gas $ (196 ) $ 126 $ (70 ) $ (378 ) $ 263 $ (115 ) Electricity (198 ) 142 (56 ) (275 ) 246 (29 ) Other (1 ) — (1 ) (1 ) 1 — Foreign currency exchange contracts (2 ) 2 — (3 ) 1 (2 ) Total derivative liabilities $ (397 ) $ 270 $ (127 ) $ (657 ) $ 511 $ (146 ) 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: March 31, 2018 December 31, 2017 Derivative Assets Derivative Liabilities Derivative Assets Derivative Liabilities Current Noncurrent Current Noncurrent Current Noncurrent Current Noncurrent (In millions) Total fair value of derivatives $ 294 $ 103 $ (289 ) $ (108 ) $ 540 $ 112 $ (558 ) $ (99 ) Counterparty netting (205 ) (43 ) 205 43 (437 ) (52 ) 437 52 Collateral adjustment (5 ) (2 ) 15 7 — (9 ) 22 — Total derivatives as reported $ 84 $ 58 $ (69 ) $ (58 ) $ 103 $ 51 $ (99 ) $ (47 ) The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations is as follows: Derivatives not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for the Three Months Ended March 31, 2018 2017 (In millions) Commodity contracts Natural gas Operating Revenues — Non-utility operations $ (110 ) $ 57 Natural gas Fuel, purchased power, and gas — non-utility 52 61 Electricity Operating Revenues — Non-utility operations 129 (7 ) Other Operating Revenues — Non-utility operations (1 ) — Foreign currency exchange contracts Operating Revenues — Non-utility operations 2 — Total $ 72 $ 111 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 March 31, 2018 : Commodity Number of Units Natural gas (MMBtu) 1,858,053,782 Electricity (MWh) 38,397,695 Foreign currency exchange (Canadian dollars) 103,281,830 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 March 31, 2018 , 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 $513 million . As of March 31, 2018 , DTE Energy had $290 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 $230 million . The net remaining amount of $60 million is derived from the $513 million noted above.

Short-Term Credit Arrangements

Short-Term Credit Arrangements and Borrowings	3 Months Ended
	Mar. 31, 2018
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 March 31, 2018 , the total funded debt to total capitalization ratios for DTE Energy, DTE Electric, and DTE Gas were 0.53 to 1, 0.51 to 1, and 0.46 to 1, respectively, and were in compliance with this financial covenant. The availability under the facilities in place at March 31, 2018 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 March 31, 2018 Commercial paper issuances — 380 255 635 Letters of credit 221 — — 221 221 380 255 856 Net availability at March 31, 2018 $ 1,199 $ 20 $ 45 $ 1,264 DTE Energy has $9 million of other outstanding letters of credit which are used for various corporate purposes and are not included in the facilities described above. In conjunction with maintaining certain exchange traded risk management positions, DTE Energy may be required to post collateral with its clearing agent. DTE Energy has a demand financing agreement for up to $100 million with its clearing agent. The agreement, as amended, also allows for up to $50 million of additional margin financing provided that DTE Energy posts a letter of credit for the incremental amount and allows the right of setoff with posted collateral. At March 31, 2018 , the capacity under this facility was $125 million . The amount outstanding under this agreement was $84 million and $56 million at March 31, 2018 and December 31, 2017 , respectively, and was fully offset by the posted collateral.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2018
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 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 descriptions with the 2015 ozone standards by the second quarter of 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 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, in 2015 the EPA finalized performance standards for emissions of carbon dioxide from new and existing EGUs. 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. 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 2014. 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 March 31, 2018 and December 31, 2017 , DTE Electric had $6 million accrued for remediation. Any change in assumptions, such as remediation techniques, nature and extent of contamination, and regulatory requirements, could impact the estimate of remedial action costs for the sites and affect DTE Electric’s financial position and cash flows. DTE Electric believes the likelihood of a material change to the accrued amount is remote based on current knowledge of the conditions at each site. Coal Combustion Residuals and Effluent Limitations Guidelines — A final EPA rule for the disposal of coal combustion residuals, commonly known as coal ash, became effective in October 2015, and was revised in October 2016. On March 15, 2018, the EPA published a proposed rule for public comment that is expected to be issued in final form in 2019. Some of the proposed rule provisions could change compliance and closure plans for CCR units if included in the final rule. 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 CCR requirements, costs associated with the building of new facilities or installation of controls are estimated to be approximately $283 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 March 31, 2018 and December 31, 2017 , DTE Gas had $40 million and $41 million accrued for remediation, respectively. Any change in assumptions, such as remediation techniques, nature and extent of contamination, and regulatory requirements, could impact the estimate of remedial action costs for the sites and affect DTE Gas' financial position and cash flows. DTE Gas anticipates the cost amortization methodology approved by the MPSC, which allows for amortization of the MGP costs over a ten -year period beginning with the year subsequent to the year the MGP costs were incurred, will prevent environmental costs from having a material adverse impact on DTE Gas' results of operations. Non-utility DTE Energy's non-utility businesses are subject to a number of environmental laws and regulations dealing with the protection of the environment from various pollutants. Other In 2010, the EPA finalized a new one -hour SO 2 ambient air quality standard that requires states to submit plans and associated timelines for non-attainment areas that demonstrate attainment with the new SO 2 standard in phases. Phase 1 addresses non-attainment areas designated based on ambient monitoring data. Phase 2 addresses non-attainment areas with large sources of SO 2 and modeled concentrations exceeding the National Ambient Air Quality Standards for SO 2 . Phase 3 addresses smaller sources of SO 2 with modeled or monitored exceedances of the new SO 2 standard. Michigan's Phase 1 non-attainment area includes DTE Energy facilities in southwest Detroit and areas of Wayne County. Modeling runs by the MDEQ suggest that emission reductions may be required by significant sources of SO 2 emissions in these areas, including DTE Electric power plants and DTE Energy's Michigan coke battery facility. As part of the state implementation plan process, DTE Energy has worked with the MDEQ to develop air permits reflecting significant SO 2 emission reductions that, in combination with other non-DTE Energy sources' emission reduction strategies, will help the state attain the standard and sustain its attainment. Since several non-DTE Energy sources are also part of the proposed compliance plan, DTE Energy is unable to determine the full impact of the final required emissions reductions at this time. Michigan's Phase 2 non-attainment area includes DTE Electric facilities in St. Clair County. State implementation plan (SIP) submittal and EPA approval describing the control strategy and timeline for demonstrating compliance with the new SO 2 standard is the next step in the process, expected to be completed by the end of the year. 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. 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 March 31, 2018 was approximately $400 million . Payments under these guarantees are 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 March 31, 2018 was approximately $420 million . Payments under these guarantees are 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 $82 million and $11 million at March 31, 2018 , 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 March 31, 2018 . Payments under these guarantees are 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 March 31, 2018 , DTE Energy had $59 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 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 5 and 8 to the Consolidated Financial Statements, " Regulatory Matters " and " Financial and Other Derivative Instruments ," respectively.

Retirement Benefits and Trustee

Retirement Benefits and Trusteed Assets	3 Months Ended
	Mar. 31, 2018
Defined Benefit Plan [Abstract]
Retirement Benefits and Trusteed Assets	RETIREMENT BENEFITS AND TRUSTEED ASSETS The following tables detail the components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits for DTE Energy: Pension Benefits Other Postretirement Benefits 2018 2017 2018 2017 Three Months Ended March 31, (In millions) Service cost $ 25 $ 24 $ 7 $ 7 Interest cost 50 54 17 18 Expected return on plan assets (82 ) (78 ) (36 ) (33 ) Amortization of: Net actuarial loss 44 43 3 3 Prior service credit — — — (3 ) Net periodic benefit cost (credit) $ 37 $ 43 $ (9 ) $ (8 ) DTE Electric participates in various plans that provide pension and other postretirement benefits for DTE Energy and its affiliates. The plans are sponsored by DTE Energy's subsidiary, DTE Energy Corporate Services, 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 participants. 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 $30 million and $35 million for the three months ended March 31, 2018 and 2017 , respectively. These amounts include recognized contractual termination benefit charges, curtailment gains, and settlement charges. The following tables detail the components of net periodic benefit costs (credits) for other postretirement benefits for DTE Electric: Other Postretirement Benefits 2018 2017 Three Months Ended March 31, (In millions) Service cost $ 5 $ 5 Interest cost 13 14 Expected return on plan assets (24 ) (23 ) Amortization of: Net actuarial loss 2 2 Prior service credit — (2 ) Net periodic benefit credit $ (4 ) $ (4 ) Pension and Other Postretirement Contributions During 2018 , DTE Energy contributed the following amounts of DTE Energy common stock to the DTE Energy Company Affiliates Employee Benefit Plans Master Trust: Date Number of Shares Price per Share Amount (In millions) March 7, 2018 1,751,401 $99.92 $ 175 The above contribution was made on behalf of DTE Electric, who paid DTE Energy cash consideration of $175 million in March 2018. During the first three months of 2017, DTE Energy made cash contributions of $126 million , including contributions from DTE Electric of $125 million , to its pension plans. At the discretion of management and depending upon financial market conditions, DTE Energy may make additional contributions up to $25 million to its pension plans in 2018 , with no additional contributions planned from DTE Electric. DTE Energy does not anticipate making any contributions to the other postretirement benefit plans in 2018 .

Segment and Related Information

Segment and Related Information	3 Months Ended
	Mar. 31, 2018
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 is primarily engaged in services related to the gathering, transportation, and storage of natural gas. 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 and pipeline-quality gas from renewable energy projects. Energy Trading consists of energy marketing and trading operations. Corporate and Other includes various holding company activities, holds certain non-utility debt, and holds energy-related investments. The federal income tax provisions or benefits of DTE Energy’s subsidiaries are determined on an individual company basis and recognize the tax benefit of tax credits and net operating losses, if applicable. The state and local income tax provisions of the utility subsidiaries are determined on an individual company basis and recognize the tax benefit of various tax credits and net operating losses, if applicable. The subsidiaries record federal, state, and local income taxes payable to or receivable from DTE Energy based on the federal, state, and local tax provisions of each company. Inter-segment billing for goods and services exchanged between segments is based upon tariffed or market-based prices of the provider and primarily consists of the sale of reduced emissions fuel, power sales, and natural gas sales in the following segments: Three Months Ended March 31, 2018 2017 (In millions) Electric $ 13 $ 12 Gas 2 3 Gas Storage and Pipelines 8 7 Power and Industrial Projects 155 168 Energy Trading 7 11 Corporate and Other 1 1 $ 186 $ 202 Financial data of DTE Energy's business segments follows: Three Months Ended March 31, 2018 2017 (In millions) Operating Revenues — Utility operations Electric $ 1,205 $ 1,175 Gas 550 557 Operating Revenues — Non-utility operations Gas Storage and Pipelines 119 105 Power and Industrial Projects 567 548 Energy Trading 1,498 1,052 Corporate and Other — 1 Reconciliation and Eliminations (186 ) (202 ) Total $ 3,753 $ 3,236 Net Income (Loss) Attributable to DTE Energy by Segment: Electric $ 140 $ 106 Gas 104 107 Gas Storage and Pipelines 62 45 Power and Industrial Projects 45 30 Energy Trading 31 96 Corporate and Other (21 ) 16 Net Income Attributable to DTE Energy Company $ 361 $ 400

Significant Accounting Polici21

Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The Consolidated Financial Statements should be read in conjunction with the Combined Notes to Consolidated Financial Statements included in the combined DTE Energy and DTE Electric 2017 Annual Report on Form 10-K. The accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The Consolidated Financial Statements are unaudited but, in the Registrants' opinions include all adjustments necessary to present a fair statement of the results for the interim periods. All adjustments are of a normal recurring nature, except as otherwise disclosed in these Consolidated Financial Statements and Combined Notes to Consolidated Financial Statements. Financial results for this interim period are not necessarily indicative of results that may be expected for any other interim period or for the fiscal year ending December 31, 2018 . 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 DTE Energy 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. The Registrants have variable interests in NEXUS, which include DTE Energy's 50% ownership interest and DTE Electric's transportation services contract. 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 its ownership interest in 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 March 31, 2018 , 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 March 31, 2018 , 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 10 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 10 to the Consolidated Financial Statements, " Commitments and Contingencies ," for further discussion of the NEXUS guarantee arrangements.
Changes in Accumulated Other Comprehensive Income (Loss)	Changes in Accumulated Other Comprehensive Income (Loss) For the three months ended March 31, 2018 and 2017 , reclassifications out of Accumulated other comprehensive income (loss) for the Registrants were not material. Changes in Accumulated other comprehensive income (loss) are presented in DTE Energy's Consolidated Statements of Changes in Equity and DTE Electric's Consolidated Statements of Changes in Shareholder's Equity. For further discussion regarding changes in Accumulated other comprehensive income (loss), see Note 3 to the Consolidated Financial Statements, " New Accounting Pronouncements ."
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.
Recently Adopted and Recently Issued Pronouncements	Recently Adopted 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 required 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 adopted the standard effective January 1, 2018 using the modified retrospective approach. Under the modified retrospective approach, the information for periods prior to the adoption date has not been restated and continues to be reported under the accounting standards in effect for those periods. As permitted under the standard, the Registrants have elected to apply the guidance only to those contracts that were not completed at January 1, 2018, and have elected not to restate the impacts of any contract modifications made prior to the earliest period presented. The adoption of the ASU did not have a significant impact on the Registrants' financial position or results of operations, but required additional disclosures for revenue. See Note 4 to the Consolidated Financial Statements, " Revenue ." 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 required 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 of income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The Registrants adopted the standard effective January 1, 2018. The standard has been 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. As permitted by the standard, the Registrants have used benefit cost amounts disclosed for prior periods as the basis for retrospective application in the income statement. As a result of regulatory mechanisms, the impact to the Consolidated Financial Statements was not material for the first quarter of 2018. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments — Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities , as amended. The new guidance is intended to improve the recognition and measurement of financial instruments. The guidance primarily impacts accounting for equity investments in unconsolidated entities (other than those accounted for using the equity method of accounting) and financial liabilities under the fair value option. The guidance requires equity investments to be generally measured at fair value, with subsequent changes in fair value recognized in net income. The guidance requires entities to make a cumulative-effect adjustment to the Statements of Financial Position as of the beginning of the first reporting period in which the guidance is effective. The Registrants adopted the standard effective January 1, 2018. Upon adoption, DTE Energy and DTE Electric recorded a cumulative-effect adjustment to reclassify $5 million and $3 million of unrealized gains from Accumulated other comprehensive income (loss) to Retained earnings, respectively. In March 2018, the FASB issued ASU No. 2018-05, Income Taxes (Topic 740): Amendments to SEC paragraphs pursuant to SEC Staff Accounting Bulletin No. 118 . The Amendments in this update add various SEC paragraphs pursuant to the issuance of SEC Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118) . SAB 118 directs 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. As described in Note 10 to the Consolidated Financial Statements, "Income Taxes," within the combined DTE Energy and DTE Electric 2017 Annual Report on Form 10-K and in accordance with SAB 118, the Registrants recorded amounts that were considered provisional. In first quarter of 2018, DTE Energy and DTE Electric recorded true-up adjustments to the remeasurement of deferred taxes of $21 million and $8 million , respectively. The impact of the true-up adjustments was an increase in Income Tax Expense, of which $16 million was attributable to the regulated utilities and offset to Regulatory liabilities. The true-up adjustments were a result of further analysis for items subject to further consideration at December 31, 2017 under SAB 118 and primarily related to timing differences not recoverable from DTE Electric and DTE Gas customers. The Registrants will continue to analyze the amounts throughout 2018, which may result in additional changes. Recently Issued Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), as amended. This guidance requires a lessee to account for leases as finance or operating leases, and disclose 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, depending on the lease classification. The Registrants will adopt the standard on January 1, 2019. As originally issued, the standard requires a modified retrospective approach for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements. The Registrants are evaluating the transition practical expedients available under the guidance, such as retaining the current lease assessment and classifications for existing leases at the effective date, and not applying the new guidance to land easements that exist or expire before the effective date. A third-party software tool is being implemented that will assist with the initial adoption and ongoing compliance of the standard. The Registrants are evaluating contracts for leases and abstracting the required data, as well as evaluating new business processes, internal controls, and accounting policies. In addition, the Registrants are monitoring utility industry implementation issues for purchase power agreements, pipeline laterals, and other industry specific arrangements. While the Registrants expect an increase in assets and liabilities, as well as additional disclosures, they are still assessing the impact of this ASU on their Consolidated Financial Statements. 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 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.
Revenue Recognition	Upon the adoption of Topic 606, revenue is measured based upon the consideration specified in a contract with a customer at the time when performance obligations are satisfied. Under Topic 606, a performance obligation is a promise in a contract to transfer a distinct good or service or a series of distinct goods or services to the customer. The Registrants recognize revenue when performance obligations are satisfied by transferring control over a product or service to a customer. The Registrants have determined control to be transferred when the product is delivered or the service is provided to the customer. For the three months ended March 31, 2018 , recognition of revenue for the Registrants subsequent to the adoption of Topic 606 is substantially similar in amount and approach to that prior to adoption. 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.
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 March 31, 2018 and December 31, 2017 . The Registrants believe they use valuation techniques that maximize the use of observable market-based inputs and minimize the use of unobservable inputs. A fair value hierarchy has been established that prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. All assets and liabilities are required to be classified in their entirety based on the lowest level of input that is significant to the fair value measurement in its entirety. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability, and may affect the valuation of the asset or liability and its placement within the fair value hierarchy. The Registrants classify fair value balances based on the fair value hierarchy defined as follows: • Level 1 — Consists of unadjusted quoted prices in active markets for identical assets or liabilities that the Registrants have the ability to access as of the reporting date. • Level 2 — Consists of inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. • Level 3 — Consists of unobservable inputs for assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost-benefit constraints.
Nuclear Decommissioning Trusts and Other Investments	Nuclear Decommissioning Trusts and Other Investments The nuclear decommissioning trusts and other investments hold debt and equity securities directly and indirectly through institutional mutual funds and commingled funds. 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.
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 2021. 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 March 31, 2018 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 $1 million and $4 million outstanding at March 31, 2018 and December 31, 2017 , 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 $5 million and $4 million at March 31, 2018 and December 31, 2017 , respectively. Such balances of letters of credit are excluded from the tables below and are not netted with the recognized assets and liabilities in DTE Energy's Consolidated Statements of Financial Position. For contracts with certain clearing agents, the fair value of derivative instruments is netted against realized positions with the net balance reflected as either 1) a Derivative asset or liability or 2) an Account receivable or payable. Other than certain clearing agents, Accounts receivable and Accounts payable that are subject to netting arrangements have not been offset against the fair value of Derivative assets and liabilities.
Derivatives, Methods of Accounting, Derivatives Not Designated or Qualifying as Hedges	Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility.
Income Tax	The federal income tax provisions or benefits of DTE Energy’s subsidiaries are determined on an individual company basis and recognize the tax benefit of tax credits and net operating losses, if applicable. The state and local income tax provisions of the utility subsidiaries are determined on an individual company basis and recognize the tax benefit of various tax credits and net operating losses, if applicable. The subsidiaries record federal, state, and local income taxes payable to or receivable from DTE Energy based on the federal, state, and local tax provisions of each company.

Organization and Basis of Pre22

Organization and Basis of Presentation (Tables)	3 Months Ended
	Mar. 31, 2018
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 March 31, 2018 and December 31, 2017 . 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. March 31, 2018 December 31, 2017 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 29 $ 12 $ 41 $ 23 $ 14 $ 37 Restricted cash — 8 8 — 8 8 Accounts receivable 11 37 48 11 42 53 Inventories 3 66 69 3 114 117 Property, plant, and equipment, net 386 73 459 400 75 475 Goodwill 25 — 25 25 — 25 Intangible assets 568 — 568 572 — 572 Other current and long-term assets 2 — 2 4 — 4 $ 1,024 $ 196 $ 1,220 $ 1,038 $ 253 $ 1,291 LIABILITIES Accounts payable and accrued current liabilities $ 2 $ 35 $ 37 $ 26 $ 47 $ 73 Current portion long-term debt, including capital leases — 4 4 — 4 4 Mortgage bonds, notes, and other — — — — 1 1 Other current and long-term liabilities 2 15 17 1 16 17 $ 4 $ 54 $ 58 $ 27 $ 68 $ 95 _____________________________________ (a) Amounts shown are 100% of SGG's assets and liabilities, of which DTE Energy owns 55% .
Summary of Amounts for Non-Consolidated Variable Interest Entities	Amounts for DTE Energy's non-consolidated VIEs are as follows: March 31, 2018 December 31, 2017 (In millions) Investments in equity method investees $ 866 $ 811 Notes receivable $ 17 $ 17 Future funding commitments $ 551 $ 598

Significant Accounting Polici23

Significant Accounting Policies (Tables)	3 Months Ended
	Mar. 31, 2018
Accounting Policies [Abstract]
Schedule of Other Income	The following is a summary of DTE Energy's Other income: Three Months Ended March 31, 2018 2017 (In millions) Income from REF entities $ 23 $ 18 Equity earnings of equity method investees 21 26 Contract services 20 4 Allowance for equity funds used during construction 7 7 Gains from equity securities — 8 Other 10 1 $ 81 $ 64 The following is a summary of DTE Electric's Other income: Three Months Ended March 31, 2018 2017 (In millions) Contract services $ 20 $ 4 Allowance for equity funds used during construction 5 6 Gains from equity securities allocated from DTE Energy — 8 Other 2 1 $ 27 $ 19
Schedule of Effective Tax Rate	The interim effective tax rate of the Registrants are as follows: Effective Tax Rate Three Months Ended March 31, 2018 2017 DTE Energy 16 % 22 % DTE Electric 25 % 35 %
Schedule of Cash and Cash Equivalents	The following is a table that provides a reconciliation of DTE Energy's Cash and cash equivalents as well as Restricted cash reported within the Consolidated Statements of Financial Position that sum to the total of the same such amounts shown in the Consolidated Statements of Cash Flows: Three Months Ended March 31, 2018 2017 (In millions) Cash and cash equivalents $ 164 $ 82 Restricted cash 22 20 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 186 $ 102
Schedule of Cash and Restricted Cash	The following is a table that provides a reconciliation of DTE Energy's Cash and cash equivalents as well as Restricted cash reported within the Consolidated Statements of Financial Position that sum to the total of the same such amounts shown in the Consolidated Statements of Cash Flows: Three Months Ended March 31, 2018 2017 (In millions) Cash and cash equivalents $ 164 $ 82 Restricted cash 22 20 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 186 $ 102

Revenue (Tables)

Revenue (Tables)	3 Months Ended
	Mar. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following is a summary of revenues disaggregated by segment for DTE Energy: Three Months Ended March 31, 2018 (In millions) Electric (a) Residential $ 586 Commercial 429 Industrial 176 Other (b) 14 Total Electric operating revenues (c) $ 1,205 Gas Gas sales $ 457 End User Transportation 85 Intermediate Transportation 18 Other (d) (10 ) Total Gas operating revenues (e) $ 550 Other segment operating revenues (f) Gas Storage and Pipelines $ 119 Power and Industrial Projects $ 567 Energy Trading $ 1,498 _______________________________________ (a) Revenues under the Electric segment generally represent those of DTE Electric. (b) Includes a reduction of $39 million in revenues related to TCJA rate reduction reserve. (c) Includes $5 million of other revenues which are outside the scope of Topic 606. (d) Includes a reduction of $32 million in revenues related to TCJA rate reduction reserve. (e) Includes a reduction of $3 million under Alternative Revenue Programs and $2 million of other revenues which are both outside the scope of Topic 606. (f) Includes revenues outside the scope of Topic 606 primarily related to $445 million of contracts accounted for as leases at the Power and Industrial Projects segment and $1.2 billion related to derivatives at the Energy Trading segment.
Contract with Customer, Liability	The following is a summary of deferred revenue activity: DTE Energy (In millions) Beginning Balance, January 1, 2018 $ 56 Increases due to cash received or receivable, excluding amounts recognized as revenue during the period 14 Revenue recognized that was included in the deferred revenue balance at the beginning of the period (16 ) Ending Balance, March 31, 2018 $ 54
Remaining Performance Obligation, Expected Timing of Satisfaction	The Registrants expect to recognize revenue for the following amounts related to fixed consideration associated with remaining performance obligations in each of the future periods noted: DTE Energy DTE Electric (In millions) 2018 $ 159 $ 6 2019 238 8 2020 168 — 2021 128 — 2022 103 — 2023 and thereafter 351 — Total $ 1,147 $ 14 The following table represents deferred revenue amounts for DTE Energy that are expected to be recognized as revenue in future periods: DTE Energy (In millions) 2018 $ 23 2019 9 2020 1 2021 5 2022 6 2023 and thereafter 10 $ 54

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Mar. 31, 2018
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted	The following is a reconciliation of DTE Energy's basic and diluted income per share calculation: Three Months Ended March 31, 2018 2017 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 361 $ 400 Less: Allocation of earnings to net restricted stock awards 1 1 Net income available to common shareholders — basic $ 360 $ 399 Average number of common shares outstanding 180 179 Basic Earnings per Common Share $ 2.01 $ 2.23 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 361 $ 400 Less: Allocation of earnings to net restricted stock awards 1 1 Net income available to common shareholders — diluted $ 360 $ 399 Average number of common shares outstanding 180 179 Diluted Earnings per Common Share (a) $ 2.00 $ 2.23 _______________________________________ (a) The 2016 Equity Units excluded from the calculation of diluted EPS were approximately 6.6 million and 6.8 million for the three months ended March 31, 2018 and 2017 , respectively, as the dilutive stock price threshold was not met.

Fair Value (Tables)

Fair Value (Tables)	3 Months Ended
	Mar. 31, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured and Recorded at Fair Value on a Recurring Basis	The following table presents assets and liabilities for DTE Energy measured and recorded at fair value on a recurring basis: March 31, 2018 December 31, 2017 Level Level Level Other (a) Netting (b) Net Balance Level Level Level Other (a) Netting (b) Net Balance (In millions) Assets Cash equivalents (c) $ 16 $ — $ — $ — $ — $ 16 $ 16 $ 3 $ — $ — $ — $ 19 Nuclear decommissioning trusts Equity securities 933 — — — — 933 978 — — — — 978 Fixed income securities 14 516 — — — 530 18 477 — — — 495 Private equity securities — — — 5 — 5 — — — 5 — 5 Cash equivalents 13 — — — — 13 14 — — — — 14 Other investments (d) Equity securities 117 — — — — 117 118 — — — — 118 Fixed income securities 70 — — — — 70 72 — — — — 72 Cash equivalents 4 — — — — 4 4 — — — — 4 Derivative assets Commodity contracts Natural gas 49 92 66 — (118 ) 89 148 112 97 — (256 ) 101 Electricity — 162 21 — (135 ) 48 — 243 42 — (241 ) 44 Other — — 5 — — 5 — — 9 — — 9 Foreign currency exchange contracts — 2 — — (2 ) — — 1 — — (1 ) — Total derivative assets 49 256 92 — (255 ) 142 148 356 148 — (498 ) 154 Total $ 1,216 $ 772 $ 92 $ 5 $ (255 ) $ 1,830 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Derivative liabilities Commodity contracts Natural gas $ (58 ) $ (62 ) $ (76 ) $ — $ 126 $ (70 ) $ (141 ) $ (111 ) $ (126 ) $ — $ 263 $ (115 ) Electricity — (164 ) (34 ) — 142 (56 ) — (245 ) (30 ) — 246 (29 ) Other — — (1 ) — — (1 ) — — (1 ) — 1 — Foreign currency exchange contracts — (2 ) — — 2 — — (3 ) — — 1 (2 ) Total derivative liabilities (58 ) (228 ) (111 ) — 270 (127 ) (141 ) (359 ) (157 ) — 511 (146 ) Total $ (58 ) $ (228 ) $ (111 ) $ — $ 270 $ (127 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,158 $ 544 $ (19 ) $ 5 $ 15 $ 1,703 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 Assets Current $ 65 $ 194 $ 51 $ — $ (210 ) $ 100 $ 157 $ 298 $ 104 $ — $ (437 ) $ 122 Noncurrent 1,151 578 41 5 (45 ) 1,730 1,211 538 44 5 (61 ) 1,737 Total Assets $ 1,216 $ 772 $ 92 $ 5 $ (255 ) $ 1,830 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Current $ (53 ) $ (183 ) $ (53 ) $ — $ 220 $ (69 ) $ (137 ) $ (313 ) $ (108 ) $ — $ 459 $ (99 ) Noncurrent (5 ) (45 ) (58 ) — 50 (58 ) (4 ) (46 ) (49 ) — 52 (47 ) Total Liabilities $ (58 ) $ (228 ) $ (111 ) $ — $ 270 $ (127 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,158 $ 544 $ (19 ) $ 5 $ 15 $ 1,703 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 _______________________________________ (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 March 31, 2018 , equity securities of $16 million consisted of $8 million and $8 million of cash equivalents included in Restricted cash and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2017 , equity securities of $19 million consisted of $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. (d) Excludes cash surrender value of life insurance investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis as of: March 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Other (a) Net Balance Level 1 Level 2 Level 3 Other (a) Net Balance (In millions) Assets Cash equivalents (b) $ 8 $ — $ — $ — $ 8 $ 8 $ 3 $ — $ — $ 11 Nuclear decommissioning trusts Equity securities 933 — — — 933 978 — — — 978 Fixed income securities 14 516 — — 530 18 477 — — 495 Private equity securities — — — 5 5 — — — 5 5 Cash equivalents 13 — — — 13 14 — — — 14 Other investments Equity securities 11 — — — 11 11 — — — 11 Derivative assets — FTRs — — 5 — 5 — — 9 — 9 Total $ 979 $ 516 $ 5 $ 5 $ 1,505 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 Assets Current $ 8 $ — $ 5 $ — $ 13 $ 8 $ 3 $ 9 $ — $ 20 Noncurrent 971 516 — 5 1,492 1,021 477 — 5 1,503 Total Assets $ 979 $ 516 $ 5 $ 5 $ 1,505 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) At March 31, 2018 , equity securities of $8 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position.
Fair Value Reconciliation of Level 3 Assets and Liabilities Measured at Fair Value on a Recurring Basis	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: Three Months Ended March 31, 2018 Three Months Ended March 31, 2017 Natural Gas Electricity Other Total Natural Gas Electricity Other Total (In millions) Net Assets (Liabilities) as of January 1 $ (29 ) $ 12 $ 8 $ (9 ) $ (96 ) $ 9 $ (1 ) $ (88 ) Transfers into Level 3 from Level 2 — — — — — — — — Transfers from Level 3 into Level 2 (3 ) — — (3 ) — — — — Total gains (losses) Included in earnings (70 ) 131 — 61 52 (9 ) 1 44 Recorded in Regulatory liabilities — — — — — — 2 2 Purchases, issuances, and settlements Settlements 92 (156 ) (4 ) (68 ) 29 (6 ) (4 ) 19 Net Assets (Liabilities) as of March 31 $ (10 ) $ (13 ) $ 4 $ (19 ) $ (15 ) $ (6 ) $ (2 ) $ (23 ) 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 March 31, 2018 and 2017 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations $ (58 ) $ (10 ) $ — $ (68 ) $ 35 $ (3 ) $ — $ 32 The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Electric: Three Months Ended March 31, 2018 2017 (In millions) Net Assets as of beginning of period $ 9 $ 2 Change in fair value recorded in Regulatory liabilities — 2 Purchases, issuances, and settlements Settlements (4 ) (3 ) Net Assets as of March 31 $ 5 $ 1 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets held at March 31, 2018 and 2017 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 3 $ —
Unobservable Inputs Related to Level 3 Assets and Liabilities	The following tables present the unobservable inputs related to DTE Energy's Level 3 assets and liabilities: March 31, 2018 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 66 $ (76 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (1.37 ) — $ 4.10 /MMBtu $ (0.08 )/MMBtu Electricity $ 21 $ (34 ) Discounted Cash Flow Forward basis price (per MWh) $ (6 ) — $ 8 /MWh $ — 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
Carrying Amount of Fair Value of Financial Instruments	The following table presents the carrying amount and fair value of financial instruments for DTE Energy: March 31, 2018 December 31, 2017 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 $ 37 $ — $ — $ 37 $ 38 $ — $ — $ 38 Dividends payable $ 160 $ 160 $ — $ — $ 158 $ 158 $ — $ — Short-term borrowings $ 635 $ — $ 635 $ — $ 621 $ — $ 621 $ — Notes payable — Other (b) , excluding capital leases $ 12 $ — $ — $ 12 $ 12 $ — $ — $ 12 Long-term debt (c) $ 12,289 $ 1,874 $ 10,136 $ 813 $ 12,288 $ 1,939 $ 10,571 $ 764 _______________________________________ (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, and issuance costs. Excludes Capital lease obligations. The following table presents the carrying amount and fair value of financial instruments for DTE Electric: March 31, 2018 December 31, 2017 Carrying Fair Value Carrying Fair Value Amount Level 1 Level 2 Level 3 Amount Level 1 Level 2 Level 3 (In millions) Short-term borrowings — affiliates $ 142 $ — $ — $ 142 $ 116 $ — $ — $ 116 Short-term borrowings — other $ 380 $ — $ 380 $ — $ 238 $ — $ 238 $ — Notes payable — Other (b) , excluding capital leases $ 2 $ — $ — $ 2 $ 2 $ — $ — $ 2 Long-term debt (c) $ 6,018 $ — $ 6,194 $ 171 $ 6,017 $ — $ 6,441 $ 171 _______________________________________ (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: March 31, 2018 December 31, 2017 (In millions) Fermi 2 $ 1,463 $ 1,475 Fermi 1 3 3 Low-level radioactive waste 15 14 $ 1,481 $ 1,492
Schedule of Realized Gains and Losses and Proceeds from Sale of Securities by Nuclear Decommissioning Trust Funds	The following table sets forth DTE Electric's gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds: Three Months Ended March 31, 2018 2017 (In millions) Realized gains $ 23 $ 23 Realized losses $ (9 ) $ (8 ) Proceeds from sale of securities $ 336 $ 394
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: March 31, 2018 December 31, 2017 Fair Unrealized Unrealized Fair Unrealized Unrealized (In millions) Equity securities $ 933 $ 302 $ (38 ) $ 978 $ 320 $ (32 ) Fixed income securities 530 8 (7 ) 495 13 (3 ) Private equity securities 5 — — 5 — — Cash equivalents 13 — — 14 — — $ 1,481 $ 310 $ (45 ) $ 1,492 $ 333 $ (35 )
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: March 31, 2018 (In millions) Due within one year $ 25 Due after one through five years 108 Due after five through ten years 117 Due after ten years 280 $ 530

Financial and Other Derivativ27

Financial and Other Derivative Instruments (Tables)	3 Months Ended
	Mar. 31, 2018
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Fair Value of Derivative Instruments	The following table presents the fair value of derivative instruments for DTE Energy: March 31, 2018 December 31, 2017 Derivative Derivative Liabilities Derivative Derivative Liabilities (In millions) Derivatives not designated as hedging instruments Commodity contracts Natural gas $ 207 $ (196 ) $ 357 $ (378 ) Electricity 183 (198 ) 285 (275 ) Other 5 (1 ) 9 (1 ) Foreign currency exchange contracts 2 (2 ) 1 (3 ) Total derivatives not designated as hedging instruments $ 397 $ (397 ) $ 652 $ (657 ) Current $ 294 $ (289 ) $ 540 $ (558 ) Noncurrent 103 (108 ) 112 (99 ) Total derivatives $ 397 $ (397 ) $ 652 $ (657 ) The following table presents the fair value of derivative instruments for DTE Electric: March 31, 2018 December 31, 2017 (In millions) FTRs — Other current assets $ 5 $ 9 Total derivatives not designated as hedging instruments $ 5 $ 9
Netting Offsets of Derivative Assets and Liabilities	The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy: March 31, 2018 December 31, 2017 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 $ 207 $ (118 ) $ 89 $ 357 $ (256 ) $ 101 Electricity 183 (135 ) 48 285 (241 ) 44 Other 5 — 5 9 — 9 Foreign currency exchange contracts 2 (2 ) — 1 (1 ) — Total derivative assets $ 397 $ (255 ) $ 142 $ 652 $ (498 ) $ 154 Derivative liabilities Commodity contracts Natural gas $ (196 ) $ 126 $ (70 ) $ (378 ) $ 263 $ (115 ) Electricity (198 ) 142 (56 ) (275 ) 246 (29 ) Other (1 ) — (1 ) (1 ) 1 — Foreign currency exchange contracts (2 ) 2 — (3 ) 1 (2 ) Total derivative liabilities $ (397 ) $ 270 $ (127 ) $ (657 ) $ 511 $ (146 )
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: March 31, 2018 December 31, 2017 Derivative Assets Derivative Liabilities Derivative Assets Derivative Liabilities Current Noncurrent Current Noncurrent Current Noncurrent Current Noncurrent (In millions) Total fair value of derivatives $ 294 $ 103 $ (289 ) $ (108 ) $ 540 $ 112 $ (558 ) $ (99 ) Counterparty netting (205 ) (43 ) 205 43 (437 ) (52 ) 437 52 Collateral adjustment (5 ) (2 ) 15 7 — (9 ) 22 — Total derivatives as reported $ 84 $ 58 $ (69 ) $ (58 ) $ 103 $ 51 $ (99 ) $ (47 )
Gain (Loss) Recognized in Income on Derivatives	The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations is as follows: Derivatives not Designated as Hedging Instruments Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for the Three Months Ended March 31, 2018 2017 (In millions) Commodity contracts Natural gas Operating Revenues — Non-utility operations $ (110 ) $ 57 Natural gas Fuel, purchased power, and gas — non-utility 52 61 Electricity Operating Revenues — Non-utility operations 129 (7 ) Other Operating Revenues — Non-utility operations (1 ) — Foreign currency exchange contracts Operating Revenues — Non-utility operations 2 — Total $ 72 $ 111
Volume of Commodity Contracts	The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of March 31, 2018 : Commodity Number of Units Natural gas (MMBtu) 1,858,053,782 Electricity (MWh) 38,397,695 Foreign currency exchange (Canadian dollars) 103,281,830

Short-Term Credit Arrangement28

Short-Term Credit Arrangements and Borrowings (Tables)	3 Months Ended
	Mar. 31, 2018
Short-term Debt [Abstract]
Schedule of Line of Credit Facilities	The availability under the facilities in place at March 31, 2018 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 March 31, 2018 Commercial paper issuances — 380 255 635 Letters of credit 221 — — 221 221 380 255 856 Net availability at March 31, 2018 $ 1,199 $ 20 $ 45 $ 1,264

Retirement Benefits and Trust29

Retirement Benefits and Trusteed Assets (Tables)	3 Months Ended
	Mar. 31, 2018
Defined Benefit Plan [Abstract]
Schedule of Net Periodic Benefit Costs (Credits)	The following tables detail the components of net periodic benefit costs (credits) for other postretirement benefits for DTE Electric: Other Postretirement Benefits 2018 2017 Three Months Ended March 31, (In millions) Service cost $ 5 $ 5 Interest cost 13 14 Expected return on plan assets (24 ) (23 ) Amortization of: Net actuarial loss 2 2 Prior service credit — (2 ) Net periodic benefit credit $ (4 ) $ (4 ) The following tables detail the components of net periodic benefit costs (credits) for pension benefits and other postretirement benefits for DTE Energy: Pension Benefits Other Postretirement Benefits 2018 2017 2018 2017 Three Months Ended March 31, (In millions) Service cost $ 25 $ 24 $ 7 $ 7 Interest cost 50 54 17 18 Expected return on plan assets (82 ) (78 ) (36 ) (33 ) Amortization of: Net actuarial loss 44 43 3 3 Prior service credit — — — (3 ) Net periodic benefit cost (credit) $ 37 $ 43 $ (9 ) $ (8 )
Schedule of Defined Benefit Plans Disclosures	During 2018 , DTE Energy contributed the following amounts of DTE Energy common stock to the DTE Energy Company Affiliates Employee Benefit Plans Master Trust: Date Number of Shares Price per Share Amount (In millions) March 7, 2018 1,751,401 $99.92 $ 175

Segment and Related Informati30

Segment and Related Information (Tables)	3 Months Ended
	Mar. 31, 2018
Segment Reporting [Abstract]
Schedule of Segment Reporting Information, by Segment	Inter-segment billing for goods and services exchanged between segments is based upon tariffed or market-based prices of the provider and primarily consists of the sale of reduced emissions fuel, power sales, and natural gas sales in the following segments: Three Months Ended March 31, 2018 2017 (In millions) Electric $ 13 $ 12 Gas 2 3 Gas Storage and Pipelines 8 7 Power and Industrial Projects 155 168 Energy Trading 7 11 Corporate and Other 1 1 $ 186 $ 202 Financial data of DTE Energy's business segments follows: Three Months Ended March 31, 2018 2017 (In millions) Operating Revenues — Utility operations Electric $ 1,205 $ 1,175 Gas 550 557 Operating Revenues — Non-utility operations Gas Storage and Pipelines 119 105 Power and Industrial Projects 567 548 Energy Trading 1,498 1,052 Corporate and Other — 1 Reconciliation and Eliminations (186 ) (202 ) Total $ 3,753 $ 3,236 Net Income (Loss) Attributable to DTE Energy by Segment: Electric $ 140 $ 106 Gas 104 107 Gas Storage and Pipelines 62 45 Power and Industrial Projects 45 30 Energy Trading 31 96 Corporate and Other (21 ) 16 Net Income Attributable to DTE Energy Company $ 361 $ 400

Organization and Basis of Pre31

Organization and Basis of Presentation (Details Textuals) customer in Millions	Mar. 31, 2018USD ($)customer
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Number of electric utility customers | customer	2.2
Number of gas utility customers | customer	1.3
Significant potential exposure | $	$ 0
DTE Electric
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Significant potential exposure | $	$ 0
NEXUS pipeline
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ownership interest	50.00%
West Virginia | Midstream Natural Gas Assets
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Percent of assets acquired	55.00%

Organization and Basis of Pre32

Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
ASSETS
Cash and cash equivalents	$ 164	$ 66	$ 82
Restricted cash	22	23	$ 20
Accounts receivable	1,709	1,758
Property, plant, and equipment, net	20,870	20,721
Goodwill	2,293	2,293
Intangible assets	867	867
Total Assets	33,841	33,767
LIABILITIES
Current portion long-term debt, including capital leases	106	109
Mortgage bonds, notes, and other	11,040	11,039
Variable interest entity, primary beneficiary, restricted
ASSETS
Cash and cash equivalents	41	37
Restricted cash	8	8
Accounts receivable	48	53
Inventories	69	117
Property, plant, and equipment, net	459	475
Goodwill	25	25
Intangible assets	568	572
Other current and long-term assets	2	4
Total Assets	1,220	1,291
LIABILITIES
Accounts payable and accrued current liabilities	37	73
Current portion long-term debt, including capital leases	4	4
Mortgage bonds, notes, and other	0	1
Other current and long-term liabilities	17	17
Total liabilities	58	95
SGG
ASSETS
Cash and cash equivalents	29	23
Restricted cash	0	0
Accounts receivable	11	11
Inventories	3	3
Property, plant, and equipment, net	386	400
Goodwill	25	25
Intangible assets	568	572
Other current and long-term assets	2	4
Total Assets	1,024	1,038
LIABILITIES
Accounts payable and accrued current liabilities	2	26
Current portion long-term debt, including capital leases	0	0
Mortgage bonds, notes, and other	0	0
Other current and long-term liabilities	2	1
Total liabilities	$ 4	27
VIE ownership and non-ownership percentage	100.00%
VIE ownership percentage	55.00%
Other
ASSETS
Cash and cash equivalents	$ 12	14
Restricted cash	8	8
Accounts receivable	37	42
Inventories	66	114
Property, plant, and equipment, net	73	75
Goodwill	0	0
Intangible assets	0	0
Other current and long-term assets	0	0
Total Assets	196	253
LIABILITIES
Accounts payable and accrued current liabilities	35	47
Current portion long-term debt, including capital leases	4	4
Mortgage bonds, notes, and other	0	1
Other current and long-term liabilities	15	16
Total liabilities	$ 54	$ 68

Organization and Basis of Pre33

Organization and Basis of Presentation (Non-Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Variable Interest Entity [Line Items]
Investments in equity method investees	$ 1,141	$ 1,073
Notes receivable	70	73
Variable interest entity, non-consolidated
Variable Interest Entity [Line Items]
Investments in equity method investees	866	811
Notes receivable	17	17
Future funding commitments	$ 551	$ 598

Significant Accounting Polici34

Significant Accounting Policies Significant Accounting Policies (Other Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Other Nonoperating Income, by Component [Line Items]
Income from REF entities	$ 23	$ 18
Equity earnings of equity method investees	21	26
Contract services	20	4
Allowance for equity funds used during construction	7	7
Gains from equity securities	0	8
Other	10	1
Total other income	81	64
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Contract services	20	4
Allowance for equity funds used during construction	5	6
Gains from equity securities	0	8
Other	2	1
Total other income	$ 27	$ 19

Significant Accounting Polici35

Significant Accounting Policies (Income Taxes) (Details)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Income Taxes [Line Items]
Effective Tax Rate	16.00%	22.00%
DTE Electric
Schedule of Income Taxes [Line Items]
Effective Tax Rate	25.00%	35.00%

Significant Accounting Polici36

Significant Accounting Policies (Details Textuals) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Effective Tax Rate	16.00%	22.00%
Effective tax rate increase (decrease)	(6.00%)
Income tax (expense) benefit due to remeasurement of deferred taxes	$ 21
Measurement period increase (decrease) in effective tax rate	5.00%
ASU 2016-09 excess tax benefit amount	$ 10
ASU 2016-09 excess tax benefit (percentage)	2.00%
Unrecognized tax benefits	$ 8
Unrecognized tax benefits that would impact effective tax rate	8
Unrecognized compensation cost	$ 111
Recognition period (in years)	1 year 9 months
DTE Electric
Significant Accounting Policies [Line Items]
Effective Tax Rate	25.00%	35.00%
Effective tax rate increase (decrease)	(10.00%)
Income tax (expense) benefit due to remeasurement of deferred taxes	$ 8
Measurement period increase (decrease) in effective tax rate	4.00%
Unrecognized tax benefits	$ 10
Unrecognized tax benefits that would impact effective tax rate	10
DTE Electric | DTE Energy
Significant Accounting Policies [Line Items]
Income tax receivable	13			$ 12
Allocated costs	$ 9	$ 8
Forecast
Significant Accounting Policies [Line Items]
Effective Tax Rate			13.00%
Forecast | DTE Electric
Significant Accounting Policies [Line Items]
Effective Tax Rate			22.00%

Significant Accounting Polici37

Significant Accounting Policies (Cash and Restricted Cash) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Cash and cash equivalents	$ 164	$ 66	$ 82
Restricted cash	22	23	20
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows	$ 186	$ 89	$ 102	$ 113

New Accounting Pronouncements -

New Accounting Pronouncements - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		$ 0
Income tax (expense) benefit	$ 21
DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		0
Income tax (expense) benefit	8
Other Regulatory Assets (Liabilities)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Income tax (expense) benefit	$ 16
Accumulated Other Comprehensive Income (Loss)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		(5)
Accumulated Other Comprehensive Income (Loss) | DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		(3)
Accumulated Other Comprehensive Income (Loss) | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		(5)
Accumulated Other Comprehensive Income (Loss) | Accounting Standards Update 2016-01 | DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		(3)
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		5
Retained Earnings | DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		3
Retained Earnings | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		5
Retained Earnings | Accounting Standards Update 2016-01 | DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-01		$ 3

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Disaggregation of Revenue [Line Items]
Revenues	$ 3,753	$ 3,236
Electric
Disaggregation of Revenue [Line Items]
Revenues	1,205
Reduction of revenue due to Tax Cuts and Jobs Act	39
Other revenue outside scope of Topic 606	5
Electric | Residential
Disaggregation of Revenue [Line Items]
Revenues	586
Electric | Commercial
Disaggregation of Revenue [Line Items]
Revenues	429
Electric | Industrial
Disaggregation of Revenue [Line Items]
Revenues	176
Electric | Other
Disaggregation of Revenue [Line Items]
Revenues	14
Gas
Disaggregation of Revenue [Line Items]
Revenues	550
Reduction of revenue due to Tax Cuts and Jobs Act	32
Other revenue outside scope of Topic 606	2
Alternative revenue programs	(3)
Gas | Other
Disaggregation of Revenue [Line Items]
Revenues	(10)
Gas | Gas sales
Disaggregation of Revenue [Line Items]
Revenues	457
Gas | End User Transportation
Disaggregation of Revenue [Line Items]
Revenues	85
Gas | Intermediate Transportation
Disaggregation of Revenue [Line Items]
Revenues	18
Gas Storage and Pipelines
Disaggregation of Revenue [Line Items]
Revenues	119
Power and Industrial Projects
Disaggregation of Revenue [Line Items]
Revenues	567
Lease revenue outside scope of Topic 606	445
Energy Trading
Disaggregation of Revenue [Line Items]
Revenues	1,498
Gain (loss) on derivative outside scope of Topic 606	$ 1,200

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue from External Customer [Line Items]
Allowance for doubtful accounts receivable write-offs	$ 25
DTE Electric
Revenue from External Customer [Line Items]
Allowance for doubtful accounts receivable write-offs	$ 14
Other | Power and Industrial Projects
Revenue from External Customer [Line Items]
Payment terms	30 days

Revenue - Deferred Revenue (Det

Revenue - Deferred Revenue (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Contract Liability [Roll Forward]
Beginning Balance, January 1, 2018	$ 56
Increases due to cash received or receivable, excluding amounts recognized as revenue during the period	14
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(16)
Ending Balance, March 31, 2018	$ 54

Revenue - Expected Recognition

Revenue - Expected Recognition of Deferred Revenue (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 23
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 9
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 5
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 6
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 10
Remaining performance obligation, expected timing of satisfaction
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 54

Revenue - Expected Timing of Pe

Revenue - Expected Timing of Performance Obligation Satisfaction (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 23
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 9
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 5
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 6
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 10
Remaining performance obligation, expected timing of satisfaction
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 54
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 159
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2018-01-01 | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 6
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 238
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 8
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 168
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 128
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 103
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation, expected timing of satisfaction	1 year
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 351
Remaining performance obligation, expected timing of satisfaction
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
Remaining performance obligation, expected timing of satisfaction
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 1,147
Fixed-price Contract | Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 14

Regulatory Matters (Details Tex

Regulatory Matters (Details Textuals) $ in Millions	Apr. 18, 2018USD ($)	Mar. 28, 2018USD ($)	Nov. 22, 2017USD ($)	Nov. 01, 2017USD ($)	Apr. 19, 2017USD ($)	Mar. 31, 2018USD ($)	Jul. 31, 2017USD ($)certificateMW
DTE Electric | MPSC
Public Utilities, General Disclosures [Line Items]
Amount of power associated with natural gas fueled combined cycle generation facility requesting to build | MW							1,100
Number of certificates of necessity requested to be issued | certificate							3
Estimated capital costs							$ 989
DTE Electric | MPSC | Electric Rate Case Filing 2017
Public Utilities, General Disclosures [Line Items]
Requested rate increase				$ 125	$ 231
Return on equity percent					10.10%
Return on equity requested percent					10.50%
DTE Electric | MPSC | Electric Rate Case Filing 2017 | Refundable self-implemented rates
Public Utilities, General Disclosures [Line Items]
Regulatory liabilities						$ 25
DTE Gas
Public Utilities, General Disclosures [Line Items]
Reduction of revenue due to Tax Cuts and Jobs Act		$ 38.2
DTE Gas | MPSC | DTE Gas Rate Case Filing 2017
Public Utilities, General Disclosures [Line Items]
Requested rate increase			$ 85.1
Return on equity percent			10.10%
Return on equity requested percent			10.50%
Subsequent event | DTE Electric | MPSC | Electric Rate Case Filing 2017
Public Utilities, General Disclosures [Line Items]
Return on equity percent	10.00%
Approved rate increase	$ 65.2

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Basic Earnings per Share
Net Income Attributable to DTE Energy Company	$ 361	$ 400
Less: Allocation of earnings to net restricted stock awards	1	1
Net income available to common shareholders — basic	$ 360	$ 399
Average number of common shares outstanding (in shares)	180	179
Basic Earnings per Common Share (in dollars per share)	$ 2.01	$ 2.23
Diluted Earnings per Share
Net Income Attributable to DTE Energy Company	$ 361	$ 400
Less: Allocation of earnings to net restricted stock awards	1	1
Net income available to common shareholders — diluted	$ 360	$ 399
Average number of common shares outstanding (in shares)	180	179
Diluted Earnings per Common Share (in dollars per share)	$ 2	$ 2.23
Antidilutive securities excluded from computation of earnings per share (in shares)	6.6	6.8

Fair Value (Assets and Liabilit

Fair Value (Assets and Liabilities Recorded at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivative assets
Derivative assets, gross	$ 397	$ 652
Derivative asset, netting	(255)	(498)
Derivative assets, net	142	154
Derivative liabilities
Derivative liabilities, gross	(397)	(657)
Derivative liability, netting	270	511
Derivative liabilities, net	(127)	(146)
Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(289)	(558)
Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(108)	(99)
Natural gas
Derivative assets
Derivative assets, gross	207	357
Derivative asset, netting	(118)	(256)
Derivative assets, net	89	101
Derivative liabilities
Derivative liabilities, gross	(196)	(378)
Derivative liability, netting	126	263
Derivative liabilities, net	(70)	(115)
Electricity
Derivative assets
Derivative assets, gross	183	285
Derivative asset, netting	(135)	(241)
Derivative assets, net	48	44
Derivative liabilities
Derivative liabilities, gross	(198)	(275)
Derivative liability, netting	142	246
Derivative liabilities, net	(56)	(29)
Other
Derivative assets
Derivative assets, gross	5	9
Derivative asset, netting	0	0
Derivative assets, net	5	9
Derivative liabilities
Derivative liabilities, gross	(1)	(1)
Derivative liability, netting	0	1
Derivative liabilities, net	(1)	0
Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	2	1
Derivative asset, netting	(2)	(1)
Derivative assets, net	0	0
Derivative liabilities
Derivative liabilities, gross	(2)	(3)
Derivative liability, netting	2	1
Derivative liabilities, net	0	(2)
Recurring
Assets
Cash equivalents	16	19
Derivative assets
Derivative asset, netting	(255)	(498)
Derivative assets, net	142	154
Total assets	1,830	1,859
Private equity securities	5	5
Derivative liabilities
Derivative liability, netting	270	511
Derivative liabilities, net	(127)	(146)
Net Assets (Liabilities) at the end of the period	1,703	1,713
Net Assets (Liabilities) at the end of the period, netting	15	13
Recurring | DTE Electric
Assets
Cash equivalents	8	11
Derivative assets
Total assets	1,505	1,523
Private equity securities	5	5
Recurring | Current assets
Derivative assets
Derivative asset, netting	(210)	(437)
Total assets	100	122
Recurring | Current assets | DTE Electric
Derivative assets
Total assets	13	20
Recurring | Noncurrent assets
Derivative assets
Derivative asset, netting	(45)	(61)
Total assets	1,730	1,737
Private equity securities	5	5
Recurring | Noncurrent assets | DTE Electric
Derivative assets
Total assets	1,492	1,503
Private equity securities	5	5
Recurring | Current derivative liabilities
Derivative liabilities
Derivative liability, netting	220	459
Derivative liabilities, net	(69)	(99)
Recurring | Noncurrent derivative liabilities
Derivative liabilities
Derivative liability, netting	50	52
Derivative liabilities, net	(58)	(47)
Recurring | Restricted assets
Assets
Cash equivalents	8	8
Recurring | Other
Assets
Cash equivalents	8	11
Recurring | Other | DTE Electric
Assets
Cash equivalents	8	11
Recurring | Natural gas
Derivative assets
Derivative asset, netting	(118)	(256)
Derivative assets, net	89	101
Derivative liabilities
Derivative liability, netting	126	263
Derivative liabilities, net	(70)	(115)
Recurring | Electricity
Derivative assets
Derivative asset, netting	(135)	(241)
Derivative assets, net	48	44
Derivative liabilities
Derivative liability, netting	142	246
Derivative liabilities, net	(56)	(29)
Recurring | Other
Derivative assets
Derivative asset, netting	0	0
Derivative assets, net	5	9
Derivative liabilities
Derivative liability, netting	0	1
Derivative liabilities, net	(1)	0
Recurring | Foreign currency exchange contracts
Derivative assets
Derivative asset, netting	(2)	(1)
Derivative assets, net	0	0
Derivative liabilities
Derivative liability, netting	2	1
Derivative liabilities, net	0	(2)
Recurring | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	5	9
Recurring | Cash equivalents
Assets
Nuclear decommissioning trusts	13	14
Other investments	4	4
Recurring | Cash equivalents | DTE Electric
Assets
Nuclear decommissioning trusts	13	14
Recurring | Equity securities
Assets
Nuclear decommissioning trusts	933	978
Other investments	117	118
Recurring | Equity securities | DTE Electric
Assets
Nuclear decommissioning trusts	933	978
Other investments	11	11
Recurring | Fixed income securities
Assets
Nuclear decommissioning trusts	530	495
Other investments	70	72
Recurring | Fixed income securities | DTE Electric
Assets
Nuclear decommissioning trusts	530	495
Recurring | Level 1
Assets
Cash equivalents	16	16
Derivative assets
Derivative assets, gross	49	148
Total assets	1,216	1,368
Derivative liabilities
Derivative liabilities, gross	(58)	(141)
Net Assets (Liabilities) at the end of the period	1,158	1,227
Recurring | Level 1 | DTE Electric
Assets
Cash equivalents	8	8
Derivative assets
Total assets	979	1,029
Recurring | Level 1 | Current assets
Derivative assets
Total assets	65	157
Recurring | Level 1 | Current assets | DTE Electric
Derivative assets
Total assets	8	8
Recurring | Level 1 | Noncurrent assets
Derivative assets
Total assets	1,151	1,211
Recurring | Level 1 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	971	1,021
Recurring | Level 1 | Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(53)	(137)
Recurring | Level 1 | Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(5)	(4)
Recurring | Level 1 | Natural gas
Derivative assets
Derivative assets, gross	49	148
Derivative liabilities
Derivative liabilities, gross	(58)	(141)
Recurring | Level 1 | Electricity
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Other
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	0	0
Recurring | Level 1 | Cash equivalents
Assets
Nuclear decommissioning trusts	13	14
Other investments	4	4
Recurring | Level 1 | Cash equivalents | DTE Electric
Assets
Nuclear decommissioning trusts	13	14
Recurring | Level 1 | Equity securities
Assets
Nuclear decommissioning trusts	933	978
Other investments	117	118
Recurring | Level 1 | Equity securities | DTE Electric
Assets
Nuclear decommissioning trusts	933	978
Other investments	11	11
Recurring | Level 1 | Fixed income securities
Assets
Nuclear decommissioning trusts	14	18
Other investments	70	72
Recurring | Level 1 | Fixed income securities | DTE Electric
Assets
Nuclear decommissioning trusts	14	18
Recurring | Level 2
Assets
Cash equivalents	0	3
Derivative assets
Derivative assets, gross	256	356
Total assets	772	836
Derivative liabilities
Derivative liabilities, gross	(228)	(359)
Net Assets (Liabilities) at the end of the period	544	477
Recurring | Level 2 | DTE Electric
Assets
Cash equivalents	0	3
Derivative assets
Total assets	516	480
Recurring | Level 2 | Current assets
Derivative assets
Total assets	194	298
Recurring | Level 2 | Current assets | DTE Electric
Derivative assets
Total assets	0	3
Recurring | Level 2 | Noncurrent assets
Derivative assets
Total assets	578	538
Recurring | Level 2 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	516	477
Recurring | Level 2 | Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(183)	(313)
Recurring | Level 2 | Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(45)	(46)
Recurring | Level 2 | Natural gas
Derivative assets
Derivative assets, gross	92	112
Derivative liabilities
Derivative liabilities, gross	(62)	(111)
Recurring | Level 2 | Electricity
Derivative assets
Derivative assets, gross	162	243
Derivative liabilities
Derivative liabilities, gross	(164)	(245)
Recurring | Level 2 | Other
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 2 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	2	1
Derivative liabilities
Derivative liabilities, gross	(2)	(3)
Recurring | Level 2 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	0	0
Recurring | Level 2 | Cash equivalents
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 2 | Cash equivalents | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Recurring | Level 2 | Equity securities
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 2 | Equity securities | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 2 | Fixed income securities
Assets
Nuclear decommissioning trusts	516	477
Other investments	0	0
Recurring | Level 2 | Fixed income securities | DTE Electric
Assets
Nuclear decommissioning trusts	516	477
Recurring | Level 3
Assets
Cash equivalents	0	0
Derivative assets
Derivative assets, gross	92	148
Total assets	92	148
Derivative liabilities
Derivative liabilities, gross	(111)	(157)
Net Assets (Liabilities) at the end of the period	(19)	(9)
Recurring | Level 3 | DTE Electric
Assets
Cash equivalents	0	0
Derivative assets
Total assets	5	9
Recurring | Level 3 | Current assets
Derivative assets
Total assets	51	104
Recurring | Level 3 | Current assets | DTE Electric
Derivative assets
Total assets	5	9
Recurring | Level 3 | Noncurrent assets
Derivative assets
Total assets	41	44
Recurring | Level 3 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	0	0
Recurring | Level 3 | Current derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(53)	(108)
Recurring | Level 3 | Noncurrent derivative liabilities
Derivative liabilities
Derivative liabilities, gross	(58)	(49)
Recurring | Level 3 | Natural gas
Derivative assets
Derivative assets, gross	66	97
Derivative liabilities
Derivative liabilities, gross	(76)	(126)
Recurring | Level 3 | Electricity
Derivative assets
Derivative assets, gross	21	42
Derivative liabilities
Derivative liabilities, gross	(34)	(30)
Recurring | Level 3 | Other
Derivative assets
Derivative assets, gross	5	9
Derivative liabilities
Derivative liabilities, gross	(1)	(1)
Recurring | Level 3 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
Derivative liabilities
Derivative liabilities, gross	0	0
Recurring | Level 3 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	5	9
Recurring | Level 3 | Cash equivalents
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Cash equivalents | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Recurring | Level 3 | Equity securities
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Equity securities | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Fixed income securities
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 3 | Fixed income securities | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Private Equity Funds | Recurring
Assets
Nuclear decommissioning trusts	5	5
Derivative assets
Private equity securities	5	5
Private Equity Funds | Recurring | DTE Electric
Assets
Nuclear decommissioning trusts	5	5
Derivative assets
Private equity securities	5	5
Private Equity Funds | Recurring | Level 1
Assets
Nuclear decommissioning trusts	0	0
Private Equity Funds | Recurring | Level 1 | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Private Equity Funds | Recurring | Level 2
Assets
Nuclear decommissioning trusts	0	0
Private Equity Funds | Recurring | Level 2 | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Private Equity Funds | Recurring | Level 3
Assets
Nuclear decommissioning trusts	0	0
Private Equity Funds | Recurring | Level 3 | DTE Electric
Assets
Nuclear decommissioning trusts	$ 0	$ 0

Fair Value (Reconciliation of L

Fair Value (Reconciliation of Level 3 Assets and Liabilities at Fair Value on a Recurring Basis) (Details) - Recurring - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	$ (9)	$ (88)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	(3)	0
Total gains (losses):
Included in earnings	61	44
Recorded in/Change in fair value recorded in Regulatory liabilities	0	2
Purchases, issuances, and settlements
Settlements	(68)	19
Net Assets (Liabilities) as of end of period	(19)	(23)
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 March 31, 2018 and 2017 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(68)	32
DTE Electric
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	9	2
Total gains (losses):
Recorded in/Change in fair value recorded in Regulatory liabilities	0	2
Purchases, issuances, and settlements
Settlements	(4)	(3)
Net Assets (Liabilities) as of end of period	5	1
The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets held at March 31, 2018 and 2017 and reflected in DTE Electric's Consolidated Statements of Financial Position	3	0
Natural gas
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	(29)	(96)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	(3)	0
Total gains (losses):
Included in earnings	(70)	52
Recorded in/Change in fair value recorded in Regulatory liabilities	0	0
Purchases, issuances, and settlements
Settlements	92	29
Net Assets (Liabilities) as of end of period	(10)	(15)
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 March 31, 2018 and 2017 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(58)	35
Electricity
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	12	9
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses):
Included in earnings	131	(9)
Recorded in/Change in fair value recorded in Regulatory liabilities	0	0
Purchases, issuances, and settlements
Settlements	(156)	(6)
Net Assets (Liabilities) as of end of period	(13)	(6)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at March 31, 2018 and 2017 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	(10)	(3)
Other
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of beginning of period	8	(1)
Transfers into Level 3 from Level 2	0	0
Transfers from Level 3 into Level 2	0	0
Total gains (losses):
Included in earnings	0	1
Recorded in/Change in fair value recorded in Regulatory liabilities	0	2
Purchases, issuances, and settlements
Settlements	(4)	(4)
Net Assets (Liabilities) as of end of period	4	(2)
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 March 31, 2018 and 2017 and reflected in Operating Revenues — Non-utility operations and Fuel, purchased power, and gas — non-utility in DTE Energy's Consolidated Statements of Operations	$ 0	$ 0

Fair Value (Unobservable Inputs

Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)$ / MMBTU$ / MWh	Dec. 31, 2017USD ($)$ / MMBTU$ / MWh
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	$ 397	$ 652
Derivative Liabilities	(397)	(657)
Recurring | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	92	148
Derivative Liabilities	(111)	(157)
Natural gas
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	207	357
Derivative Liabilities	(196)	(378)
Natural gas | Recurring | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	66	97
Derivative Liabilities	$ (76)	$ (126)
Natural gas | Minimum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(1.37)	(1.10)
Natural gas | Maximum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	4.10	9.75
Natural gas | Weighted Average | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(0.08)	(0.03)
Electricity
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	$ 183	$ 285
Derivative Liabilities	(198)	(275)
Electricity | Recurring | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Derivative Assets	21	42
Derivative Liabilities	$ (34)	$ (30)
Electricity | Minimum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(6)	(5)
Electricity | Maximum | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MWh	8	15
Electricity | Weighted Average | Discounted Cash Flow | Level 3
Unobservable Inputs Valuation Techniques [Line Items]
Forward basis price | $ / MWh	0	2

Fair Value (Fair Value of Finan

Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Carrying amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	$ 37	$ 38
Dividends payable	160	158
Short-term borrowings	635	621
Notes payable — Other	12	12
Long-term debt	12,289	12,288
Carrying amount | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	380	238
Notes payable — Other	2	2
Long-term debt	6,018	6,017
Carrying amount | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	142	116
Fair value | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Dividends payable	160	158
Short-term borrowings	0	0
Notes payable — Other	0	0
Long-term debt	1,874	1,939
Fair value | Level 1 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	0	0
Notes payable — Other	0	0
Long-term debt	0	0
Fair value | Level 1 | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	0	0
Fair value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Dividends payable	0	0
Short-term borrowings	635	621
Notes payable — Other	0	0
Long-term debt	10,136	10,571
Fair value | Level 2 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	380	238
Notes payable — Other	0	0
Long-term debt	6,194	6,441
Fair value | Level 2 | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	0	0
Fair value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	37	38
Dividends payable	0	0
Short-term borrowings	0	0
Notes payable — Other	12	12
Long-term debt	813	764
Fair value | Level 3 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	0	0
Notes payable — Other	2	2
Long-term debt	171	171
Fair value | Level 3 | DTE Electric | Affiliates
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	$ 142	$ 116

Fair Value (Fair Value of Nucle

Fair Value (Fair Value of Nuclear Decommissioning Trust Fund Assets) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 1,481	$ 1,492
DTE Electric
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,481	1,492
DTE Electric | Nuclear decommissioning trust fund
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,481	1,492
DTE Electric | Nuclear decommissioning trust fund | Fermi 2
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	1,463	1,475
DTE Electric | Nuclear decommissioning trust fund | Fermi 1
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	3	3
DTE Electric | Nuclear decommissioning trust fund | Low-level radioactive waste
Schedule of Available-for-sale Securities [Line Items]
Nuclear decommissioning trust funds	$ 15	$ 14

Fair Value (Gains and Losses an

Fair Value (Gains and Losses and Proceeds from the Sale of Securities by the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - Nuclear decommissioning trust fund - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Realized gains	$ 23	$ 23
Realized losses	(9)	(8)
Proceeds from sale of securities	$ 336	$ 394

Fair Value (Fair Value and Unre

Fair Value (Fair Value and Unrealized Gains and Losses for the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - Nuclear decommissioning trust fund - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Schedule of Available-for-sale Securities [Line Items]
Equity securities, fair value	$ 933	$ 978
Fixed income securities, fair value	530	495
Private equity securities, fair value	5	5
Cash equivalents, fair value	13	14
Fair Value	1,481	1,492
Equity securities, unrealized gains	302	320
Fixed income securities, unrealized gains	8	13
Private equity securities, unrealized gains	0	0
Unrealized Gains	310	333
Equity securities, unrealized losses	(38)	(32)
Fixed income securities, unrealized losses	(7)	(3)
Private equity securities, unrealized losses	0	0
Unrealized Losses	$ (45)	$ (35)

Fair Value (Fair Value of Fixed

Fair Value (Fair Value of Fixed Income Securities Held in Nuclear Decommissioning Trust Funds (Details) - Fixed income securities - Nuclear decommissioning trust fund $ in Millions	Mar. 31, 2018USD ($)
Schedule of Available-for-sale Securities [Line Items]
Due within one year	$ 25
Due after one through five years	108
Due after five through ten years	117
Due after ten years	280
Available-for-sale securities total	$ 530

Fair Value (Details Textuals)

Fair Value (Details Textuals) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Fair Value, Option, Quantitative Disclosures [Line Items]
Equity securities realized loss	$ 3,000,000
Equity securities realized gain (loss)	0	$ 8,000,000
DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Equity securities realized gain (loss)	0	8,000,000
Accumulated net unrealized investment gain (loss)
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	0	0
Accumulated net unrealized investment gain (loss) | DTE Electric
Fair Value, Option, Quantitative Disclosures [Line Items]
Unrealized losses on available for sale securities	$ 0	$ 0

Financial and Other Derivativ55

Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 397	$ 652
Derivative Liabilities	(397)	(657)
Current derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	294	540
Current derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(289)	(558)
Noncurrent derivative assets
Derivatives, Fair Value [Line Items]
Derivative Assets	103	112
Noncurrent derivative liabilities
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(108)	(99)
Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	207	357
Derivative Liabilities	(196)	(378)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	183	285
Derivative Liabilities	(198)	(275)
Other
Derivatives, Fair Value [Line Items]
Derivative Assets	5	9
Derivative Liabilities	(1)	(1)
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	2	1
Derivative Liabilities	(2)	(3)
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	397	652
Derivative Liabilities	(397)	(657)
Derivatives not designated as hedging instruments | DTE Electric
Derivatives, Fair Value [Line Items]
Derivative Assets	5	9
Derivatives not designated as hedging instruments | Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	207	357
Derivative Liabilities	(196)	(378)
Derivatives not designated as hedging instruments | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	183	285
Derivative Liabilities	(198)	(275)
Derivatives not designated as hedging instruments | Other
Derivatives, Fair Value [Line Items]
Derivative Assets	5	9
Derivative Liabilities	(1)	(1)
Derivatives not designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	2	1
Derivative Liabilities	(2)	(3)
Derivatives not designated as hedging instruments | FTRs — Other current assets | DTE Electric
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 5	$ 9

Financial and Other Derivativ56

Financial and Other Derivative Instruments (Details Textuals) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Letters of credit that could be used to offset net derivative liabilities	$ 1,000,000	$ 4,000,000
Letters of credit received that could be used to offset net derivative assets	5,000,000	4,000,000
Cash collateral posted, net of cash collateral received	18,000,000	28,000,000
Collateral adjustment on derivative assets	7,000,000	9,000,000
Collateral adjustment on derivative liabilities	22,000,000	22,000,000
Cash collateral paid	15,000,000	18,000,000
Cash collateral received	12,000,000	$ 3,000,000
Additional collateral, aggregate fair value	513,000,000
Derivative net liability position aggregate fair value	290,000,000
Collateral already posted fair value	0
Derivative net asset position, fair value	230,000,000
Remaining amount of offsets to derivative net liability positions for hard and soft trigger provisions	$ 60,000,000

Financial and Other Derivativ57

Financial and Other Derivative Instruments (Netting Offsets of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivative assets
Derivative assets	$ 397	$ 652
Gross Amounts Offset in the Consolidated Statements of Financial Position	(255)	(498)
Derivative assets, net	142	154
Derivative liabilities
Derivative liabilities	(397)	(657)
Gross Amounts Offset in the Consolidated Statements of Financial Position	270	511
Derivative liabilities, net	(127)	(146)
Natural gas
Derivative assets
Derivative assets	207	357
Gross Amounts Offset in the Consolidated Statements of Financial Position	(118)	(256)
Derivative assets, net	89	101
Derivative liabilities
Derivative liabilities	(196)	(378)
Gross Amounts Offset in the Consolidated Statements of Financial Position	126	263
Derivative liabilities, net	(70)	(115)
Electricity
Derivative assets
Derivative assets	183	285
Gross Amounts Offset in the Consolidated Statements of Financial Position	(135)	(241)
Derivative assets, net	48	44
Derivative liabilities
Derivative liabilities	(198)	(275)
Gross Amounts Offset in the Consolidated Statements of Financial Position	142	246
Derivative liabilities, net	(56)	(29)
Other
Derivative assets
Derivative assets	5	9
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	0
Derivative assets, net	5	9
Derivative liabilities
Derivative liabilities	(1)	(1)
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	1
Derivative liabilities, net	(1)	0
Foreign currency exchange contracts
Derivative assets
Derivative assets	2	1
Gross Amounts Offset in the Consolidated Statements of Financial Position	(2)	(1)
Derivative assets, net	0	0
Derivative liabilities
Derivative liabilities	(2)	(3)
Gross Amounts Offset in the Consolidated Statements of Financial Position	2	1
Derivative liabilities, net	$ 0	$ (2)

Financial and Other Derivativ58

Financial and Other Derivative Instruments (Netting Offsets Reconciliation to Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Derivative Assets
Derivative assets	$ 397	$ 652
Collateral adjustment	(7)	(9)
Derivative assets, current	84	103
Derivative assets, noncurrent	58	51
Derivative Liabilities
Derivative liabilities	(397)	(657)
Collateral adjustment	22	22
Derivative liabilities, current	(69)	(99)
Derivative liabilities, noncurrent	(58)	(47)
Current derivative assets
Derivative Assets
Derivative assets	294	540
Counterparty netting	(205)	(437)
Collateral adjustment	(5)	0
Derivative assets, current	84	103
Noncurrent derivative assets
Derivative Assets
Derivative assets	103	112
Counterparty netting	(43)	(52)
Collateral adjustment	(2)	(9)
Derivative assets, noncurrent	58	51
Current derivative liabilities
Derivative Liabilities
Derivative liabilities	(289)	(558)
Counterparty netting	205	437
Collateral adjustment	15	22
Derivative liabilities, current	(69)	(99)
Noncurrent derivative liabilities
Derivative Liabilities
Derivative liabilities	(108)	(99)
Counterparty netting	43	52
Collateral adjustment	7	0
Derivative liabilities, noncurrent	$ (58)	$ (47)

Financial and Other Derivativ59

Financial and Other Derivative Instruments (Effect of Derivatives not Designated as Hedging Instruments on the Consolidated Statement of Operations) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	$ 72	$ 111
Natural gas | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	(110)	57
Natural gas | Fuel, purchased power, and gas — non-utility
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	52	61
Electricity | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	129	(7)
Other | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	(1)	0
Foreign currency exchange contracts | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	$ 2	$ 0

Financial and Other Derivativ60

Financial and Other Derivative Instruments (Cumulative Gross Volume of Derivative Contracts Outstanding) (Details)	3 Months Ended
	Mar. 31, 2018CAD ($)MMBTUMWh
Natural gas (MMBtu)
Derivative [Line Items]
Commodity | MMBTU	1,858,053,782
Electricity (MWh)
Derivative [Line Items]
Commodity | MWh	38,397,695
Foreign currency exchange (Canadian dollars)
Derivative [Line Items]
Foreign currency exchange (Canadian dollars) | $	$ 103,281,830

Short-Term Credit Arrangement61

Short-Term Credit Arrangements and Borrowings (Details Textuals)	Mar. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 856,000,000
Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 221,000,000
DTE Electric
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.51
Other outstanding letters of credit	$ 380,000,000
DTE Electric | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
DTE Gas
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.46
Other outstanding letters of credit	$ 255,000,000
DTE Gas | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
DTE Energy
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.53
Other outstanding letters of credit	$ 221,000,000
DTE Energy | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	221,000,000
DTE Energy | Demand financing agreement
Short-term Debt [Line Items]
Maximum borrowing capacity, financing agreement	100,000,000
Maximum additional margin financing	50,000,000
Amount outstanding	84,000,000	$ 56,000,000
DTE Energy | Demand financing agreement plus letter of credit
Short-term Debt [Line Items]
Maximum borrowing capacity, financing agreement	125,000,000
DTE Energy | Other outstanding letters of credit | Letter of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 9,000,000
Maximum
Short-term Debt [Line Items]
Ratio of indebtedness to net capital	0.65

Short-Term Credit Arrangement62

Short-Term Credit Arrangements and Borrowings (Details)	Mar. 31, 2018USD ($)
Availability under combined facilities
Maximum borrowing capacity	$ 2,120,000,000
Amounts outstanding	856,000,000
Net availability	1,264,000,000
DTE Electric
Availability under combined facilities
Maximum borrowing capacity	400,000,000
Amounts outstanding	380,000,000
Net availability	20,000,000
DTE Gas
Availability under combined facilities
Maximum borrowing capacity	300,000,000
Amounts outstanding	255,000,000
Net availability	45,000,000
DTE Energy
Availability under combined facilities
Maximum borrowing capacity	1,420,000,000
Amounts outstanding	221,000,000
Net availability	1,199,000,000
Letter of credit
Availability under combined facilities
Amounts outstanding	221,000,000
Letter of credit | DTE Electric
Availability under combined facilities
Amounts outstanding	0
Letter of credit | DTE Gas
Availability under combined facilities
Amounts outstanding	0
Letter of credit | DTE Energy
Availability under combined facilities
Amounts outstanding	221,000,000
Letter of credit | Unsecured letter of credit facility, expiring in February 2019
Availability under combined facilities
Maximum borrowing capacity	150,000,000
Letter of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Electric
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Gas
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Energy
Availability under combined facilities
Maximum borrowing capacity	150,000,000
Letter of credit | Unsecured letter of credit facility, expiring in September 2019
Availability under combined facilities
Maximum borrowing capacity	70,000,000
Letter of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Electric
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Gas
Availability under combined facilities
Maximum borrowing capacity	0
Letter of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Energy
Availability under combined facilities
Maximum borrowing capacity	70,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022
Availability under combined facilities
Maximum borrowing capacity	1,900,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Electric
Availability under combined facilities
Maximum borrowing capacity	400,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Gas
Availability under combined facilities
Maximum borrowing capacity	300,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Energy
Availability under combined facilities
Maximum borrowing capacity	1,200,000,000
Commercial paper issuances
Availability under combined facilities
Amounts outstanding	635,000,000
Commercial paper issuances | DTE Electric
Availability under combined facilities
Amounts outstanding	380,000,000
Commercial paper issuances | DTE Gas
Availability under combined facilities
Amounts outstanding	255,000,000
Commercial paper issuances | DTE Energy
Availability under combined facilities
Amounts outstanding	$ 0

Commitments and Contingencies (

Commitments and Contingencies (Details Textuals) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018USD ($)employeesitefacilityNOV	Dec. 31, 2017USD ($)	Jul. 31, 2009plant
Loss Contingencies [Line Items]
Unrecorded unconditional purchase obligation	$ 3,600
Workforce subject to collective bargaining arrangements | Labor force concentration risk
Loss Contingencies [Line Items]
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	$ 400
Reduced emissions fuel guarantees
Loss Contingencies [Line Items]
Number of days after expiration of statutes of limitations	90 days
Maximum potential liability	$ 420
NEXUS pipeline
Loss Contingencies [Line Items]
Guarantee termination, minimum threshold, period following end of primary term of capacity lease agreements	2 months
Other guarantees
Loss Contingencies [Line Items]
Maximum potential liability	$ 55
Performance surety bonds
Loss Contingencies [Line Items]
Performance bonds outstanding	$ 59
DTE Electric
Loss Contingencies [Line Items]
Number of power plants in violation | plant			5
Number of NOVs/FOVs | NOV	2
Environmental capital expenditures through prior year end		$ 2,400
Number of former Mgp sites | site	3
Accrued for remediation	$ 6	6
Number of permitted engineered coal ash storage facilities owned | facility	3
Time period to comply with coal combustion residual requirements and effluent limitations guidelines	6 years
Unrecorded unconditional purchase obligation	$ 1,900
DTE Electric | Workforce subject to collective bargaining arrangements | Labor force concentration risk
Loss Contingencies [Line Items]
Number of employees | employee	2,700
DTE Electric | Coal combustion residual rule
Loss Contingencies [Line Items]
Estimated costs associated with building new facilities	$ 283
DTE Gas
Loss Contingencies [Line Items]
Number of former Mgp sites | site	14
Accrued for remediation	$ 40	$ 41
Amortization period (in years)	10 years
DTE Gas | NEXUS pipeline
Loss Contingencies [Line Items]
Maximum potential liability	$ 82
Lease agreement term	15 years
Percentage of payment obligations due	50.00%
DTE Gas | Clean up completed and site closed
Loss Contingencies [Line Items]
Number of former Mgp sites | site	6
DTE Gas | Partial closure complete
Loss Contingencies [Line Items]
Number of former Mgp sites | site	6
Texas Eastern Transmission, LP | NEXUS pipeline
Loss Contingencies [Line Items]
Maximum potential liability	$ 11
Lease agreement term	15 years
Percentage of payment obligations due	50.00%

Retirement Benefits and Trust64

Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 25	$ 24
Interest cost	50	54
Expected return on plan assets	(82)	(78)
Amortization of net actuarial loss	44	43
Amortization of prior service cost (credit)	0	0
Net periodic benefit cost (credit)	37	43
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	7	7
Interest cost	17	18
Expected return on plan assets	(36)	(33)
Amortization of net actuarial loss	3	3
Amortization of prior service cost (credit)	0	(3)
Net periodic benefit cost (credit)	(9)	(8)
Other Postretirement Benefits | DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	5	5
Interest cost	13	14
Expected return on plan assets	(24)	(23)
Amortization of net actuarial loss	2	2
Amortization of prior service cost (credit)	0	(2)
Net periodic benefit cost (credit)	$ (4)	$ (4)

Retirement Benefits and Trust65

Retirement Benefits and Trusteed Assets (Details Textuals) - USD ($)	Mar. 07, 2018	Mar. 31, 2018	Mar. 31, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Maximum contribution amount		$ 25,000,000
Pension Benefits | DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Pension cost	$ 175,000,000	30,000,000	$ 35,000,000
Maximum contribution amount		0
Other Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Maximum contribution amount		$ 0
Qualified Plan | Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer			126,000,000
Qualified Plan | Pension Benefits | DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Contributions by employer			$ 125,000,000

Retirement Benefits and Trust66

Retirement Benefits and Trusteed Assets - VEBA Contributions (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 07, 2018	Mar. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Contribution of common stock to pension plan		$ 175
Pension Benefits
Defined Contribution Plan Disclosure [Line Items]
Shares contributed to VEBA trust (in shares)	1,751,401
Shares contributed to VEBA trust (in dollars per share)	$ 99.92
Contribution of common stock to pension plan	$ 175

Segment and Related Informati67

Segment and Related Information (Details Textuals) customer in Millions	Mar. 31, 2018customer
Segment Reporting [Abstract]
Number of electric utility customers	2.2
Number of gas utility customers	1.3

Segment and Related Informati68

Segment and Related Information (Financial Data - Inter-segment Billing) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting Information [Line Items]
Revenues	$ (3,753)	$ (3,236)
Electric
Segment Reporting Information [Line Items]
Revenues	(1,205)
Gas
Segment Reporting Information [Line Items]
Revenues	(550)
Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Revenues	(119)
Power and Industrial Projects
Segment Reporting Information [Line Items]
Revenues	(567)
Energy Trading
Segment Reporting Information [Line Items]
Revenues	(1,498)
Reconciliation and Eliminations
Segment Reporting Information [Line Items]
Revenues	186	202
Reconciliation and Eliminations | Electric
Segment Reporting Information [Line Items]
Revenues	13	12
Reconciliation and Eliminations | Gas
Segment Reporting Information [Line Items]
Revenues	2	3
Reconciliation and Eliminations | Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Revenues	8	7
Reconciliation and Eliminations | Power and Industrial Projects
Segment Reporting Information [Line Items]
Revenues	155	168
Reconciliation and Eliminations | Energy Trading
Segment Reporting Information [Line Items]
Revenues	7	11
Reconciliation and Eliminations | Corporate and Other
Segment Reporting Information [Line Items]
Revenues	$ 1	$ 1

Segment and Related Informati69

Segment and Related Information (Financial Data - Operating Revenues including Inter-segment Revenues) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Utility operations	$ 1,740	$ 1,718
Operating Revenues — Non-utility operations	2,013	1,518
Revenues	3,753	3,236
Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	(186)	(202)
Revenues	(186)	(202)
Electric
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,205
Electric | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Utility operations	1,205	1,175
Electric | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(13)	(12)
Gas
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	550
Gas | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Utility operations	550	557
Gas | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(2)	(3)
Gas Storage and Pipelines
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	119
Gas Storage and Pipelines | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	119	105
Gas Storage and Pipelines | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(8)	(7)
Power and Industrial Projects
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	567
Power and Industrial Projects | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	567	548
Power and Industrial Projects | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(155)	(168)
Energy Trading
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	1,498
Energy Trading | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	1,498	1,052
Energy Trading | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	(7)	(11)
Corporate and Other | Operating segments
Segment Reporting, Revenue Reconciling Item [Line Items]
Operating Revenues — Non-utility operations	0	1
Corporate and Other | Reconciliation and Eliminations
Segment Reporting, Revenue Reconciling Item [Line Items]
Revenues	$ (1)	$ (1)

Segment and Related Informati70

Segment and Related Information (Financial Data - Net Income (Loss) Attributable to DTE Energy by Segment) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	$ 361	$ 400
Electric
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	140	106
Gas
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	104	107
Gas Storage and Pipelines
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	62	45
Power and Industrial Projects
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	45	30
Energy Trading
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	31	96
Corporate and Other
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Net Income Attributable to DTE Energy Company	$ (21)	$ 16