DTE Energy (DTE) 10-K 7 Feb 19 2018 FY Annual report Financial data

Document and Entity Information

Document and Entity Information Document and Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2018	Jan. 25, 2019	Jun. 29, 2018
Entity Information [Line Items]
Entity Registrant Name	DTE ENERGY CO
Entity Central Index Key	936,340
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Document Type	10-K
Document Period End Date	Dec. 31, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		181,923,685
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 18,500,000,000
DTE Electric
Entity Information [Line Items]
Entity Registrant Name	DTE ELECTRIC CO
Entity Central Index Key	28,385
Entity Filer Category	Non-accelerated Filer
Document Type	10-K
Document Fiscal Period Focus	FY
Amendment Flag	false
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		138,632,324
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Public Float			$ 0

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Revenues
Utility operations	$ 6,670	$ 6,434	$ 6,497
Non-utility operations	7,542	6,173	4,133
Operating Revenues	14,212	12,607	10,630
Operating Expenses
Fuel, purchased power, and gas — utility	1,981	1,881	1,968
Fuel, purchased power, and gas — non-utility	6,630	5,283	3,562
Operation and maintenance	2,451	2,270	2,261
Depreciation and amortization	1,124	1,030	976
Taxes other than income	405	391	370
Asset (gains) losses and impairments, net	27	41	7
Operating Expenses	12,618	10,896	9,144
Operating Income	1,594	1,711	1,486
Other (Income) and Deductions
Interest expense	559	536	472
Interest income	(12)	(12)	(20)
Non-operating retirement benefits, net	37	65	41
Other income	(333)	(268)	(207)
Other expenses	127	103	95
Other (Income) and Deductions	378	424	381
Income Before Income Taxes	1,216	1,287	1,105
Income Tax Expense	98	175	271
Net Income	1,118	1,112	834
Less: Net Loss Attributable to Noncontrolling Interests	(2)	(22)	(34)
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 1,120	$ 1,134	$ 868
Basic Earnings per Common Share
Net income attributable to DTE Energy Company (in dollars per share)	$ 6.18	$ 6.32	$ 4.84
Diluted Earnings per Common Share
Net income attributable to DTE Energy Company (in dollars per share)	$ 6.17	$ 6.32	$ 4.83
Weighted Average Common Shares Outstanding
Basic (in shares)	181	179	179
Diluted (in shares)	181	179	179
DTE Electric
Operating Revenues
Utility operations	$ 5,298	$ 5,102	$ 5,225
Operating Revenues	5,298	5,102
Operating Expenses
Fuel, purchased power, and gas — utility	1,552	1,454	1,532
Operation and maintenance	1,470	1,428	1,455
Depreciation and amortization	836	753	750
Taxes other than income	307	302	284
Asset (gains) losses and impairments, net	(1)	0	0
Operating Expenses	4,164	3,937	4,021
Operating Income	1,134	1,165	1,204
Other (Income) and Deductions
Interest expense	283	274	264
Interest income	0	0	(8)
Other income	(83)	(77)	(61)
Other expenses	77	40	34
Other (Income) and Deductions	277	237	229
Income Before Income Taxes	857	928	975
Income Tax Expense	193	327	353
Net Income Attributable to DTE Energy Company/DTE Electric Company	$ 664	$ 601	$ 622

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Net Income	$ 1,118	$ 1,112	$ 834
Net Income	1,120	1,134	868
Other comprehensive income (loss), net of tax:
Benefit obligations, net of taxes	8	10	11
Net unrealized gains (losses) on derivatives during the period, net of taxes	(1)	1	0
Net unrealized gains on investments during the period, net of taxes	0	1	1
Foreign currency translation	(2)	1	0
Other comprehensive income	5	13	12
Comprehensive income	1,123	1,125	846
Less: Comprehensive loss attributable to noncontrolling interests	(2)	(22)	(34)
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company	1,125	1,147	880
DTE Electric
Net Income	664	601	622
Other comprehensive income (loss), net of tax:
Net unrealized gains on investments during the period, net of taxes	0	1	0
Other comprehensive income	0	1	0
Comprehensive Income Attributable to DTE Energy Company/DTE Electric Company	$ 664	$ 602	$ 622

Consolidated Statements of Co_2

Consolidated Statements of Comprehensive Income (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Tax effect on benefit obligation	$ 2	$ 5	$ 6
Tax effect on net unrealized gains (losses) on derivatives during the period	0	0	0
Tax effect on net unrealized gains (losses) on investments during the period	0	1	1
DTE Electric
Tax effect on net unrealized gains (losses) on investments during the period	$ 0	$ 1	$ 0

Consolidated Statements of Fina

Consolidated Statements of Financial Position - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current Assets
Cash and cash equivalents	$ 71	$ 66
Restricted cash	5	23
Accounts receivable (less allowance for doubtful accounts)
Customer	1,789	1,758
Other	108	98
Inventories
Fuel and gas	406	399
Materials and supplies	405	380
Derivative assets	102	103
Regulatory assets	153	55
Other	221	199
Total Current Assets	3,260	3,081
Investments
Nuclear decommissioning trust funds	1,378	1,492
Investments in equity method investees	1,771	1,073
Other	219	232
Total Investments	3,368	2,797
Property
Property, plant, and equipment	31,810	31,424
Accumulated depreciation and amortization	(10,160)	(10,703)
Property, plant and equipment, net	21,650	20,721
Other Assets
Goodwill	2,293	2,293
Regulatory assets	4,568	3,723
Intangible assets	849	867
Notes receivable	64	73
Derivative assets	31	51
Prepaid postretirement costs	45	0
Other	160	161
Total Other Assets	8,010	7,168
Total Assets	36,288	33,767
Current Liabilities
Accounts payable	1,329	1,171
Accounts payable
Accrued interest	127	111
Dividends payable	172	158
Short-term borrowings	609	621
Current portion long-term debt, including capital leases	1,499	109
Derivative liabilities	67	99
Regulatory liabilities	126	18
Short-term borrowings
Other	509	525
Total Current Liabilities	4,438	2,812
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	10,982	11,039
Junior subordinated debentures	1,145	1,145
Capital lease obligations	7	1
Total Long-Term Debt (net of current portion)	12,134	12,185
Other Liabilities
Deferred income taxes	1,975	1,888
Regulatory liabilities	2,922	2,875
Asset retirement obligations	2,469	2,320
Unamortized investment tax credit	138	122
Derivative liabilities	89	47
Accrued pension liability	837	924
Accrued postretirement liability	0	61
Nuclear decommissioning	205	220
Other	364	323
Total Other Liabilities	8,999	8,780
Commitments and Contingencies (Notes 9 and 18)
Equity
Common stock	4,245	3,989
Retained earnings	6,112	5,643
Accumulated other comprehensive (loss) income	(120)	(120)
Total DTE Energy Company/DTE Electric Company Equity	10,237	9,512
Noncontrolling interests	480	478
Total Equity	10,717	9,990
Total Liabilities and Equity	36,288	33,767
DTE Electric
Current Assets
Cash and cash equivalents	18	15
Accounts receivable (less allowance for doubtful accounts)
Customer	750	791
Affiliates	11	20
Other	54	37
Inventories
Fuel and gas	171	190
Materials and supplies	279	275
Regulatory assets	148	50
Other	89	68
Total Current Assets	1,520	1,446
Investments
Nuclear decommissioning trust funds	1,378	1,492
Other	34	36
Total Investments	1,412	1,528
Property
Property, plant, and equipment	22,747	22,972
Accumulated depreciation and amortization	(7,310)	(7,984)
Property, plant and equipment, net	15,437	14,988
Other Assets
Regulatory assets	3,829	3,005
Intangible assets	21	25
Prepaid postretirement costs — affiliates	189	113
Other	121	123
Total Other Assets	4,160	3,266
Total Assets	22,529	21,228
Accounts payable
Affiliates	71	52
Other	441	416
Accrued interest	74	72
Current portion long-term debt, including capital leases	4	5
Regulatory liabilities	98	17
Short-term borrowings
Affiliates	101	116
Other	149	238
Other	139	145
Total Current Liabilities	1,077	1,061
Long-Term Debt (net of current portion)
Mortgage bonds, notes, and other	6,538	6,017
Capital lease obligations	7	1
Total Long-Term Debt (net of current portion)	6,545	6,018
Other Liabilities
Deferred income taxes	2,246	2,088
Regulatory liabilities	2,171	2,137
Asset retirement obligations	2,271	2,125
Unamortized investment tax credit	137	120
Nuclear decommissioning	205	220
Accrued pension liability — affiliates	718	811
Accrued postretirement liability — affiliates	278	311
Other	88	72
Total Other Liabilities	8,114	7,884
Commitments and Contingencies (Notes 9 and 18)
Equity
Common stock	4,631	4,306
Retained earnings	2,162	1,956
Accumulated other comprehensive (loss) income	0	3
Total DTE Energy Company/DTE Electric Company Equity	6,793	6,265
Total Liabilities and Equity	$ 22,529	$ 21,228

Consolidated Statements of Fi_2

Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Current Assets:
Allowance for doubtful accounts	$ 91	$ 49
Stockholders' Equity:
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	181,925,281	179,386,967
Common stock, shares outstanding (in shares)	181,925,281	179,386,967
DTE Electric
Current Assets:
Allowance for doubtful accounts	$ 53	$ 31
Stockholders' Equity:
Common stock, par value (in dollars per share)	$ 10	$ 10
Common stock, shares authorized (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	138,632,234	138,632,234
Common stock, shares outstanding (in shares)	138,632,234	138,632,234

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating Activities
Net Income	$ 1,118	$ 1,112	$ 834
Net Income	1,120	1,134	868
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	1,124	1,030	976
Nuclear fuel amortization	45	53	58
Allowance for equity funds used during construction	(28)	(23)	(21)
Deferred income taxes	114	196	265
Equity earnings of equity method investees	(132)	(102)	(68)
Dividends from equity method investees	74	74	68
Asset (gains) losses and impairments, net	29	38	8
Changes in assets and liabilities:
Accounts receivable, net	(44)	(252)	(226)
Inventories	(32)	(4)	37
Prepaid postretirement benefit costs	(45)	0	0
Accounts payable	146	129	145
Accrued pension liability	(87)	(228)	19
Accrued postretirement liability	(61)	25	(192)
Derivative assets and liabilities	31	(94)	126
Regulatory assets and liabilities	15	217	(40)
Other current and noncurrent assets and liabilities	413	(54)	95
Net cash from operating activities	2,680	2,117	2,084
Investing Activities
Plant and equipment expenditures — utility	(2,439)	(2,037)	(1,898)
Plant and equipment expenditures — non-utility	(274)	(213)	(147)
Acquisition, net of cash acquired	0	0	(1,147)
Proceeds from sale of nuclear decommissioning trust fund assets	1,203	1,240	1,457
Investment in nuclear decommissioning trust funds	(1,188)	(1,226)	(1,463)
Distributions from equity method investees	9	10	11
Contributions to equity method investees	(637)	(299)	(239)
Other	(21)	(37)	36
Net cash used for investing activities	(3,347)	(2,562)	(3,390)
Financing Activities
Issuance of long-term debt, net of issuance costs	1,432	1,398	2,035
Redemption of long-term debt	(105)	(385)	(807)
Repurchase of long-term debt	0	0	(59)
Issuance of equity units, net of issuance costs	0	0	654
Short-term borrowings, net	(12)
Short-term borrowings, net		122	0
Repurchase of common stock	0	(51)	(33)
Dividends on common stock	(620)	(592)	(531)
Contributions from noncontrolling interests, principally REF entities	53	50	114
Distributions to noncontrolling interests	(48)	(40)	(5)
Other	(46)	(81)	(9)
Net cash from (used for) financing activities	654	421	1,359
Net Increase (Decrease) in Cash, Cash Equivalents, and Restricted Cash	(13)	(24)	53
Cash, Cash Equivalents, and Restricted Cash at Beginning of Period	89	113	60
Cash, Cash Equivalents, and Restricted Cash at End of Period	76	89	113
Cash and Cash Equivalents at Beginning of Period	66
Cash and Cash Equivalents at End of Period	71	66
Supplemental disclosure of cash information
Cash paid (received) for: Interest, net of interest capitalized	572	495	448
Cash paid (received) for: Income taxes	(26)	4	(1)
Supplemental disclosure of non-cash investing and financing activities
Plant and equipment expenditures in accounts payable	307	295	312
Premium on equity units	0	0	98
DTE Electric
Operating Activities
Net Income	664	601	622
Adjustments to reconcile Net Income to Net cash from operating activities:
Depreciation and amortization	836	753	750
Nuclear fuel amortization	45	53	58
Allowance for equity funds used during construction	(19)	(18)	(18)
Deferred income taxes	189	345	342
Changes in assets and liabilities:
Accounts receivable, net	33	(80)	(64)
Inventories	15	31	26
Prepaid postretirement benefit costs — affiliates	(76)	1	(90)
Accounts payable	54	(2)	59
Accrued pension liability — affiliates	(93)	(197)	32
Accrued postretirement liability — affiliates	(33)	42	(38)
Regulatory assets and liabilities	4	202	10
Other current and noncurrent assets and liabilities	101	(147)	(34)
Net cash from operating activities	1,720	1,584	1,655
Investing Activities
Plant and equipment expenditures	(1,989)	(1,574)	(1,503)
Proceeds from sale of nuclear decommissioning trust fund assets	1,203	1,240	1,457
Investment in nuclear decommissioning trust funds	(1,188)	(1,226)	(1,463)
Other	(15)	18	36
Net cash used for investing activities	(1,989)	(1,542)	(1,473)
Financing Activities
Issuance of long-term debt, net of issuance costs	519	435	355
Redemption of long-term debt	0	(300)	(10)
Repurchase of long-term debt	0	0	(59)
Capital contribution by parent company	325	100	120
Short-term borrowings, net — affiliate	(15)	(1)	41
Short-term borrowings, net — other	(89)	176	(210)
Dividends on common stock	(461)	(432)	(420)
Other	(7)	(18)	(1)
Net cash from (used for) financing activities	272	(40)	(184)
Net Increase (Decrease) in Cash and Cash Equivalents	3	2	(2)
Cash and Cash Equivalents at Beginning of Period	15	13	15
Cash and Cash Equivalents at End of Period	18	15	13
Supplemental disclosure of cash information
Cash paid (received) for: Interest, net of interest capitalized	283	252	252
Cash paid (received) for: Income taxes	0	(16)	6
Supplemental disclosure of non-cash investing and financing activities
Plant and equipment expenditures in accounts payable	$ 181	$ 191	$ 232

Consolidated Statements of Chan

Consolidated Statements of Changes in Equity - USD ($) $ in Millions	Total	Common Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	DTE Electric	DTE ElectricCommon Stock	DTE ElectricAdditional Paid-in Capital	DTE ElectricRetained Earnings	DTE ElectricAccumulated Other Comprehensive Income (Loss)
Beginning balance (in shares) at Dec. 31, 2015		179,470,000					138,632,000
Beginning balance at Dec. 31, 2015	$ 8,795	$ 4,123	$ 4,794	$ (145)	$ 23
Beginning balance at Dec. 31, 2015						$ 5,673	$ 1,386	$ 2,700	$ 1,585	$ 2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	834		868		(34)
Net Income	868					622			622
Dividends declared on common stock	(548)		(548)			(420)			(420)
Repurchase of common stock (in shares)		(394,000)
Repurchase of common stock	(33)	$ (33)
Premium on equity units	(98)	(98)
Issuance costs of equity units	(18)	$ (18)
Acquisition of SGG	390				390
Other comprehensive income, net of tax	12			12		0
Other comprehensive income, net of tax	1					0
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		357,000
Stock-based compensation, net contributions from noncontrolling interests, and other	162	$ 56	(3)		109
Capital contribution by parent company						120		120
Ending balance (in shares) at Dec. 31, 2016		179,433,000					138,632,000
Ending balance at Dec. 31, 2016	9,499	$ 4,030	5,114	(133)	488
Ending balance at Dec. 31, 2016						5,995	$ 1,386	2,820	1,787	2
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	1,112		1,134		(22)
Net Income	1,134					601			601
Dividends declared on common stock	(602)		(602)			(432)			(432)
Repurchase of common stock (in shares)		(524,000)
Repurchase of common stock	(51)	$ (51)
Other comprehensive income, net of tax	13			13		1				1
Other comprehensive income, net of tax	1					1
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		478,000
Stock-based compensation, net contributions from noncontrolling interests, and other	$ 19	$ 10	(3)		12
Capital contribution by parent company						$ 100		100
Ending balance (in shares) at Dec. 31, 2017	179,386,967	179,387,000				138,632,234	138,632,000
Ending balance at Dec. 31, 2017	$ 9,990	$ 3,989	5,643	(120)	478
Ending balance at Dec. 31, 2017	9,512					$ 6,265	$ 1,386	2,920	1,956	3
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (Loss)	1,118		1,120		(2)
Net Income	1,120					664			664
Dividends declared on common stock	(653)		(653)			(461)			(461)
Issuance of common stock (in shares)		255,000
Issuance of common stock	26	$ 26
Contribution of common stock to pension plan (in shares)		1,751,000
Contribution of common stock to pension plan	175	$ 175
Other comprehensive income, net of tax	5			5		0
Other comprehensive income, net of tax	0					0
Stock-based compensation, net contributions from noncontrolling interests, and other (in shares)		532,000
Stock-based compensation, net contributions from noncontrolling interests, and other	$ 56	$ 55	(3)		4
Capital contribution by parent company						$ 325		325
Ending balance (in shares) at Dec. 31, 2018	181,925,281	181,925,000				138,632,234	138,632,000
Ending balance at Dec. 31, 2018	$ 10,717	$ 4,245	$ 6,112	$ (120)	$ 480
Ending balance at Dec. 31, 2018	$ 10,237					$ 6,793	$ 1,386	$ 3,245	$ 2,162	$ 0

Consolidated Statements of Ch_2

Consolidated Statements of Changes in Shareholders' Equity (Parenthetical) - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Stockholders' Equity [Abstract]
Dividends declared on common stock (in dollars per share)	$ 3.60	$ 3.36	$ 3.06

Organization and Basis of Prese

Organization and Basis of Presentation	12 Months Ended
	Dec. 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 accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The information in these combined notes relates to each of the Registrants as noted in the Index of Combined Notes to Consolidated Financial Statements. However, DTE Electric does not make any representation as to information related solely to DTE Energy or the subsidiaries of DTE Energy other than itself. Certain prior year balances for the Registrants were reclassified to match the current year's Consolidated Financial Statements presentation. 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 generally 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 owns a 256-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 December 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 December 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 for DTE Energy, in Note 18 to the Consolidated Financial Statements, " Commitments and Contingencies ," related to the REF guarantees and indemnities. For non-consolidated VIEs, the maximum risk exposure of the Registrants is generally limited to their investment, notes receivable, future funding commitments, and amounts which DTE Energy has guaranteed. See Note 18 to the Consolidated Financial Statements, " Commitments and Contingencies ," for further discussion of the NEXUS guarantee arrangements. The following table summarizes the major Consolidated Statements of Financial Position items for consolidated VIEs as of December 31, 2018 and 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. Amounts for DTE Energy's consolidated VIEs are as follows: December 31, 2018 December 31, 2017 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 25 $ 14 $ 39 $ 23 $ 14 $ 37 Restricted cash — 5 5 — 8 8 Accounts receivable 9 37 46 11 42 53 Inventories 1 92 93 3 114 117 Property, plant, and equipment, net 395 46 441 400 75 475 Goodwill 25 — 25 25 — 25 Intangible assets 557 — 557 572 — 572 Other current and long-term assets 3 — 3 4 — 4 $ 1,015 $ 194 $ 1,209 $ 1,038 $ 253 $ 1,291 LIABILITIES Accounts payable and accrued current liabilities $ 3 $ 31 $ 34 $ 26 $ 47 $ 73 Current portion long-term debt, including capital leases — — — — 4 4 Mortgage bonds, notes, and other — — — — 1 1 Other current and long-term liabilities 9 10 19 1 16 17 $ 12 $ 41 $ 53 $ 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: December 31, 2018 2017 (In millions) Investments in equity method investees $ 1,425 $ 811 Notes receivable $ 15 $ 17 Future funding commitments $ 55 $ 598 Equity Method Investments Investments in non-consolidated affiliates that are not controlled by the Registrants, but over which they have significant influence, are accounted for using the equity method. Certain of the equity method investees are also considered VIEs and disclosed in the non-consolidated VIEs table above. At December 31, 2018 and 2017 , DTE Energy's share of the underlying equity in the net assets of the investees exceeded the carrying amounts of Investments in equity method investees by $59 million and $72 million , respectively. The difference is being amortized over the life of the underlying assets. DTE Energy equity method investees are described below: Investments % Owned Segment 2018 2017 2018 2017 Description (In millions) Significant Equity Method Investees Gas Storage and Pipelines NEXUS Pipeline $ 1,260 $ 640 50% 50% 256-mile pipeline to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers Vector Pipeline 123 115 40% 40% 348-mile pipeline connecting Chicago, Michigan, and Ontario market centers Millennium Pipeline 202 124 26% 26% 269-mile pipeline serving markets in the Northeast 1,585 879 Other Equity Method Investees Other Segments 186 194 $ 1,771 $ 1,073 The balances in Other Equity Method Investees are individually insignificant and are primarily from the Power and Industrial Projects segment. These investments are comprised of projects that deliver energy and utility-type products and services to an industrial customer, sell electricity from renewable energy projects under long-term power purchase agreements, and produce and sell metallurgical coke. For further information by segment, see Note 22 to the Consolidated Financial Statements, " Segment and Related Information ." The following table presents summarized financial information of subsidiaries not consolidated and 50 percent or less owned by DTE Energy. The amounts included in the table below represents 100% of the results of continuing operations of such entities accounted for under the equity method of accounting. Summarized balance sheet data is as follows: December 31, 2018 2017 (In millions) Current Assets $ 358 $ 344 Non-current assets $ 5,101 $ 3,576 Current Liabilities $ 391 $ 345 Non-current liabilities $ 762 $ 858 Summarized income statement data is as follows: December 31, 2018 2017 2016 (In millions) Operating Revenues $ 883 $ 756 $ 767 Operating Expenses $ 622 $ 561 $ 526 Net Income $ 365 $ 254 $ 225

Significant Accounting Policies

Significant Accounting Policies	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Significant Accounting Policies	SIGNIFICANT ACCOUNTING POLICIES Other Income Other income for the Registrants is recognized for non-operating income such as equity earnings of equity method investees, allowance for equity funds used during construction, contract services, and gains (losses) from trading securities. DTE Energy's Power and Industrial Projects segment also recognizes Other income in connection with the sale of membership interests in reduced emissions fuel facilities to investors. In exchange for the cash received, the investors will receive a portion of the economic attributes of the facilities, including income tax attributes. The transactions are not treated as a sale of membership interests for financial reporting purposes. Other income related to fixed non-refundable cash payments received from investors for which the earnings process is not contingent upon production of refined coal is recognized on a straight-line basis over the non-cancelable contract term as the economic benefit from the ownership of the facility is transferred to investors. Other income related to cash payments that is contingent upon production of refined coal is considered earned and recognized when the contingency regarding the timing and amount of payment is resolved, generally as refined coal is produced and tax credits are generated. The following is a summary of DTE Energy's Other income: 2018 2017 2016 (In millions) Equity earnings of equity method investees $ 132 $ 102 $ 68 Income from REF entities 98 77 75 Contract services 51 19 21 Allowance for equity funds used during construction 28 23 21 Gains from trading securities 6 26 15 Other 18 21 7 $ 333 $ 268 $ 207 The following is a summary of DTE Electric's Other income: 2018 2017 2016 (In millions) Contract services $ 51 $ 21 $ 20 Allowance for equity funds used during construction 19 18 18 Gains from trading securities allocated from DTE Energy 6 26 15 Other 7 12 8 $ 83 $ 77 $ 61 For information on equity earnings of equity method investees by segment, see Note 22 to the Consolidated Financial Statements, " Segment and Related Information ." Accounting for ISO Transactions DTE Electric participates in the energy market through MISO. MISO requires that DTE Electric submit hourly day-ahead, real-time, and FTR bids and offers for energy at locations across the MISO region. DTE Electric accounts for MISO transactions on a net hourly basis in each of the day-ahead, real-time, and FTR markets and net transactions across all MISO energy market locations. In any single hour DTE Electric records net purchases in Fuel, purchased power, and gas — utility and net sales in Operating Revenues — Utility operations on the Registrants' Consolidated Statements of Operations. The Energy Trading segment participates in the energy markets through various ISOs and RTOs. These markets require that Energy Trading submits hourly day-ahead, real-time bids and offers for energy at locations across each region. Energy Trading submits bids in the annual and monthly auction revenue rights and FTR auctions to the RTOs. Energy Trading accounts for these transactions on a net hourly basis for the day-ahead, real-time, and FTR markets. These transactions are related to trading contracts which, if derivatives, are presented on a net basis in Operating Revenues — Non-utility operations, and if non-derivatives, the realized gains and losses for sales are recorded in Operating Revenues — Non-utility operations and purchases are recorded in Fuel, purchased power, and gas — non-utility in the DTE Energy Consolidated Statements of Operations. DTE Electric and Energy Trading record accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual costs when invoices are received from MISO and other ISOs and RTOs. Changes in Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including Net Income. The amounts recorded to Accumulated other comprehensive income (loss) for the Registrants include unrealized gains and losses on available-for-sale securities and changes in benefit obligations, consisting of deferred actuarial losses and prior service costs. The amounts recorded to Accumulated other comprehensive income (loss) relating solely to DTE Energy also include unrealized gains and losses from derivatives accounted for as cash flow hedges, DTE Energy's interest in other comprehensive income of equity investees which comprise the net unrealized gains and losses on investments, and foreign currency translation adjustments. The following table summarizes the changes in DTE Energy's Accumulated other comprehensive income (loss) by component (a) for the years ended December 31, 2018 and 2017 : Net Unrealized Gain (Loss) on Deri vatives Net Unrealized Gain (Loss) on Investments Benefit Obligations (b) Foreign Currency Translation Total (In millions) Balance, December 31, 2016 $ (4 ) $ (3 ) $ (120 ) $ (6 ) $ (133 ) Other comprehensive income (loss) before reclassifications — 1 (3 ) 1 (1 ) Amounts reclassified from Accumulated other comprehensive income 1 — 13 — 14 Net current-period Other comprehensive income 1 1 10 1 13 Balance, December 31, 2017 $ (3 ) $ (2 ) $ (110 ) $ (5 ) $ (120 ) Implementation of ASU 2016-01 (7 ) 2 — — (5 ) Other comprehensive loss before reclassifications (2 ) — (1 ) (2 ) (5 ) Amounts reclassified from Accumulated other comprehensive income 1 — 9 — 10 Net current-period Other comprehensive income (loss) (8 ) 2 8 (2 ) — Balance, December 31, 2018 $ (11 ) $ — $ (102 ) $ (7 ) $ (120 ) ______________________________________ (a) All amounts are net of tax, except for Foreign currency translation. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 20 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets "). Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include cash on hand, cash in banks, and temporary investments purchased with remaining maturities of three months or less. Restricted cash consists of funds held to satisfy requirements of certain debt and DTE Energy partnership operating agreements. Restricted cash designated for interest and principal payments within one year is classified as a Current Asset. 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: 2018 2017 (In millions) Cash and cash equivalents $ 71 $ 66 Restricted cash 5 23 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 76 $ 89 Receivables Accounts receivable are primarily composed of trade receivables and unbilled revenue. The Registrants' Accounts receivable are stated at net realizable value. The allowance for doubtful accounts for DTE Electric and DTE Gas is generally calculated using the aging approach that utilizes rates developed in reserve studies. DTE Electric and DTE Gas establish an allowance for uncollectible accounts based on historical losses and management’s assessment of existing economic conditions, customer trends, and other factors. Customer accounts are generally considered delinquent if the amount billed is not received by the due date, which is typically in 21 days, however, factors such as assistance programs may delay aggressive action. DTE Electric and DTE Gas assess late payment fees on trade receivables based on past-due terms with customers. Customer accounts are written off when collection efforts have been exhausted. The time period for write-off is 150 days after service has been terminated. The customer allowance for doubtful accounts for DTE Energy's other businesses is calculated based on specific review of probable future collections based on receivable balances generally in excess of 30 days. DTE Energy unbilled revenues of $1.0 billion at December 31, 2018 and 2017 include $264 million and $290 million of DTE Electric unbilled revenues, respectively, included in Customer Accounts receivable. Notes Receivable Notes receivable, or financing receivables, for DTE Energy are primarily comprised of capital lease receivables and loans and are included in Notes receivable and Other current assets on DTE Energy’s Consolidated Statements of Financial Position. Notes receivable, or financing receivables, for DTE Electric are primarily comprised of loans. Notes receivable are typically considered delinquent when payment is not received for periods ranging from 60 to 120 days. The Registrants cease accruing interest (nonaccrual status), consider a note receivable impaired, and establish an allowance for credit loss when it is probable that all principal and interest amounts due will not be collected in accordance with the contractual terms of the note receivable. Cash payments received on nonaccrual status notes receivable, that do not bring the account contractually current, are first applied to contractually owed past due interest, with any remainder applied to principal. Accrual of interest is generally resumed when the note receivable becomes contractually current. In determining the allowance for credit losses for notes receivable, the Registrants consider the historical payment experience and other factors that are expected to have a specific impact on the counterparty’s ability to pay. In addition, the Registrants monitor the credit ratings of the counterparties from which they have notes receivable. Inventories Inventory related to utility operations is generally valued at average cost. Inventory related to non-utility operations is valued at the lower of cost or net realizable value. DTE Gas' natural gas inventory of $48 million and $29 million as of December 31, 2018 and 2017 , respectively, is determined using the last-in, first-out (LIFO) method. The replacement cost of gas in inventory exceeded the LIFO cost by $113 million and $81 million at December 31, 2018 and 2017 , respectively. Property, Retirement and Maintenance, and Depreciation and Amortization Property is stated at cost and includes construction-related labor, materials, overheads, and AFUDC for utility property. The cost of utility properties retired is charged to accumulated depreciation. Expenditures for maintenance and repairs are charged to expense when incurred, except for outage-related maintenance repairs for Fermi 2. Utility property at DTE Electric and DTE Gas is depreciated over its estimated useful life using straight-line rates approved by the MPSC. DTE Energy's non-utility property is depreciated over its estimated useful life using the straight-line method. Depreciation and amortization expense also includes the amortization of certain regulatory assets for the Registrants. Approximately $4 million and $15 million of expenses related to Fermi 2 refueling outages were accrued at December 31, 2018 and 2017 , respectively. Amounts are accrued on a pro-rata basis, generally over an 18 -month period, that coincides with scheduled refueling outages at Fermi 2. This accrual of outage costs matches the regulatory recovery of these costs in rates set by the MPSC. See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." The cost of nuclear fuel is capitalized. The amortization of nuclear fuel is included within Fuel, purchased power, and gas — utility in the DTE Energy Consolidated Statements of Operations, and Fuel and purchased power in the DTE Electric Consolidated Statements of Operations, and is recorded using the units-of-production method. See Note 6 to the Consolidated Financial Statements, " Property, Plant, and Equipment ." Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If the carrying amount of the asset exceeds the expected undiscounted future cash flows generated by the asset, an impairment loss is recognized resulting in the asset being written down to its estimated fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less costs to sell. Intangible Assets The Registrants have certain Intangible assets as shown below: December 31, 2018 December 31, 2017 Useful Lives Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (In millions) Intangible assets subject to amortization Customer relationships 25 - 40 years (a) $ 779 $ (44 ) $ 735 $ 770 $ (24 ) $ 746 Contract intangibles 6 to 26 years 159 (66 ) 93 168 (72 ) 96 938 (110 ) 828 938 (96 ) 842 DTE Electric renewable energy credits (b) 20 — 20 24 — 24 DTE Electric emission allowances (b) 1 — 1 1 — 1 21 — 21 25 — 25 Long-term intangible assets DTE Electric $ 21 $ — $ 21 $ 25 $ — $ 25 DTE Energy $ 959 $ (110 ) $ 849 $ 963 $ (96 ) $ 867 ______________________________________ (a) The useful life of the customer relationship intangible assets is based on the number of years in which the assets are expected to economically contribute to the business. The expected economic benefit incorporates existing customer contracts and expected renewal rates based on the estimated volume and production lives of gas resources in the region. (b) Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the business. The following table summarizes DTE Energy's estimated customer relationship and contract intangible amortization expense expected to be recognized during each year through 2023 : 2019 2020 2021 2022 2023 (In millions) Estimated amortization expense $ 27 $ 26 $ 25 $ 25 $ 25 DTE Energy amortizes customer relationship and contract intangible assets on a straight-line basis over the expected period of benefit. DTE Energy's Intangible assets amortization expense was $27 million in 2018 , $29 million in 2017 , and $16 million in 2016 . Excise and Sales Taxes The Registrants record the billing of excise and sales taxes as a receivable with an offsetting payable to the applicable taxing authority, with no net impact on the Registrants’ Consolidated Statements of Operations. Deferred Debt Costs The costs related to the issuance of long-term debt are deferred and amortized over the life of each debt issue. The deferred amounts are included as a direct deduction from the carrying amount of each debt issue in Mortgage bonds, notes, and other and Junior subordinated debentures on DTE Energy's Consolidated Statements of Financial Position and in Mortgage bonds, notes, and other on DTE Electric's Consolidated Statements of Financial Position. In accordance with MPSC regulations applicable to DTE Energy’s electric and gas utilities, the unamortized discount, premium, and expense related to utility debt redeemed with a refinancing are amortized over the life of the replacement issue. Discount, premium, and expense on early redemptions of debt associated with DTE Energy's non-utility operations are charged to earnings. Investments in Debt and Equity Securities The Registrants generally record investments in debt and equity securities at market value with unrealized gains or losses included in earnings. Changes in the fair value of Fermi 2 nuclear decommissioning investments are recorded as adjustments to Regulatory assets or liabilities, due to a recovery mechanism from customers. The Registrants' equity investments are reviewed for impairment each reporting period. If the assessment indicates that an impairment exists, a loss is recognized resulting in the equity investment being written down to its estimated fair value. See Note 12 of the Consolidated Financial Statements, " Fair Value ." DTE Energy Foundation DTE Energy's charitable contributions to the DTE Energy Foundation were $22 million , $43 million , and $26 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute to and assist charitable organizations. Other Accounting Policies See the following notes for other accounting policies impacting the Registrants’ Consolidated Financial Statements: Note Title 4 Revenue 8 Asset Retirement Obligations 9 Regulatory Matters 10 Income Taxes 12 Fair Value 13 Financial and Other Derivative Instruments 20 Retirement Benefits and Trusteed Assets 21 Stock-Based Compensation

New Accounting Pronouncements

New Accounting Pronouncements	12 Months Ended
	Dec. 31, 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 using either a full retrospective or modified retrospective approach. 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 year ended December 31, 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. During the year ended December 31, 2018 , DTE Energy and DTE Electric finalized their SAB 118 analysis and recorded true-up adjustments to the remeasurement of deferred taxes of $21 million and $7 million , respectively. The impact of the true-up adjustments was an increase in Income Tax Expense, of which $17 million was attributable to the regulated utilities and increased 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. 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. The standard allows lessees and lessors to apply either, 1) a modified retrospective approach for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements, or 2) a prospective transition approach for leases existing as of January 1, 2019 with a cumulative effect adjustment to be recorded to retained earnings. The Registrants will apply the standard on a prospective basis. The Registrants will elect the package of practical expedients allowing entities to not reassess whether an agreement is a lease, to carryforward the existing lease classification, and to not reassess initial direct costs associated with existing leases. These practical expedients apply to leases that commenced prior to January 1, 2019. The Registrants will also elect to exclude leases from the balance sheet that are for a period of one year or less, as well as, the practical expedient allowing entities to not evaluate land easements under the new guidance at adoption if they were not previously accounted for as leases. A third-party software tool has been implemented that will assist with the initial adoption and ongoing compliance of the standard. The Registrants are implementing new business processes, internal controls, and accounting policies. The Registrants are in the process of drafting disclosures to satisfy the standard's requirements. In addition, the Registrants are continuing to monitor utility industry implementation guidance and interpretation. 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. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurements (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement . The amendments in this update modify the disclosure requirements on fair value measurements in Topic 820. The ASU is effective for the Registrants for fiscal years 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 August 2018, the FASB issued ASU No. 2018-14, Compensation — Retirement Benefits — Defined Benefit Plans (Subtopic 715-20): Disclosure Framework — Changes to the Disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans . The amendments in this update modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The ASU is effective for the Registrants for fiscal years ending after December 15, 2020. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. In August 2018, the FASB issued ASU No. 2018-15, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract . The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The ASU is effective for the Registrants for fiscal years 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 October 2018, the FASB issued ASU No. 2018-17, Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities . The amendments in this update modify the requirements for determining whether a decision-making fee is a variable interest and require reporting entities to consider indirect interests held through related parties under common control on a proportional basis. The ASU is effective for the Registrants for fiscal years 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.

Revenue

Revenue	12 Months Ended
	Dec. 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 year ended December 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 13 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: 2018 (In millions) Electric (a) Residential $ 2,494 Commercial 1,794 Industrial 690 Other 320 Total Electric operating revenues (b) $ 5,298 Gas Gas sales $ 1,055 End User Transportation 232 Intermediate Transportation 58 Other 91 Total Gas operating revenues (c) $ 1,436 Other segment operating revenues Gas Storage and Pipelines $ 485 Power and Industrial Projects (d) $ 2,204 Energy Trading (e) $ 5,557 _______________________________________ (a) Revenues under the Electric segment generally represent those of DTE Electric. (b) Includes $21 million under Alternative Revenue Programs and $20 million of other revenues, which are both outside the scope of Topic 606 for the year ended December 31, 2018 . (c) Includes $2 million under Alternative Revenue Programs and $7 million of other revenues, which are both outside the scope of Topic 606 for the year ended December 31, 2018 . (d) Includes revenues outside the scope of Topic 606 primarily related to $125 million of contracts accounted for as leases for the year ended December 31, 2018 . (e) Includes revenues outside the scope of Topic 606 primarily related to $4.5 billion of derivatives for the year ended December 31, 2018 . 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 22 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 standalone 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 unit or monthly basis. Gas Gas consists principally of DTE 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 include 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 refined coal, coal, blast furnace coke, 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 48 Revenue recognized that was included in the deferred revenue balance at the beginning of the period (30 ) Ending Balance, December 31, 2018 $ 74 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) 2019 $ 46 2020 1 2021 5 2022 7 2023 5 2024 and thereafter 10 $ 74 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) 2019 $ 267 $ 8 2020 263 — 2021 219 — 2022 172 — 2023 139 — 2024 and thereafter 658 — $ 1,718 $ 8 Other Matters DTE Energy and DTE Electric have recognized charges of $140 million and $85 million related to expense recognized for estimated uncollectible accounts receivable for the year ended December 31, 2018 , respectively.

Goodwill

Goodwill	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	GOODWILL DTE Energy has goodwill resulting from business combinations. The following is the summary of change in the carrying amount of goodwill for the years ended December 31: 2018 2017 (In millions) Balance as of January 1 $ 2,293 $ 2,286 Goodwill attributable to Gas Storage and Pipelines 2016 acquisition of AGS and SGG — 7 Balance at December 31 $ 2,293 $ 2,293

Property, Plant, and Equipment

Property, Plant, and Equipment	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
Property, Plant, and Equipment	PROPERTY, PLANT, AND EQUIPMENT The following is a summary of Property, plant, and equipment by classification as of December 31: 2018 2017 Property, plant, and equipment (In millions) DTE Electric Generation $ 11,027 $ 12,166 Distribution 9,153 8,637 Other 2,567 2,169 Total DTE Electric 22,747 22,972 DTE Gas Distribution 3,823 3,523 Storage 548 533 Transmission and other 1,204 1,118 Total DTE Gas 5,575 5,174 Non-utility and other 3,488 3,278 Total DTE Energy 31,810 31,424 Accumulated depreciation and amortization DTE Electric Generation (3,609 ) (4,403 ) Distribution (2,974 ) (2,914 ) Other (727 ) (667 ) Total DTE Electric (7,310 ) (7,984 ) DTE Gas Distribution (1,283 ) (1,238 ) Storage (165 ) (159 ) Transmission and other (404 ) (384 ) Total DTE Gas (1,852 ) (1,781 ) Non-utility and other (998 ) (938 ) Total DTE Energy (10,160 ) (10,703 ) Net DTE Energy Property, plant, and equipment $ 21,650 $ 20,721 Net DTE Electric Property, plant, and equipment $ 15,437 $ 14,988 The following is a summary of the Registrants' AFUDC and interest capitalized for the years ended December 31: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Allowance for debt funds used during construction and interest capitalized $ 15 $ 13 $ 9 $ 8 Allowance for equity funds used during construction 28 23 19 18 Total $ 43 $ 36 $ 28 $ 26 The composite depreciation rate for DTE Electric was approximately 3.7% , 3.6% , and 3.5% in 2018 , 2017 and 2016 , respectively. The composite depreciation rate for DTE Gas was 2.7% , in 2018 and 2017 , and 2.4% in 2016 . The average estimated useful life for each major class of utility Property, plant, and equipment as of December 31, 2018 follows: Estimated Useful Lives in Years Utility Generation Distribution Storage DTE Electric 40 41 N/A DTE Gas N/A 50 53 The estimated useful lives for DTE Electric's Other utility assets range from 3 to 62 years, while the estimated useful lives for DTE Gas' Transmission and other utility assets range from 5 to 70 years. The estimated useful lives for major classes of DTE Energy's non-utility assets and facilities range from 3 to 83 years. The following is a summary of Depreciation and amortization expense for DTE Energy: 2018 2017 2016 (In millions) Property, plant, and equipment $ 912 $ 865 $ 783 Regulatory assets and liabilities 212 165 193 $ 1,124 $ 1,030 $ 976 The following is a summary of Depreciation and amortization expense for DTE Electric: 2018 2017 2016 (In millions) Property, plant, and equipment $ 657 $ 620 $ 582 Regulatory assets and liabilities 179 133 168 $ 836 $ 753 $ 750 Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 1 to 15 years for DTE Energy and 3 to 15 years for DTE Electric. The following balances for capitalized software relate to DTE Energy: Year Ended December 31, 2018 2017 2016 (In millions) Amortization expense of capitalized software $ 108 $ 101 $ 89 Gross carrying value of capitalized software $ 905 $ 890 Accumulated amortization of capitalized software $ 534 $ 500 The following balances for capitalized software relate to DTE Electric: Year Ended December 31, 2018 2017 2016 (In millions) Amortization expense of capitalized software $ 101 $ 93 $ 83 Gross carrying value of capitalized software $ 799 $ 774 Accumulated amortization of capitalized software $ 463 $ 423 DTE Energy is the lessor under certain operating leases for energy facilities and related equipment. Property under operating leases for DTE Energy is as follows: DTE Energy 2018 2017 (In millions) Gross property under operating leases $ 447 $ 327 Accumulated amortization of property under operating leases $ 148 $ 108 The Registrants are the lessee under certain capital leases related to software and information technology related equipment. Property under capital leases for the Registrants is as follows: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Gross property under capital leases $ 18 $ 44 $ 18 $ 18 Accumulated amortization of property under capital leases $ 7 $ 38 $ 7 $ 12

Jointly-Owned Utility Plant

Jointly-Owned Utility Plant	12 Months Ended
	Dec. 31, 2018
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Jointly-Owned Utility Plant	JOINTLY-OWNED UTILITY PLANT DTE Electric has joint ownership interest in two power plants, Belle River and Ludington Hydroelectric Pumped Storage. DTE Electric’s share of direct expenses of the jointly-owned plants are included in Fuel, purchased power, and gas — utility and Operation and maintenance expenses in the DTE Energy Consolidated Statements of Operations and Fuel and purchased power — utility and Operation and maintenance expenses in the DTE Electric Consolidated Statements of Operations. DTE Electric's ownership information of the two utility plants as of December 31, 2018 was as follows: Belle River Ludington Hydroelectric Pumped Storage In-service date 1984-1985 1973 Ownership interest 81% 49% Investment in Property, plant, and equipment (in millions) $ 1,819 $ 586 Accumulated depreciation (in millions) $ 1,068 $ 187 Belle River The Michigan Public Power Agency (MPPA) has ownership interests in Belle River Unit No. 1 and other related facilities. The MPPA is entitled to 19% of the total capacity and energy of the plant and is responsible for the same percentage of the plant’s operation, maintenance, and capital improvement costs. Ludington Hydroelectric Pumped Storage Consumers Energy Company has an ownership interest in the Ludington Hydroelectric Pumped Storage Plant. Consumers Energy is entitled to 51% of the total capacity and energy of the plant and is responsible for the same percentage of the plant’s operation, maintenance, and capital improvement costs.

Asset Retirement Obligations

Asset Retirement Obligations	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS DTE Electric has a legal retirement obligation for the decommissioning costs for its Fermi 1 and Fermi 2 nuclear plants, dismantlement of facilities located on leased property, and various other operations. DTE Electric has conditional retirement obligations for asbestos and PCB removal at certain of its power plants and various distribution equipment. DTE Gas has conditional retirement obligations for gas pipelines, certain service centers, compressor and gate stations. The Registrants recognize such obligations as liabilities at fair market value when they are incurred, which generally is at the time the associated assets are placed in service. Fair value is measured using expected future cash outflows discounted at the Registrants' credit-adjusted risk-free rate. For its utility operations, the Registrants recognize in the Consolidated Statements of Operations removal costs in accordance with regulatory treatment. Any differences between costs recognized related to asset retirement and those reflected in rates are recognized as either a Regulatory asset or liability on the Consolidated Statements of Financial Position. If a reasonable estimate of fair value cannot be made in the period in which the retirement obligation is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. Natural gas storage system and certain other distribution assets for DTE Gas and substations, manholes, and certain other distribution assets for DTE Electric have an indeterminate life. Therefore, no liability has been recorded for these assets. A reconciliation of the asset retirement obligations for 2018 follows: DTE Energy DTE Electric (In millions) Asset retirement obligations at December 31, 2017 $ 2,320 $ 2,125 Accretion 140 129 Liabilities incurred 27 27 Liabilities settled (16 ) (8 ) Revision in estimated cash flows (2 ) (2 ) Asset retirement obligations at December 31, 2018 $ 2,469 $ 2,271 Approximately $2.0 billion of the asset retirement obligations represent nuclear decommissioning liabilities that are funded through a surcharge to electric customers over the life of the Fermi 2 nuclear plant. The NRC has jurisdiction over the decommissioning of nuclear power plants and requires minimum decommissioning funding based upon a formula. The MPSC and FERC regulate the recovery of costs of decommissioning nuclear power plants and both require the use of external trust funds to finance the decommissioning of Fermi 2. Rates approved by the MPSC provide for the recovery of decommissioning costs of Fermi 2 and the disposal of low-level radioactive waste. DTE Electric believes the MPSC collections will be adequate to fund the estimated cost of decommissioning. The decommissioning assets, anticipated earnings thereon, and future revenues from decommissioning collections will be used to decommission Fermi 2. DTE Electric expects the liabilities to be reduced to zero at the conclusion of the decommissioning activities. If amounts remain in the trust funds for Fermi 2 following the completion of the decommissioning activities, those amounts will be disbursed based on rulings by the MPSC and FERC. A portion of the funds recovered through the Fermi 2 decommissioning surcharge and deposited in external trust accounts is designated for the removal of non-radioactive assets and returning the site to greenfield. This removal and greenfielding is not considered a legal liability. Therefore, it is not included in the asset retirement obligation, but is reflected as the Nuclear decommissioning liability. The decommissioning of Fermi 1 is funded by DTE Electric. Contributions to the Fermi 1 trust are discretionary. For additional discussion of Nuclear decommissioning trust fund assets, see Note 12 to the Consolidated Financial Statements, " Fair Value ."

Regulatory Matters

Regulatory Matters	12 Months Ended
	Dec. 31, 2018
Regulatory Assets and Liabilities Disclosure [Abstract]
Regulatory Matters	REGULATORY MATTERS Regulation DTE Electric and DTE Gas are subject to the regulatory jurisdiction of the MPSC, which issues orders pertaining to rates, recovery of certain costs, including the costs of generating facilities and regulatory assets, conditions of service, accounting, and operating-related matters. DTE Electric is also regulated by the FERC with respect to financing authorization and wholesale electric activities. Regulation results in differences in the application of generally accepted accounting principles between regulated and non-regulated businesses. The Registrants are unable to predict the outcome of the unresolved regulatory matters discussed herein. Resolution of these matters is dependent upon future MPSC orders and appeals, which may materially impact the Consolidated Financial Statements of the Registrants. Regulatory Assets and Liabilities DTE Electric and DTE Gas are required to record Regulatory assets and liabilities for certain transactions that would have been treated as revenue or expense in non-regulated businesses. Continued applicability of regulatory accounting treatment requires that rates be designed to recover specific costs of providing regulated services and be charged to and collected from customers. Future regulatory changes or changes in the competitive environment could result in the discontinuance of this accounting treatment for Regulatory assets and liabilities for some or all of the Registrants' businesses and may require the write-off of the portion of any Regulatory asset or liability that was no longer probable of recovery through regulated rates. Management believes that currently available facts support the continued use of Regulatory assets and liabilities and that all Regulatory assets and liabilities are recoverable or refundable in the current regulatory environment. The following are balances and a brief description of the Registrants' Regulatory assets and liabilities at December 31: DTE Energy DTE Electric 2018 2017 2018 2017 Assets (In millions) Recoverable pension and other postretirement costs Pension $ 1,961 $ 2,000 $ 1,476 $ 1,502 Other postretirement costs 213 278 121 211 Asset retirement obligation 778 569 778 569 Recoverable undepreciated costs on retiring plants 630 — 630 — Removal costs asset 407 299 407 299 Recoverable Michigan income taxes 201 213 161 171 Accrued PSCR/GCR revenue 116 17 116 17 Deferred environmental costs 69 75 — — Unamortized loss on reacquired debt 60 65 43 46 Recoverable income taxes related to AFUDC equity 51 41 41 35 Energy Waste Reduction incentive 49 39 39 30 Nuclear Performance Evaluation and Review Committee Tracker 43 22 43 22 Customer360 deferred costs 42 45 42 45 Other recoverable income taxes 23 26 23 26 Transitional Reconciliation Mechanism 21 46 21 46 Other 57 43 36 36 4,721 3,778 3,977 3,055 Less amount included in Current Assets (153 ) (55 ) (148 ) (50 ) $ 4,568 $ 3,723 $ 3,829 $ 3,005 DTE Energy DTE Electric 2018 2017 2018 2017 Liabilities (In millions) Refundable federal income taxes $ 2,410 $ 2,384 $ 1,958 $ 1,946 Removal costs liability 253 265 — — TCJA rate reduction liability 118 — 93 — Negative other postretirement offset 101 80 79 67 Renewable energy 86 112 86 112 Refundable self-implemented rates 26 2 26 2 Negative pension offset 9 21 — — Fermi 2 refueling outage 4 15 4 15 Other 41 14 23 12 3,048 2,893 2,269 2,154 Less amount included in Current Liabilities (126 ) (18 ) (98 ) (17 ) $ 2,922 $ 2,875 $ 2,171 $ 2,137 As noted below, certain Regulatory assets for which costs have been incurred have been included (or are expected to be included, for costs incurred subsequent to the most recently approved rate case) in DTE Electric's or DTE Gas' rate base, thereby providing a return on invested costs (except as noted). Certain other regulatory assets are not included in rate base but accrue recoverable carrying charges until surcharges to collect the assets are billed. Certain Regulatory assets do not result from cash expenditures and therefore do not represent investments included in rate base or have offsetting liabilities that reduce rate base. ASSETS • Recoverable pension and other postretirement costs — Accounting standards for pension and other postretirement benefit costs require, among other things, the recognition in Other comprehensive income of the actuarial gains or losses and the prior service costs that arise during the period but that are not immediately recognized as components of net periodic benefit costs. DTE Electric and DTE Gas record the impact of actuarial gains or losses and prior service costs as a Regulatory asset since the traditional rate setting process allows for the recovery of pension and other postretirement costs. The asset will reverse as the deferred items are amortized and recognized as components of net periodic benefit costs. (a) • Asset retirement obligation — This obligation is for Fermi 2 decommissioning costs. The asset captures the timing differences between expense recognition and current recovery in rates and will reverse over the remaining life of the related plant. (a) • Recoverable undepreciated costs on retiring plants — Deferral of estimated remaining balances associated with coal power plants expected to be retired within the 2020 to 2023 time-frame. • Removal costs asset — Receivable for the recovery of asset removal expenditures in excess of amounts collected from customers. (a) • Recoverable Michigan income taxes — The State of Michigan enacted a corporate income tax resulting in the establishment of state deferred tax liabilities for DTE Energy's utilities. Offsetting Regulatory assets were also recorded as the impacts of the deferred tax liabilities will be reflected in rates as the related taxable temporary differences reverse and flow through current income tax expense. • Accrued PSCR/GCR revenue — Receivable for the temporary under-recovery of and carrying costs on fuel and purchased power costs incurred by DTE Electric which are recoverable through the PSCR mechanism and temporary under-recovery of and carrying costs on gas costs incurred by DTE Gas which are recoverable through the GCR mechanism. • Deferred environmental costs — The MPSC approved the deferral of investigation and remediation costs associated with DTE Gas' former MGP sites. Amortization of deferred costs is over a ten -year period beginning in the year after costs were incurred, with recovery (net of any insurance proceeds) through base rate filings. (a) • Unamortized loss on reacquired debt — The unamortized discount, premium, and expense related to debt redeemed with a refinancing are deferred, amortized, and recovered over the life of the replacement issue. • Recoverable income taxes related to AFUDC equity — Accounting standards for income taxes require recognition of a deferred tax liability for the equity component of AFUDC. A regulatory asset is required for the future increase in taxes payable related to the equity component of AFUDC that will be recovered from customers through future rates over the remaining life of the related plant. • Energy Waste Reduction incentive — DTE Electric and DTE Gas operate MPSC approved energy waste reduction programs designed to reduce overall energy usage by their customers. The utilities are eligible to earn an incentive by exceeding statutory savings targets. The utilities have consistently exceeded the savings targets and recognize the incentive as a regulatory asset in the period earned. (a) • Nuclear Performance Evaluation and Review Committee Tracker — Deferral and amortization of certain costs associated with oversight and review of DTE Electric's nuclear power generation program, including safety and regulatory compliance, nuclear leadership, nuclear facilities, as well as operation and financial performance, pursuant to the MPSC authorization. The approved five -year amortization period began January 1, 2018, with recovery (net of carrying costs) through base rate filings. • Customer360 deferred costs — The MPSC approved the deferral and amortization of certain costs associated with implementing Customer360, which is an integrated software application that enables improved interface among customer service, billing, meter reading, credit and collections, device management, account management, and retail access. Amortization of deferred costs over a 15 -year amortization period began after the billing system was put into operation during the second quarter of 2017. • Other recoverable income taxes — Income taxes receivable from DTE Electric's customers representing the difference in property-related deferred income taxes and amounts previously reflected in DTE Electric's rates. This asset will reverse over the remaining life of the related plant. • Transitional Reconciliation Mechanism — The MPSC approved the recovery of the deferred net incremental revenue requirement associated with the transition of PLD customers to DTE Electric's distribution system, effective July 1, 2014. Annual reconciliations will be filed and surcharges will be implemented to recover approved amounts. ________________________________________________ (a) Regulatory assets not earning a return or accruing carrying charges. LIABILITIES • Refundable federal income taxes — DTE Electric and DTE Gas' remeasurement of deferred taxes due to the enactment of the TCJA, which reflects the net impact of the tax rate change on cumulative temporary differences expected to reverse after the effective date of January 1, 2018. Refer to "2017 Tax Reform" section below for additional information. • Removal costs liability — The amount collected from customers for the funding of future asset removal activities. • TCJA rate reduction liability — Due to the change in the corporate Federal income tax rate from 35% to 21%, DTE Electric and DTE Gas reduced rates charged to customers during 2018. A regulatory liability equal to the difference between revenues billed based on a 35% rate, and revenues based on a 21% rate, was accrued for the period January 1, 2018 through the date the lower rates were implemented. The refund of the liability will commence on January 1, 2019 through June 30, 2019. • Negative other postretirement offset — DTE Electric and DTE Gas' negative other postretirement costs are not included as a reduction to their authorized rates; therefore, DTE Electric and DTE Gas are accruing a Regulatory liability to eliminate the impact on earnings of the negative other postretirement expense accrual. The Regulatory liabilities will reverse to the extent DTE Electric and DTE Gas' other postretirement expense is positive in future years. • Renewable energy — Amounts collected in rates in excess of renewable energy expenditures. • Refundable self-implemented rates — Amounts refundable to customers for base rates implemented from November 1, 2017 to May 1, 2018 in excess of amounts authorized in the June 2018 DTE Electric rate order from the MPSC. • Negative pension offset — DTE Gas' negative pension costs are not included as a reduction to its authorized rates; therefore, DTE Gas is accruing a Regulatory liability to eliminate the impact on earnings of the negative pension expense accrued. This Regulatory liability will reverse to the extent DTE Gas' pension expense is positive in future years. • Fermi 2 refueling outage — Accrued liability for refueling outage at Fermi 2 pursuant to MPSC authorization. 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. 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% . On June 28, 2018, the MPSC issued an order on a rehearing granting in part and denying in part, petitions for rehearings of DTE Electric and other intervenors. As a result, the approved addition to base rates increased from $65.2 million to $74.4 million . In August 2018, DTE Electric filed to refund its customers $26.2 million , inclusive of interest, based on their pro rata share of the revenue collected through the self-implementation surcharge in effect from November 1, 2017 to May 1, 2018. DTE Electric has recorded a refund liability as of December 31, 2018 . 2018 Electric Rate Case Filing DTE Electric filed a rate case with the MPSC on July 6, 2018 requesting an increase in base rates of $328 million based on a projected twelve-month period ending April 30, 2020. The requested increase in base rates is primarily due to an increase in net plant resulting from infrastructure investments, depreciation expense, as requested in the 2016 DTE Electric Depreciation Case Filing, and reliability improvement projects. The rate filing also requests an increase in return on equity from 10.0% to 10.5% and includes projected changes in sales, operation and maintenance expenses, and working capital. In addition, the rate filing requests an Infrastructure Recovery Mechanism to recover the incremental revenue requirement associated with certain distribution, fossil generation, and nuclear generation capital expenditures through 2022. Finally, as noted in the 2017 Tax Reform section below, DTE Electric addressed Calculation C in this filing. A final MPSC order in this case is expected by May 2019. 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. The MPSC issued an order April 27, 2018 approving DTE Electric's request for the three CONs with recoverable amounts through rates up to $951.8 million . In August 2018, DTE Electric began construction on its natural gas fueled combined cycle generation facility. 2016 DTE Electric Depreciation Case Filing DTE Electric filed a depreciation case with the MPSC on November 1, 2016 requesting an increase in depreciation rates for plant in service balances as of December 31, 2015. The MPSC issued an order on December 6, 2018 authorizing DTE Electric to increase its depreciation rates from 3.06% to 3.72% . The new rates will be effective upon a final order in DTE Electric's 2018 rate case filing expected by May 2019. 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 was primarily due to an increase in net plant. The rate filing also requested an increase in return on equity from 10.1% to 10.5% and included projected changes in sales, operations and maintenance expenses, and working capital. On May 24, 2018, DTE Gas reduced its initial requested increase in base rates to $38.1 million , primarily due to the effects of the TCJA on the original request. On September 13, 2018, the MPSC issued an order approving an annual revenue increase of $9 million for services rendered on or after October 1, 2018. The MPSC authorized a return on equity of 10.0% . Refer to the 2017 Tax Reform section below for further detail regarding the impact of the TCJA Credit A filing for DTE Gas. 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 MPSC approved the $38.2 million reduction on May 30, 2018, effective July 1, 2018. With approval of the DTE Gas Rate Order on September 13, 2018, effective October 1, 2018, this separate Credit A was terminated. DTE Electric filed its Credit A application on May 18, 2018, reflecting a reduction in revenues of $157 million . On July 24, 2018, the MPSC issued an order approving a settlement in DTE Electric's Credit A filing reflecting a reduction in revenues of $157 million . Rates reflecting this reduction were effective August 1, 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 up to the date Credit A is implemented. The Credit B filing is required within sixty days after Credit A is implemented. For Credit B, DTE Electric and DTE Gas have been deferring the impact of the reduction to the corporate tax rate since January 1, 2018. DTE Gas submitted its Credit B filing on July 30, 2018, reflecting a $25 million refund effective January 2019 through June 2019. On October 24, 2018, the MPSC issued an order approving the refund in DTE Gas' Credit B filing. DTE Electric submitted its Credit B filing on September 21, 2018, reflecting a $93 million refund effective January 2019 through June 2019. On December 20, 2018, the MPSC issued an order approving the $93 million refund, inclusive of interest, in DTE Electric's Credit B filing, which commenced on January 1, 2019 through June 30, 2019. The third step is to perform Calculation C to 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 Gas filed its Calculation C case on November 16, 2018 to reduce the revenue requirement by $12 million related to the amortization of deferred tax remeasurement. DTE Electric addressed Calculation C in its general rate case filed July 6, 2018.

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Income Taxes	INCOME TAXES Income Tax Summary DTE Energy files a consolidated federal income tax return. DTE Electric is a part of the consolidated federal income tax return of DTE Energy. DTE Energy and its subsidiaries file consolidated and/or separate company income tax returns in various states and localities, including a consolidated return in the State of Michigan. DTE Electric is part of the Michigan consolidated income tax return of DTE Energy. The federal, state and local income tax expense for DTE Electric is determined on an individual company basis with no allocation of tax expenses or benefits from other affiliates of DTE Energy. DTE Electric had income tax receivables with DTE Energy of $8 million and $12 million at December 31, 2018 and 2017 , respectively. The Registrants' total Income Tax Expense varied from the statutory federal income tax rate for the following reasons: 2018 2017 2016 DTE Energy (In millions) Income Before Income Taxes $ 1,216 $ 1,287 $ 1,105 Income tax expense at statutory rate - 21% in 2018 - 35% in 2017 and 2016 $ 255 $ 450 $ 387 Production tax credits (223 ) (189 ) (145 ) Investment tax credits (4 ) (4 ) (5 ) Depreciation 2 (4 ) (4 ) Noncontrolling interests 2 8 12 AFUDC equity (14 ) (18 ) (10 ) Employee Stock Ownership Plan dividends (3 ) (5 ) (5 ) Stock based compensation (3 ) (14 ) — Subsidiary stock loss — — (10 ) State and local income taxes, net of federal benefit 60 51 58 Enactment of the Tax Cuts and Jobs Act 21 (105 ) — Other, net 5 5 (7 ) Income Tax Expense $ 98 $ 175 $ 271 Effective income tax rate 8.1 % 13.6 % 24.5 % 2018 2017 2016 DTE Electric (In millions) Income Before Income Taxes $ 857 $ 928 $ 975 Income tax expense at statutory rate - 21% in 2018 - 35% in 2017 and 2016 $ 180 $ 325 $ 341 Production tax credits (35 ) (36 ) (30 ) Investment tax credits (3 ) (4 ) (4 ) Depreciation 2 3 3 AFUDC equity (3 ) (5 ) (6 ) Employee Stock Ownership Plan dividends (2 ) (3 ) (3 ) State and local income taxes, net of federal benefit 49 48 56 Enactment of the Tax Cuts and Jobs Act 7 — — Other, net (2 ) (1 ) (4 ) Income Tax Expense $ 193 $ 327 $ 353 Effective income tax rate 22.5 % 35.2 % 36.2 % Components of the Registrants' Income Tax Expense were as follows: 2018 2017 2016 DTE Energy (In millions) Current income tax expense (benefit) Federal $ (17 ) $ (22 ) $ (1 ) State and other income tax 1 1 7 Total current income taxes (16 ) (21 ) 6 Deferred income tax expense Federal 38 118 184 State and other income tax 76 78 81 Total deferred income taxes 114 196 265 $ 98 $ 175 $ 271 2018 2017 2016 DTE Electric (In millions) Current income tax expense (benefit) Federal $ — $ (17 ) $ — State and other income tax 4 (1 ) 11 Total current income taxes 4 (18 ) 11 Deferred income tax expense Federal 131 270 268 State and other income tax 58 75 74 Total deferred income taxes 189 345 342 $ 193 $ 327 $ 353 Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts in the Registrant's Consolidated Financial Statements. Consistent with the original establishment of these deferred tax liabilities (assets), no recognition of these non-cash transactions have been reflected in the Consolidated Statements of Cash Flows. The Registrants' deferred tax assets (liabilities) were comprised of the following at December 31: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Property, plant, and equipment $ (3,462 ) $ (3,276 ) $ (2,840 ) $ (2,698 ) Regulatory assets and liabilities (54 ) (94 ) (3 ) (31 ) Tax credit carry-forwards 1,178 947 250 193 Pension and benefits 311 334 258 302 Federal net operating loss carry-forward 117 83 2 47 State and local net operating loss carry-forwards 59 70 1 5 Investments in equity method investees (216 ) (82 ) (1 ) — Other 125 170 87 94 (1,942 ) (1,848 ) (2,246 ) (2,088 ) Less valuation allowance (33 ) (40 ) — — Long-term deferred income tax liabilities $ (1,975 ) $ (1,888 ) $ (2,246 ) $ (2,088 ) Deferred income tax assets $ 2,021 $ 1,814 $ 855 $ 830 Deferred income tax liabilities (3,996 ) (3,702 ) (3,101 ) (2,918 ) $ (1,975 ) $ (1,888 ) $ (2,246 ) $ (2,088 ) Tax credit carry-forwards for DTE Energy include $871 million of general business credits that expire from 2034 through 2038 and $307 million of alternative minimum tax credits that will be refundable over the next four years. The alternative minimum tax credits are production tax credits earned prior to 2006 but not utilized. The majority of these alternative minimum tax credits were generated from projects that had received a private letter ruling (PLR) from the IRS. These PLRs provide assurance as to the appropriateness of using these credits to offset taxable income, however, these tax credits are subject to IRS audit and adjustment. No valuation allowance is required for the tax credits carry-forward deferred tax asset. DTE Energy has a federal net operating loss carry-forward of $555 million as of December 31, 2018 . The net operating loss carry-forwards generated in 2015 and 2016 will expire from 2035 through 2036 , and the net operating loss carry-forward generated in 2018 will be carried forward indefinitely. No valuation allowance is required for the federal net operating loss deferred tax asset. DTE Energy has state and local deferred tax assets related to net operating loss carry-forwards of $59 million and $70 million at December 31, 2018 and 2017 , respectively. The state and local net operating loss carry-forwards expire from 2019 through 2038 . DTE Energy has recorded valuation allowances at December 31, 2018 and 2017 of approximately $33 million and $40 million , respectively, with respect to these deferred tax assets. In assessing the realizability of deferred tax assets, DTE Energy considers whether it is more likely than not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the periods in which those temporary differences become deductible. Tax credit carry-forwards for DTE Electric include $250 million of general business credits that expire from 2035 through 2038 . No valuation allowance is required for the tax credits carry-forward deferred tax asset. DTE Electric has a federal net operating loss carry-forward of $11 million as of December 31, 2018 , which will expire in 2035 . No valuation allowance is required for the federal net operating loss deferred tax asset. DTE Electric has state and local deferred tax assets related to net operating loss carry-forwards of $1 million at December 31, 2018 , while there was $5 million state and local deferred tax asset related to net operating loss carry-forwards at December 31, 2017 . No valuation allowance is required for DTE Electric's state and local net operating loss carry-forwards. The above tables exclude unamortized investment tax credits that are shown separately on the Registrants' Consolidated Statements of Financial Position. Investment tax credits are deferred and amortized to income over the average life of the related property. Tax Cuts and Jobs Act On December 22, 2017, the TCJA was enacted reducing the corporate income tax rate from 35% to 21% , effective January 1, 2018. As a result of the enactment, the deferred tax assets and liabilities were remeasured to reflect the impact of the TCJA on the cumulative temporary differences expected to reverse after the effective date. The net impact of this remeasurement was a decrease in deferred tax liabilities of $2.56 billion , of which $2.45 billion was attributable to regulated utilities and offset to regulatory assets and liabilities. This regulatory treatment is consistent with prior precedent set by the MPSC from previous tax law changes. The remaining $105 million was attributable to the non-utility entities and was recognized as a net reduction to income tax expense in 2017. On December 22, 2017, the SEC issued guidance under Staff Accounting Bulletin No. 118, Income Tax Accounting Implications of the Tax Cuts and Jobs Act (SAB 118), directing taxpayers to consider the implications of the TCJA as provisional when it does not have the necessary information available, prepared, or analyzed in reasonable detail to complete its accounting for the change in the tax law. Refer to Note 3 to the Consolidated Financial Statements, " New Accounting Pronouncements ," for a description of true-up adjustments to the remeasurement of deferred taxes recorded in 2018. Uncertain Tax Positions A reconciliation of the beginning and ending amount of unrecognized tax benefits for the Registrants is as follows: 2018 2017 2016 DTE Energy (In millions) Balance at January 1 $ 10 $ 10 $ 3 Additions for tax positions of prior years — — 7 Balance at December 31 $ 10 $ 10 $ 10 2018 2017 2016 DTE Electric (In millions) Balance at January 1 $ 13 $ 13 $ 4 Additions for tax positions of prior years — — 9 Balance at December 31 $ 13 $ 13 $ 13 DTE Energy had $8 million of unrecognized tax benefits at December 31, 2018 and 2017 that, if recognized, would favorably impact its effective tax rate. DTE Energy does not anticipate any material decrease in unrecognized tax benefits in the next twelve months. DTE Electric had $10 million of unrecognized tax benefits at December 31, 2018 and 2017 that, if recognized, would favorably impact its effective tax rate. DTE Electric does not anticipate any material decrease in unrecognized tax benefits in the next twelve months. The Registrants recognize interest and penalties pertaining to income taxes in Interest expense and Other expenses, respectively, on their Consolidated Statements of Operations. Accrued interest pertaining to income taxes for DTE Energy totaled $4 million and $3 million at December 31, 2018 and 2017 , respectively. DTE Energy recognized interest expense related to income taxes of $1 million in 2018 , a nominal amount in 2017 , and $2 million in 2016 . DTE Energy had accrued no penalties pertaining to income taxes. Accrued interest pertaining to income taxes for DTE Electric totaled $5 million and $4 million at December 31, 2018 and 2017 , respectively. DTE Electric recognized interest expense related to income taxes of $1 million in 2018 , a nominal amount in 2017 , and $3 million in 2016 . DTE Electric had accrued no penalties pertaining to income taxes. In 2018 , DTE Energy, including DTE Electric, settled a federal tax audit for the 2016 tax year. DTE Energy's federal income tax returns for 2017 and subsequent years remain subject to examination by the IRS. DTE Energy's Michigan Business Tax and Michigan Corporate Income Tax returns for the year 2008 and subsequent years remain subject to examination by the State of Michigan. DTE Energy also files tax returns in numerous state and local jurisdictions with varying statutes of limitation.

Earnings Per Share

Earnings Per Share	12 Months Ended
	Dec. 31, 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. For additional information, see Notes 14 and 21 to Consolidated Financial Statements, " Long-Term Debt " and " Stock-Based Compensation ," respectively. The following is a reconciliation of DTE Energy's basic and diluted income per share calculation for the years ended December 31 : 2018 2017 2016 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 1,120 $ 1,134 $ 868 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — basic $ 1,118 $ 1,132 $ 866 Average number of common shares outstanding — basic 181 179 179 Basic Earnings per Common Share $ 6.18 $ 6.32 $ 4.84 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 1,120 $ 1,134 $ 868 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — diluted $ 1,118 $ 1,132 $ 866 Average number of common shares outstanding — diluted 181 179 179 Diluted Earnings per Common Share (a) $ 6.17 $ 6.32 $ 4.83 _______________________________________ (a) The 2016 Equity Units excluded from the calculation of diluted EPS were approximately 6.3 million for the years ended December 31, 2018 and 2017 as the dilutive stock price threshold was not met. For more information, see Note 14 to the Consolidated Financial Statements, " Long-Term Debt ."

Fair Value

Fair Value	12 Months Ended
	Dec. 31, 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 December 31, 2018 and 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 (a) : December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Other (b) Netting (c) Net Balance Level 1 Level 2 Level 3 Other (b) Netting (c) Net Balance (In millions) Assets Cash equivalents (d) $ 16 $ 2 $ — $ — $ — $ 18 $ 16 $ 3 $ — $ — $ — $ 19 Nuclear decommissioning trusts Equity securities 851 — — — — 851 978 — — — — 978 Fixed income securities 12 490 — — — 502 18 477 — — — 495 Private equity and other — — — 20 — 20 — — — 5 — 5 Cash equivalents 5 — — — — 5 14 — — — — 14 Other investments (e) Equity securities 110 — — — — 110 118 — — — — 118 Fixed income securities 69 — — — — 69 72 — — — — 72 Cash equivalents 4 — — — — 4 4 — — — — 4 Derivative assets: Commodity Contracts: Natural Gas 199 87 63 — (277 ) 72 148 112 97 — (256 ) 101 Electricity — 247 56 — (252 ) 51 — 243 42 — (241 ) 44 Other — — 7 — (1 ) 6 — — 9 — — 9 Foreign currency exchange contracts — 4 — — — 4 — 1 — — (1 ) — Total derivative assets 199 338 126 — (530 ) 133 148 356 148 — (498 ) 154 Total $ 1,266 $ 830 $ 126 $ 20 $ (530 ) $ 1,712 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Derivative liabilities: Commodity Contracts: Natural Gas $ (197 ) $ (71 ) $ (112 ) $ — $ 272 $ (108 ) $ (141 ) $ (111 ) $ (126 ) $ — $ 263 $ (115 ) Electricity — (227 ) (58 ) — 240 (45 ) — (245 ) (30 ) — 246 (29 ) Other — (1 ) — — 1 — — — (1 ) — 1 — Interest rate contracts — (3 ) — — — (3 ) — — — — — — Foreign currency exchange contracts — — — — — — — (3 ) — — 1 (2 ) Total derivative liabilities (197 ) (302 ) (170 ) — 513 (156 ) (141 ) (359 ) (157 ) — 511 (146 ) Total $ (197 ) $ (302 ) $ (170 ) $ — $ 513 $ (156 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,069 $ 528 $ (44 ) $ 20 $ (17 ) $ 1,556 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 Assets Current $ 212 $ 273 $ 96 $ — $ (461 ) $ 120 $ 157 $ 298 $ 104 $ — $ (437 ) $ 122 Noncurrent 1,054 557 30 20 (69 ) 1,592 1,211 538 44 5 (61 ) 1,737 Total Assets $ 1,266 $ 830 $ 126 $ 20 $ (530 ) $ 1,712 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Current $ (191 ) $ (251 ) $ (76 ) $ — $ 451 $ (67 ) $ (137 ) $ (313 ) $ (108 ) $ — $ 459 $ (99 ) Noncurrent (6 ) (51 ) (94 ) — 62 (89 ) (4 ) (46 ) (49 ) — 52 (47 ) Total Liabilities $ (197 ) $ (302 ) $ (170 ) $ — $ 513 $ (156 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,069 $ 528 $ (44 ) $ 20 $ (17 ) $ 1,556 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 _______________________________________ (a) See footnotes on following page. _______________________________________ (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) 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. (d) At December 31, 2018 , the $18 million consisted of $3 million , $5 million , and $10 million of cash equivalents included in Cash and Cash equivalents, Restricted cash, and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2017 , the $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. (e) Excludes cash surrender value of life insurance investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis: December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Other (a) Net Balance Level 1 Level 2 Level 3 Other Net Balance (In millions) Assets Cash equivalents (b) $ 8 $ 2 $ — $ — $ 10 $ 8 $ 3 $ — $ — $ 11 Nuclear decommissioning trusts Equity securities 851 — — — 851 978 — — — 978 Fixed income securities 12 490 — — 502 18 477 — — 495 Private equity and other — — — 20 20 — — — 5 5 Cash equivalents 5 — — — 5 14 — — — 14 Other investments Equity securities 10 — — — 10 11 — — — 11 Derivative assets — FTRs — — 6 — 6 — — 9 — 9 Total $ 886 $ 492 $ 6 $ 20 $ 1,404 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 Assets Current $ 8 $ 2 $ 6 $ — $ 16 $ 8 $ 3 $ 9 $ — $ 20 Noncurrent 878 490 — 20 1,388 1,021 477 — 5 1,503 Total Assets $ 886 $ 492 $ 6 $ 20 $ 1,404 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) At December 31, 2018 , the $10 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. At December 31, 2017 , the $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 commingled funds. Other assets such as private equity investments are used to enhance long-term returns while improving portfolio diversification. All pricing for private equity 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. Commingled funds that 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. 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: Year Ended December 31, 2018 Year Ended December 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 (146 ) 29 1 (116 ) (29 ) 109 2 82 Recorded in Regulatory liabilities — — 9 9 — — 25 25 Purchases, issuances, and settlements: Purchases — — — — — — — — Issuances — — — — — — — — Settlements 129 (43 ) (11 ) 75 96 (106 ) (18 ) (28 ) Net Assets (Liabilities) as of December 31 $ (49 ) $ (2 ) $ 7 $ (44 ) $ (29 ) $ 12 $ 8 $ (9 ) The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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 $ (119 ) $ 15 $ (16 ) $ (120 ) $ (30 ) $ 50 $ 1 $ 21 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: Year Ended December 31, 2018 2017 (In millions) Net Assets as of January 1 $ 9 $ 2 Change in fair value recorded in Regulatory liabilities 9 25 Purchases, issuances, and settlements: Settlements (12 ) (18 ) Net Assets as of December 31 $ 6 $ 9 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2018 and 2017 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 6 $ 9 Derivatives are transferred between levels primarily due to changes in the source data used to construct price curves as a result of changes in market liquidity. Transfers in and transfers out are reflected as if they had occurred at the beginning of the period. There were no transfers between Levels 1 and 2 for the Registrants during the years ended December 31, 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: December 31, 2018 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 63 $ (112 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (2.15 ) — $ 5.59 /MMBtu $ (0.1 )/MMBtu Electricity $ 56 $ (58 ) Discounted Cash Flow Forward basis price (per MWh) $ (7 ) — $ 9 /MWh $ 1 /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: December 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 $ 40 $ — $ — $ 40 $ 38 $ — $ — $ 38 Dividends payable $ 172 $ 172 $ — $ — $ 158 $ 158 $ — $ — Short-term borrowings $ 609 $ — $ 609 $ — $ 621 $ — $ 621 $ — Notes payable — Other (b) , excluding capital leases $ 41 $ — $ — $ 41 $ 12 $ — $ — $ 12 Long-term debt (c) $ 13,622 $ 1,796 $ 10,712 $ 1,317 $ 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: December 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, excluding capital leases $ 6 $ — $ — $ 6 $ — $ — $ — $ — Short-term borrowings — affiliates $ 101 $ — $ 101 $ 116 $ — $ — $ 116 Short-term borrowings — other $ 149 $ — $ 149 $ — 238 $ — $ 238 $ — Notes payable — Other (a) , excluding capital leases $ 21 $ — $ — $ 21 $ 2 $ — $ — $ 2 Long-term debt (b) $ 6,538 $ — $ 6,552 $ 161 $ 6,017 $ — $ 6,441 $ 171 _______________________________________ (a) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Electric's Consolidated Statements of Financial Position. (b) Includes debt due within one year, unamortized debt discounts, and issuance costs. Excludes Capital lease obligations. For further fair value information on financial and derivative instruments, see Note 13 to the Consolidated Financial Statements, " Financial and Other Derivative Instruments ." Nuclear Decommissioning Trust Funds DTE Electric has a legal obligation to decommission its nuclear power plants following the expiration of its operating licenses. This obligation is reflected as an Asset retirement obligation on DTE Electric's Consolidated Statements of Financial Position. Rates approved by the MPSC provide for the recovery of decommissioning costs of Fermi 2 and the disposal of low-level radioactive waste. See Note 8 to the Consolidated Financial Statements, " Asset Retirement Obligations ." The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: December 31, 2018 2017 (In millions) Fermi 2 $ 1,372 $ 1,475 Fermi 1 3 3 Low-level radioactive waste 3 14 $ 1,378 $ 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: Year Ended December 31, 2018 2017 2016 (In millions) Realized gains $ 65 $ 83 $ 74 Realized losses $ (42 ) $ (29 ) $ (63 ) Proceeds from sale of securities $ 1,203 $ 1,240 $ 1,457 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: December 31, 2018 December 31, 2017 Fair Unrealized Unrealized Losses Fair Unrealized Unrealized Losses (In millions) Equity securities $ 851 $ 235 $ (79 ) $ 978 $ 320 $ (32 ) Fixed income securities 502 7 (8 ) 495 13 (3 ) Private equity and other 20 — — 5 — — Cash equivalents 5 — — 14 — — $ 1,378 $ 242 $ (87 ) $ 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: December 31, 2018 (In millions) Due within one year $ 29 Due after one through five years 89 Due after five through ten years 113 Due after ten years 271 $ 502 Other Securities At December 31, 2018 and 2017 , the Registrants' securities, included in Other investments on the Consolidated Statements of Financial Position, were comprised primarily of money market and equity securities. Net losses related to equity securities held at December 31, 2018 were $11 million and net gains related to equity securities held at December 31, 2017 and 2016 were $26 million , and $15 million , respectively, for the Registrants. Gains or losses related to the Rabbi Trust assets are allocated from DTE Energy to DTE Electric.

Financial and Other Derivative

Financial and Other Derivative Instruments	12 Months Ended
	Dec. 31, 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 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, renewable gas recovery, and power generation assets. Primarily fixed-price contracts are used in the marketing and management of the segment assets. These contracts are generally not derivatives and are therefore accounted for under the accrual method. Energy Trading — Commodity Price Risk — Energy Trading markets and trades electricity, natural gas physical products, and energy financial instruments, and provides energy and asset management services utilizing energy commodity derivative instruments. Forwards, futures, options, and swap agreements are used to manage exposure to the risk of market price and volume fluctuations in its operations. These derivatives are accounted for by recording changes in fair value to earnings unless hedge accounting criteria are met. Energy Trading — Foreign Currency Exchange Risk — Energy Trading has foreign currency exchange forward contracts to economically hedge fixed Canadian dollar commitments existing under natural gas and power purchase and sale contracts and natural gas transportation contracts. Energy Trading enters into these contracts to mitigate price volatility with respect to fluctuations of the Canadian dollar relative to the U.S. dollar. These derivatives are accounted for by recording changes in fair value to earnings unless hedge accounting criteria are met. Corporate and Other — Interest Rate Risk — DTE Energy may use interest rate swaps, treasury locks, and other derivatives to hedge the risk associated with interest rate market volatility. Credit Risk — DTE Energy maintains credit policies that significantly minimize overall credit risk. These policies include an evaluation of potential customers’ and counterparties’ financial condition, including the viability of underlying productive assets, credit rating, collateral requirements, or other credit enhancements such as letters of credit or guarantees. DTE Energy generally uses standardized agreements that allow the netting of positive and negative transactions associated with a single counterparty. DTE Energy maintains a provision for credit losses based on factors surrounding the credit risk of its customers, historical trends, and other information. Based on DTE Energy's credit policies and its December 31, 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: December 31, 2018 December 31, 2017 Derivative Derivative Derivative Derivative (In millions) Derivatives designated as hedging instruments Interest rate contracts $ — $ (3 ) $ — $ — Derivatives not designated as hedging instruments Commodity contracts Natural gas $ 349 $ (380 ) $ 357 $ (378 ) Electricity 303 (285 ) 285 (275 ) Other 7 (1 ) 9 (1 ) Foreign currency exchange contracts 4 — 1 (3 ) Total derivatives not designated as hedging instruments $ 663 $ (666 ) $ 652 $ (657 ) Current $ 563 $ (518 ) $ 540 $ (558 ) Noncurrent 100 (151 ) 112 (99 ) Total derivatives $ 663 $ (669 ) $ 652 $ (657 ) The following table presents the fair value of derivative instruments for DTE Electric: December 31, 2018 2017 (In millions) FTRs — Other current assets $ 6 $ 9 Total derivatives not designated as hedging instruments $ 6 $ 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 approximately $4 million outstanding at December 31, 2018 and 2017 , 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 $8 million and $4 million at December 31, 2018 and 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 received, net of cash collateral posted, was $13 million as of December 31, 2018 . DTE Energy had $28 million total cash collateral posted, net of cash collateral received, as of December 31, 2017 . DTE Energy had $17 million of cash collateral related to unrealized positions to net against Derivative assets and no cash collateral related to unrealized positions to net against Derivative liabilities as of December 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 $10 million and cash collateral received of $6 million not related to unrealized derivative positions as of December 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: December 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 $ 349 $ (277 ) $ 72 $ 357 $ (256 ) $ 101 Electricity 303 (252 ) 51 285 (241 ) 44 Other 7 (1 ) 6 9 — 9 Foreign currency exchange contracts 4 — 4 1 (1 ) — Total derivative assets $ 663 $ (530 ) $ 133 $ 652 $ (498 ) $ 154 Derivative liabilities Commodity contracts Natural gas $ (380 ) $ 272 $ (108 ) $ (378 ) $ 263 $ (115 ) Electricity (285 ) 240 (45 ) (275 ) 246 (29 ) Other (1 ) 1 — (1 ) 1 — Interest rate contracts (3 ) — (3 ) — — — Foreign currency exchange contracts — — — (3 ) 1 (2 ) Total derivative liabilities $ (669 ) $ 513 $ (156 ) $ (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: December 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 $ 563 $ 100 $ (518 ) $ (151 ) $ 540 $ 112 $ (558 ) $ (99 ) Counterparty netting (451 ) (62 ) 451 62 (437 ) (52 ) 437 52 Collateral adjustment (10 ) (7 ) — — — (9 ) 22 — Total derivatives as reported $ 102 $ 31 $ (67 ) $ (89 ) $ 103 $ 51 $ (99 ) $ (47 ) The effect of derivatives not designated as hedging instruments on DTE Energy's Consolidated Statements of Operations is as follows: Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31, 2018 2017 2016 (In millions) Derivatives not Designated as Hedging Instruments Commodity contracts Natural gas Operating Revenues — Non-utility operations $ (42 ) $ (74 ) $ (153 ) Natural gas Fuel, purchased power, and gas — non-utility (94 ) 97 (2 ) Electricity Operating Revenues — Non-utility operations 49 105 43 Other Operating Revenues — Non-utility operations (1 ) 2 5 Foreign currency exchange contracts Operating Revenues — Non-utility operations 7 (2 ) (2 ) Total $ (81 ) $ 128 $ (109 ) Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility. The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of December 31, 2018 : Commodity Number of Units Natural Gas (MMBtu) 2,171,541,994 Electricity (MWh) 36,163,761 Foreign Currency Exchange (Canadian dollars) 101,975,644 Various subsidiaries of DTE Energy have entered into contracts which contain ratings triggers and are guaranteed by DTE Energy. These contracts contain provisions which allow the counterparties to require that DTE Energy post cash or letters of credit as collateral in the event that DTE Energy’s credit rating is downgraded below investment grade. Certain of these provisions (known as "hard triggers") state specific circumstances under which DTE Energy can be required to post collateral upon the occurrence of a credit downgrade, while other provisions (known as "soft triggers") are not as specific. For contracts with soft triggers, it is difficult to estimate the amount of collateral which may be requested by counterparties and/or which DTE Energy may ultimately be required to post. The amount of such collateral which could be requested fluctuates based on commodity prices (primarily natural gas, power, and coal) and the provisions and maturities of the underlying transactions. As of December 31, 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 $638 million . As of December 31, 2018 , DTE Energy had $541 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 $495 million . The net remaining amount of $46 million is derived from the $638 million noted above.

Long-Term Debt

Long-Term Debt	12 Months Ended
	Dec. 31, 2018
Long-term Debt, Unclassified [Abstract]
Long-Term Debt	LONG-TERM DEBT Long-Term Debt DTE Energy's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2018 2017 (In millions) Mortgage bonds, notes, and other DTE Energy Debt, Unsecured 3.2% 2019 — 2033 $ 4,425 $ 3,825 DTE Electric Taxable Debt, Principally Secured 4.3% 2020 — 2048 6,280 5,755 DTE Electric Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 DTE Gas Taxable Debt, Principally Secured 4.5% 2019 — 2048 1,550 1,330 Other Long-Term Debt, including Non-Recourse Debt 1 7 12,566 11,227 Unamortized debt discount and premium, net (16 ) (15 ) Unamortized debt issuance costs (73 ) (69 ) Long-term debt due within one year (1,495 ) (104 ) $ 10,982 $ 11,039 Junior Subordinated Debentures Subordinated Debentures 5.5% 2062 — 2077 $ 1,180 $ 1,180 Unamortized debt issuance costs (35 ) (35 ) $ 1,145 $ 1,145 _______________________________________ (a) Weighted average interest rate as of December 31, 2018 . (b) DTE Electric Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds. DTE Electric's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2018 2017 (In millions) Mortgage bonds, notes, and other Taxable Debt, Principally Secured 4.3% 2020 — 2048 $ 6,280 $ 5,755 Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 6,590 6,065 Unamortized debt discount (11 ) (10 ) Unamortized debt issuance costs (41 ) (38 ) $ 6,538 $ 6,017 _______________________________________ (a) Weighted average interest rate as of December 31, 2018 . (b) Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds. Debt Issuances In 2018 , the following debt was issued: Company Month Type Interest Rate Maturity Date Amount (In millions) DTE Electric May Mortgage Bonds (a) 4.05% 2048 $ 525 DTE Energy August Senior Notes (b) 3.70% 2023 600 DTE Gas August Mortgage Bonds (b) 3.81% 2028 195 DTE Gas August Mortgage Bonds (b) 4.14% 2048 125 $ 1,445 _______________________________________ (a) Bonds were issued as Green Bonds and the proceeds will be used to finance expenditures for solar and wind energy, payments under power purchase agreements for solar and wind energy, and energy optimization programs. (b) Proceeds were used for the repayment of short-term borrowings and general corporate purposes. Debt Redemptions In 2018 , the following debt was redeemed: Company Month Type Interest Rate Maturity Date Amount (In millions) DTE Gas April Senior Notes 6.04% 2018 $ 100 DTE Energy Various Other Long-Term Debt Various 2018 5 $ 105 The following table shows the Registrants' scheduled debt maturities, excluding any unamortized discount or premium on debt: 2019 2020 2021 2022 2023 2024 and Thereafter Total (In millions) DTE Energy (a) $ 1,495 $ 682 $ 462 $ 616 $ 1,177 $ 9,314 $ 13,746 DTE Electric $ — $ 632 $ 462 $ 316 $ 202 $ 4,978 $ 6,590 _______________________________________ (a) Amounts include DTE Electric's scheduled debt maturities. Junior Subordinated Debentures At December 31, 2018 , DTE Energy had the following Junior Subordinated Debentures: Interest Rate Maturity Date Amount (In millions) 2012 Series C 5.25% 2062 $ 200 2016 Series B 5.375% 2076 300 2016 Series F 6.00% 2076 280 2017 Series E 5.25% 2077 400 $ 1,180 DTE Energy has the right to defer interest payments on the debt securities. Should DTE Energy exercise this right, it cannot declare or pay dividends on, or redeem, purchase or acquire, any of its capital stock during the deferral period. Any deferred interest payments will bear additional interest at the rate associated with the related debt issue. As of December 31, 2018 , no interest payments have been deferred on the debt securities. Cross Default Provisions Substantially all of the net utility properties of DTE Electric and DTE Gas are subject to the lien of mortgages. Should DTE Electric or DTE Gas fail to timely pay their indebtedness under these mortgages, such failure may create cross defaults in the indebtedness of DTE Energy. Acquisition Financing Effective October 1, 2016 , DTE Energy closed on the purchase of midstream natural gas assets. DTE Energy purchased 100% of AGS, located in Pennsylvania and West Virginia, and 40% of SGG, located in West Virginia, from M3 Midstream. In addition, DTE Energy purchased 15% of SGG from Vega Energy Partners, resulting in 55% total ownership of SGG by DTE Energy. The acquisition was financed through the issuance of Equity Units and Senior Notes. In October 2016, DTE issued $675 million of Equity Units. Each Equity Unit has a stated amount of $ 50 , initially in the form of a Corporate Unit, is comprised of (i) a forward purchase contract to buy DTE Energy common stock (stock purchase contract) and (ii) a 1/20 undivided beneficial ownership interest in $1,000 principal amount of DTE Energy’s 2016 Series C 1.5% RSNs due 2024 . The RSN debt instruments and the stock purchase contract equity instruments are deemed to be separate instruments as the investor may trade the RSNs separately from the stock purchase contracts and may also settle the stock purchase contracts separately. The Corporate Units are listed on the New York Stock Exchange under the symbol DTV. The stock purchase contract obligates the holder to purchase from DTE Energy on the settlement date, October 1, 2019, for a price of $ 50 per stock purchase contract, the following number of shares of DTE Energy’s common stock, subject to anti-dilution adjustments: • if the AMV of DTE Energy’s common stock, which is the average volume-weighted average price of DTE Energy’s common stock for the trading days during the 20 consecutive scheduled trading day period ending on the third scheduled trading day immediately preceding the stock purchase contract settlement date, is equal to or greater than $116.31 , 0.4299 shares of common stock; • if the AMV is less than $116.31 but greater than $ 93.05 , a number of shares of common stock equal to $50 divided by the AMV, rounded to the nearest 1/10,000th of a share; and • if the AMV is less than or equal to $93.05 , 0.5373 shares of common stock. The RSNs bear interest at a rate of 1.5% per year, payable quarterly, and mature on October 1, 2024 . The RSNs will be remarketed in 2019. If this remarketing is successful, the interest rate on the RSNs will be reset, and thereafter interest will be payable semi-annually at the reset rate. If there is no successful remarketing, the interest rate on the RSNs will not be reset, and the holders of the RSNs will have the right to put the RSNs to DTE Energy at a price equal to 100% of the principal amount, and the proceeds of the put right will be deemed to have been applied against the holders’ obligation under the stock purchase contracts. DTE Energy may also redeem, in whole or in part, the RSNs in the event of a failed final remarketing. On January 1, 2017, DTE Energy began paying the stock purchase contract holders quarterly contract adjustment payments at a rate of 5% per year of the stated amount of $50 per Equity Unit, or $2.50 per year. The present value of the future contract adjustment payments of $98 million was recorded as a reduction of shareholders’ equity, offset by the stock purchase contract liability. The stock purchase contract liability is included in Current Liabilities — Other and Other Liabilities — Other on DTE Energy’s Consolidated Statements of Financial Position. Interest payments on the RSNs are recorded as interest expense and stock purchase contract payments are charged against the liability. Accretion of the stock purchase contract liability is recorded as imputed interest expense. The treasury stock method is used to compute diluted EPS for the stock purchase contract. Under the treasury stock method, the stock purchase contract will only have a dilutive effect when the settlement rate is based on the market value of DTE’s common stock that is greater than $116.31 (the threshold appreciation price). At December 31, 2018 , the stock purchase price contract was anti-dilutive and, therefore, not included in the computation of diluted earnings per share. If payments for the stock purchase contract are deferred, DTE Energy may not make any cash distributions related to its capital stock, including dividends, redemptions, repurchases, liquidation payments or guarantee payments. Also, during the deferral period, DTE Energy may not make any payments on or redeem or repurchase any debt securities that are equal in right of payment with, or subordinated to, the RSNs. Until settlement of the stock purchase contracts, the shares of stock underlying each contract are not outstanding. Under the terms of the stock purchase contracts, assuming no anti-dilution or other adjustments, DTE Energy will issue between 5.8 million and 7.3 million shares of its common stock in October 2019. A total of 9 million shares of DTE Energy’s common stock have been reserved for issuance in connection with the stock purchase contracts. Selected information about DTE Energy’s 2016 Equity Units is presented below: Issuance Date Units Issued Total Net Proceeds Total Long-Term Debt RSN Annual Interest Rate Stock Purchase Contract Annual Rate Stock Purchase Settlement Date Stock Purchase Contract Liability (a) RSN Maturity Date (In millions, except interest rates) 10/5/2016 13.5 $ 654 $ 675 1.5% 5.0% 10/1/2019 $ 98 10/1/2024 _______________________________________ (a) Payments of $33 million and $32 million were made in 2018 and 2017, respectively. The stock purchase contract liability, exclusive of interest, was $33 million and $66 million at December 31, 2018 and 2017 , respectively.

Preferred and Preference Securi

Preferred and Preference Securities	12 Months Ended
	Dec. 31, 2018
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Preferred and Preference Securities	PREFERRED AND PREFERENCE SECURITIES As of December 31, 2018 , the amount of authorized and unissued stock is as follows: Company Type of Stock Par Value Shares Authorized DTE Energy Preferred $ — 5,000,000 DTE Electric Preferred $ 100 6,747,484 DTE Electric Preference $ 1 30,000,000 DTE Gas Preferred $ 1 7,000,000 DTE Gas Preference $ 1 4,000,000

Short-Term Credit Arrangements

Short-Term Credit Arrangements and Borrowings	12 Months Ended
	Dec. 31, 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 December 31, 2018 , the total funded debt to total capitalization ratios for DTE Energy, DTE Electric, and DTE Gas were 0.55 to 1, 0.50 to 1, and 0.48 to 1, respectively, and were in compliance with this financial covenant. The availability under the facilities in place at December 31, 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 December 31, 2018 Commercial paper issuances 271 149 189 609 Letters of credit 168 — — 168 439 149 189 777 Net availability at December 31, 2018 $ 981 $ 251 $ 111 $ 1,343 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. The weighted average interest rate for short-term borrowings was 2.9% and 1.9% at December 31, 2018 and 2017 , respectively, for DTE Energy. The weighted average interest rate for short-term borrowings was 2.9% and 1.5% at December 31, 2018 and 2017 , respectively, for DTE Electric. In conjunction with maintaining certain exchange-traded risk management positions, DTE Energy may be required to post collateral with its clearing agent. DTE Energy has a demand financing agreement for up to $100 million with its clearing agent. The agreement, as amended, also allows for up to $50 million of additional margin financing provided that DTE Energy posts a letter of credit for the incremental amount and allows the right of setoff with posted collateral. At December 31, 2018 , the capacity under this facility was $125 million . The amount outstanding under this agreement was $93 million and $56 million at December 31, 2018 and 2017 , respectively, and was fully offset by the posted collateral. Dividend Restrictions Certain of DTE Energy’s credit facilities contain a provision requiring DTE Energy to maintain a total funded debt to capitalization ratio, as defined in the agreements, of no more than 0.65 to 1, which has the effect of limiting the amount of dividends DTE Energy can pay in order to maintain compliance with this provision. At December 31, 2018 , the effect of this provision was to restrict the payment of approximately $2.4 billion of Retained earnings totaling $6.1 billion . There are no other effective limitations with respect to DTE Energy’s ability to pay dividends.

Capital and Operating Leases

Capital and Operating Leases	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Capital and Operating Leases	CAPITAL AND OPERATING LEASES Lessee Operating Lease — The Registrants lease various assets under operating leases, including coal railcars, office buildings, a warehouse, computers, vehicles, and other equipment. The lease arrangements expire at various dates through 2051 and 2046 for DTE Energy and DTE Electric, respectively. The Registrants' future minimum lease payments under non-cancelable operating leases at December 31, 2018 were: DTE Energy DTE Electric (In millions) 2019 $ 42 $ 17 2020 30 12 2021 18 10 2022 11 7 2023 8 5 2024 and thereafter 45 29 Total minimum lease payments $ 154 $ 80 Rental expense for DTE Energy operating leases was $44 million in 2018 , $51 million in 2017 , and $43 million in 2016 , including rental expense for DTE Electric operating leases of $18 million in 2018 and $28 million in 2017 and 2016 . Lessor Operating Lease — DTE Energy leases various assets under operating leases for energy facilities and related equipment. DTE Energy's minimum future rental revenues under non-cancelable operating leases as of December 31, 2018 were: DTE Energy (In millions) 2019 $ 66 2020 66 2021 64 2022 20 2023 20 2024 and thereafter 196 Total minimum future rental revenue under non-cancelable operating leases $ 432 The amounts listed above do not include contingent rentals associated with the leased assets. DTE Energy had contingent rental revenues of $107 million , $91 million , and $101 million in 2018 , 2017 , and 2016 , respectively. Capital Lease — DTE Energy leases a portion of its pipeline system to the Vector Pipeline through a capital lease contract that expires in 2020, with renewal options extending for five years. DTE Energy owns a 40% interest in the Vector Pipeline. In addition, DTE Energy has two energy services agreements, for which a portion of are accounted for as capital leases. These agreements expire in 2019 and 2026. The components of DTE Energy's net investment in capital leases at December 31, 2018 , were as follows: DTE Energy (In millions) 2019 $ 10 2020 9 2021 — 2022 — 2023 — 2024 and thereafter 1 Total minimum future lease receipts 20 Residual value of leased pipeline 40 Less unearned income (9 ) Net investment in capital lease 51 Less current portion (5 ) $ 46

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 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. On April 30, 2018, the EPA finalized the state of Michigan's recommended non-attainment designation for southeast Michigan. The State is required to develop and implement a plan to address the southeast Michigan ozone non-attainment area by 2021. DTE Electric cannot predict the financial impact of the State's plan to address the ozone non-attainment area 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 and on June 14, 2018 the case was stayed pending settlement negotiations. The proceedings at the District Court remain stayed while the parties discuss potential resolution of the matter. The Registrants believe that the plants and generating units identified by the EPA and the Sierra Club have complied with all applicable federal environmental regulations. Depending upon the outcome of the litigation and further discussions with the EPA regarding the two NOVs/FOVs, DTE Electric could be required to install additional pollution control equipment at some or all of the power plants in question, implement early retirement of facilities where control equipment is not economical, engage in supplemental environmental programs, and/or pay fines. The Registrants cannot predict the financial impact or outcome of this matter, or the timing of its resolution. The EPA has implemented regulatory actions under the Clean Air Act to address emissions of GHGs from the utility sector and other sectors of the economy. Among these actions, in 2015 the EPA finalized performance standards for emissions of carbon dioxide from new and existing fossil-fuel fired 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 in August 2018, the EPA proposed revised emission guidelines for GHGs from existing electric utility generating units. This proposed rule, named the Affordable Clean Energy (ACE) rule, is intended to replace the Clean Power Plan rule. In addition, in December 2018, the EPA issued proposed revisions to the carbon dioxide performance standards for new, modified, or reconstructed fossil-fuel fired EGUs. The carbon standards for new sources are not expected to have a material impact on DTE Electric, since DTE Electric has no plans to build new coal-fired generation and any potential new gas generation will be able to comply with the standards. These proposed rules do not impact DTE Energy's goal to reduce carbon emissions 30% by the early 2020s, 45% by 2030, 75% by 2040, and more than 80% by 2050. 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 2018 . DTE Electric does not anticipate additional capital expenditures through 2025 . 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 December 31, 2018 and 2017 , DTE Electric had $7 million and $6 million , respectively, 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 and July 2018. Additionally, a D.C. District Court Decision on August 21, 2018 (effective October 12, 2018) may affect the timing of closure of coal ash impoundments that are not lined with an engineered liner system. In 2019, the EPA is expected to affirmatively undertake rulemaking to implement the D.C. District Court's decision that will determine any changes to DTE Electric's plans in the operation and closure of coal ash impoundments. At the State level, legislation was signed by the Governor in December 2018. The bill provides for a CCR program to be regulated in Michigan once approval is requested and received from the EPA. 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. Under the current CCR rules and uncertainty regarding the D.C. District Court decision, capital costs and timing associated with the building of new CCR facilities or retirement of existing CCR facilities are being evaluated. In November 2015, the EPA finalized the ELG Rule for the steam electric power generating industry which requires additional controls to be installed between 2018 and 2023. Compliance schedules for individual facilities and individual waste streams are determined through issuance of new National Pollutant Discharge Elimination System (NPDES) permits by the State of Michigan. The State of Michigan has issued a NPDES permit for the Belle River Power Plant establishing a compliance deadline of December 31, 2021. No new permits that would require ELG compliance have been issued for other facilities, consequently no compliance timelines have been established. 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. The final rule nullified the administrative stay but also extended the earliest compliance deadlines for the FGD wastewater and bottom ash transport water until November 1, 2020 in order for the EPA to propose and finalize a new ruling. The ELG compliance requirements and final deadlines for bottom ash transport water and FGD wastewater, and total ELG related compliance costs will not be known until the EPA completes its reconsideration of the ELG Rule. Over the next six years , to comply with the November 2015 ELG requirements and CCR requirements, costs associated with the building of new facilities or installation of controls are estimated to be approximately $565 million . DTE Gas Contaminated and Other Sites — DTE Gas owns or previously owned, 14 former MGP sites. Investigations have revealed contamination related to the by-products of gas manufacturing at each site. Cleanup of six of the MGP sites is complete and the sites are closed. DTE Gas has also completed partial closure of six additional sites. Cleanup activities associated with the remaining sites will continue over the next several years. The MPSC has established a cost deferral and rate recovery mechanism for investigation and remediation costs incurred at former MGP sites. In addition to the MGP sites, DTE Gas is also in the process of cleaning up other contaminated sites, including gate stations, gas pipeline releases, and underground storage tank locations. As of December 31, 2018 and 2017 , DTE Gas had $25 million and $41 million , respectively, 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 Gas' financial position and cash flows. DTE Gas anticipates the cost amortization methodology approved by the MPSC, which allows for amortization of the MGP costs over a ten -year period beginning with the year subsequent to the year the MGP costs were incurred, will prevent environmental costs from having a material adverse impact on DTE Gas' results of operations. Non-utility DTE Energy's non-utility businesses are subject to a number of environmental laws and regulations dealing with the protection of the environment from various pollutants. Other In 2010, the EPA finalized a new one -hour SO 2 ambient air quality standard that requires states to submit plans and associated timelines for non-attainment areas that demonstrate attainment with the new SO 2 standard in phases. Phase 1 addresses non-attainment areas designated based on ambient monitoring data. Phase 2 addresses non-attainment areas with large sources of SO 2 and modeled concentrations exceeding the National Ambient Air Quality Standards for SO 2 . Phase 3 addresses smaller sources of SO 2 with modeled or monitored exceedances of the new SO 2 standard. Michigan's Phase 1 non-attainment area includes DTE Energy facilities in southwest Detroit and areas of Wayne County. Modeling runs by the MDEQ suggest that emission reductions may be required by significant sources of SO 2 emissions in these areas, including DTE Electric power plants and DTE Energy's Michigan coke battery facility. As part of the state implementation plan process, DTE Energy has worked with the MDEQ to develop air permits reflecting significant SO2 emission reductions that, in combination with other non-DTE Energy sources' emission reduction strategies, will help the state attain the standard and sustain its attainment. Since several non-DTE Energy sources are also part of the proposed compliance plan, DTE Energy is unable to determine the full impact of the final required emissions reductions at this time. Michigan's Phase 2 non-attainment area includes DTE Electric facilities in St. Clair County. State implementation 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 and is expected to be completed by the end of 2019. 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 December 31, 2018 was approximately $400 million . Payment 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 December 31, 2018 was $359 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 $242 million and $377 million at December 31, 2018 , respectively; each representing 50% of all payment obligations due and payable by NEXUS. 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. In October 2018, NEXUS Pipeline was placed in service. The amount of each guarantee decreases annually as payments are made by NEXUS to each of the aforementioned counterparties. NEXUS also entered into certain 15 -year capacity lease agreements for the transportation of natural gas with Vector, an equity method investee of DTE Energy. Pursuant to the terms of those agreements, in October 2018, DTE Energy executed a guarantee agreement with Vector, with a maximum potential payment totaling $7 million at December 31, 2018, representing 50% of the first-year payment obligations due and payable by NEXUS. The guarantee terminates at the earlier of (i) such time as all of the guaranteed obligations have been fully performed or (ii) 15 years from the date DTE Energy entered into the guarantee. Should NEXUS fail to perform under the terms of these agreements, DTE Energy is required to perform on its behalf. 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 $64 million at December 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 December 31, 2018 , DTE Energy had $76 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 5,200 represented employees, including DTE Electric's approximate 2,800 represented employees. The majority of the represented employees are under contracts that expire in 2020 and 2021 . Purchase Commitments As of December 31, 2018 , the Registrants were party to numerous long-term purchase commitments relating to a variety of goods and services required for their businesses. These agreements primarily consist of fuel supply commitments and renewable energy contracts for the Registrants, as well as energy trading contracts for DTE Energy. The Registrants estimate the following commitments from 2019 through 2051 for DTE Energy, and 2019 through 2039 for DTE Electric, as detailed in the following table: DTE Energy DTE Electric (In millions) 2019 $ 2,691 $ 777 2020 1,311 541 2021 632 171 2022 409 88 2023 351 85 2024 and thereafter 1,953 737 $ 7,347 $ 2,399 Utility capital expenditures, expenditures for non-utility businesses, and contributions to equity method investees will be approximately $3.9 billion and $2.2 billion in 2019 for DTE Energy and DTE Electric, respectively. The Registrants have made certain commitments in connection with the estimated 2019 annual capital expenditures and contributions to equity method investees. Bankruptcies DTE Energy's Power and Industrial Projects segment holds ownership interests in, and operates, five generating plants that sell electric output from renewable sources under long-term power purchase agreements with PG&E. PG&E filed for Chapter 11 bankruptcy protection on January 29, 2019. As of December 31, 2018, uncollected pre-petition accounts receivable from PG&E were approximately $12 million . Currently, PG&E has been paying amounts owed in a timely manner and its account is current. As of December 31, 2018, DTE Energy has not recorded a reserve related to the pre-petition receivables. As of December 31, 2018, the book value of long-lived assets used in producing electric output for sale to PG&E was approximately $106 million . As of December 31, 2018, DTE Energy performed an impairment analysis on its long-lived assets in accordance with ASC 360, Property, Plant and Equipment . Based on its undiscounted cash flow projections, DTE Energy determined that it did not have an impairment loss as of December 31, 2018. DTE Energy’s assumptions and conclusions may change, and it could have impairment losses if any of the terms of the contracts are not honored by PG&E or the contracts are rejected through the bankruptcy process. The Power and Industrial Projects segment also has equity investments, including a note receivable, of approximately $77 million in entities that sell power to PG&E. DTE Energy has determined that it does not have an other than temporary decline in its equity investments as described in ASC 323, Investments-Equity Method and Joint Ventures . DTE Energy’s assumptions and conclusions may change in the future, and it could have an impairment loss if certain facilities are not utilized as currently anticipated or the contracts are rejected through the bankruptcy process. Other Contingencies The Registrants are involved in certain other legal, regulatory, administrative, and environmental proceedings before various courts, arbitration panels, and governmental agencies concerning claims arising in the ordinary course of business. These proceedings include certain contract disputes, additional environmental reviews and investigations, audits, inquiries from various regulators, and pending judicial matters. The Registrants cannot predict the final disposition of such proceedings. The Registrants regularly review legal matters and record provisions for claims that they can estimate and are considered probable of loss. The resolution of these pending proceedings is not expected to have a material effect on the Registrants' Consolidated Financial Statements in the periods they are resolved. For a discussion of contingencies related to regulatory matters and derivatives, see Notes 9 and 13 to the Consolidated Financial Statements, " Regulatory Matters " and " Financial and Other Derivative Instruments ," respectively.

Nuclear Operations

Nuclear Operations	12 Months Ended
	Dec. 31, 2018
Nuclear Operations [Abstract]
Nuclear Operations	NUCLEAR OPERATIONS Property Insurance DTE Electric maintains property insurance policies specifically for the Fermi 2 plant. These policies cover such items as replacement power and property damage. NEIL is the primary supplier of the insurance policies. DTE Electric maintains a policy for extra expenses, including replacement power costs necessitated by Fermi 2’s unavailability due to an insured event. This policy has a 12-week waiting period and provides an aggregate $490 million of coverage over a three -year period. DTE Electric has $1.5 billion in primary coverage and $1.25 billion of excess coverage for stabilization, decontamination, debris removal, repair and/or replacement of property, and decommissioning. The combined coverage limit for total property damage is $2.75 billion . The total limit for property damage for non-nuclear events is $2.0 billion and an aggregate of $328 million of coverage for extra expenses over a two -year period. On January 13, 2015, the Terrorism Risk Insurance Program Reauthorization Act of 2015 was signed, extending TRIA through December 31, 2020. For multiple terrorism losses caused by acts of terrorism not covered under the TRIA occurring within one year after the first loss from terrorism, the NEIL policies would make available to all insured entities up to $3.2 billion , plus any amounts recovered from reinsurance, government indemnity, or other sources to cover losses. Under NEIL policies, DTE Electric could be liable for maximum assessments of up to $41 million per event if the loss associated with any one event at any nuclear plant should exceed the accumulated funds available to NEIL. Public Liability Insurance As required by federal law, DTE Electric maintains $450 million of public liability insurance for a nuclear incident. For liabilities arising from a terrorist act outside the scope of TRIA, the policy is subject to one industry aggregate limit of $300 million . Further, under the Price-Anderson Amendments Act of 2005, deferred premium charges up to $138 million could be levied against each licensed nuclear facility, but not more than $20 million per year per facility. Thus, deferred premium charges could be levied against all owners of licensed nuclear facilities in the event of a nuclear incident at any of these facilities. Nuclear Fuel Disposal Costs In accordance with the Federal Nuclear Waste Policy Act of 1982, DTE Electric has a contract with the DOE for the future storage and disposal of spent nuclear fuel from Fermi 2 that required DTE Electric to pay the DOE a fee of 1 mill per kWh of Fermi 2 electricity generated and sold. The fee was a component of nuclear fuel expense. The 1 mill per kWh DOE fee was reduced to zero effective May 16, 2014. The DOE's Yucca Mountain Nuclear Waste Repository program for the acceptance and disposal of spent nuclear fuel was terminated in 2011. DTE Electric is a party in the litigation against the DOE for both past and future costs associated with the DOE's failure to accept spent nuclear fuel under the timetable set forth in the Federal Nuclear Waste Policy Act of 1982. In July 2012, DTE Electric executed a settlement agreement with the federal government for costs associated with the DOE's delay in acceptance of spent nuclear fuel from Fermi 2 for permanent storage. The settlement agreement, including extensions, provides for a claims process and payment of delay-related costs experienced by DTE Electric through 2019. DTE Electric's claims are being settled and paid on a timely basis. The settlement proceeds reduce the cost of the dry cask storage facility assets and provide reimbursement for related operating expenses. DTE Electric currently employs a spent nuclear fuel storage strategy utilizing a fuel pool and a dry cask storage facility. The spent nuclear fuel storage strategy is expected to provide sufficient spent fuel storage capability for the life of the plant as defined by the original operating license. The federal government continues to maintain its legal obligation to accept spent nuclear fuel from Fermi 2 for permanent storage. Issues relating to long-term waste disposal policy and to the disposition of funds contributed by DTE Electric ratepayers to the federal waste fund await future governmental action.

Retirement Benefits and Trustee

Retirement Benefits and Trusteed Assets	12 Months Ended
	Dec. 31, 2018
Defined Benefit Plan [Abstract]
Retirement Benefits and Trusteed Assets	RETIREMENT BENEFITS AND TRUSTEED ASSETS DTE Energy's subsidiary, DTE Energy Corporate Services, LLC (LLC), sponsors defined benefit pension plans and other postretirement plans covering certain employees of the Registrants. The table below represents the pension and other postretirement benefit plans of each Registrant at December 31, 2018 : Registrants DTE Energy DTE Electric Qualified Pension Plans DTE Energy Company Retirement Plan X X DTE Gas Company Retirement Plan for Employees Covered by Collective Bargaining Agreements X Shenango Inc. Pension Plan X Nonqualified Pension Plans DTE Energy Company Supplemental Retirement Plan X X DTE Energy Company Executive Supplemental Retirement Plan (a) X X DTE Energy Company Supplemental Severance Benefit Plan X Other Postretirement Benefit Plans The DTE Energy Company Comprehensive Non-Health Welfare Plan X X The DTE Energy Company Comprehensive Retiree Group Health Care Plan X X DTE Supplemental Retiree Benefit Plan X X DTE Energy Company Retiree Reimbursement Arrangement Plan X X _____________________________________ (a) Sponsored by the DTE Energy subsidiary, DTE Energy Holding Company. DTE Electric participates in various plans that provide pension and other postretirement benefits for DTE Energy and its affiliates. The plans are sponsored by the LLC. DTE Electric accounts for its participation in DTE Energy's qualified and nonqualified pension plans by applying multiemployer accounting. DTE Electric accounts for its participation in other postretirement benefit plans by applying multiple-employer accounting. Within multiemployer and multiple-employer plans, participants pool plan assets for investment purposes and to reduce the cost of plan administration. The primary difference between plan types is assets contributed in multiemployer plans can be used to provide benefits for all participating employers, while assets contributed within a multiple-employer plan are restricted for use by the contributing employer. As a result of multiemployer accounting treatment, capitalized costs associated with these plans are reflected in Property, plant, and equipment in DTE Electric's Consolidated Statements of Financial Position. The same capitalized costs are reflected as Regulatory assets and liabilities in DTE Energy's Consolidated Statements of Financial Position. In addition, the service cost and non-service cost components are presented in Operation and maintenance in DTE Electric's Consolidated Statements of Operations. The same non-service cost components are presented in Other (Income) and Deductions — Non-operating retirement benefits, net in DTE Energy's Consolidated Statements of Operations. Plan participants of all plans are solely DTE Energy and affiliate participants. Pension Plan Benefits DTE Energy has qualified defined benefit retirement plans for eligible represented and non-represented employees. The plans are noncontributory and provide traditional retirement benefits based on the employee's years of benefit service, average final compensation, and age at retirement. In addition, certain represented and non-represented employees are covered under cash balance provisions that determine benefits on annual employer contributions and interest credits. DTE Energy also maintains supplemental nonqualified, noncontributory, retirement benefit plans for certain management employees. These plans provide for benefits that supplement those provided by DTE Energy’s other retirement plans. Net pension cost for DTE Energy includes the following components: 2018 2017 2016 (In millions) Service cost $ 99 $ 92 $ 92 Interest cost 202 214 219 Expected return on plan assets (329 ) (311 ) (309 ) Amortization of: Net actuarial loss 176 176 164 Prior service cost — 1 1 Net pension cost $ 148 $ 172 $ 167 2018 2017 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial loss $ 125 $ 27 Amortization of net actuarial loss (176 ) (176 ) Prior service credit — (11 ) Amortization of prior service cost — (1 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (51 ) $ (161 ) Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 97 $ 11 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 131 $ 178 Prior service cost $ 1 $ — The following table reconciles the obligations, assets, and funded status of the plans as well as the amounts recognized as prepaid pension cost or pension liability in DTE Energy's Consolidated Statements of Financial Position at December 31: DTE Energy 2018 2017 (In millions) Accumulated benefit obligation, end of year $ 4,779 $ 5,149 Change in projected benefit obligation Projected benefit obligation, beginning of year $ 5,576 $ 5,171 Service cost 99 92 Interest cost 202 214 Plan amendments — (11 ) Actuarial (gain) loss (438 ) 391 Benefits paid (315 ) (281 ) Projected benefit obligation, end of year $ 5,124 $ 5,576 Change in plan assets Plan assets at fair value, beginning of year $ 4,636 $ 4,012 Actual return on plan assets (233 ) 674 Company contributions 185 231 Benefits paid (315 ) (281 ) Plan assets at fair value, end of year $ 4,273 $ 4,636 Funded status $ (851 ) $ (940 ) Amount recorded as: Current liabilities $ (14 ) $ (16 ) Noncurrent liabilities (837 ) (924 ) $ (851 ) $ (940 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 152 $ 163 Prior service cost 5 6 $ 157 $ 169 Amounts recognized in Regulatory assets (a) Net actuarial loss $ 1,973 $ 2,014 Prior service credit (12 ) (14 ) $ 1,961 $ 2,000 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." The Registrants' policy is to fund pension costs by contributing amounts consistent with the provisions of the Pension Protection Act of 2006, and additional amounts when it deems appropriate. The following table provides contributions to the qualified pension plans in: 2018 2017 2016 (In millions) DTE Energy $ 175 $ 223 $ 179 DTE Electric 175 185 145 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, for which DTE Electric paid DTE Energy cash consideration of $175 million in March 2018. At the discretion of management, and depending upon financial market conditions, DTE Energy anticipates making up to $150 million in contributions, including $100 million of DTE Electric contributions, to the qualified pension plans in 2019 . 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 $120 million for the year ended December 31, 2018 and $136 million for the years ended December 31, 2017 and 2016 . These amounts include recognized contractual termination benefit charges, curtailment gains, and settlement charges. At December 31, 2018 , the benefits related to DTE Energy's qualified and nonqualified pension plans expected to be paid in each of the next five years and in the aggregate for the five fiscal years thereafter are as follows: (In millions) 2019 $ 311 2020 317 2021 317 2022 323 2023 332 2024-2028 1,713 Total $ 3,313 Assumptions used in determining the projected benefit obligation and net pension costs of DTE Energy are: 2018 2017 2016 Projected benefit obligation Discount rate 4.40% 3.70% 4.25% Rate of compensation increase 4.98% 4.98% 4.65% Net pension costs Discount rate 3.70% 4.25% 4.50% Rate of compensation increase 4.98% 4.65% 4.65% Expected long-term rate of return on plan assets 7.50% 7.50% 7.75% DTE Energy employs a formal process in determining the long-term rate of return for various asset classes. Management reviews historic financial market risks and returns and long-term historic relationships between the asset classes of equities, fixed income, and other assets, consistent with the widely accepted capital market principle that asset classes with higher volatility generate a greater return over the long-term. Current market factors such as inflation, interest rates, asset class risks, and asset class returns are evaluated and considered before long-term capital market assumptions are determined. The long-term portfolio return is also established employing a consistent formal process, with due consideration of diversification, active investment management, and rebalancing. Peer data is reviewed to check for reasonableness. As a result of this process, the Registrants have long-term rate of return assumptions for the pension plans of 7.30% and other postretirement benefit plans of 7.75% for 2019 . The Registrants believe these rates are a reasonable assumption for the long-term rate of return on plan assets for 2019 given the current investment strategy. The DTE Energy Company Affiliates Employee Benefit Plans Master Trust employs a liability driven investment program whereby the characteristics of plan liabilities are considered when determining investment policy. Risk tolerance is established through consideration of future plan cash flows, plan funded status, and corporate financial considerations. The investment portfolio contains a diversified blend of equity, fixed income, and other investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks and large and small market capitalizations. Fixed income investments generally include U.S. Treasuries, other governmental debt, diversified corporate bonds, bank loans, and mortgage-backed securities. Other investments are used to enhance long-term returns while improving portfolio diversification. Derivatives may be utilized in a risk controlled manner, to potentially increase the portfolio beyond the market value of invested assets and/or reduce portfolio investment risk. Investment risk is measured and monitored on an ongoing basis through annual liability measurements, periodic asset/liability studies, and quarterly investment portfolio reviews. Target allocations for DTE Energy's pension plan assets as of December 31, 2018 are listed below: U.S. Large Capitalization (Cap) Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 15 Fixed Income Securities 42 Hedge Funds and Similar Investments 15 Private Equity and Other 8 100 % The following tables provide the fair value measurement amounts for DTE Energy's pension plan assets at December 31, 2018 and 2017 (a) : December 31, 2018 December 31, 2017 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total (In millions) DTE Energy asset category: Short-term Investments (c) $ — $ 27 $ — $ 27 $ — $ 114 $ — $ 114 Equity Securities U.S. Large Cap (d) 606 3 — 609 821 5 — 826 U.S. Small Cap and Mid Cap (e) 123 1 — 124 229 5 — 234 Non-U.S. (f) 337 9 240 586 529 13 280 822 Fixed Income Securities (g) 6 1,892 — 1,898 1 1,453 — 1,454 Hedge Funds and Similar Investments (h) 88 — 542 630 265 — 593 858 Private Equity and Other (i) — — 399 399 — — 328 328 Securities Lending (j) (22 ) (8 ) — (30 ) (53 ) (13 ) — (66 ) Securities Lending Collateral (j) 22 8 — 30 53 13 — 66 DTE Energy Total $ 1,160 $ 1,932 $ 1,181 $ 4,273 $ 1,845 $ 1,590 $ 1,201 $ 4,636 _______________________________________ (a) For a description of levels within the fair value hierarchy, see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, other governmental debt, bank loans, and mortgage-backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds and limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in real estate and private debt. All pricing for investments in this category are classified as NAV assets. (j) DTE Energy has a securities lending program with a third-party agent. The program allows the agent to lend certain securities from DTE Energy's pension trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. The pension trust holds debt and equity securities directly and indirectly through commingled funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The commingled funds hold exchange-traded equity or debt securities and are valued based on stated NAVs. Non-exchange traded fixed income securities are valued by the trustee based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee challenges an assigned price and determines that another price source is considered preferable. DTE Energy has obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. There were no significant transfers between Level 2 and Level 1 in the years ended December 31, 2018 and 2017 for DTE Energy. Other Postretirement Benefits The Registrants participate in defined benefit plans sponsored by the LLC that provide certain other postretirement health care and life insurance benefits for employees who are eligible for these benefits. The Registrants' policy is to fund certain trusts to meet its other postretirement benefit obligations. DTE Energy did not make any contributions to these trusts during 2018 and does not anticipate making any contributions to the trusts in 2019 . DTE Energy and DTE Electric offer a defined contribution VEBA for eligible represented and non-represented employees, in lieu of defined benefit post-employment health care benefits. The Registrants allocate a fixed amount per year to an account in a defined contribution VEBA for each employee. These accounts are managed either by the Registrant (for non-represented and certain represented groups) or by the Utility Workers of America for Local 223 employees. DTE Energy contributions to the VEBA for these accounts were $11 million in 2018 , $8 million in 2017 , and $6 million in 2016 , including DTE Electric contributions of $5 million in 2018 , 2017 , and 2016 . The Registrants also contribute a fixed amount to a Retiree Reimbursement Account, for certain non-represented and represented retirees, spouses, and surviving spouses when the youngest of the retiree's covered household becomes eligible for Medicare Part A based on age. The amount of the annual allocation to each participant is determined by the employee's retirement date, and increases each year for each eligible participant at the lower of the rate of medical inflation or 2% . Net other postretirement credit for DTE Energy includes the following components: 2018 2017 2016 (In millions) Service cost $ 27 $ 27 $ 27 Interest cost 69 73 80 Expected return on plan assets (143 ) (130 ) (129 ) Amortization of: Net actuarial loss 11 13 30 Prior service credit — (14 ) (118 ) Other — — (1 ) Net other postretirement credit $ (36 ) $ (31 ) $ (111 ) 2018 2017 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial gain $ (8 ) $ (21 ) Amortization of net actuarial loss (11 ) (13 ) Prior service credit (44 ) (1 ) Amortization of prior service credit — 14 Total recognized in Regulatory assets and Other comprehensive income (loss) $ (63 ) $ (21 ) Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (99 ) $ (52 ) Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 12 $ 11 Prior service credit $ (9 ) $ (1 ) Net other postretirement credit for DTE Electric includes the following components: 2018 2017 2016 (In millions) Service cost $ 20 $ 20 $ 20 Interest cost 53 56 61 Expected return on plan assets (98 ) (90 ) (90 ) Amortization of: Net actuarial loss 8 8 21 Prior service credit — (10 ) (89 ) Net other postretirement credit $ (17 ) $ (16 ) $ (77 ) 2018 2017 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets Net actuarial (gai n) loss $ (46 ) $ 2 Amortization of net actuarial loss (8 ) (8 ) Amortization of prior service (cost) credit (35 ) 10 Total recognized in Regulatory assets $ (89 ) $ 4 Total recognized in net periodic benefit cost and Regulatory assets $ (106 ) $ (12 ) Estimated amounts to be amortized from Regulatory assets into net periodic benefit cost during next fiscal year Net actuarial loss $ 5 $ 8 Prior service credit $ (7 ) $ — The following table reconciles the obligations, assets, and funded status of the plans including amounts recorded as Accrued postretirement liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Change in accumulated postretirement benefit obligation Accumulated postretirement benefit obligation, beginning of year $ 1,910 $ 1,795 $ 1,470 $ 1,373 Service cost 27 27 20 20 Interest cost 69 73 53 56 Plan amendments (44 ) — (35 ) — Actuarial (gai n) loss (227 ) 101 (196 ) 84 Benefits paid (90 ) (86 ) (65 ) (63 ) Accumulated postretirement benefit obligation, end of year $ 1,645 $ 1,910 $ 1,247 $ 1,470 Change in plan assets Plan assets at fair value, beginning of year $ 1,848 $ 1,758 $ 1,272 $ 1,218 Actual return on plan assets (75 ) 252 (52 ) 172 Benefits paid (84 ) (162 ) (62 ) (118 ) Plan assets at fair value, end of year $ 1,689 $ 1,848 $ 1,158 $ 1,272 Funded status $ 44 $ (62 ) $ (89 ) $ (198 ) Amount recorded as: Noncurrent assets $ 45 $ — $ 189 $ 113 Current liabilities (1 ) (1 ) — — Noncurrent liabilities — (61 ) (278 ) (311 ) $ 44 $ (62 ) $ (89 ) $ (198 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial (gain) loss $ 1 $ (1 ) $ — $ — $ 1 $ (1 ) $ — $ — Amounts recognized in Regulatory assets (a) Net actuarial loss $ 257 $ 279 $ 156 $ 211 Prior service credit (44 ) (1 ) (35 ) — $ 213 $ 278 $ 121 $ 211 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." At December 31, 2018 , the benefits expected to be paid, including prescription drug benefits, in each of the next five years and in the aggregate for the five fiscal years thereafter for the Registrants are as follows: DTE Energy DTE Electric (In millions) 2019 $ 88 $ 66 2020 92 70 2021 96 73 2022 100 75 2023 102 77 2024-2028 532 402 Total $ 1,010 $ 763 Assumptions used in determining the accumulated postretirement benefit obligation and net other postretirement benefit costs of the Registrants are: 2018 2017 2016 Accumulated postretirement benefit obligation Discount rate 4.40% 3.70% 4.25% Health care trend rate pre- and post- 65 6.75 / 7.25% 6.75 / 7.25% 6.50 / 6.75% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2031 2030 2028 Other postretirement benefit costs Discount rate 3.70% 4.25% 4.50% Expected long-term rate of return on plan assets 7.75% 7.75% 8.00% Health care trend rate pre- and post- 65 6.75 / 7.25% 6.50 / 6.75% 6.25 / 6.75% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2030 2028 2027 A one percentage point increase in health care cost trend rates would have increased the total service cost and interest cost components of benefit costs for DTE Energy by $4 million , including $3 million for DTE Electric, in 2018 and would have increased the accumulated benefit obligation for DTE Energy by $72 million , including $51 million for DTE Electric, at December 31, 2018 . A one percentage point decrease in the health care cost trend rates would have decreased the total service and interest cost components of benefit costs for DTE Energy by $4 million , including $3 million for DTE Electric, in 2018 and would have decreased the accumulated benefit obligation for DTE Energy by $63 million , including $45 million for DTE Electric, at December 31, 2018 . The process used in determining the long-term rate of return on assets for the other postretirement benefit plans is similar to that previously described for the pension plans. The DTE Energy Master VEBA Trust employs a total return investment approach. The investment portfolio contains a diversified blend of equity, fixed income, and other investments. Furthermore, equity investments are diversified across U.S. and non-U.S. stocks and large and small market capitalizations. Fixed income investments generally include U.S. Treasuries, other governmental debt, diversified corporate bonds, bank loans, and mortgage-backed securities. Other investments are used to enhance long-term returns while improving portfolio diversification. Derivatives may be utilized in a risk controlled manner to potentially increase the portfolio beyond the market value of invested assets and/or reduce portfolio investment risk. Investment risk is measured and monitored on an ongoing basis through annual liability measurements, periodic asset/liability studies, and quarterly investment portfolio reviews. Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2018 are listed below: U.S. Large Cap Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 19 Fixed Income Securities 28 Hedge Funds and Similar Investments 19 Private Equity and Other 14 100 % The following tables provide the fair value measurement amounts for the Registrants' other postretirement benefit plan assets at December 31, 2018 and 2017 (a) : December 31, 2018 December 31, 2017 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total DTE Energy asset category: (In millions) Short-term Investments (c) $ 14 $ 2 $ — $ 16 $ 13 $ 2 $ — $ 15 Equity Securities U.S. Large Cap (d) 225 — — 225 284 — — 284 U.S. Small Cap and Mid Cap (e) 75 — — 75 131 — — 131 Non-U.S. (f) 234 — 67 301 288 1 77 366 Fixed Income Securities (g) 11 350 130 491 29 324 130 483 Hedge Funds and Similar Investments (h) 97 — 203 300 116 — 219 335 Private Equity and Other (i) — — 281 281 — — 234 234 Securities Lending (j) (21 ) (1 ) — (22 ) (39 ) (1 ) — (40 ) Securities Lending Collateral (j) 21 1 — 22 39 1 — 40 DTE Energy Total $ 656 $ 352 $ 681 $ 1,689 $ 861 $ 327 $ 660 $ 1,848 DTE Electric asset category: Short-term Investments (c) $ 10 $ 1 $ — $ 11 $ 9 $ 1 $ — $ 10 Equity Securities U.S. Large Cap (d) 154 — — 154 195 — — 195 U.S. Small Cap and Mid Cap (e) 52 — — 52 91 — — 91 Non-U.S. (f) 163 — 45 208 200 1 52 253 Fixed Income Securities (g) 7 232 92 331 20 218 92 330 Hedge Funds and Similar Investments (h) 68 — 139 207 80 — 150 230 Private Equity and Other (i) — — 195 195 — — 163 163 Securities Lending (j) (15 ) — — (15 ) (27 ) (1 ) — (28 ) Securities Lending Collateral (j) 15 — — 15 27 1 — 28 DTE Electric Total $ 454 $ 233 $ 471 $ 1,158 $ 595 $ 220 $ 457 $ 1,272 _______________________________________ (a) For a description of levels within the fair value hierarchy see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, other governmental debt, bank loans, and mortgage backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as NAV assets. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds and limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in real estate and private debt. All investments in this category are classified as NAV assets. (j) The Registrants have a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' VEBA trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. The DTE Energy Company Master VEBA Trust holds debt and equity securities directly and indirectly through commingled funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. The commingled funds hold exchange-traded equity or debt securities and are valued based on NAVs. Non-exchange traded fixed income securities are valued by the trustee based upon quotations available from brokers or pricing services. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee challenges an assigned price and determines that another price source is considered preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. There were no significant transfers between Level 2 and Level 1 in the years ended December 31, 2018 and 2017 for either of the Registrants. Defined Contribution Plans The Registrants also sponsor defined contribution retirement savings plans. Participation in one of these plans is available to substantially all represented and non-represented employees. For substantially all employees, the Registrants match employee contributions up to certain predefined limits based upon eligible compensation and the employee’s contribution rate. Additionally, for eligible represented and non-represented employees who do not participate in the Pension Plans, the Registrants annually contribute an amount equivalent to 4% ( 8% for certain DTE Gas represented employees) of an employee's eligible pay to the employee's defined contribution retirement savings plan. For DTE Energy, the cost of these plans was $61 million , $57 million , and $51 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. For DTE Electric, the cost of these plans was $29 million , $27 million , and $23 million for the years ended December 31, 2018 , 2017 , and 2016 .

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2018
Share-based Compensation [Abstract]
Stock-Based Compensation	STOCK-BASED COMPENSATION DTE Energy’s stock incentive program permits the grant of incentive stock options, non-qualifying stock options, stock awards, performance shares, and performance units to employees and members of its Board of Directors. As a result of a stock award, a settlement of an award of performance shares, or by exercise of a participant’s stock option, DTE Energy may deliver common stock from its authorized but unissued common stock and/or from outstanding common stock acquired by or on behalf of DTE Energy in the name of the participant. Key provisions of the stock incentive program are: • Authorized limit is 16,500,000 shares of common stock; • Prohibits the grant of a stock option with an exercise price that is less than the fair market value of DTE Energy’s stock on the date of the grant; and • Imposes the following award limits to a single participant in a single calendar year, (1) options for more than 500,000 shares of common stock; (2) stock awards for more than 150,000 shares of common stock; (3) performance share awards for more than 300,000 shares of common stock (based on the maximum payout under the award); or (4) more than 1,000,000 performance units, which have a face amount of $1.00 each. DTE Energy records compensation expense at fair value over the vesting period for all awards it grants. The following table summarizes the components of stock-based compensation for DTE Energy: 2018 2017 2016 (In millions) Stock-based compensation expense $ 64 $ 58 $ 61 Tax benefit $ 13 $ 23 $ 24 Stock-based compensation cost capitalized in Property, plant, and equipment $ 11 $ 9 $ 10 Stock Options Options are exercisable according to the terms of the individual stock option award agreements and expire ten years after the date of the grant. The option exercise price equals the fair value of the stock on the date that the option was granted. Stock options vest ratably over a three -year period. The following table summarizes DTE Energy's stock option activity for the year ended December 31, 2018 : Number of Options Weighted Average Exercise Price Aggregate Intrinsic Options outstanding and exercisable at December 31, 2017 105,994 $ 42.95 Exercised (53,894 ) $ 42.62 Options outstanding and exercisable at December 31, 2018 52,100 $ 43.30 $ 4 As of December 31, 2018 , the weighted average remaining contractual life for the exercisable shares is 1.11 years. As of December 31, 2018 , all options were vested. No options vested during 2018 . There were no options granted during 2018 , 2017 , or 2016 . The intrinsic value of options exercised for the years ended December 31, 2018 was $4 million . The intrinsic value of options for the years ended December 31, 2017 and 2016 was $4 million . No option expense was recognized for 2018 , 2017 , or 2016 . The number, weighted average exercise price, and weighted average remaining contractual life of DTE Energy options outstanding as of December 31, 2018 were as follows: Range of Exercise Prices Number of Options Weighted Average Weighted Average $ 27.00 — $ 38.00 2,100 $ 27.70 0.16 $ 42.01 — $ 45.00 50,000 $ 43.95 1.15 52,100 $ 43.30 1.11 Restricted Stock Awards Stock awards granted under the plan are restricted for varying periods, generally for three years . Participants have all rights of a shareholder with respect to a stock award, including the right to receive dividends and vote the shares. Prior to vesting in stock awards, the participant: (i) may not sell, transfer, pledge, exchange, or otherwise dispose of shares; (ii) shall not retain custody of the share certificates; and (iii) will deliver to DTE Energy a stock power with respect to each stock award upon request. The stock awards are recorded at cost that approximates fair value on the date of grant. The cost is amortized to compensation expense over the vesting period. Stock award activity for DTE Energy for the years ended December 31 was: 2018 2017 2016 Fair value of awards vested (in millions) $ 11 $ 10 $ 9 Restricted common shares awarded 109,393 136,825 145,240 Weighted average market price of shares awarded $ 105.80 $ 99.53 $ 87.28 Compensation cost charged against income (in millions) $ 11 $ 11 $ 11 The following table summarizes DTE Energy’s restricted stock awards activity for the year ended December 31, 2018 : Restricted Weighted Average Balance at December 31, 2017 365,764 $ 90.26 Grants 109,393 $ 105.80 Forfeitures (21,939 ) $ 98.59 Vested and issued (125,813 ) $ 85.24 Balance at December 31, 2018 327,405 $ 96.79 Performance Share Awards Performance shares awarded under the plan are for a specified number of shares of DTE Energy common stock that entitle the holder to receive a cash payment, shares of DTE Energy common stock, or a combination thereof. The final value of the award is determined by the achievement of certain performance objectives and market conditions. The awards vest at the end of a specified period, usually three years . Awards granted in 2018 , 2017 , and 2016 were primarily deemed to be equity awards. The DTE Energy stock price and number of probable shares attributable to market conditions for such equity awards are fair valued only at the grant date. DTE Energy accounts for performance share awards by accruing compensation expense over the vesting period based on: (i) the number of shares expected to be paid which is based on the probable achievement of performance objectives; and (ii) the closing stock price market value. The settlement of the award is based on the closing price at the settlement date. DTE Energy recorded compensation expense for performance share awards as follows: 2018 2017 2016 (In millions) Compensation expense $ 53 $ 47 $ 50 Cash settlements (a) $ 13 $ 15 $ 7 Stock settlements (a) $ 39 $ 66 $ 38 _______________________________________ (a) Sum of cash and stock settlements approximates the intrinsic value of the awards. During the vesting period, the recipient of a performance share award has no shareholder rights. During the period beginning on the date the performance shares are awarded and ending on the certification date of the performance objectives, the number of performance shares awarded will be increased, assuming full dividend reinvestment at the fair market value on the dividend payment date. The cumulative number of performance shares will be adjusted to determine the final payment based on the performance objectives achieved. Performance share awards are nontransferable and are subject to risk of forfeiture. The following table summarizes DTE Energy’s performance share activity for the period ended December 31, 2018 : Performance Shares Weighted Average Balance at December 31, 2017 1,324,401 $ 90.31 Grants 437,508 $ 105.64 Forfeitures (56,435 ) $ 96.02 Payouts (418,788 ) $ 84.84 Balance at December 31, 2018 1,286,686 $ 97.17 Unrecognized Compensation Costs As of December 31, 2018 , DTE Energy's total unrecognized compensation cost related to non-vested stock incentive plan arrangements and the weighted average recognition period was as follows: Unrecognized Weighted Average (In millions) (In years) Stock awards $ 12 1.03 Performance shares 59 1.04 $ 71 1.04 Allocated Stock-Based Compensation DTE Electric received an allocation of costs from DTE Energy associated with stock-based compensation. DTE Electric's allocation for 2018 , 2017 , and 2016 for stock-based compensation expense was $38 million , $34 million , and $38 million , respectively.

Segment and Related Information

Segment and Related Information	12 Months Ended
	Dec. 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: Year Ended December 31, 2018 2017 2016 (In millions) Electric $ 52 $ 48 $ 43 Gas 12 8 9 Gas Storage and Pipelines 36 42 9 Power and Industrial Projects 642 569 602 Energy Trading 27 35 39 Corporate and Other 2 2 2 $ 771 $ 704 $ 704 Financial data of DTE Energy's business segments follows: Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2018 Operating Revenues — Utility operations $ 5,298 1,436 — — — — (64 ) $ 6,670 Operating Revenues — Non-utility operations $ — — 485 2,204 5,557 3 (707 ) $ 7,542 Depreciation and amortization $ 836 133 82 67 5 1 — $ 1,124 Interest expense $ 283 70 68 31 6 220 (119 ) $ 559 Interest income $ — (6 ) (9 ) (9 ) (3 ) (104 ) 119 $ (12 ) Equity in earnings of equity method investees $ — 2 123 3 — 4 — $ 132 Income Tax Expense (Benefit) $ 193 67 68 (195 ) 13 (48 ) — $ 98 Net Income (Loss) Attributable to DTE Energy Company $ 664 150 235 161 39 (129 ) — $ 1,120 Investment in equity method investees $ 7 12 1,585 134 — 33 — $ 1,771 Capital expenditures and acquisitions $ 1,979 460 176 91 5 2 — $ 2,713 Goodwill $ 1,208 743 299 26 17 — — $ 2,293 Total Assets $ 22,501 5,378 3,161 495 909 6,153 (2,309 ) $ 36,288 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2017 Operating Revenues — Utility operations $ 5,102 1,388 — — — — (56 ) $ 6,434 Operating Revenues — Non-utility operations $ — — 453 2,089 4,277 2 (648 ) $ 6,173 Depreciation and amortization $ 753 123 76 72 5 1 — $ 1,030 Interest expense $ 274 65 77 29 5 192 (106 ) $ 536 Interest income $ — (7 ) (14 ) (7 ) (2 ) (88 ) 106 $ (12 ) Equity in earnings of equity method investees $ 1 2 90 9 — — — $ 102 Income Tax Expense (Benefit) $ 321 78 (30 ) (195 ) 49 (48 ) — $ 175 Net Income (Loss) Attributable to DTE Energy Company $ 606 146 275 138 72 (103 ) — $ 1,134 Investment in equity method investees $ 7 11 879 150 — 26 — $ 1,073 Capital expenditures and acquisitions $ 1,574 463 137 56 7 13 — $ 2,250 Goodwill $ 1,208 743 299 26 17 — — $ 2,293 Total Assets $ 21,163 5,072 2,594 593 725 5,324 (1,704 ) $ 33,767 _____________________________________ (a) Includes Income Tax Expense (Benefit) of $(5) million , $(115) million , $(21) million , $2 million , and $34 million for Electric — non-utility, Gas Storage and Pipelines, Power and Industrial Projects, Energy Trading, and Corporate and Other, respectively, related to the enactment of the TCJA. Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2016 Operating Revenues — Utility operations $ 5,225 1,324 — — — — (52 ) $ 6,497 Operating Revenues — Non-utility operations $ — — 302 1,906 2,575 2 (652 ) $ 4,133 Depreciation and amortization $ 750 106 45 72 3 — — $ 976 Interest expense $ 264 60 39 32 6 148 (77 ) $ 472 Interest income $ (8 ) (6 ) (9 ) (8 ) (1 ) (65 ) 77 $ (20 ) Equity in earnings of equity method investees $ 2 6 60 — — — — $ 68 Income Tax Expense (Benefit) $ 353 77 71 (140 ) (29 ) (61 ) — $ 271 Net Income (Loss) Attributable to DTE Energy Company $ 622 138 119 95 (45 ) (61 ) — $ 868 Investment in equity method investees $ 11 10 538 166 — 27 — $ 752 Capital expenditures and acquisitions $ 1,503 395 1,322 39 7 3 — $ 3,269 Goodwill $ 1,208 743 292 26 17 — — $ 2,286 Total Assets $ 20,417 4,729 2,417 683 660 4,648 (1,513 ) $ 32,041

Related Party Transactions

Related Party Transactions	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Related Party Transactions	RELATED PARTY TRANSACTIONS DTE Electric has agreements with affiliated companies to sell energy for resale, purchase fuel and power, provide fuel supply services, and provide power plant operation and maintenance services. DTE Electric has agreements with certain DTE Energy affiliates where DTE Electric charges the affiliates for their use of the shared capital assets of DTE Electric. A shared services company accumulates various corporate support services expenses and charges various subsidiaries of DTE Energy, including DTE Electric. DTE Electric records federal, state, and local income taxes payable to or receivable from DTE Energy based on its federal, state, and local tax provisions. The following is a summary of DTE Electric's transactions with affiliated companies: 2018 2017 2016 (In millions) Revenues Energy sales $ 9 $ 9 $ 10 Other services $ (4 ) $ (4 ) $ (1 ) Shared capital assets $ 43 $ 39 $ 33 Costs Fuel and purchased power $ 7 $ 6 $ 10 Other services and interest $ 33 $ (2 ) $ (1 ) Corporate expenses, net $ 377 $ 370 $ 370 Other Dividends declared $ 461 $ 432 $ 420 Dividends paid $ 461 $ 432 $ 420 Capital contribution from DTE Energy $ 325 $ 100 $ 120 DTE Electric's Accounts receivable and Accounts payable related to Affiliates are payable upon demand and are generally settled in cash within a monthly business cycle. Notes receivable and Short-term borrowings related to Affiliates are subject to a credit agreement with DTE Energy whereby short-term excess cash or cash shortfalls are remitted to or funded by DTE Energy. This credit arrangement involves the charge and payment of interest at market-based rates. Refer to DTE Electric's Consolidated Statements of Financial Position for affiliate balances at December 31, 2018 and 2017 . There were no contributions by DTE Electric to the DTE Energy Foundation for the years ended December 31, 2018 and 2016. DTE Electric's charitable contributions to the DTE Energy Foundation was $7 million for the year ended December 31, 2017 . The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute and assist charitable organizations. See the following notes for other related party transactions impacting DTE Electric’s Consolidated Financial Statements: Note Title 1 Organization and Basis of Presentation 20 Retirement Benefits and Trusteed Assets 21 Stock-Based Compensation

Supplementary Quarterly Financi

Supplementary Quarterly Financial Information (Unaudited)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Supplementary Quarterly Financial Information (Unaudited)	SUPPLEMENTARY QUARTERLY FINANCIAL INFORMATION (UNAUDITED) DTE Energy Quarterly earnings per share may not equal full year totals, since quarterly computations are based on weighted average common shares outstanding during each quarter. First Second Third Fourth Year (In millions, except per share amounts) 2018 Operating Revenues $ 3,753 $ 3,159 $ 3,550 $ 3,750 $ 14,212 Operating Income $ 504 $ 329 $ 429 $ 332 $ 1,594 Net Income Attributable to DTE Energy Company $ 361 $ 234 $ 334 $ 191 $ 1,120 Basic Earnings per Share $ 2.01 $ 1.29 $ 1.84 $ 1.05 $ 6.18 Diluted Earnings per Share $ 2.00 $ 1.29 $ 1.84 $ 1.05 $ 6.17 2017 Operating Revenues $ 3,236 $ 2,855 $ 3,245 $ 3,271 $ 12,607 Operating Income (a) $ 585 $ 320 $ 434 $ 372 $ 1,711 Net Income Attributable to DTE Energy Company (b) $ 400 $ 177 $ 270 $ 287 $ 1,134 Basic Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 Diluted Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 _____________________________________ (a) Pursuant to the implementation of ASU 2017-07, amounts previously included in Operating Income — Operation and maintenance were reclassified to Other (Income) and Deductions — Non-operating retirement benefits, net on DTE Energy's Consolidated Statements of Operations. (b) Includes a net Income Tax Benefit of $(105) million related to the enactment of the TCJA in the fourth quarter. DTE Electric First Second Third Fourth Year (In millions) 2018 Operating Revenues $ 1,205 $ 1,276 $ 1,521 $ 1,296 $ 5,298 Operating Income $ 253 $ 269 $ 444 $ 168 $ 1,134 Net Income $ 140 $ 163 $ 305 $ 56 $ 664 2017 Operating Revenues $ 1,175 $ 1,218 $ 1,434 $ 1,275 $ 5,102 Operating Income $ 217 $ 272 $ 395 $ 281 $ 1,165 Net Income $ 106 $ 138 $ 219 $ 138 $ 601

Schedule II - Valuation and Qua

Schedule II - Valuation and Qualifying Accounts	12 Months Ended
	Dec. 31, 2018
SEC Schedule, 12-09, Valuation and Qualifying Accounts [Abstract]
Schedule II - Valuation and Qualifying Accounts	DTE Energy Company Schedule II — Valuation and Qualifying Accounts Year Ending December 31, 2018 2017 2016 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 49 $ 41 $ 49 Additions: Charged to costs and expenses 140 80 78 Charged to other accounts (a) 55 26 18 Deductions (b) (153 ) (98 ) (104 ) Balance at End of Period $ 91 $ 49 $ 41 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off. DTE Electric Company Schedule II — Valuation and Qualifying Accounts Year Ending December 31, 2018 2017 2016 (In millions) Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Electric's Consolidated Statements of Financial Position) Balance at Beginning of Period $ 31 $ 25 $ 28 Additions: Charged to costs and expenses 85 55 49 Charged to other accounts (a) 36 14 8 Deductions (b) (99 ) (63 ) (60 ) Balance at End of Period $ 53 $ 31 $ 25 _______________________________________ (a) Collection of accounts previously written off. (b) Uncollectible accounts written off.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The information in these combined notes relates to each of the Registrants as noted in the Index of Combined Notes to Consolidated Financial Statements. However, DTE Electric does not make any representation as to information related solely to DTE Energy or the subsidiaries of DTE Energy other than itself.
Reclassification	Certain prior year balances for the Registrants were reclassified to match the current year's Consolidated Financial Statements presentation.
Principles of Consolidation	Principles of Consolidation The Registrants consolidate all majority-owned subsidiaries and investments in entities in which they have controlling influence. Non-majority owned investments are accounted for using the equity method when the Registrants are able to significantly influence the operating policies of the investee. When the Registrants do not influence the operating policies of an investee, the cost method is used. These Consolidated Financial Statements also reflect the Registrants' proportionate interests in certain jointly-owned utility plants. The Registrants eliminate all intercompany balances and transactions. The Registrants evaluate whether an entity is a VIE whenever reconsideration events occur. The Registrants consolidate VIEs for which they are the primary beneficiary. If a Registrant is not the primary beneficiary and an ownership interest is held, the VIE is accounted for under the equity method of accounting. When assessing the determination of the primary beneficiary, a Registrant considers all relevant facts and circumstances, including: the power, through voting or similar rights, to direct the activities of the VIE that most significantly impact the VIE's economic performance and the obligation to absorb the expected losses and/or the right to receive the expected returns of the VIE. The Registrants perform ongoing reassessments of all VIEs to determine if the primary beneficiary status has changed. Legal entities within DTE Energy's Power and Industrial Projects segment enter into long-term contractual arrangements with customers to supply energy-related products or services. The entities are generally designed to pass-through the commodity risk associated with these contracts to the customers, with DTE Energy retaining operational and customer default risk. These entities generally are VIEs and consolidated when DTE Energy is the primary beneficiary. In addition, DTE Energy has interests in certain VIEs through which control of all significant activities is shared with partners, and therefore are generally 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 owns a 256-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 December 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 December 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 for DTE Energy, in Note 18 to the Consolidated Financial Statements, " Commitments and Contingencies ," related to the REF guarantees and indemnities. For non-consolidated VIEs, the maximum risk exposure of the Registrants is generally limited to their investment, notes receivable, future funding commitments, and amounts which DTE Energy has guaranteed. See Note 18 to the Consolidated Financial Statements, " Commitments and Contingencies ," for further discussion of the NEXUS guarantee arrangements.
Other Income	Other Income Other income for the Registrants is recognized for non-operating income such as equity earnings of equity method investees, allowance for equity funds used during construction, contract services, and gains (losses) from trading securities. DTE Energy's Power and Industrial Projects segment also recognizes Other income in connection with the sale of membership interests in reduced emissions fuel facilities to investors. In exchange for the cash received, the investors will receive a portion of the economic attributes of the facilities, including income tax attributes. The transactions are not treated as a sale of membership interests for financial reporting purposes. Other income related to fixed non-refundable cash payments received from investors for which the earnings process is not contingent upon production of refined coal is recognized on a straight-line basis over the non-cancelable contract term as the economic benefit from the ownership of the facility is transferred to investors. Other income related to cash payments that is contingent upon production of refined coal is considered earned and recognized when the contingency regarding the timing and amount of payment is resolved, generally as refined coal is produced and tax credits are generated.
Accounting for ISO Transactions	Accounting for ISO Transactions DTE Electric participates in the energy market through MISO. MISO requires that DTE Electric submit hourly day-ahead, real-time, and FTR bids and offers for energy at locations across the MISO region. DTE Electric accounts for MISO transactions on a net hourly basis in each of the day-ahead, real-time, and FTR markets and net transactions across all MISO energy market locations. In any single hour DTE Electric records net purchases in Fuel, purchased power, and gas — utility and net sales in Operating Revenues — Utility operations on the Registrants' Consolidated Statements of Operations. The Energy Trading segment participates in the energy markets through various ISOs and RTOs. These markets require that Energy Trading submits hourly day-ahead, real-time bids and offers for energy at locations across each region. Energy Trading submits bids in the annual and monthly auction revenue rights and FTR auctions to the RTOs. Energy Trading accounts for these transactions on a net hourly basis for the day-ahead, real-time, and FTR markets. These transactions are related to trading contracts which, if derivatives, are presented on a net basis in Operating Revenues — Non-utility operations, and if non-derivatives, the realized gains and losses for sales are recorded in Operating Revenues — Non-utility operations and purchases are recorded in Fuel, purchased power, and gas — non-utility in the DTE Energy Consolidated Statements of Operations. DTE Electric and Energy Trading record accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual costs when invoices are received from MISO and other ISOs and RTOs.
Changes in Accumulated Other Comprehensive Income (Loss)	Changes in Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including Net Income. The amounts recorded to Accumulated other comprehensive income (loss) for the Registrants include unrealized gains and losses on available-for-sale securities and changes in benefit obligations, consisting of deferred actuarial losses and prior service costs. The amounts recorded to Accumulated other comprehensive income (loss) relating solely to DTE Energy also include unrealized gains and losses from derivatives accounted for as cash flow hedges, DTE Energy's interest in other comprehensive income of equity investees which comprise the net unrealized gains and losses on investments, and foreign currency translation adjustments.
Cash, Cash Equivalents, and Restricted Cash	Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include cash on hand, cash in banks, and temporary investments purchased with remaining maturities of three months or less. Restricted cash consists of funds held to satisfy requirements of certain debt and DTE Energy partnership operating agreements. Restricted cash designated for interest and principal payments within one year is classified as a Current Asset.
Receivables and Notes Receivable	Receivables Accounts receivable are primarily composed of trade receivables and unbilled revenue. The Registrants' Accounts receivable are stated at net realizable value. The allowance for doubtful accounts for DTE Electric and DTE Gas is generally calculated using the aging approach that utilizes rates developed in reserve studies. DTE Electric and DTE Gas establish an allowance for uncollectible accounts based on historical losses and management’s assessment of existing economic conditions, customer trends, and other factors. Customer accounts are generally considered delinquent if the amount billed is not received by the due date, which is typically in 21 days, however, factors such as assistance programs may delay aggressive action. DTE Electric and DTE Gas assess late payment fees on trade receivables based on past-due terms with customers. Customer accounts are written off when collection efforts have been exhausted. The time period for write-off is 150 days after service has been terminated. The customer allowance for doubtful accounts for DTE Energy's other businesses is calculated based on specific review of probable future collections based on receivable balances generally in excess of 30 days. DTE Energy unbilled revenues of $1.0 billion at December 31, 2018 and 2017 include $264 million and $290 million of DTE Electric unbilled revenues, respectively, included in Customer Accounts receivable. Notes Receivable Notes receivable, or financing receivables, for DTE Energy are primarily comprised of capital lease receivables and loans and are included in Notes receivable and Other current assets on DTE Energy’s Consolidated Statements of Financial Position. Notes receivable, or financing receivables, for DTE Electric are primarily comprised of loans. Notes receivable are typically considered delinquent when payment is not received for periods ranging from 60 to 120 days. The Registrants cease accruing interest (nonaccrual status), consider a note receivable impaired, and establish an allowance for credit loss when it is probable that all principal and interest amounts due will not be collected in accordance with the contractual terms of the note receivable. Cash payments received on nonaccrual status notes receivable, that do not bring the account contractually current, are first applied to contractually owed past due interest, with any remainder applied to principal. Accrual of interest is generally resumed when the note receivable becomes contractually current. In determining the allowance for credit losses for notes receivable, the Registrants consider the historical payment experience and other factors that are expected to have a specific impact on the counterparty’s ability to pay. In addition, the Registrants monitor the credit ratings of the counterparties from which they have notes receivable.
Inventories	Inventories Inventory related to utility operations is generally valued at average cost. Inventory related to non-utility operations is valued at the lower of cost or net realizable value.
Property, Retirement and Maintenance, and Depreciation and Amortization	Property, Retirement and Maintenance, and Depreciation and Amortization Property is stated at cost and includes construction-related labor, materials, overheads, and AFUDC for utility property. The cost of utility properties retired is charged to accumulated depreciation. Expenditures for maintenance and repairs are charged to expense when incurred, except for outage-related maintenance repairs for Fermi 2. Utility property at DTE Electric and DTE Gas is depreciated over its estimated useful life using straight-line rates approved by the MPSC. DTE Energy's non-utility property is depreciated over its estimated useful life using the straight-line method. Depreciation and amortization expense also includes the amortization of certain regulatory assets for the Registrants. Approximately $4 million and $15 million of expenses related to Fermi 2 refueling outages were accrued at December 31, 2018 and 2017 , respectively. Amounts are accrued on a pro-rata basis, generally over an 18 -month period, that coincides with scheduled refueling outages at Fermi 2. This accrual of outage costs matches the regulatory recovery of these costs in rates set by the MPSC. See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." The cost of nuclear fuel is capitalized. The amortization of nuclear fuel is included within Fuel, purchased power, and gas — utility in the DTE Energy Consolidated Statements of Operations, and Fuel and purchased power in the DTE Electric Consolidated Statements of Operations, and is recorded using the units-of-production method. Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 1 to 15 years for DTE Energy and 3 to 15 years for DTE Electric.
Long-Lived Assets	Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If the carrying amount of the asset exceeds the expected undiscounted future cash flows generated by the asset, an impairment loss is recognized resulting in the asset being written down to its estimated fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less costs to sell.
Intangible Assets	DTE Energy amortizes customer relationship and contract intangible assets on a straight-line basis over the expected period of benefit.
Excise and Sales Taxes and Income Taxes	Excise and Sales Taxes The Registrants record the billing of excise and sales taxes as a receivable with an offsetting payable to the applicable taxing authority, with no net impact on the Registrants’ Consolidated Statements of Operations. Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts in the Registrant's Consolidated Financial Statements. Consistent with the original establishment of these deferred tax liabilities (assets), no recognition of these non-cash transactions have been reflected in the Consolidated Statements of Cash Flows. The federal income tax provisions or benefits of DTE Energy’s subsidiaries are determined on an individual company basis and recognize the tax benefit of tax credits and net operating losses, if applicable. The state and local income tax provisions of the utility subsidiaries are determined on an individual company basis and recognize the tax benefit of various tax credits and net operating losses, if applicable. The subsidiaries record federal, state, and local income taxes payable to or receivable from DTE Energy based on the federal, state, and local tax provisions of each company.
Deferred Debt Costs	Deferred Debt Costs The costs related to the issuance of long-term debt are deferred and amortized over the life of each debt issue. The deferred amounts are included as a direct deduction from the carrying amount of each debt issue in Mortgage bonds, notes, and other and Junior subordinated debentures on DTE Energy's Consolidated Statements of Financial Position and in Mortgage bonds, notes, and other on DTE Electric's Consolidated Statements of Financial Position. In accordance with MPSC regulations applicable to DTE Energy’s electric and gas utilities, the unamortized discount, premium, and expense related to utility debt redeemed with a refinancing are amortized over the life of the replacement issue. Discount, premium, and expense on early redemptions of debt associated with DTE Energy's non-utility operations are charged to earnings.
Investments in Debt and Equity Securities	Investments in Debt and Equity Securities The Registrants generally record investments in debt and equity securities at market value with unrealized gains or losses included in earnings. Changes in the fair value of Fermi 2 nuclear decommissioning investments are recorded as adjustments to Regulatory assets or liabilities, due to a recovery mechanism from customers. The Registrants' equity investments are reviewed for impairment each reporting period. If the assessment indicates that an impairment exists, a loss is recognized resulting in the equity investment being written down to its estimated fair value.
DTE Energy Foundation	DTE Energy Foundation DTE Energy's charitable contributions to the DTE Energy Foundation were $22 million , $43 million , and $26 million for the years ended December 31, 2018 , 2017 , and 2016 , respectively. The DTE Energy Foundation is a non-consolidated not-for-profit private foundation, the purpose of which is to contribute to and assist charitable organizations.
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS Recently 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 using either a full retrospective or modified retrospective approach. 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 year ended December 31, 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. During the year ended December 31, 2018 , DTE Energy and DTE Electric finalized their SAB 118 analysis and recorded true-up adjustments to the remeasurement of deferred taxes of $21 million and $7 million , respectively. The impact of the true-up adjustments was an increase in Income Tax Expense, of which $17 million was attributable to the regulated utilities and increased 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. 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. The standard allows lessees and lessors to apply either, 1) a modified retrospective approach for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements, or 2) a prospective transition approach for leases existing as of January 1, 2019 with a cumulative effect adjustment to be recorded to retained earnings. The Registrants will apply the standard on a prospective basis. The Registrants will elect the package of practical expedients allowing entities to not reassess whether an agreement is a lease, to carryforward the existing lease classification, and to not reassess initial direct costs associated with existing leases. These practical expedients apply to leases that commenced prior to January 1, 2019. The Registrants will also elect to exclude leases from the balance sheet that are for a period of one year or less, as well as, the practical expedient allowing entities to not evaluate land easements under the new guidance at adoption if they were not previously accounted for as leases. A third-party software tool has been implemented that will assist with the initial adoption and ongoing compliance of the standard. The Registrants are implementing new business processes, internal controls, and accounting policies. The Registrants are in the process of drafting disclosures to satisfy the standard's requirements. In addition, the Registrants are continuing to monitor utility industry implementation guidance and interpretation. 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. In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurements (Topic 820): Disclosure Framework — Changes to the Disclosure Requirements for Fair Value Measurement . The amendments in this update modify the disclosure requirements on fair value measurements in Topic 820. The ASU is effective for the Registrants for fiscal years 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 August 2018, the FASB issued ASU No. 2018-14, Compensation — Retirement Benefits — Defined Benefit Plans (Subtopic 715-20): Disclosure Framework — Changes to the Disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans . The amendments in this update modify the disclosure requirements for employers that sponsor defined benefit pension or other postretirement plans. The ASU is effective for the Registrants for fiscal years ending after December 15, 2020. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. In August 2018, the FASB issued ASU No. 2018-15, Intangibles — Goodwill and Other — Internal-Use Software (Subtopic 350-40): Customer's Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract . The amendments in this update align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for capitalizing implementation costs incurred to develop or obtain internal-use software (and hosting arrangements that include an internal use software license). The ASU is effective for the Registrants for fiscal years 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 October 2018, the FASB issued ASU No. 2018-17, Consolidation (Topic 810): Targeted Improvements to Related Party Guidance for Variable Interest Entities . The amendments in this update modify the requirements for determining whether a decision-making fee is a variable interest and require reporting entities to consider indirect interests held through related parties under common control on a proportional basis. The ASU is effective for the Registrants for fiscal years 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.
Revenues	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 year ended December 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.
Asset Retirement Obligations	ASSET RETIREMENT OBLIGATIONS DTE Electric has a legal retirement obligation for the decommissioning costs for its Fermi 1 and Fermi 2 nuclear plants, dismantlement of facilities located on leased property, and various other operations. DTE Electric has conditional retirement obligations for asbestos and PCB removal at certain of its power plants and various distribution equipment. DTE Gas has conditional retirement obligations for gas pipelines, certain service centers, compressor and gate stations. The Registrants recognize such obligations as liabilities at fair market value when they are incurred, which generally is at the time the associated assets are placed in service. Fair value is measured using expected future cash outflows discounted at the Registrants' credit-adjusted risk-free rate. For its utility operations, the Registrants recognize in the Consolidated Statements of Operations removal costs in accordance with regulatory treatment. Any differences between costs recognized related to asset retirement and those reflected in rates are recognized as either a Regulatory asset or liability on the Consolidated Statements of Financial Position. If a reasonable estimate of fair value cannot be made in the period in which the retirement obligation is incurred, such as for assets with indeterminate lives, the liability is recognized when a reasonable estimate of fair value can be made. Natural gas storage system and certain other distribution assets for DTE Gas and substations, manholes, and certain other distribution assets for DTE Electric have an indeterminate life. Therefore, no liability has been recorded for these assets.
Regulatory Assets and Liabilities	Regulatory Assets and Liabilities DTE Electric and DTE Gas are required to record Regulatory assets and liabilities for certain transactions that would have been treated as revenue or expense in non-regulated businesses. Continued applicability of regulatory accounting treatment requires that rates be designed to recover specific costs of providing regulated services and be charged to and collected from customers. Future regulatory changes or changes in the competitive environment could result in the discontinuance of this accounting treatment for Regulatory assets and liabilities for some or all of the Registrants' businesses and may require the write-off of the portion of any Regulatory asset or liability that was no longer probable of recovery through regulated rates. Management believes that currently available facts support the continued use of Regulatory assets and liabilities and that all Regulatory assets and liabilities are recoverable or refundable in the current regulatory environment.
Fair Value Measurement	Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date in a principal or most advantageous market. Fair value is a market-based measurement that is determined based on inputs, which refer broadly to assumptions that market participants use in pricing assets or liabilities. These inputs can be readily observable, market corroborated, or generally unobservable inputs. The Registrants make certain assumptions they believe that market participants would use in pricing assets or liabilities, including assumptions about risk, and the risks inherent in the inputs to valuation techniques. Credit risk of the Registrants and their counterparties is incorporated in the valuation of assets and liabilities through the use of credit reserves, the impact of which was immaterial at December 31, 2018 and 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 commingled funds. Other assets such as private equity investments are used to enhance long-term returns while improving portfolio diversification. All pricing for private equity 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. Commingled funds that 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. 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 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, renewable gas recovery, and power generation assets. Primarily fixed-price contracts are used in the marketing and management of the segment assets. These contracts are generally not derivatives and are therefore accounted for under the accrual method. Energy Trading — Commodity Price Risk — Energy Trading markets and trades electricity, natural gas physical products, and energy financial instruments, and provides energy and asset management services utilizing energy commodity derivative instruments. Forwards, futures, options, and swap agreements are used to manage exposure to the risk of market price and volume fluctuations in its operations. These derivatives are accounted for by recording changes in fair value to earnings unless hedge accounting criteria are met. Energy Trading — Foreign Currency Exchange Risk — Energy Trading has foreign currency exchange forward contracts to economically hedge fixed Canadian dollar commitments existing under natural gas and power purchase and sale contracts and natural gas transportation contracts. Energy Trading enters into these contracts to mitigate price volatility with respect to fluctuations of the Canadian dollar relative to the U.S. dollar. These derivatives are accounted for by recording changes in fair value to earnings unless hedge accounting criteria are met. Corporate and Other — Interest Rate Risk — DTE Energy may use interest rate swaps, treasury locks, and other derivatives to hedge the risk associated with interest rate market volatility. Credit Risk — DTE Energy maintains credit policies that significantly minimize overall credit risk. These policies include an evaluation of potential customers’ and counterparties’ financial condition, including the viability of underlying productive assets, credit rating, collateral requirements, or other credit enhancements such as letters of credit or guarantees. DTE Energy generally uses standardized agreements that allow the netting of positive and negative transactions associated with a single counterparty. DTE Energy maintains a provision for credit losses based on factors surrounding the credit risk of its customers, historical trends, and other information. Based on DTE Energy's credit policies and its December 31, 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 approximately $4 million outstanding at December 31, 2018 and 2017 , 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 $8 million and $4 million at December 31, 2018 and 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	Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility.
Stock-Based Compensation	DTE Energy records compensation expense at fair value over the vesting period for all awards it grants.

Organization and Basis of Pre_2

Organization and Basis of Presentation (Tables)	12 Months Ended
	Dec. 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 December 31, 2018 and 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. Amounts for DTE Energy's consolidated VIEs are as follows: December 31, 2018 December 31, 2017 SGG (a) Other Total SGG (a) Other Total (In millions) ASSETS Cash and cash equivalents $ 25 $ 14 $ 39 $ 23 $ 14 $ 37 Restricted cash — 5 5 — 8 8 Accounts receivable 9 37 46 11 42 53 Inventories 1 92 93 3 114 117 Property, plant, and equipment, net 395 46 441 400 75 475 Goodwill 25 — 25 25 — 25 Intangible assets 557 — 557 572 — 572 Other current and long-term assets 3 — 3 4 — 4 $ 1,015 $ 194 $ 1,209 $ 1,038 $ 253 $ 1,291 LIABILITIES Accounts payable and accrued current liabilities $ 3 $ 31 $ 34 $ 26 $ 47 $ 73 Current portion long-term debt, including capital leases — — — — 4 4 Mortgage bonds, notes, and other — — — — 1 1 Other current and long-term liabilities 9 10 19 1 16 17 $ 12 $ 41 $ 53 $ 27 $ 68 $ 95 _____________________________________ (a) Amounts shown are 100% of SGG's assets and liabilities, of which DTE Energy owns 55% .
Summary of Amounts For Nonconsolidated Variable Interest Entities	Amounts for DTE Energy's non-consolidated VIEs are as follows: December 31, 2018 2017 (In millions) Investments in equity method investees $ 1,425 $ 811 Notes receivable $ 15 $ 17 Future funding commitments $ 55 $ 598
Equity Method Investments	Summarized balance sheet data is as follows: December 31, 2018 2017 (In millions) Current Assets $ 358 $ 344 Non-current assets $ 5,101 $ 3,576 Current Liabilities $ 391 $ 345 Non-current liabilities $ 762 $ 858 Summarized income statement data is as follows: December 31, 2018 2017 2016 (In millions) Operating Revenues $ 883 $ 756 $ 767 Operating Expenses $ 622 $ 561 $ 526 Net Income $ 365 $ 254 $ 225 DTE Energy equity method investees are described below: Investments % Owned Segment 2018 2017 2018 2017 Description (In millions) Significant Equity Method Investees Gas Storage and Pipelines NEXUS Pipeline $ 1,260 $ 640 50% 50% 256-mile pipeline to transport Utica and Marcellus shale gas to Ohio, Michigan, and Ontario market centers Vector Pipeline 123 115 40% 40% 348-mile pipeline connecting Chicago, Michigan, and Ontario market centers Millennium Pipeline 202 124 26% 26% 269-mile pipeline serving markets in the Northeast 1,585 879 Other Equity Method Investees Other Segments 186 194 $ 1,771 $ 1,073

Significant Accounting Polici_3

Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2018
Accounting Policies [Abstract]
Schedule of Other Income	The following is a summary of DTE Energy's Other income: 2018 2017 2016 (In millions) Equity earnings of equity method investees $ 132 $ 102 $ 68 Income from REF entities 98 77 75 Contract services 51 19 21 Allowance for equity funds used during construction 28 23 21 Gains from trading securities 6 26 15 Other 18 21 7 $ 333 $ 268 $ 207 The following is a summary of DTE Electric's Other income: 2018 2017 2016 (In millions) Contract services $ 51 $ 21 $ 20 Allowance for equity funds used during construction 19 18 18 Gains from trading securities allocated from DTE Energy 6 26 15 Other 7 12 8 $ 83 $ 77 $ 61
Schedule of Accumulated Other Comprehensive Income (Loss)	The following table summarizes the changes in DTE Energy's Accumulated other comprehensive income (loss) by component (a) for the years ended December 31, 2018 and 2017 : Net Unrealized Gain (Loss) on Deri vatives Net Unrealized Gain (Loss) on Investments Benefit Obligations (b) Foreign Currency Translation Total (In millions) Balance, December 31, 2016 $ (4 ) $ (3 ) $ (120 ) $ (6 ) $ (133 ) Other comprehensive income (loss) before reclassifications — 1 (3 ) 1 (1 ) Amounts reclassified from Accumulated other comprehensive income 1 — 13 — 14 Net current-period Other comprehensive income 1 1 10 1 13 Balance, December 31, 2017 $ (3 ) $ (2 ) $ (110 ) $ (5 ) $ (120 ) Implementation of ASU 2016-01 (7 ) 2 — — (5 ) Other comprehensive loss before reclassifications (2 ) — (1 ) (2 ) (5 ) Amounts reclassified from Accumulated other comprehensive income 1 — 9 — 10 Net current-period Other comprehensive income (loss) (8 ) 2 8 (2 ) — Balance, December 31, 2018 $ (11 ) $ — $ (102 ) $ (7 ) $ (120 ) ______________________________________ (a) All amounts are net of tax, except for Foreign currency translation. (b) The amounts reclassified from Accumulated other comprehensive income (loss) are included in the computation of the net periodic pension and other postretirement benefit costs (see Note 20 to the Consolidated Financial Statements, " Retirement Benefits and Trusteed Assets ").
Schedule of 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: 2018 2017 (In millions) Cash and cash equivalents $ 71 $ 66 Restricted cash 5 23 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 76 $ 89
Schedule of 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: 2018 2017 (In millions) Cash and cash equivalents $ 71 $ 66 Restricted cash 5 23 Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows $ 76 $ 89
Schedule of Finite-Lived Intangible Assets by Major Class	The Registrants have certain Intangible assets as shown below: December 31, 2018 December 31, 2017 Useful Lives Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (In millions) Intangible assets subject to amortization Customer relationships 25 - 40 years (a) $ 779 $ (44 ) $ 735 $ 770 $ (24 ) $ 746 Contract intangibles 6 to 26 years 159 (66 ) 93 168 (72 ) 96 938 (110 ) 828 938 (96 ) 842 DTE Electric renewable energy credits (b) 20 — 20 24 — 24 DTE Electric emission allowances (b) 1 — 1 1 — 1 21 — 21 25 — 25 Long-term intangible assets DTE Electric $ 21 $ — $ 21 $ 25 $ — $ 25 DTE Energy $ 959 $ (110 ) $ 849 $ 963 $ (96 ) $ 867 ______________________________________ (a) The useful life of the customer relationship intangible assets is based on the number of years in which the assets are expected to economically contribute to the business. The expected economic benefit incorporates existing customer contracts and expected renewal rates based on the estimated volume and production lives of gas resources in the region. (b) Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the business.
Schedule of Indefinite-Lived Intangible Assets	The Registrants have certain Intangible assets as shown below: December 31, 2018 December 31, 2017 Useful Lives Gross Carrying Value Accumulated Amortization Net Carrying Value Gross Carrying Value Accumulated Amortization Net Carrying Value (In millions) Intangible assets subject to amortization Customer relationships 25 - 40 years (a) $ 779 $ (44 ) $ 735 $ 770 $ (24 ) $ 746 Contract intangibles 6 to 26 years 159 (66 ) 93 168 (72 ) 96 938 (110 ) 828 938 (96 ) 842 DTE Electric renewable energy credits (b) 20 — 20 24 — 24 DTE Electric emission allowances (b) 1 — 1 1 — 1 21 — 21 25 — 25 Long-term intangible assets DTE Electric $ 21 $ — $ 21 $ 25 $ — $ 25 DTE Energy $ 959 $ (110 ) $ 849 $ 963 $ (96 ) $ 867 ______________________________________ (a) The useful life of the customer relationship intangible assets is based on the number of years in which the assets are expected to economically contribute to the business. The expected economic benefit incorporates existing customer contracts and expected renewal rates based on the estimated volume and production lives of gas resources in the region. (b) Emission allowances and renewable energy credits are charged to expense, using average cost, as the allowances and credits are consumed in the operation of the business.
Schedule of Finite-Lived Intangible Assets, Future Amortization Expense	The following table summarizes DTE Energy's estimated customer relationship and contract intangible amortization expense expected to be recognized during each year through 2023 : 2019 2020 2021 2022 2023 (In millions) Estimated amortization expense $ 27 $ 26 $ 25 $ 25 $ 25
Schedule of Accounting Policies	See the following notes for other accounting policies impacting the Registrants’ Consolidated Financial Statements: Note Title 4 Revenue 8 Asset Retirement Obligations 9 Regulatory Matters 10 Income Taxes 12 Fair Value 13 Financial and Other Derivative Instruments 20 Retirement Benefits and Trusteed Assets 21 Stock-Based Compensation

Revenue (Tables)

Revenue (Tables)	12 Months Ended
	Dec. 31, 2018
Revenue from Contract with Customer [Abstract]
Disaggregation of Revenue	The following is a summary of revenues disaggregated by segment for DTE Energy: 2018 (In millions) Electric (a) Residential $ 2,494 Commercial 1,794 Industrial 690 Other 320 Total Electric operating revenues (b) $ 5,298 Gas Gas sales $ 1,055 End User Transportation 232 Intermediate Transportation 58 Other 91 Total Gas operating revenues (c) $ 1,436 Other segment operating revenues Gas Storage and Pipelines $ 485 Power and Industrial Projects (d) $ 2,204 Energy Trading (e) $ 5,557 _______________________________________ (a) Revenues under the Electric segment generally represent those of DTE Electric. (b) Includes $21 million under Alternative Revenue Programs and $20 million of other revenues, which are both outside the scope of Topic 606 for the year ended December 31, 2018 . (c) Includes $2 million under Alternative Revenue Programs and $7 million of other revenues, which are both outside the scope of Topic 606 for the year ended December 31, 2018 . (d) Includes revenues outside the scope of Topic 606 primarily related to $125 million of contracts accounted for as leases for the year ended December 31, 2018 . (e) Includes revenues outside the scope of Topic 606 primarily related to $4.5 billion of derivatives for the year ended December 31, 2018 .
Summary of Deferred Revenue Activity	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 48 Revenue recognized that was included in the deferred revenue balance at the beginning of the period (30 ) Ending Balance, December 31, 2018 $ 74
Deferred Revenue Amounts Expected to be Recognized as Revenue in Future Periods	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) 2019 $ 267 $ 8 2020 263 — 2021 219 — 2022 172 — 2023 139 — 2024 and thereafter 658 — $ 1,718 $ 8 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) 2019 $ 46 2020 1 2021 5 2022 7 2023 5 2024 and thereafter 10 $ 74

Goodwill (Tables)

Goodwill (Tables)	12 Months Ended
	Dec. 31, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Schedule of Goodwill	The following is the summary of change in the carrying amount of goodwill for the years ended December 31: 2018 2017 (In millions) Balance as of January 1 $ 2,293 $ 2,286 Goodwill attributable to Gas Storage and Pipelines 2016 acquisition of AGS and SGG — 7 Balance at December 31 $ 2,293 $ 2,293

Property, Plant, and Equipment

Property, Plant, and Equipment (Tables)	12 Months Ended
	Dec. 31, 2018
Property, Plant and Equipment [Abstract]
PP&E by Classification, Summary of Depreciation and Amortization	The following is a summary of Depreciation and amortization expense for DTE Energy: 2018 2017 2016 (In millions) Property, plant, and equipment $ 912 $ 865 $ 783 Regulatory assets and liabilities 212 165 193 $ 1,124 $ 1,030 $ 976 The following is a summary of Depreciation and amortization expense for DTE Electric: 2018 2017 2016 (In millions) Property, plant, and equipment $ 657 $ 620 $ 582 Regulatory assets and liabilities 179 133 168 $ 836 $ 753 $ 750 The following is a summary of Property, plant, and equipment by classification as of December 31: 2018 2017 Property, plant, and equipment (In millions) DTE Electric Generation $ 11,027 $ 12,166 Distribution 9,153 8,637 Other 2,567 2,169 Total DTE Electric 22,747 22,972 DTE Gas Distribution 3,823 3,523 Storage 548 533 Transmission and other 1,204 1,118 Total DTE Gas 5,575 5,174 Non-utility and other 3,488 3,278 Total DTE Energy 31,810 31,424 Accumulated depreciation and amortization DTE Electric Generation (3,609 ) (4,403 ) Distribution (2,974 ) (2,914 ) Other (727 ) (667 ) Total DTE Electric (7,310 ) (7,984 ) DTE Gas Distribution (1,283 ) (1,238 ) Storage (165 ) (159 ) Transmission and other (404 ) (384 ) Total DTE Gas (1,852 ) (1,781 ) Non-utility and other (998 ) (938 ) Total DTE Energy (10,160 ) (10,703 ) Net DTE Energy Property, plant, and equipment $ 21,650 $ 20,721 Net DTE Electric Property, plant, and equipment $ 15,437 $ 14,988
Schedule of AFUDC and Interest Capitalized	The following is a summary of the Registrants' AFUDC and interest capitalized for the years ended December 31: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Allowance for debt funds used during construction and interest capitalized $ 15 $ 13 $ 9 $ 8 Allowance for equity funds used during construction 28 23 19 18 Total $ 43 $ 36 $ 28 $ 26
Schedule of Utility Property, Plant, and Equipment	The average estimated useful life for each major class of utility Property, plant, and equipment as of December 31, 2018 follows: Estimated Useful Lives in Years Utility Generation Distribution Storage DTE Electric 40 41 N/A DTE Gas N/A 50 53
Schedule of Capitalized Software	The following balances for capitalized software relate to DTE Energy: Year Ended December 31, 2018 2017 2016 (In millions) Amortization expense of capitalized software $ 108 $ 101 $ 89 Gross carrying value of capitalized software $ 905 $ 890 Accumulated amortization of capitalized software $ 534 $ 500 The following balances for capitalized software relate to DTE Electric: Year Ended December 31, 2018 2017 2016 (In millions) Amortization expense of capitalized software $ 101 $ 93 $ 83 Gross carrying value of capitalized software $ 799 $ 774 Accumulated amortization of capitalized software $ 463 $ 423
Schedule of Property Under Operating Leases	Property under operating leases for DTE Energy is as follows: DTE Energy 2018 2017 (In millions) Gross property under operating leases $ 447 $ 327 Accumulated amortization of property under operating leases $ 148 $ 108
Schedule of Capital Leased Assets	Property under capital leases for the Registrants is as follows: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Gross property under capital leases $ 18 $ 44 $ 18 $ 18 Accumulated amortization of property under capital leases $ 7 $ 38 $ 7 $ 12

Jointly-Owned Utility Plant (Ta

Jointly-Owned Utility Plant (Tables)	12 Months Ended
	Dec. 31, 2018
Jointly Owned Utility Plant, Net Ownership Amount [Abstract]
Schedule of Jointly-Owned Utility Plants	DTE Electric's ownership information of the two utility plants as of December 31, 2018 was as follows: Belle River Ludington Hydroelectric Pumped Storage In-service date 1984-1985 1973 Ownership interest 81% 49% Investment in Property, plant, and equipment (in millions) $ 1,819 $ 586 Accumulated depreciation (in millions) $ 1,068 $ 187

Asset Retirement Obligations (T

Asset Retirement Obligations (Tables)	12 Months Ended
	Dec. 31, 2018
Asset Retirement Obligation Disclosure [Abstract]
Schedule of Change in Asset Retirement Obligations	A reconciliation of the asset retirement obligations for 2018 follows: DTE Energy DTE Electric (In millions) Asset retirement obligations at December 31, 2017 $ 2,320 $ 2,125 Accretion 140 129 Liabilities incurred 27 27 Liabilities settled (16 ) (8 ) Revision in estimated cash flows (2 ) (2 ) Asset retirement obligations at December 31, 2018 $ 2,469 $ 2,271

Regulatory Matters (Tables)

Regulatory Matters (Tables)	12 Months Ended
	Dec. 31, 2018
Regulatory Assets and Liabilities Disclosure [Abstract]
Schedule of Regulatory Assets	The following are balances and a brief description of the Registrants' Regulatory assets and liabilities at December 31: DTE Energy DTE Electric 2018 2017 2018 2017 Assets (In millions) Recoverable pension and other postretirement costs Pension $ 1,961 $ 2,000 $ 1,476 $ 1,502 Other postretirement costs 213 278 121 211 Asset retirement obligation 778 569 778 569 Recoverable undepreciated costs on retiring plants 630 — 630 — Removal costs asset 407 299 407 299 Recoverable Michigan income taxes 201 213 161 171 Accrued PSCR/GCR revenue 116 17 116 17 Deferred environmental costs 69 75 — — Unamortized loss on reacquired debt 60 65 43 46 Recoverable income taxes related to AFUDC equity 51 41 41 35 Energy Waste Reduction incentive 49 39 39 30 Nuclear Performance Evaluation and Review Committee Tracker 43 22 43 22 Customer360 deferred costs 42 45 42 45 Other recoverable income taxes 23 26 23 26 Transitional Reconciliation Mechanism 21 46 21 46 Other 57 43 36 36 4,721 3,778 3,977 3,055 Less amount included in Current Assets (153 ) (55 ) (148 ) (50 ) $ 4,568 $ 3,723 $ 3,829 $ 3,005
Schedule of Regulatory Liabilities	DTE Energy DTE Electric 2018 2017 2018 2017 Liabilities (In millions) Refundable federal income taxes $ 2,410 $ 2,384 $ 1,958 $ 1,946 Removal costs liability 253 265 — — TCJA rate reduction liability 118 — 93 — Negative other postretirement offset 101 80 79 67 Renewable energy 86 112 86 112 Refundable self-implemented rates 26 2 26 2 Negative pension offset 9 21 — — Fermi 2 refueling outage 4 15 4 15 Other 41 14 23 12 3,048 2,893 2,269 2,154 Less amount included in Current Liabilities (126 ) (18 ) (98 ) (17 ) $ 2,922 $ 2,875 $ 2,171 $ 2,137

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Schedule of Effective Income Tax Rate Reconciliation	The Registrants' total Income Tax Expense varied from the statutory federal income tax rate for the following reasons: 2018 2017 2016 DTE Energy (In millions) Income Before Income Taxes $ 1,216 $ 1,287 $ 1,105 Income tax expense at statutory rate - 21% in 2018 - 35% in 2017 and 2016 $ 255 $ 450 $ 387 Production tax credits (223 ) (189 ) (145 ) Investment tax credits (4 ) (4 ) (5 ) Depreciation 2 (4 ) (4 ) Noncontrolling interests 2 8 12 AFUDC equity (14 ) (18 ) (10 ) Employee Stock Ownership Plan dividends (3 ) (5 ) (5 ) Stock based compensation (3 ) (14 ) — Subsidiary stock loss — — (10 ) State and local income taxes, net of federal benefit 60 51 58 Enactment of the Tax Cuts and Jobs Act 21 (105 ) — Other, net 5 5 (7 ) Income Tax Expense $ 98 $ 175 $ 271 Effective income tax rate 8.1 % 13.6 % 24.5 % 2018 2017 2016 DTE Electric (In millions) Income Before Income Taxes $ 857 $ 928 $ 975 Income tax expense at statutory rate - 21% in 2018 - 35% in 2017 and 2016 $ 180 $ 325 $ 341 Production tax credits (35 ) (36 ) (30 ) Investment tax credits (3 ) (4 ) (4 ) Depreciation 2 3 3 AFUDC equity (3 ) (5 ) (6 ) Employee Stock Ownership Plan dividends (2 ) (3 ) (3 ) State and local income taxes, net of federal benefit 49 48 56 Enactment of the Tax Cuts and Jobs Act 7 — — Other, net (2 ) (1 ) (4 ) Income Tax Expense $ 193 $ 327 $ 353 Effective income tax rate 22.5 % 35.2 % 36.2 %
Schedule of Components of Income Tax Expense (Benefit)	Components of the Registrants' Income Tax Expense were as follows: 2018 2017 2016 DTE Energy (In millions) Current income tax expense (benefit) Federal $ (17 ) $ (22 ) $ (1 ) State and other income tax 1 1 7 Total current income taxes (16 ) (21 ) 6 Deferred income tax expense Federal 38 118 184 State and other income tax 76 78 81 Total deferred income taxes 114 196 265 $ 98 $ 175 $ 271 2018 2017 2016 DTE Electric (In millions) Current income tax expense (benefit) Federal $ — $ (17 ) $ — State and other income tax 4 (1 ) 11 Total current income taxes 4 (18 ) 11 Deferred income tax expense Federal 131 270 268 State and other income tax 58 75 74 Total deferred income taxes 189 345 342 $ 193 $ 327 $ 353
Schedule of Deferred Tax Assets and Liabilities	The Registrants' deferred tax assets (liabilities) were comprised of the following at December 31: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Property, plant, and equipment $ (3,462 ) $ (3,276 ) $ (2,840 ) $ (2,698 ) Regulatory assets and liabilities (54 ) (94 ) (3 ) (31 ) Tax credit carry-forwards 1,178 947 250 193 Pension and benefits 311 334 258 302 Federal net operating loss carry-forward 117 83 2 47 State and local net operating loss carry-forwards 59 70 1 5 Investments in equity method investees (216 ) (82 ) (1 ) — Other 125 170 87 94 (1,942 ) (1,848 ) (2,246 ) (2,088 ) Less valuation allowance (33 ) (40 ) — — Long-term deferred income tax liabilities $ (1,975 ) $ (1,888 ) $ (2,246 ) $ (2,088 ) Deferred income tax assets $ 2,021 $ 1,814 $ 855 $ 830 Deferred income tax liabilities (3,996 ) (3,702 ) (3,101 ) (2,918 ) $ (1,975 ) $ (1,888 ) $ (2,246 ) $ (2,088 )
Schedule of Unrecognized Tax Benefits Roll Forward	A reconciliation of the beginning and ending amount of unrecognized tax benefits for the Registrants is as follows: 2018 2017 2016 DTE Energy (In millions) Balance at January 1 $ 10 $ 10 $ 3 Additions for tax positions of prior years — — 7 Balance at December 31 $ 10 $ 10 $ 10 2018 2017 2016 DTE Electric (In millions) Balance at January 1 $ 13 $ 13 $ 4 Additions for tax positions of prior years — — 9 Balance at December 31 $ 13 $ 13 $ 13

Earnings Per Share (Tables)

Earnings Per Share (Tables)	12 Months Ended
	Dec. 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 for the years ended December 31 : 2018 2017 2016 (In millions, except per share amounts) Basic Earnings per Share Net Income Attributable to DTE Energy Company $ 1,120 $ 1,134 $ 868 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — basic $ 1,118 $ 1,132 $ 866 Average number of common shares outstanding — basic 181 179 179 Basic Earnings per Common Share $ 6.18 $ 6.32 $ 4.84 Diluted Earnings per Share Net Income Attributable to DTE Energy Company $ 1,120 $ 1,134 $ 868 Less: Allocation of earnings to net restricted stock awards (2 ) (2 ) (2 ) Net income available to common shareholders — diluted $ 1,118 $ 1,132 $ 866 Average number of common shares outstanding — diluted 181 179 179 Diluted Earnings per Common Share (a) $ 6.17 $ 6.32 $ 4.83 _______________________________________ (a) The 2016 Equity Units excluded from the calculation of diluted EPS were approximately 6.3 million for the years ended December 31, 2018 and 2017 as the dilutive stock price threshold was not met. For more information, see Note 14 to the Consolidated Financial Statements, " Long-Term Debt ."

Fair Value (Tables)

Fair Value (Tables)	12 Months Ended
	Dec. 31, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Recorded at Fair Value on a Recurring Basis	The following table presents assets and liabilities for DTE Energy measured and recorded at fair value on a recurring basis (a) : December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Other (b) Netting (c) Net Balance Level 1 Level 2 Level 3 Other (b) Netting (c) Net Balance (In millions) Assets Cash equivalents (d) $ 16 $ 2 $ — $ — $ — $ 18 $ 16 $ 3 $ — $ — $ — $ 19 Nuclear decommissioning trusts Equity securities 851 — — — — 851 978 — — — — 978 Fixed income securities 12 490 — — — 502 18 477 — — — 495 Private equity and other — — — 20 — 20 — — — 5 — 5 Cash equivalents 5 — — — — 5 14 — — — — 14 Other investments (e) Equity securities 110 — — — — 110 118 — — — — 118 Fixed income securities 69 — — — — 69 72 — — — — 72 Cash equivalents 4 — — — — 4 4 — — — — 4 Derivative assets: Commodity Contracts: Natural Gas 199 87 63 — (277 ) 72 148 112 97 — (256 ) 101 Electricity — 247 56 — (252 ) 51 — 243 42 — (241 ) 44 Other — — 7 — (1 ) 6 — — 9 — — 9 Foreign currency exchange contracts — 4 — — — 4 — 1 — — (1 ) — Total derivative assets 199 338 126 — (530 ) 133 148 356 148 — (498 ) 154 Total $ 1,266 $ 830 $ 126 $ 20 $ (530 ) $ 1,712 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Derivative liabilities: Commodity Contracts: Natural Gas $ (197 ) $ (71 ) $ (112 ) $ — $ 272 $ (108 ) $ (141 ) $ (111 ) $ (126 ) $ — $ 263 $ (115 ) Electricity — (227 ) (58 ) — 240 (45 ) — (245 ) (30 ) — 246 (29 ) Other — (1 ) — — 1 — — — (1 ) — 1 — Interest rate contracts — (3 ) — — — (3 ) — — — — — — Foreign currency exchange contracts — — — — — — — (3 ) — — 1 (2 ) Total derivative liabilities (197 ) (302 ) (170 ) — 513 (156 ) (141 ) (359 ) (157 ) — 511 (146 ) Total $ (197 ) $ (302 ) $ (170 ) $ — $ 513 $ (156 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,069 $ 528 $ (44 ) $ 20 $ (17 ) $ 1,556 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 Assets Current $ 212 $ 273 $ 96 $ — $ (461 ) $ 120 $ 157 $ 298 $ 104 $ — $ (437 ) $ 122 Noncurrent 1,054 557 30 20 (69 ) 1,592 1,211 538 44 5 (61 ) 1,737 Total Assets $ 1,266 $ 830 $ 126 $ 20 $ (530 ) $ 1,712 $ 1,368 $ 836 $ 148 $ 5 $ (498 ) $ 1,859 Liabilities Current $ (191 ) $ (251 ) $ (76 ) $ — $ 451 $ (67 ) $ (137 ) $ (313 ) $ (108 ) $ — $ 459 $ (99 ) Noncurrent (6 ) (51 ) (94 ) — 62 (89 ) (4 ) (46 ) (49 ) — 52 (47 ) Total Liabilities $ (197 ) $ (302 ) $ (170 ) $ — $ 513 $ (156 ) $ (141 ) $ (359 ) $ (157 ) $ — $ 511 $ (146 ) Net Assets (Liabilities) at end of period $ 1,069 $ 528 $ (44 ) $ 20 $ (17 ) $ 1,556 $ 1,227 $ 477 $ (9 ) $ 5 $ 13 $ 1,713 _______________________________________ (a) See footnotes on following page. _______________________________________ (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) 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. (d) At December 31, 2018 , the $18 million consisted of $3 million , $5 million , and $10 million of cash equivalents included in Cash and Cash equivalents, Restricted cash, and Other investments on DTE Energy's Consolidated Statements of Financial Position, respectively. At December 31, 2017 , the $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. (e) Excludes cash surrender value of life insurance investments. The following table presents assets for DTE Electric measured and recorded at fair value on a recurring basis: December 31, 2018 December 31, 2017 Level 1 Level 2 Level 3 Other (a) Net Balance Level 1 Level 2 Level 3 Other Net Balance (In millions) Assets Cash equivalents (b) $ 8 $ 2 $ — $ — $ 10 $ 8 $ 3 $ — $ — $ 11 Nuclear decommissioning trusts Equity securities 851 — — — 851 978 — — — 978 Fixed income securities 12 490 — — 502 18 477 — — 495 Private equity and other — — — 20 20 — — — 5 5 Cash equivalents 5 — — — 5 14 — — — 14 Other investments Equity securities 10 — — — 10 11 — — — 11 Derivative assets — FTRs — — 6 — 6 — — 9 — 9 Total $ 886 $ 492 $ 6 $ 20 $ 1,404 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 Assets Current $ 8 $ 2 $ 6 $ — $ 16 $ 8 $ 3 $ 9 $ — $ 20 Noncurrent 878 490 — 20 1,388 1,021 477 — 5 1,503 Total Assets $ 886 $ 492 $ 6 $ 20 $ 1,404 $ 1,029 $ 480 $ 9 $ 5 $ 1,523 _______________________________________ (a) Amounts represent assets valued at NAV as a practical expedient for fair value. (b) At December 31, 2018 , the $10 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position. At December 31, 2017 , the $11 million consisted of cash equivalents included in Other investments on DTE Electric's Consolidated Statements of Financial Position.
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis Level 3 Roll Forward	The following table presents the fair value reconciliation of Level 3 assets and liabilities measured at fair value on a recurring basis for DTE Energy: Year Ended December 31, 2018 Year Ended December 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 (146 ) 29 1 (116 ) (29 ) 109 2 82 Recorded in Regulatory liabilities — — 9 9 — — 25 25 Purchases, issuances, and settlements: Purchases — — — — — — — — Issuances — — — — — — — — Settlements 129 (43 ) (11 ) 75 96 (106 ) (18 ) (28 ) Net Assets (Liabilities) as of December 31 $ (49 ) $ (2 ) $ 7 $ (44 ) $ (29 ) $ 12 $ 8 $ (9 ) The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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 $ (119 ) $ 15 $ (16 ) $ (120 ) $ (30 ) $ 50 $ 1 $ 21 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: Year Ended December 31, 2018 2017 (In millions) Net Assets as of January 1 $ 9 $ 2 Change in fair value recorded in Regulatory liabilities 9 25 Purchases, issuances, and settlements: Settlements (12 ) (18 ) Net Assets as of December 31 $ 6 $ 9 The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2018 and 2017 and reflected in DTE Electric's Consolidated Statements of Financial Position $ 6 $ 9
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques	The following tables present the unobservable inputs related to DTE Energy's Level 3 assets and liabilities: December 31, 2018 Commodity Contracts Derivative Assets Derivative Liabilities Valuation Techniques Unobservable Input Range Weighted Average (In millions) Natural Gas $ 63 $ (112 ) Discounted Cash Flow Forward basis price (per MMBtu) $ (2.15 ) — $ 5.59 /MMBtu $ (0.1 )/MMBtu Electricity $ 56 $ (58 ) Discounted Cash Flow Forward basis price (per MWh) $ (7 ) — $ 9 /MWh $ 1 /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
Fair Value of Financial Instruments	The following table presents the carrying amount and fair value of financial instruments for DTE Energy: December 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 $ 40 $ — $ — $ 40 $ 38 $ — $ — $ 38 Dividends payable $ 172 $ 172 $ — $ — $ 158 $ 158 $ — $ — Short-term borrowings $ 609 $ — $ 609 $ — $ 621 $ — $ 621 $ — Notes payable — Other (b) , excluding capital leases $ 41 $ — $ — $ 41 $ 12 $ — $ — $ 12 Long-term debt (c) $ 13,622 $ 1,796 $ 10,712 $ 1,317 $ 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: December 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, excluding capital leases $ 6 $ — $ — $ 6 $ — $ — $ — $ — Short-term borrowings — affiliates $ 101 $ — $ 101 $ 116 $ — $ — $ 116 Short-term borrowings — other $ 149 $ — $ 149 $ — 238 $ — $ 238 $ — Notes payable — Other (a) , excluding capital leases $ 21 $ — $ — $ 21 $ 2 $ — $ — $ 2 Long-term debt (b) $ 6,538 $ — $ 6,552 $ 161 $ 6,017 $ — $ 6,441 $ 171 _______________________________________ (a) Included in Current Liabilities — Other and Other Liabilities — Other on DTE Electric's Consolidated Statements of Financial Position. (b) Includes debt due within one year, unamortized debt discounts, and issuance costs. Excludes Capital lease obligations.
Fair Value of Nuclear Decommissioning Trust Fund Assets	The following table summarizes DTE Electric's fair value of the nuclear decommissioning trust fund assets: December 31, 2018 2017 (In millions) Fermi 2 $ 1,372 $ 1,475 Fermi 1 3 3 Low-level radioactive waste 3 14 $ 1,378 $ 1,492
Schedule of Realized Gain (Loss) for 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: Year Ended December 31, 2018 2017 2016 (In millions) Realized gains $ 65 $ 83 $ 74 Realized losses $ (42 ) $ (29 ) $ (63 ) Proceeds from sale of securities $ 1,203 $ 1,240 $ 1,457
Fair Value and Unrealized Gains and Losses for Nuclear Decommissioning Trust Funds	The following table sets forth DTE Electric's fair value and unrealized gains and losses for the nuclear decommissioning trust funds: December 31, 2018 December 31, 2017 Fair Unrealized Unrealized Losses Fair Unrealized Unrealized Losses (In millions) Equity securities $ 851 $ 235 $ (79 ) $ 978 $ 320 $ (32 ) Fixed income securities 502 7 (8 ) 495 13 (3 ) Private equity and other 20 — — 5 — — Cash equivalents 5 — — 14 — — $ 1,378 $ 242 $ (87 ) $ 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: December 31, 2018 (In millions) Due within one year $ 29 Due after one through five years 89 Due after five through ten years 113 Due after ten years 271 $ 502

Financial and Other Derivativ_2

Financial and Other Derivative Instruments (Tables)	12 Months Ended
	Dec. 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: December 31, 2018 December 31, 2017 Derivative Derivative Derivative Derivative (In millions) Derivatives designated as hedging instruments Interest rate contracts $ — $ (3 ) $ — $ — Derivatives not designated as hedging instruments Commodity contracts Natural gas $ 349 $ (380 ) $ 357 $ (378 ) Electricity 303 (285 ) 285 (275 ) Other 7 (1 ) 9 (1 ) Foreign currency exchange contracts 4 — 1 (3 ) Total derivatives not designated as hedging instruments $ 663 $ (666 ) $ 652 $ (657 ) Current $ 563 $ (518 ) $ 540 $ (558 ) Noncurrent 100 (151 ) 112 (99 ) Total derivatives $ 663 $ (669 ) $ 652 $ (657 ) The following table presents the fair value of derivative instruments for DTE Electric: December 31, 2018 2017 (In millions) FTRs — Other current assets $ 6 $ 9 Total derivatives not designated as hedging instruments $ 6 $ 9
Offsetting Assets	The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy: December 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 $ 349 $ (277 ) $ 72 $ 357 $ (256 ) $ 101 Electricity 303 (252 ) 51 285 (241 ) 44 Other 7 (1 ) 6 9 — 9 Foreign currency exchange contracts 4 — 4 1 (1 ) — Total derivative assets $ 663 $ (530 ) $ 133 $ 652 $ (498 ) $ 154 Derivative liabilities Commodity contracts Natural gas $ (380 ) $ 272 $ (108 ) $ (378 ) $ 263 $ (115 ) Electricity (285 ) 240 (45 ) (275 ) 246 (29 ) Other (1 ) 1 — (1 ) 1 — Interest rate contracts (3 ) — (3 ) — — — Foreign currency exchange contracts — — — (3 ) 1 (2 ) Total derivative liabilities $ (669 ) $ 513 $ (156 ) $ (657 ) $ 511 $ (146 )
Offsetting Liabilities	The following table presents the netting offsets of Derivative assets and liabilities for DTE Energy: December 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 $ 349 $ (277 ) $ 72 $ 357 $ (256 ) $ 101 Electricity 303 (252 ) 51 285 (241 ) 44 Other 7 (1 ) 6 9 — 9 Foreign currency exchange contracts 4 — 4 1 (1 ) — Total derivative assets $ 663 $ (530 ) $ 133 $ 652 $ (498 ) $ 154 Derivative liabilities Commodity contracts Natural gas $ (380 ) $ 272 $ (108 ) $ (378 ) $ 263 $ (115 ) Electricity (285 ) 240 (45 ) (275 ) 246 (29 ) Other (1 ) 1 — (1 ) 1 — Interest rate contracts (3 ) — (3 ) — — — Foreign currency exchange contracts — — — (3 ) 1 (2 ) Total derivative liabilities $ (669 ) $ 513 $ (156 ) $ (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: December 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 $ 563 $ 100 $ (518 ) $ (151 ) $ 540 $ 112 $ (558 ) $ (99 ) Counterparty netting (451 ) (62 ) 451 62 (437 ) (52 ) 437 52 Collateral adjustment (10 ) (7 ) — — — (9 ) 22 — Total derivatives as reported $ 102 $ 31 $ (67 ) $ (89 ) $ 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: Location of Gain (Loss) Recognized in Income on Derivatives Gain (Loss) Recognized in Income on Derivatives for Years Ended December 31, 2018 2017 2016 (In millions) Derivatives not Designated as Hedging Instruments Commodity contracts Natural gas Operating Revenues — Non-utility operations $ (42 ) $ (74 ) $ (153 ) Natural gas Fuel, purchased power, and gas — non-utility (94 ) 97 (2 ) Electricity Operating Revenues — Non-utility operations 49 105 43 Other Operating Revenues — Non-utility operations (1 ) 2 5 Foreign currency exchange contracts Operating Revenues — Non-utility operations 7 (2 ) (2 ) Total $ (81 ) $ 128 $ (109 )
Volume of Commodity Contracts	The following represents the cumulative gross volume of DTE Energy's derivative contracts outstanding as of December 31, 2018 : Commodity Number of Units Natural Gas (MMBtu) 2,171,541,994 Electricity (MWh) 36,163,761 Foreign Currency Exchange (Canadian dollars) 101,975,644

Long-Term Debt (Tables)

Long-Term Debt (Tables)	12 Months Ended
	Dec. 31, 2018
Long-term Debt, Unclassified [Abstract]
Schedule of Long-term Debt Instruments	At December 31, 2018 , DTE Energy had the following Junior Subordinated Debentures: Interest Rate Maturity Date Amount (In millions) 2012 Series C 5.25% 2062 $ 200 2016 Series B 5.375% 2076 300 2016 Series F 6.00% 2076 280 2017 Series E 5.25% 2077 400 $ 1,180 Selected information about DTE Energy’s 2016 Equity Units is presented below: Issuance Date Units Issued Total Net Proceeds Total Long-Term Debt RSN Annual Interest Rate Stock Purchase Contract Annual Rate Stock Purchase Settlement Date Stock Purchase Contract Liability (a) RSN Maturity Date (In millions, except interest rates) 10/5/2016 13.5 $ 654 $ 675 1.5% 5.0% 10/1/2019 $ 98 10/1/2024 _______________________________________ (a) Payments of $33 million and $32 million were made in 2018 and 2017, respectively. The stock purchase contract liability, exclusive of interest, was $33 million and $66 million at December 31, 2018 and 2017 , respectively. DTE Energy's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2018 2017 (In millions) Mortgage bonds, notes, and other DTE Energy Debt, Unsecured 3.2% 2019 — 2033 $ 4,425 $ 3,825 DTE Electric Taxable Debt, Principally Secured 4.3% 2020 — 2048 6,280 5,755 DTE Electric Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 DTE Gas Taxable Debt, Principally Secured 4.5% 2019 — 2048 1,550 1,330 Other Long-Term Debt, including Non-Recourse Debt 1 7 12,566 11,227 Unamortized debt discount and premium, net (16 ) (15 ) Unamortized debt issuance costs (73 ) (69 ) Long-term debt due within one year (1,495 ) (104 ) $ 10,982 $ 11,039 Junior Subordinated Debentures Subordinated Debentures 5.5% 2062 — 2077 $ 1,180 $ 1,180 Unamortized debt issuance costs (35 ) (35 ) $ 1,145 $ 1,145 _______________________________________ (a) Weighted average interest rate as of December 31, 2018 . (b) DTE Electric Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds. DTE Electric's long-term debt outstanding and weighted average interest rates of debt outstanding at December 31 were: Interest Rate (a) Maturity Date 2018 2017 (In millions) Mortgage bonds, notes, and other Taxable Debt, Principally Secured 4.3% 2020 — 2048 $ 6,280 $ 5,755 Tax-Exempt Revenue Bonds (b) 4.3% 2020 — 2030 310 310 6,590 6,065 Unamortized debt discount (11 ) (10 ) Unamortized debt issuance costs (41 ) (38 ) $ 6,538 $ 6,017 _______________________________________ (a) Weighted average interest rate as of December 31, 2018 . (b) Tax-Exempt Revenue Bonds are issued by a public body that loans the proceeds to DTE Electric on terms substantially mirroring the Revenue Bonds.
Schedule of Issued Debt	In 2018 , the following debt was issued: Company Month Type Interest Rate Maturity Date Amount (In millions) DTE Electric May Mortgage Bonds (a) 4.05% 2048 $ 525 DTE Energy August Senior Notes (b) 3.70% 2023 600 DTE Gas August Mortgage Bonds (b) 3.81% 2028 195 DTE Gas August Mortgage Bonds (b) 4.14% 2048 125 $ 1,445 _______________________________________ (a) Bonds were issued as Green Bonds and the proceeds will be used to finance expenditures for solar and wind energy, payments under power purchase agreements for solar and wind energy, and energy optimization programs. (b) Proceeds were used for the repayment of short-term borrowings and general corporate purposes.
Schedule of Debt Redeemed	In 2018 , the following debt was redeemed: Company Month Type Interest Rate Maturity Date Amount (In millions) DTE Gas April Senior Notes 6.04% 2018 $ 100 DTE Energy Various Other Long-Term Debt Various 2018 5 $ 105
Schedule of Maturities of Long-term Debt	The following table shows the Registrants' scheduled debt maturities, excluding any unamortized discount or premium on debt: 2019 2020 2021 2022 2023 2024 and Thereafter Total (In millions) DTE Energy (a) $ 1,495 $ 682 $ 462 $ 616 $ 1,177 $ 9,314 $ 13,746 DTE Electric $ — $ 632 $ 462 $ 316 $ 202 $ 4,978 $ 6,590 _______________________________________ (a) Amounts include DTE Electric's scheduled debt maturities.

Preferred and Preference Secu_2

Preferred and Preference Securities (Tables)	12 Months Ended
	Dec. 31, 2018
Preferred Stock, Number of Shares, Par Value and Other Disclosures [Abstract]
Schedule of Preferred and Preference Securities	As of December 31, 2018 , the amount of authorized and unissued stock is as follows: Company Type of Stock Par Value Shares Authorized DTE Energy Preferred $ — 5,000,000 DTE Electric Preferred $ 100 6,747,484 DTE Electric Preference $ 1 30,000,000 DTE Gas Preferred $ 1 7,000,000 DTE Gas Preference $ 1 4,000,000

Short-Term Credit Arrangement_2

Short-Term Credit Arrangements and Borrowings (Tables)	12 Months Ended
	Dec. 31, 2018
Short-term Debt [Abstract]
Schedule of Line of Credit Facilities	The availability under the facilities in place at December 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 December 31, 2018 Commercial paper issuances 271 149 189 609 Letters of credit 168 — — 168 439 149 189 777 Net availability at December 31, 2018 $ 981 $ 251 $ 111 $ 1,343

Capital and Operating Leases (T

Capital and Operating Leases (Tables)	12 Months Ended
	Dec. 31, 2018
Leases [Abstract]
Schedule of Future Minimum Lease Payments for Operating Leases	The Registrants' future minimum lease payments under non-cancelable operating leases at December 31, 2018 were: DTE Energy DTE Electric (In millions) 2019 $ 42 $ 17 2020 30 12 2021 18 10 2022 11 7 2023 8 5 2024 and thereafter 45 29 Total minimum lease payments $ 154 $ 80
Schedule of Future Rental Revenue for Operating Leases	DTE Energy's minimum future rental revenues under non-cancelable operating leases as of December 31, 2018 were: DTE Energy (In millions) 2019 $ 66 2020 66 2021 64 2022 20 2023 20 2024 and thereafter 196 Total minimum future rental revenue under non-cancelable operating leases $ 432
Schedule of Future Minimum Lease Receivables for Capital Leases	The components of DTE Energy's net investment in capital leases at December 31, 2018 , were as follows: DTE Energy (In millions) 2019 $ 10 2020 9 2021 — 2022 — 2023 — 2024 and thereafter 1 Total minimum future lease receipts 20 Residual value of leased pipeline 40 Less unearned income (9 ) Net investment in capital lease 51 Less current portion (5 ) $ 46

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]
Schedule of Long-term Purchase Commitments	The Registrants estimate the following commitments from 2019 through 2051 for DTE Energy, and 2019 through 2039 for DTE Electric, as detailed in the following table: DTE Energy DTE Electric (In millions) 2019 $ 2,691 $ 777 2020 1,311 541 2021 632 171 2022 409 88 2023 351 85 2024 and thereafter 1,953 737 $ 7,347 $ 2,399

Retirement Benefits and Trust_2

Retirement Benefits and Trusteed Assets (Tables)	12 Months Ended
	Dec. 31, 2018
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures	The table below represents the pension and other postretirement benefit plans of each Registrant at December 31, 2018 : Registrants DTE Energy DTE Electric Qualified Pension Plans DTE Energy Company Retirement Plan X X DTE Gas Company Retirement Plan for Employees Covered by Collective Bargaining Agreements X Shenango Inc. Pension Plan X Nonqualified Pension Plans DTE Energy Company Supplemental Retirement Plan X X DTE Energy Company Executive Supplemental Retirement Plan (a) X X DTE Energy Company Supplemental Severance Benefit Plan X Other Postretirement Benefit Plans The DTE Energy Company Comprehensive Non-Health Welfare Plan X X The DTE Energy Company Comprehensive Retiree Group Health Care Plan X X DTE Supplemental Retiree Benefit Plan X X DTE Energy Company Retiree Reimbursement Arrangement Plan X X _____________________________________ (a) Sponsored by the DTE Energy subsidiary, DTE Energy Holding Company.
Pension Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures	The following table reconciles the obligations, assets, and funded status of the plans as well as the amounts recognized as prepaid pension cost or pension liability in DTE Energy's Consolidated Statements of Financial Position at December 31: DTE Energy 2018 2017 (In millions) Accumulated benefit obligation, end of year $ 4,779 $ 5,149 Change in projected benefit obligation Projected benefit obligation, beginning of year $ 5,576 $ 5,171 Service cost 99 92 Interest cost 202 214 Plan amendments — (11 ) Actuarial (gain) loss (438 ) 391 Benefits paid (315 ) (281 ) Projected benefit obligation, end of year $ 5,124 $ 5,576 Change in plan assets Plan assets at fair value, beginning of year $ 4,636 $ 4,012 Actual return on plan assets (233 ) 674 Company contributions 185 231 Benefits paid (315 ) (281 ) Plan assets at fair value, end of year $ 4,273 $ 4,636 Funded status $ (851 ) $ (940 ) Amount recorded as: Current liabilities $ (14 ) $ (16 ) Noncurrent liabilities (837 ) (924 ) $ (851 ) $ (940 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial loss $ 152 $ 163 Prior service cost 5 6 $ 157 $ 169 Amounts recognized in Regulatory assets (a) Net actuarial loss $ 1,973 $ 2,014 Prior service credit (12 ) (14 ) $ 1,961 $ 2,000 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." 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 following table provides contributions to the qualified pension plans in: 2018 2017 2016 (In millions) DTE Energy $ 175 $ 223 $ 179 DTE Electric 175 185 145
Schedule of Net Benefit Costs	Net pension cost for DTE Energy includes the following components: 2018 2017 2016 (In millions) Service cost $ 99 $ 92 $ 92 Interest cost 202 214 219 Expected return on plan assets (329 ) (311 ) (309 ) Amortization of: Net actuarial loss 176 176 164 Prior service cost — 1 1 Net pension cost $ 148 $ 172 $ 167
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	2018 2017 (In millions) Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial loss $ 125 $ 27 Amortization of net actuarial loss (176 ) (176 ) Prior service credit — (11 ) Amortization of prior service cost — (1 ) Total recognized in Regulatory assets and Other comprehensive income (loss) $ (51 ) $ (161 ) Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss) $ 97 $ 11 Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 131 $ 178 Prior service cost $ 1 $ —
Schedule of Expected Benefit Payments	At December 31, 2018 , the benefits related to DTE Energy's qualified and nonqualified pension plans expected to be paid in each of the next five years and in the aggregate for the five fiscal years thereafter are as follows: (In millions) 2019 $ 311 2020 317 2021 317 2022 323 2023 332 2024-2028 1,713 Total $ 3,313
Schedule of Assumptions Used	Assumptions used in determining the projected benefit obligation and net pension costs of DTE Energy are: 2018 2017 2016 Projected benefit obligation Discount rate 4.40% 3.70% 4.25% Rate of compensation increase 4.98% 4.98% 4.65% Net pension costs Discount rate 3.70% 4.25% 4.50% Rate of compensation increase 4.98% 4.65% 4.65% Expected long-term rate of return on plan assets 7.50% 7.50% 7.75%
Schedule of Allocation of Plan Assets	The following tables provide the fair value measurement amounts for DTE Energy's pension plan assets at December 31, 2018 and 2017 (a) : December 31, 2018 December 31, 2017 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total (In millions) DTE Energy asset category: Short-term Investments (c) $ — $ 27 $ — $ 27 $ — $ 114 $ — $ 114 Equity Securities U.S. Large Cap (d) 606 3 — 609 821 5 — 826 U.S. Small Cap and Mid Cap (e) 123 1 — 124 229 5 — 234 Non-U.S. (f) 337 9 240 586 529 13 280 822 Fixed Income Securities (g) 6 1,892 — 1,898 1 1,453 — 1,454 Hedge Funds and Similar Investments (h) 88 — 542 630 265 — 593 858 Private Equity and Other (i) — — 399 399 — — 328 328 Securities Lending (j) (22 ) (8 ) — (30 ) (53 ) (13 ) — (66 ) Securities Lending Collateral (j) 22 8 — 30 53 13 — 66 DTE Energy Total $ 1,160 $ 1,932 $ 1,181 $ 4,273 $ 1,845 $ 1,590 $ 1,201 $ 4,636 _______________________________________ (a) For a description of levels within the fair value hierarchy, see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, other governmental debt, bank loans, and mortgage-backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds and limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in real estate and private debt. All pricing for investments in this category are classified as NAV assets. (j) DTE Energy has a securities lending program with a third-party agent. The program allows the agent to lend certain securities from DTE Energy's pension trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements. Target allocations for DTE Energy's pension plan assets as of December 31, 2018 are listed below: U.S. Large Capitalization (Cap) Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 15 Fixed Income Securities 42 Hedge Funds and Similar Investments 15 Private Equity and Other 8 100 %
Other postretirement benefit plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Schedule of Defined Benefit Plans Disclosures	The following table reconciles the obligations, assets, and funded status of the plans including amounts recorded as Accrued postretirement liability in the Registrants' Consolidated Statements of Financial Position at December 31: DTE Energy DTE Electric 2018 2017 2018 2017 (In millions) Change in accumulated postretirement benefit obligation Accumulated postretirement benefit obligation, beginning of year $ 1,910 $ 1,795 $ 1,470 $ 1,373 Service cost 27 27 20 20 Interest cost 69 73 53 56 Plan amendments (44 ) — (35 ) — Actuarial (gai n) loss (227 ) 101 (196 ) 84 Benefits paid (90 ) (86 ) (65 ) (63 ) Accumulated postretirement benefit obligation, end of year $ 1,645 $ 1,910 $ 1,247 $ 1,470 Change in plan assets Plan assets at fair value, beginning of year $ 1,848 $ 1,758 $ 1,272 $ 1,218 Actual return on plan assets (75 ) 252 (52 ) 172 Benefits paid (84 ) (162 ) (62 ) (118 ) Plan assets at fair value, end of year $ 1,689 $ 1,848 $ 1,158 $ 1,272 Funded status $ 44 $ (62 ) $ (89 ) $ (198 ) Amount recorded as: Noncurrent assets $ 45 $ — $ 189 $ 113 Current liabilities (1 ) (1 ) — — Noncurrent liabilities — (61 ) (278 ) (311 ) $ 44 $ (62 ) $ (89 ) $ (198 ) Amounts recognized in Accumulated other comprehensive income (loss), pre-tax Net actuarial (gain) loss $ 1 $ (1 ) $ — $ — $ 1 $ (1 ) $ — $ — Amounts recognized in Regulatory assets (a) Net actuarial loss $ 257 $ 279 $ 156 $ 211 Prior service credit (44 ) (1 ) (35 ) — $ 213 $ 278 $ 121 $ 211 ______________________________________ (a) See Note 9 to the Consolidated Financial Statements, " Regulatory Matters ."
Schedule of Net Benefit Costs	Net other postretirement credit for DTE Energy includes the following components: 2018 2017 2016 (In millions) Service cost $ 27 $ 27 $ 27 Interest cost 69 73 80 Expected return on plan assets (143 ) (130 ) (129 ) Amortization of: Net actuarial loss 11 13 30 Prior service credit — (14 ) (118 ) Other — — (1 ) Net other postretirement credit $ (36 ) $ (31 ) $ (111 ) Net other postretirement credit for DTE Electric includes the following components: 2018 2017 2016 (In millions) Service cost $ 20 $ 20 $ 20 Interest cost 53 56 61 Expected return on plan assets (98 ) (90 ) (90 ) Amortization of: Net actuarial loss 8 8 21 Prior service credit — (10 ) (89 ) Net other postretirement credit $ (17 ) $ (16 ) $ (77 )
Schedule of Amounts Recognized in Other Comprehensive Income (Loss)	2018 2017 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets Net actuarial (gai n) loss $ (46 ) $ 2 Amortization of net actuarial loss (8 ) (8 ) Amortization of prior service (cost) credit (35 ) 10 Total recognized in Regulatory assets $ (89 ) $ 4 Total recognized in net periodic benefit cost and Regulatory assets $ (106 ) $ (12 ) Estimated amounts to be amortized from Regulatory assets into net periodic benefit cost during next fiscal year Net actuarial loss $ 5 $ 8 Prior service credit $ (7 ) $ — 2018 2017 (In millions) Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss) Net actuarial gain $ (8 ) $ (21 ) Amortization of net actuarial loss (11 ) (13 ) Prior service credit (44 ) (1 ) Amortization of prior service credit — 14 Total recognized in Regulatory assets and Other comprehensive income (loss) $ (63 ) $ (21 ) Total recognized in net periodic benefit cost, Regulatory assets, and Other comprehensive income (loss) $ (99 ) $ (52 ) Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year Net actuarial loss $ 12 $ 11 Prior service credit $ (9 ) $ (1 )
Schedule of Expected Benefit Payments	At December 31, 2018 , the benefits expected to be paid, including prescription drug benefits, in each of the next five years and in the aggregate for the five fiscal years thereafter for the Registrants are as follows: DTE Energy DTE Electric (In millions) 2019 $ 88 $ 66 2020 92 70 2021 96 73 2022 100 75 2023 102 77 2024-2028 532 402 Total $ 1,010 $ 763
Schedule of Assumptions Used	Assumptions used in determining the accumulated postretirement benefit obligation and net other postretirement benefit costs of the Registrants are: 2018 2017 2016 Accumulated postretirement benefit obligation Discount rate 4.40% 3.70% 4.25% Health care trend rate pre- and post- 65 6.75 / 7.25% 6.75 / 7.25% 6.50 / 6.75% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2031 2030 2028 Other postretirement benefit costs Discount rate 3.70% 4.25% 4.50% Expected long-term rate of return on plan assets 7.75% 7.75% 8.00% Health care trend rate pre- and post- 65 6.75 / 7.25% 6.50 / 6.75% 6.25 / 6.75% Ultimate health care trend rate 4.50% 4.50% 4.50% Year in which ultimate reached pre- and post- 65 2030 2028 2027
Schedule of Allocation of Plan Assets	Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2018 are listed below: U.S. Large Cap Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 19 Fixed Income Securities 28 Hedge Funds and Similar Investments 19 Private Equity and Other 14 100 % Target allocations for the Registrants' other postretirement benefit plan assets as of December 31, 2018 are listed below: U.S. Large Cap Equity Securities 16 % U.S. Small Cap and Mid Cap Equity Securities 4 Non-U.S. Equity Securities 19 Fixed Income Securities 28 Hedge Funds and Similar Investments 19 Private Equity and Other 14 100 % The following tables provide the fair value measurement amounts for the Registrants' other postretirement benefit plan assets at December 31, 2018 and 2017 (a) : December 31, 2018 December 31, 2017 Level 1 Level 2 Other (b) Total Level 1 Level 2 Other (b) Total DTE Energy asset category: (In millions) Short-term Investments (c) $ 14 $ 2 $ — $ 16 $ 13 $ 2 $ — $ 15 Equity Securities U.S. Large Cap (d) 225 — — 225 284 — — 284 U.S. Small Cap and Mid Cap (e) 75 — — 75 131 — — 131 Non-U.S. (f) 234 — 67 301 288 1 77 366 Fixed Income Securities (g) 11 350 130 491 29 324 130 483 Hedge Funds and Similar Investments (h) 97 — 203 300 116 — 219 335 Private Equity and Other (i) — — 281 281 — — 234 234 Securities Lending (j) (21 ) (1 ) — (22 ) (39 ) (1 ) — (40 ) Securities Lending Collateral (j) 21 1 — 22 39 1 — 40 DTE Energy Total $ 656 $ 352 $ 681 $ 1,689 $ 861 $ 327 $ 660 $ 1,848 DTE Electric asset category: Short-term Investments (c) $ 10 $ 1 $ — $ 11 $ 9 $ 1 $ — $ 10 Equity Securities U.S. Large Cap (d) 154 — — 154 195 — — 195 U.S. Small Cap and Mid Cap (e) 52 — — 52 91 — — 91 Non-U.S. (f) 163 — 45 208 200 1 52 253 Fixed Income Securities (g) 7 232 92 331 20 218 92 330 Hedge Funds and Similar Investments (h) 68 — 139 207 80 — 150 230 Private Equity and Other (i) — — 195 195 — — 163 163 Securities Lending (j) (15 ) — — (15 ) (27 ) (1 ) — (28 ) Securities Lending Collateral (j) 15 — — 15 27 1 — 28 DTE Electric Total $ 454 $ 233 $ 471 $ 1,158 $ 595 $ 220 $ 457 $ 1,272 _______________________________________ (a) For a description of levels within the fair value hierarchy see Note 12 to the Consolidated Financial Statements, " Fair Value ." (b) Amounts represent assets valued at NAV as a practical expedient for fair value. (c) This category predominantly represents certain short-term fixed income securities and money market investments that are managed in separate accounts or commingled funds. Pricing for investments in this category are obtained from quoted prices in actively traded markets or valuations from brokers or pricing services. (d) This category represents portfolios of large capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (e) This category represents portfolios of small and medium capitalization domestic equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. (f) This category primarily consists of portfolios of non-U.S. developed and emerging market equities. Investments in this category are exchange-traded securities whereby unadjusted quoted prices can be obtained. Exchange-traded securities held in a commingled fund are classified as NAV assets. (g) This category includes corporate bonds from diversified industries, U.S. Treasuries, other governmental debt, bank loans, and mortgage backed securities. Pricing for investments in this category is obtained from quoted prices in actively traded markets and quotations from broker or pricing services. Non-exchange traded securities and exchange-traded securities held in commingled funds are classified as NAV assets. (h) This category utilizes a diversified group of strategies that attempt to capture financial market inefficiencies and includes publicly traded mutual funds, commingled funds and limited partnership funds. Pricing for mutual funds in this category is obtained from quoted prices in actively traded markets. Commingled funds and limited partnership funds are classified as NAV assets. (i) This category includes a diversified group of funds and strategies that primarily invests in private equity partnerships. This category also includes investments in real estate and private debt. All investments in this category are classified as NAV assets. (j) The Registrants have a securities lending program with a third-party agent. The program allows the agent to lend certain securities from the Registrants' VEBA trust to selected entities against receipt of collateral (in the form of cash) as provided for and determined in accordance with their securities lending agency agreements.

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2018
Share-based Compensation [Abstract]
Schedule of Components of Stock-Based Compensation	The following table summarizes the components of stock-based compensation for DTE Energy: 2018 2017 2016 (In millions) Stock-based compensation expense $ 64 $ 58 $ 61 Tax benefit $ 13 $ 23 $ 24 Stock-based compensation cost capitalized in Property, plant, and equipment $ 11 $ 9 $ 10
Schedule of Stock-based Compensation, Stock Options, Activity	The following table summarizes DTE Energy's stock option activity for the year ended December 31, 2018 : Number of Options Weighted Average Exercise Price Aggregate Intrinsic Options outstanding and exercisable at December 31, 2017 105,994 $ 42.95 Exercised (53,894 ) $ 42.62 Options outstanding and exercisable at December 31, 2018 52,100 $ 43.30 $ 4
Schedule of Stock-based Compensation, Shares Authorized Under Stock Option Plans, by Exercise Price Range	The number, weighted average exercise price, and weighted average remaining contractual life of DTE Energy options outstanding as of December 31, 2018 were as follows: Range of Exercise Prices Number of Options Weighted Average Weighted Average $ 27.00 — $ 38.00 2,100 $ 27.70 0.16 $ 42.01 — $ 45.00 50,000 $ 43.95 1.15 52,100 $ 43.30 1.11
Schedule of Stock-based Compensation, Stock Award Activity	Stock award activity for DTE Energy for the years ended December 31 was: 2018 2017 2016 Fair value of awards vested (in millions) $ 11 $ 10 $ 9 Restricted common shares awarded 109,393 136,825 145,240 Weighted average market price of shares awarded $ 105.80 $ 99.53 $ 87.28 Compensation cost charged against income (in millions) $ 11 $ 11 $ 11
Schedule of Stock-based Compensation, Restricted Stock Activity Rollforward	The following table summarizes DTE Energy’s restricted stock awards activity for the year ended December 31, 2018 : Restricted Weighted Average Balance at December 31, 2017 365,764 $ 90.26 Grants 109,393 $ 105.80 Forfeitures (21,939 ) $ 98.59 Vested and issued (125,813 ) $ 85.24 Balance at December 31, 2018 327,405 $ 96.79
Stock-based Compensation Expense	DTE Energy recorded compensation expense for performance share awards as follows: 2018 2017 2016 (In millions) Compensation expense $ 53 $ 47 $ 50 Cash settlements (a) $ 13 $ 15 $ 7 Stock settlements (a) $ 39 $ 66 $ 38 _______________________________________ (a) Sum of cash and stock settlements approximates the intrinsic value of the awards.
Schedule of Stock-based Compensation, Performance Shares Activity Rollforward	The following table summarizes DTE Energy’s performance share activity for the period ended December 31, 2018 : Performance Shares Weighted Average Balance at December 31, 2017 1,324,401 $ 90.31 Grants 437,508 $ 105.64 Forfeitures (56,435 ) $ 96.02 Payouts (418,788 ) $ 84.84 Balance at December 31, 2018 1,286,686 $ 97.17
Schedule of Unrecognized Compensation Cost, Non-Vested Awards	As of December 31, 2018 , DTE Energy's total unrecognized compensation cost related to non-vested stock incentive plan arrangements and the weighted average recognition period was as follows: Unrecognized Weighted Average (In millions) (In years) Stock awards $ 12 1.03 Performance shares 59 1.04 $ 71 1.04

Segment and Related Informati_2

Segment and Related Information (Tables)	12 Months Ended
	Dec. 31, 2018
Segment Reporting [Abstract]
Financial Data of Business Segments	Inter-segment billing for goods and services exchanged between segments is based upon tariffed or market-based prices of the provider and primarily consists of the sale of reduced emissions fuel, power sales, and natural gas sales in the following segments: Year Ended December 31, 2018 2017 2016 (In millions) Electric $ 52 $ 48 $ 43 Gas 12 8 9 Gas Storage and Pipelines 36 42 9 Power and Industrial Projects 642 569 602 Energy Trading 27 35 39 Corporate and Other 2 2 2 $ 771 $ 704 $ 704 Financial data of DTE Energy's business segments follows: Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2018 Operating Revenues — Utility operations $ 5,298 1,436 — — — — (64 ) $ 6,670 Operating Revenues — Non-utility operations $ — — 485 2,204 5,557 3 (707 ) $ 7,542 Depreciation and amortization $ 836 133 82 67 5 1 — $ 1,124 Interest expense $ 283 70 68 31 6 220 (119 ) $ 559 Interest income $ — (6 ) (9 ) (9 ) (3 ) (104 ) 119 $ (12 ) Equity in earnings of equity method investees $ — 2 123 3 — 4 — $ 132 Income Tax Expense (Benefit) $ 193 67 68 (195 ) 13 (48 ) — $ 98 Net Income (Loss) Attributable to DTE Energy Company $ 664 150 235 161 39 (129 ) — $ 1,120 Investment in equity method investees $ 7 12 1,585 134 — 33 — $ 1,771 Capital expenditures and acquisitions $ 1,979 460 176 91 5 2 — $ 2,713 Goodwill $ 1,208 743 299 26 17 — — $ 2,293 Total Assets $ 22,501 5,378 3,161 495 909 6,153 (2,309 ) $ 36,288 Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2017 Operating Revenues — Utility operations $ 5,102 1,388 — — — — (56 ) $ 6,434 Operating Revenues — Non-utility operations $ — — 453 2,089 4,277 2 (648 ) $ 6,173 Depreciation and amortization $ 753 123 76 72 5 1 — $ 1,030 Interest expense $ 274 65 77 29 5 192 (106 ) $ 536 Interest income $ — (7 ) (14 ) (7 ) (2 ) (88 ) 106 $ (12 ) Equity in earnings of equity method investees $ 1 2 90 9 — — — $ 102 Income Tax Expense (Benefit) $ 321 78 (30 ) (195 ) 49 (48 ) — $ 175 Net Income (Loss) Attributable to DTE Energy Company $ 606 146 275 138 72 (103 ) — $ 1,134 Investment in equity method investees $ 7 11 879 150 — 26 — $ 1,073 Capital expenditures and acquisitions $ 1,574 463 137 56 7 13 — $ 2,250 Goodwill $ 1,208 743 299 26 17 — — $ 2,293 Total Assets $ 21,163 5,072 2,594 593 725 5,324 (1,704 ) $ 33,767 _____________________________________ (a) Includes Income Tax Expense (Benefit) of $(5) million , $(115) million , $(21) million , $2 million , and $34 million for Electric — non-utility, Gas Storage and Pipelines, Power and Industrial Projects, Energy Trading, and Corporate and Other, respectively, related to the enactment of the TCJA. Electric Gas Gas Storage and Pipelines Power and Industrial Projects Energy Trading Corporate and Other Reclassifications Total (In millions) 2016 Operating Revenues — Utility operations $ 5,225 1,324 — — — — (52 ) $ 6,497 Operating Revenues — Non-utility operations $ — — 302 1,906 2,575 2 (652 ) $ 4,133 Depreciation and amortization $ 750 106 45 72 3 — — $ 976 Interest expense $ 264 60 39 32 6 148 (77 ) $ 472 Interest income $ (8 ) (6 ) (9 ) (8 ) (1 ) (65 ) 77 $ (20 ) Equity in earnings of equity method investees $ 2 6 60 — — — — $ 68 Income Tax Expense (Benefit) $ 353 77 71 (140 ) (29 ) (61 ) — $ 271 Net Income (Loss) Attributable to DTE Energy Company $ 622 138 119 95 (45 ) (61 ) — $ 868 Investment in equity method investees $ 11 10 538 166 — 27 — $ 752 Capital expenditures and acquisitions $ 1,503 395 1,322 39 7 3 — $ 3,269 Goodwill $ 1,208 743 292 26 17 — — $ 2,286 Total Assets $ 20,417 4,729 2,417 683 660 4,648 (1,513 ) $ 32,041

Related Party Transactions (Tab

Related Party Transactions (Tables)	12 Months Ended
	Dec. 31, 2018
Related Party Transactions [Abstract]
Transactions With Affiliated Companies	See the following notes for other related party transactions impacting DTE Electric’s Consolidated Financial Statements: Note Title 1 Organization and Basis of Presentation 20 Retirement Benefits and Trusteed Assets 21 Stock-Based Compensation The following is a summary of DTE Electric's transactions with affiliated companies: 2018 2017 2016 (In millions) Revenues Energy sales $ 9 $ 9 $ 10 Other services $ (4 ) $ (4 ) $ (1 ) Shared capital assets $ 43 $ 39 $ 33 Costs Fuel and purchased power $ 7 $ 6 $ 10 Other services and interest $ 33 $ (2 ) $ (1 ) Corporate expenses, net $ 377 $ 370 $ 370 Other Dividends declared $ 461 $ 432 $ 420 Dividends paid $ 461 $ 432 $ 420 Capital contribution from DTE Energy $ 325 $ 100 $ 120

Supplementary Quarterly Finan_2

Supplementary Quarterly Financial Information (Unaudited ) (Tables)	12 Months Ended
	Dec. 31, 2018
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	DTE Energy Quarterly earnings per share may not equal full year totals, since quarterly computations are based on weighted average common shares outstanding during each quarter. First Second Third Fourth Year (In millions, except per share amounts) 2018 Operating Revenues $ 3,753 $ 3,159 $ 3,550 $ 3,750 $ 14,212 Operating Income $ 504 $ 329 $ 429 $ 332 $ 1,594 Net Income Attributable to DTE Energy Company $ 361 $ 234 $ 334 $ 191 $ 1,120 Basic Earnings per Share $ 2.01 $ 1.29 $ 1.84 $ 1.05 $ 6.18 Diluted Earnings per Share $ 2.00 $ 1.29 $ 1.84 $ 1.05 $ 6.17 2017 Operating Revenues $ 3,236 $ 2,855 $ 3,245 $ 3,271 $ 12,607 Operating Income (a) $ 585 $ 320 $ 434 $ 372 $ 1,711 Net Income Attributable to DTE Energy Company (b) $ 400 $ 177 $ 270 $ 287 $ 1,134 Basic Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 Diluted Earnings per Share $ 2.23 $ 0.99 $ 1.51 $ 1.60 $ 6.32 _____________________________________ (a) Pursuant to the implementation of ASU 2017-07, amounts previously included in Operating Income — Operation and maintenance were reclassified to Other (Income) and Deductions — Non-operating retirement benefits, net on DTE Energy's Consolidated Statements of Operations. (b) Includes a net Income Tax Benefit of $(105) million related to the enactment of the TCJA in the fourth quarter. DTE Electric First Second Third Fourth Year (In millions) 2018 Operating Revenues $ 1,205 $ 1,276 $ 1,521 $ 1,296 $ 5,298 Operating Income $ 253 $ 269 $ 444 $ 168 $ 1,134 Net Income $ 140 $ 163 $ 305 $ 56 $ 664 2017 Operating Revenues $ 1,175 $ 1,218 $ 1,434 $ 1,275 $ 5,102 Operating Income $ 217 $ 272 $ 395 $ 281 $ 1,165 Net Income $ 106 $ 138 $ 219 $ 138 $ 601

Organization and Basis of Pre_3

Organization and Basis of Presentation (Details) customer in Millions	Dec. 31, 2018USD ($)customer	Dec. 31, 2017USD ($)	Oct. 01, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Number of electric utility customers | customer	2.2
Number of gas utility customers | customer	1.3
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Significant potential exposure	$ 0
Amount in excess of carrying amount	59,000,000	$ 72,000,000
DTE Electric
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Significant potential exposure	$ 0
NEXUS Pipeline
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Ownership interest	50.00%
SGG | Midstream Natural Gas Assets
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Percentage of voting interests acquired	55.00%		55.00%

Organization and Basis of Pre_4

Organization and Basis of Presentation (Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 71	$ 66
Restricted cash	5	23
Accounts receivable	1,789	1,758
Property, plant, and equipment, net	21,650	20,721
Goodwill	2,293	2,293	$ 2,286
Intangible assets	828	842
Total Assets	36,288	33,767	$ 32,041
LIABILITIES
Current portion long-term debt, including capital leases	1,499	109
Mortgage bonds, notes, and other	10,982	11,039
Variable interest entity, primary beneficiary, restricted
ASSETS
Cash and cash equivalents	39	37
Restricted cash	5	8
Accounts receivable	46	53
Inventories	93	117
Property, plant, and equipment, net	441	475
Goodwill	25	25
Intangible assets	557	572
Other current and long-term assets	3	4
Total Assets	1,209	1,291
LIABILITIES
Accounts payable and accrued current liabilities	34	73
Current portion long-term debt, including capital leases	0	4
Mortgage bonds, notes, and other	0	1
Other current and long-term liabilities	19	17
Total liabilities	53	95
SGG
ASSETS
Cash and cash equivalents	25	23
Restricted cash	0	0
Accounts receivable	9	11
Inventories	1	3
Property, plant, and equipment, net	395	400
Goodwill	25	25
Intangible assets	557	572
Other current and long-term assets	3	4
Total Assets	1,015	1,038
LIABILITIES
Accounts payable and accrued current liabilities	3	26
Current portion long-term debt, including capital leases	0	0
Mortgage bonds, notes, and other	0	0
Other current and long-term liabilities	9	1
Total liabilities	$ 12	27
VIE percentage	100.00%
VIE ownership percentage	55.00%
Other
ASSETS
Cash and cash equivalents	$ 14	14
Restricted cash	5	8
Accounts receivable	37	42
Inventories	92	114
Property, plant, and equipment, net	46	75
Goodwill	0	0
Intangible assets	0	0
Other current and long-term assets	0	0
Total Assets	194	253
LIABILITIES
Accounts payable and accrued current liabilities	31	47
Current portion long-term debt, including capital leases	0	4
Mortgage bonds, notes, and other	0	1
Other current and long-term liabilities	10	16
Total liabilities	$ 41	$ 68

Organization and Basis of Pre_5

Organization and Basis of Presentation (Non-Consolidated Variable Interest Entities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Variable Interest Entity [Line Items]
Investments in equity method investees	$ 1,771	$ 1,073	$ 752
Notes receivable	64	73
Variable interest entity, nonconsolidated
Variable Interest Entity [Line Items]
Investments in equity method investees	1,425	811
Notes receivable	15	17
Future funding commitments	$ 55	$ 598

Organization and Basis of Pre_6

Organization and Basis of Presentation (Equity Method Investees) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Equity Method Investments [Line Items]
Investments	$ 1,771	$ 1,073	$ 752
NEXUS Pipeline
Schedule of Equity Method Investments [Line Items]
Percent Owned	50.00%
Gas Storage and Pipelines
Schedule of Equity Method Investments [Line Items]
Investments	$ 1,585	879
Gas Storage and Pipelines | NEXUS Pipeline
Schedule of Equity Method Investments [Line Items]
Investments	$ 1,260	$ 640
Percent Owned	50.00%	50.00%
Gas Storage and Pipelines | Vector Pipeline
Schedule of Equity Method Investments [Line Items]
Investments	$ 123	$ 115
Percent Owned	40.00%	40.00%
Gas Storage and Pipelines | Millennium Pipeline
Schedule of Equity Method Investments [Line Items]
Investments	$ 202	$ 124
Percent Owned	26.00%	26.00%
Other Segments
Schedule of Equity Method Investments [Line Items]
Investments	$ 186	$ 194

Organization and Basis of Pre_7

Organization and Basis of Presentation (Summarized Balance Sheet Data) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Current Assets	$ 358	$ 344
Non-current assets	5,101	3,576
Current Liabilities	391	345
Non-current liabilities	$ 762	$ 858

Organization and Basis of Pre_8

Organization and Basis of Presentation (Summarized Income Statement Data) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Operating Revenues	$ 883	$ 756	$ 767
Operating Expenses	622	561	526
Net Income	$ 365	$ 254	$ 225

Significant Accounting Polici_4

Significant Accounting Policies (Schedule of Other Income) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Schedule of Other Nonoperating Income, by Component [Line Items]
Equity in earnings of equity method investees	$ 132	$ 102	$ 68
Income from REF entities	98	77	75
Contract services	51	19	21
Allowance for equity funds used during construction	28	23	21
Gains from trading securities	6	26	15
Other	18	21	7
Other income	333	268	207
DTE Electric
Schedule of Other Nonoperating Income, by Component [Line Items]
Contract services	51	21	20
Allowance for equity funds used during construction	19	18	18
Gains from trading securities	6	26	15
Other	7	12	8
Other income	$ 83	$ 77	$ 61

Significant Accounting Polici_5

Significant Accounting Policies (Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ 9,990	$ 9,499	$ 8,795
Net current-period Other comprehensive income (loss)	5	13	12
Ending balance	10,717	9,990	9,499
AOCI including portion attributable to noncontrolling interest
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(120)	(133)
Implementation of ASU 2016-01				$ (5)
Other comprehensive income (loss) before reclassifications	(5)	(1)
Amounts reclassified from Accumulated other comprehensive income	10	14
Net current-period Other comprehensive income (loss)	0	13
Ending balance	(120)	(120)	(133)
Net Unrealized Gain (Loss) on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(3)	(4)
Implementation of ASU 2016-01				(7)
Other comprehensive income (loss) before reclassifications	(2)	0
Amounts reclassified from Accumulated other comprehensive income	1	1
Net current-period Other comprehensive income (loss)	(8)	1
Ending balance	(11)	(3)	(4)
Net Unrealized Gain (Loss) on Investments
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(2)	(3)
Implementation of ASU 2016-01				2
Other comprehensive income (loss) before reclassifications	0	1
Amounts reclassified from Accumulated other comprehensive income	0	0
Net current-period Other comprehensive income (loss)	2	1
Ending balance	0	(2)	(3)
Benefit Obligations
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(110)	(120)
Implementation of ASU 2016-01				0
Other comprehensive income (loss) before reclassifications	(1)	(3)
Amounts reclassified from Accumulated other comprehensive income	9	13
Net current-period Other comprehensive income (loss)	8	10
Ending balance	(102)	(110)	(120)
Foreign Currency Translation
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(5)	(6)
Implementation of ASU 2016-01				$ 0
Other comprehensive income (loss) before reclassifications	(2)	1
Amounts reclassified from Accumulated other comprehensive income	0	0
Net current-period Other comprehensive income (loss)	(2)	1
Ending balance	(7)	(5)	(6)
DTE Electric
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Net current-period Other comprehensive income (loss)	$ 0	$ 1	$ 0

Significant Accounting Polici_6

Significant Accounting Policies (Cash and Restricted Cash) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accounting Policies [Abstract]
Cash and cash equivalents	$ 71	$ 66
Restricted cash	5	23
Total cash, cash equivalents, and restricted cash shown in the Consolidated Statements of Cash Flows	$ 76	$ 89	$ 113	$ 60

Significant Accounting Polici_7

Significant Accounting Policies (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Significant Accounting Policies [Line Items]
Specific review of probable future collections based on receivable balances in excess of 90 days	30 days
Unbilled revenues	$ 1,789,000,000	$ 1,758,000,000
Regulatory liabilities	$ 3,048,000,000	2,893,000,000
Property maintenance accrual period	18 months
Amortization of intangible assets	$ 27,000,000	29,000,000	$ 16,000,000
Excise and sales taxes net impact on statement of operations	0
Charitable contributions	22,000,000	43,000,000	$ 26,000,000
Fermi 2 refueling outage
Significant Accounting Policies [Line Items]
Regulatory liabilities	4,000,000	15,000,000
Natural gas inventory
Significant Accounting Policies [Line Items]
LIFO inventory amount	48,000,000	29,000,000
Excess of replacement costs over stated LIFO value	$ 113,000,000	81,000,000
Minimum
Significant Accounting Policies [Line Items]
Notes receivable considered delinquent period	60 days
Maximum
Significant Accounting Policies [Line Items]
Notes receivable considered delinquent period	120 days
DTE Electric and DTE Gas
Significant Accounting Policies [Line Items]
Receivables due date	21 days
Threshold period past due for write-off of trade accounts receivable	150 days
DTE Electric
Significant Accounting Policies [Line Items]
Unbilled revenues	$ 750,000,000	791,000,000
Regulatory liabilities	2,269,000,000	2,154,000,000
DTE Electric | Fermi 2 refueling outage
Significant Accounting Policies [Line Items]
Regulatory liabilities	4,000,000	15,000,000
Unbilled revenues
Significant Accounting Policies [Line Items]
Unbilled revenues	1,000,000,000	1,000,000,000
Unbilled revenues | DTE Electric
Significant Accounting Policies [Line Items]
Unbilled revenues	$ 264,000,000	$ 290,000,000

Significant Accounting Polici_8

Significant Accounting Policies (Intangible Assets) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value	$ 938	$ 938
Accumulated Amortization	(110)	(96)
Finite-lived intangible assets, net carrying value	828	842
Intangible assets, gross carrying value	959	963
Intangible assets, net carrying value	849	867
DTE Electric
Finite-Lived Intangible Assets [Line Items]
Accumulated Amortization	0	0
Intangible assets, gross carrying value	21	25
Intangible assets, net carrying value	21	25
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	21	25
DTE Electric renewable energy credits | DTE Electric
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	20	24
DTE Electric emission allowances | DTE Electric
Indefinite-lived Intangible Assets [Line Items]
Indefinite-lived intangible assets	1	1
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value	779	770
Accumulated Amortization	(44)	(24)
Finite-lived intangible assets, net carrying value	$ 735	746
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	25 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	40 years
Contract intangibles
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross carrying value	$ 159	168
Accumulated Amortization	(66)	(72)
Finite-lived intangible assets, net carrying value	$ 93	$ 96
Contract intangibles | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	6 years
Contract intangibles | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Lives	26 years

Significant Accounting Polici_9

Significant Accounting Policies (Future Amortization Expense Intangible Assets) (Details) $ in Millions	Dec. 31, 2018USD ($)
Estimated amortization expense
2,019	$ 27
2,020	26
2,021	25
2,022	25
2,023	$ 25

New Accounting Pronouncements

New Accounting Pronouncements (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Jan. 01, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
True-up adjustment to the remeasurement of deferred taxes	$ 21
Regulatory Liabilities
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
True-up adjustment to the remeasurement of deferred taxes	17
DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
True-up adjustment to the remeasurement of deferred taxes	$ 7
Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-09		$ 0
Accounting Standards Update 2016-01 | DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-09		0
Accumulated Other Comprehensive Income (Loss) | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-09		(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 2016-09		(3)
Retained Earnings | Accounting Standards Update 2016-01
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-09		5
Retained Earnings | Accounting Standards Update 2016-01 | DTE Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Implementation of ASU 2016-09		$ 3

Revenue - Disaggregation of Rev

Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disaggregation of Revenue [Line Items]
Revenues	$ 3,750	$ 3,550	$ 3,159	$ 3,753	$ 3,271	$ 3,245	$ 2,855	$ 3,236	$ 14,212	$ 12,607	$ 10,630
Electric
Disaggregation of Revenue [Line Items]
Revenues									5,298
Electric | Other
Disaggregation of Revenue [Line Items]
Revenues									20
Electric | Alternative Revenue Programs
Disaggregation of Revenue [Line Items]
Revenues									21
Electric | Residential
Disaggregation of Revenue [Line Items]
Revenues									2,494
Electric | Commercial
Disaggregation of Revenue [Line Items]
Revenues									1,794
Electric | Industrial
Disaggregation of Revenue [Line Items]
Revenues									690
Electric | Other
Disaggregation of Revenue [Line Items]
Revenues									320
Gas
Disaggregation of Revenue [Line Items]
Revenues									1,436
Gas | Other
Disaggregation of Revenue [Line Items]
Revenues									7
Gas | Alternative Revenue Programs
Disaggregation of Revenue [Line Items]
Revenues									2
Gas | Other
Disaggregation of Revenue [Line Items]
Revenues									91
Gas | Gas sales
Disaggregation of Revenue [Line Items]
Revenues									1,055
Gas | End User Transportation
Disaggregation of Revenue [Line Items]
Revenues									232
Gas | Intermediate Transportation
Disaggregation of Revenue [Line Items]
Revenues									58
Gas Storage and Pipelines
Disaggregation of Revenue [Line Items]
Revenues									485
Power and Industrial Projects
Disaggregation of Revenue [Line Items]
Revenues									2,204
Lease revenue outside scope of Topic 606									125
Energy Trading
Disaggregation of Revenue [Line Items]
Revenues									5,557
Gain (loss) on derivative outside scope of Topic 606									$ 4,500

Revenue - Narrative (Details)

Revenue - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Revenue from External Customer [Line Items]
Charges related to expense recognized for estimated uncollectible accounts receivable	$ 140
DTE Electric
Revenue from External Customer [Line Items]
Charges related to expense recognized for estimated uncollectible accounts receivable	$ 85
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	12 Months Ended
	Dec. 31, 2018USD ($)
Contract Liability [Roll Forward]
Beginning Balance	$ 56
Increases due to cash received or receivable, excluding amounts recognized as revenue during the period	48
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(30)
Ending Balance	$ 74

Revenue - Expected Recognition

Revenue - Expected Recognition of Deferred Revenue (Details) $ in Millions	Dec. 31, 2018USD ($)
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	$ 46
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	$ 7
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	$ 5
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
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	$ 74

Revenue - Expected Timing of Pe

Revenue - Expected Timing of Performance Obligation Satisfaction (Details) $ in Millions	Dec. 31, 2018USD ($)
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	$ 46
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 | Fixed Consideration
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 267
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-01-01 | Fixed Consideration | 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
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]: 2020-01-01 | Fixed Consideration
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 263
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01 | Fixed Consideration | 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
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]: 2021-01-01 | Fixed Consideration
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 219
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01 | Fixed Consideration | 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
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	$ 7
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Fixed Consideration
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 172
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01 | Fixed Consideration | 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
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	$ 5
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Fixed Consideration
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 139
Remaining performance obligation, expected timing of satisfaction	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01 | Fixed Consideration | 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
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01
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]: 2024-01-01 | Fixed Consideration
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 658
Remaining performance obligation, expected timing of satisfaction
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2024-01-01 | Fixed Consideration | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 0
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	$ 74
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Fixed Consideration
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	1,718
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: (nil) | Fixed Consideration | DTE Electric
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Remaining performance obligation	$ 8

Goodwill (Details)

Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Balance as of January 1	$ 2,293	$ 2,286
Goodwill attributable to Gas Storage and Pipelines 2016 acquisition of AGS and SGG	0	7
Balance at December 31	$ 2,293	$ 2,293

Property, Plant, and Equipmen_2

Property, Plant, and Equipment (Summary of Property by Classification) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	$ 31,810	$ 31,424
Accumulated depreciation and amortization	(10,160)	(10,703)
Net property, plant, and equipment	21,650	20,721
Non-utility and other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	3,488	3,278
Accumulated depreciation and amortization	(998)	(938)
DTE Electric
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	22,747	22,972
Accumulated depreciation and amortization	(7,310)	(7,984)
Net property, plant, and equipment	15,437	14,988
DTE Electric | Generation
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	11,027	12,166
Accumulated depreciation and amortization	(3,609)	(4,403)
DTE Electric | Distribution
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	9,153	8,637
Accumulated depreciation and amortization	(2,974)	(2,914)
DTE Electric | Other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	2,567	2,169
Accumulated depreciation and amortization	(727)	(667)
DTE Gas
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	5,575	5,174
Accumulated depreciation and amortization	(1,852)	(1,781)
DTE Gas | Distribution
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	3,823	3,523
Accumulated depreciation and amortization	(1,283)	(1,238)
DTE Gas | Storage
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	548	533
Accumulated depreciation and amortization	(165)	(159)
DTE Gas | Transmission and other
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	1,204	1,118
Accumulated depreciation and amortization	$ (404)	$ (384)

Property, Plant, and Equipmen_3

Property, Plant, and Equipment (Schedule of Interest Costs Capitalized) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property, Plant, and Equipment [Line Items]
Allowance for debt funds used during construction and interest capitalized	$ 15	$ 13
Allowance for equity funds used during construction	28	23
Total	43	36
DTE Electric
Property, Plant, and Equipment [Line Items]
Allowance for debt funds used during construction and interest capitalized	9	8
Allowance for equity funds used during construction	19	18
Total	$ 28	$ 26

Property, Plant, and Equipmen_4

Property, Plant, and Equipment (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Minimum | Non-utility
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	3 years
Minimum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	1 year
Maximum | Non-utility
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	83 years
Maximum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	15 years
DTE Electric | Minimum | Other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	3 years
DTE Electric | Minimum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	3 years
DTE Electric | Maximum | Other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	62 years
DTE Electric | Maximum | Capitalized software
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	15 years
DTE Gas | Minimum | Transmission and other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	5 years
DTE Gas | Maximum | Transmission and other
Public Utility Property, Plant, and Equipment [Line Items]
Property plant and equipment, useful life	70 years
DTE Electric
Public Utility Property, Plant, and Equipment [Line Items]
Composite depreciation rate for plants in service	3.70%	3.60%	3.50%
DTE Gas
Public Utility Property, Plant, and Equipment [Line Items]
Composite depreciation rate for plants in service	2.70%	2.70%	2.40%

Property, Plant, and Equipmen_5

Property, Plant, and Equipment (Average Estimated Useful Life of Each Major Class) (Details)	12 Months Ended
	Dec. 31, 2018
DTE Electric
Public Utility Property, Plant, and Equipment [Line Items]
Useful Life - Generation	40 years
Useful Life - Distribution	41 years
DTE Gas
Public Utility Property, Plant, and Equipment [Line Items]
Useful Life - Distribution	50 years
Useful Life - Storage	53 years

Property, Plant, and Equipmen_6

Property, Plant, and Equipment (Depreciation and Amortization) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	$ 912	$ 865	$ 783
Regulatory assets and liabilities	212	165	193
Depreciation and amortization	1,124	1,030	976
DTE Electric
Property, Plant, and Equipment [Line Items]
Property, plant, and equipment	657	620	582
Regulatory assets and liabilities	179	133	168
Depreciation and amortization	$ 836	$ 753	$ 750

Property, Plant, and Equipmen_7

Property, Plant, and Equipment (Capitalized Software) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant, and Equipment [Line Items]
Amortization expense of capitalized software	$ 108	$ 101	$ 89
Gross carrying value of capitalized software	905	890
Accumulated amortization of capitalized software	534	500
DTE Electric
Property, Plant, and Equipment [Line Items]
Amortization expense of capitalized software	101	93	$ 83
Gross carrying value of capitalized software	799	774
Accumulated amortization of capitalized software	$ 463	$ 423

Property, Plant, and Equipmen_8

Property, Plant, and Equipment (Operating Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Gross property under operating leases	$ 447	$ 327
Accumulated amortization of property under operating leases	$ 148	$ 108

Property, Plant, and Equipmen_9

Property, Plant, and Equipment (Capital Leases) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Capital Leased Assets [Line Items]
Gross property under capital leases	$ 18	$ 44
Accumulated amortization of property under capital leases	7	38
DTE Electric
Capital Leased Assets [Line Items]
Gross property under capital leases	18	18
Accumulated amortization of property under capital leases	$ 7	$ 12

Jointly-Owned Utility Plant (De

Jointly-Owned Utility Plant (Details)	Dec. 31, 2018plant
Belle River Unit 1
Jointly-Owned Utility Plant Interests [Line Items]
Percent of the total capacity and energy of the plant	19.00%
Ludington Hydroelectric Pumped Storage
Jointly-Owned Utility Plant Interests [Line Items]
Percent of the total capacity and energy of the plant	51.00%
DTE Electric
Jointly-Owned Utility Plant Interests [Line Items]
Number of power plants owned	2

Jointly-Owned Utility Plant (Ow

Jointly-Owned Utility Plant (Ownership Information) (Details) - DTE Electric $ in Millions	Dec. 31, 2018USD ($)
Belle River
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	81.00%
Investment in Property, plant, and equipment (in millions)	$ 1,819
Accumulated depreciation (in millions)	$ 1,068
Ludington Hydroelectric Pumped Storage
Jointly-Owned Utility Plant Interests [Line Items]
Ownership interest	49.00%
Investment in Property, plant, and equipment (in millions)	$ 586
Accumulated depreciation (in millions)	$ 187

Asset Retirement Obligations (R

Asset Retirement Obligations (Rollforward) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at December 31, 2017	$ 2,320
Accretion	140
Liabilities incurred	27
Liabilities settled	(16)
Revision in estimated cash flows	(2)
Asset retirement obligations at December 31, 2018	2,469
DTE Electric
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligations at December 31, 2017	2,125
Accretion	129
Liabilities incurred	27
Liabilities settled	(8)
Revision in estimated cash flows	(2)
Asset retirement obligations at December 31, 2018	$ 2,271

Asset Retirement Obligations (D

Asset Retirement Obligations (Details) - Fermi 2	Dec. 31, 2018USD ($)
Asset Retirement Obligations [Line Items]
Nuclear decommissioning liabilities funded through surcharge and included in ARO balance	$ 2,000,000,000
Liabilities balance upon completion of decommissioning	$ 0

Regulatory Matters (Schedule of

Regulatory Matters (Schedule of Regulatory Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Regulatory Assets [Line Items]
Regulatory assets	$ 4,721	$ 3,778
Less amount included in Current Assets	(153)	(55)
Regulatory assets, noncurrent	4,568	3,723
Pension
Regulatory Assets [Line Items]
Regulatory assets	1,961	2,000
Other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets	213	278
Asset retirement obligation
Regulatory Assets [Line Items]
Regulatory assets	778	569
Recoverable undepreciated costs on retiring plants
Regulatory Assets [Line Items]
Regulatory assets	630	0
Removal costs asset
Regulatory Assets [Line Items]
Regulatory assets	407	299
Recoverable Michigan income taxes
Regulatory Assets [Line Items]
Regulatory assets	201	213
Accrued PSCR/GCR revenue
Regulatory Assets [Line Items]
Regulatory assets	116	17
Deferred environmental costs
Regulatory Assets [Line Items]
Regulatory assets	69	75
Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	60	65
Recoverable income taxes related to AFUDC equity
Regulatory Assets [Line Items]
Regulatory assets	51	41
Energy Waste Reduction incentive
Regulatory Assets [Line Items]
Regulatory assets	49	39
Nuclear Performance Evaluation and Review Committee Tracker
Regulatory Assets [Line Items]
Regulatory assets	43	22
Customer360 deferred costs
Regulatory Assets [Line Items]
Regulatory assets	42	45
Other recoverable income taxes
Regulatory Assets [Line Items]
Regulatory assets	23	26
Transitional Reconciliation Mechanism
Regulatory Assets [Line Items]
Regulatory assets	21	46
Other
Regulatory Assets [Line Items]
Regulatory assets	57	43
DTE Electric
Regulatory Assets [Line Items]
Regulatory assets	3,977	3,055
Less amount included in Current Assets	(148)	(50)
Regulatory assets, noncurrent	3,829	3,005
DTE Electric | Pension
Regulatory Assets [Line Items]
Regulatory assets	1,476	1,502
DTE Electric | Other postretirement costs
Regulatory Assets [Line Items]
Regulatory assets	121	211
DTE Electric | Asset retirement obligation
Regulatory Assets [Line Items]
Regulatory assets	778	569
DTE Electric | Recoverable undepreciated costs on retiring plants
Regulatory Assets [Line Items]
Regulatory assets	630	0
DTE Electric | Removal costs asset
Regulatory Assets [Line Items]
Regulatory assets	407	299
DTE Electric | Recoverable Michigan income taxes
Regulatory Assets [Line Items]
Regulatory assets	161	171
DTE Electric | Accrued PSCR/GCR revenue
Regulatory Assets [Line Items]
Regulatory assets	116	17
DTE Electric | Deferred environmental costs
Regulatory Assets [Line Items]
Regulatory assets	0	0
DTE Electric | Unamortized loss on reacquired debt
Regulatory Assets [Line Items]
Regulatory assets	43	46
DTE Electric | Recoverable income taxes related to AFUDC equity
Regulatory Assets [Line Items]
Regulatory assets	41	35
DTE Electric | Energy Waste Reduction incentive
Regulatory Assets [Line Items]
Regulatory assets	39	30
DTE Electric | Nuclear Performance Evaluation and Review Committee Tracker
Regulatory Assets [Line Items]
Regulatory assets	43	22
DTE Electric | Customer360 deferred costs
Regulatory Assets [Line Items]
Regulatory assets	42	45
DTE Electric | Other recoverable income taxes
Regulatory Assets [Line Items]
Regulatory assets	23	26
DTE Electric | Transitional Reconciliation Mechanism
Regulatory Assets [Line Items]
Regulatory assets	21	46
DTE Electric | Other
Regulatory Assets [Line Items]
Regulatory assets	$ 36	$ 36

Regulatory Matters (Schedule _2

Regulatory Matters (Schedule of Regulatory Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 3,048	$ 2,893
Less amount included in Current Liabilities	(126)	(18)
Regulatory liabilities, noncurrent	2,922	2,875
Refundable federal income taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	2,410	2,384
Removal costs liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	253	265
TCJA rate reduction liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	118	0
Negative other postretirement offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	101	80
Renewable energy
Regulatory Liabilities [Line Items]
Regulatory liabilities	86	112
Refundable self-implemented rates
Regulatory Liabilities [Line Items]
Regulatory liabilities	26	2
Negative pension offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	9	21
Fermi 2 refueling outage
Regulatory Liabilities [Line Items]
Regulatory liabilities	4	15
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	41	14
DTE Electric
Regulatory Liabilities [Line Items]
Regulatory liabilities	2,269	2,154
Less amount included in Current Liabilities	(98)	(17)
Regulatory liabilities, noncurrent	2,171	2,137
DTE Electric | Refundable federal income taxes
Regulatory Liabilities [Line Items]
Regulatory liabilities	1,958	1,946
DTE Electric | Removal costs liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	0
DTE Electric | TCJA rate reduction liability
Regulatory Liabilities [Line Items]
Regulatory liabilities	93	0
DTE Electric | Negative other postretirement offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	79	67
DTE Electric | Renewable energy
Regulatory Liabilities [Line Items]
Regulatory liabilities	86	112
DTE Electric | Refundable self-implemented rates
Regulatory Liabilities [Line Items]
Regulatory liabilities	26	2
DTE Electric | Negative pension offset
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	0
DTE Electric | Fermi 2 refueling outage
Regulatory Liabilities [Line Items]
Regulatory liabilities	4	15
DTE Electric | Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 23	$ 12

Regulatory Matters (Details)

Regulatory Matters (Details) $ in Millions

Dec. 20, 2018USD ($)

Dec. 06, 2018

Dec. 05, 2018

Nov. 16, 2018USD ($)

Sep. 21, 2018USD ($)

Sep. 13, 2018USD ($)

Jul. 30, 2018USD ($)

Jul. 24, 2018USD ($)

Jul. 06, 2018USD ($)

Jun. 28, 2018USD ($)

May 30, 2018USD ($)

May 24, 2018USD ($)

May 18, 2018USD ($)

Apr. 18, 2018USD ($)

Mar. 28, 2018USD ($)

Nov. 22, 2017USD ($)

Nov. 01, 2017USD ($)

Apr. 19, 2017USD ($)

Dec. 31, 2018

Aug. 31, 2018USD ($)

Apr. 27, 2018USD ($)certificate

Jul. 31, 2017USD ($)certificateMW

Regulatory Assets [Line Items]

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

10 years

DTE Electric

Regulatory Assets [Line Items]

Reduction of revenue due to Tax Cuts and Jobs Act, requested

$ 157

Reduction of revenue due to Tax Cuts and Jobs Act, approved

$ 157

Refund due to Tax Cuts and Jobs Act, requested

$ 93

Refund due to Tax Cuts and Jobs Act, approved

$ 93

DTE Electric | MPSC | Electric Rate Case Filing 2017

Regulatory Assets [Line Items]

Requested rate increase

$ 125

$ 231

Approved rate increase

$ 74.4

$ 65.2

Return on equity, percent

10.00%

DTE Electric | MPSC | Electric Rate Case Filing 2017 | Refundable Self-Implemented Rates

Regulatory Assets [Line Items]

Amount filed to refund to customers

$ 26.2

DTE Electric | MPSC | Electric Rate Case Filing 2018

Regulatory Assets [Line Items]

Requested rate increase

$ 328

Return on equity, percent

10.00%

Return on equity, requested percent

10.50%

DTE Electric | MPSC | Certificate of Necessity Request

Regulatory Assets [Line Items]

Amount of power associated with natural gas fueled combined cycle generation facility | MW

1,100

Number of certificates of necessity requested to be issued | certificate

3

Estimated capital costs

$ 989

Number of certificates of necessity approved for issuance | certificate

3

Approved recoverable amounts, maximum rate

$ 951.8

DTE Electric | MPSC | 2016 DTE Main Electric Depreciation Case Filing

Regulatory Assets [Line Items]

Approved depreciation rate increase

3.72%

3.06%

DTE Gas

Regulatory Assets [Line Items]

Reduction of revenue due to Tax Cuts and Jobs Act, requested

$ 38.2

Reduction of revenue due to Tax Cuts and Jobs Act, approved

$ 38.2

Refund due to Tax Cuts and Jobs Act, requested

$ 25

Calculation C, reduction of revenue due to Tax Cuts and Jobs Act, requested

$ 12

DTE Gas | MPSC | DTE Gas Rate Case Filing 2017

Regulatory Assets [Line Items]

Requested rate increase

$ 38.1

$ 85.1

Approved rate increase

$ 9

Return on equity, percent

10.00%

10.10%

Return on equity, requested percent

10.50%

Nuclear Performance Evaluation and Review Committee Tracker

Regulatory Assets [Line Items]

Approved amortization period

5 years

Customer360 deferred costs

Regulatory Assets [Line Items]

Approved amortization period

15 years

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Entity Information [Line Items]
Deferred tax asset, general business tax credit carryforwards	$ 871
Deferred tax asset, alternative minimum tax credit carryforwards	$ 307
Tax credit carry forwards refundable period	4 years
State and local net operating loss carry-forwards	$ 59	$ 70
Valuation allowance	33	40
Adjustment to deferred tax liabilities related to Tax Cuts and Jobs Act of 2017	2,560
Unrecognized tax benefits that would impact effective tax rate	8	8
Interest on income taxes accrued	4	3
Interest on income taxes expense	1	0	$ 2
Unregulated Operation
Entity Information [Line Items]
Adjustment to deferred tax liabilities related to Tax Cuts and Jobs Act of 2017	105
Refundable federal income taxes
Entity Information [Line Items]
Adjustment to deferred tax liabilities related to Tax Cuts and Jobs Act of 2017	2,450
Federal
Entity Information [Line Items]
Operating loss carryforward	555
DTE Electric
Entity Information [Line Items]
Income tax receivable from related party	8	12
State and local net operating loss carry-forwards	1	5
Valuation allowance	0	0
Unrecognized tax benefits that would impact effective tax rate	10	10
Interest on income taxes accrued	5	4
Interest on income taxes expense	1	$ 0	$ 3
DTE Electric | General Business Credits
Entity Information [Line Items]
Tax credit carry-forward	250
DTE Electric | Federal
Entity Information [Line Items]
Operating loss carryforward	$ 11

Income Taxes (Reconciliation of

Income Taxes (Reconciliation of Income Tax Expense to the Statutory Federal Income Tax Rate) (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Entity Information [Line Items]
Statutory rate		21.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Before Income Taxes		$ 1,216	$ 1,287	$ 1,105
Income tax expense at statutory rate - 21% in 2018 - 35% in 2017 and 2016		255	450	387
Production tax credits		(223)	(189)	(145)
Investment tax credits		(4)	(4)	(5)
Depreciation		2	(4)	(4)
Noncontrolling interests		2	8	12
AFUDC equity		(14)	(18)	(10)
Employee Stock Ownership Plan dividends		(3)	(5)	(5)
Stock based compensation		(3)	(14)	0
Subsidiary stock loss		0	0	(10)
State and local income taxes, net of federal benefit		60	51	58
Enactment of the Tax Cuts and Jobs Act	$ (105)	21	(105)	0
Other, net		5	5	(7)
Income Tax Expense		$ 98	$ 175	$ 271
Effective income tax rate		8.10%	13.60%	24.50%
DTE Electric
Entity Information [Line Items]
Statutory rate		21.00%	35.00%	35.00%
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Income Before Income Taxes		$ 857	$ 928	$ 975
Income tax expense at statutory rate - 21% in 2018 - 35% in 2017 and 2016		180	325	341
Production tax credits		(35)	(36)	(30)
Investment tax credits		(3)	(4)	(4)
Depreciation		2	3	3
AFUDC equity		(3)	(5)	(6)
Employee Stock Ownership Plan dividends		(2)	(3)	(3)
State and local income taxes, net of federal benefit		49	48	56
Enactment of the Tax Cuts and Jobs Act		7	0	0
Other, net		(2)	(1)	(4)
Income Tax Expense		$ 193	$ 327	$ 353
Effective income tax rate		22.50%	35.20%	36.20%

Income Taxes (Components of Inc

Income Taxes (Components of Income Tax Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income tax expense (benefit)
Federal	$ (17)	$ (22)	$ (1)
State and other income tax	1	1	7
Total current income taxes	(16)	(21)	6
Deferred income tax expense
Federal	38	118	184
State and other income tax	76	78	81
Total deferred income taxes	114	196	265
Total	98	175	271
DTE Electric
Current income tax expense (benefit)
Federal	0	(17)	0
State and other income tax	4	(1)	11
Total current income taxes	4	(18)	11
Deferred income tax expense
Federal	131	270	268
State and other income tax	58	75	74
Total deferred income taxes	189	345	342
Total	$ 193	$ 327	$ 353

Income Taxes (Deferred Tax Asse

Income Taxes (Deferred Tax Assets (Liabilities)) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Components of Deferred Tax Assets and Liabilities [Abstract]
Property, plant, and equipment	$ (3,462)	$ (3,276)
Regulatory assets and liabilities	(54)	(94)
Tax credit carry-forwards	1,178	947
Pension and benefits	311	334
Federal net operating loss carry-forward	117	83
State and local net operating loss carry-forwards	59	70
Investments in equity method investees	(216)	(82)
Other	125	170
Deferred tax liabilities, gross	(1,942)	(1,848)
Less valuation allowance	(33)	(40)
Deferred income tax liabilities	(1,975)	(1,888)
Deferred income tax assets	2,021	1,814
Deferred income tax liabilities	(3,996)	(3,702)
DTE Electric
Components of Deferred Tax Assets and Liabilities [Abstract]
Property, plant, and equipment	(2,840)	(2,698)
Regulatory assets and liabilities	(3)	(31)
Tax credit carry-forwards	250	193
Pension and benefits	258	302
Federal net operating loss carry-forward	2	47
State and local net operating loss carry-forwards	1	5
Investments in equity method investees	(1)	0
Other	87	94
Deferred tax liabilities, gross	(2,246)	(2,088)
Less valuation allowance	0	0
Deferred income tax liabilities	(2,246)	(2,088)
Deferred income tax assets	855	830
Deferred income tax liabilities	$ (3,101)	$ (2,918)

Income Taxes (Reconciliation _2

Income Taxes (Reconciliation of Unrecognized Tax Benefits) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	$ 10	$ 10	$ 3
Additions for tax positions of prior years	0	0	7
Unrecognized tax benefits, ending balance	10	10	10
DTE Electric
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits, beginning balance	13	13	4
Additions for tax positions of prior years	0	0	9
Unrecognized tax benefits, ending balance	$ 13	$ 13	$ 13

Earnings Per Share (Details)

Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Basic Earnings per Share
Net Income Attributable to DTE Energy Company	$ 191	$ 334	$ 234	$ 361	$ 287	$ 270	$ 177	$ 400	$ 1,120	$ 1,134	$ 868
Less: Allocation of earnings to net restricted stock awards									(2)	(2)	(2)
Net income available to common shareholders — basic									$ 1,118	$ 1,132	$ 866
Average number of common shares outstanding — basic (in shares)									181	179	179
Basic Earnings per Common Share (in dollars per share)	$ 1.05	$ 1.84	$ 1.29	$ 2.01	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 6.18	$ 6.32	$ 4.84
Diluted Earnings per Share
Net Income Attributable to DTE Energy Company	$ 191	$ 334	$ 234	$ 361	$ 287	$ 270	$ 177	$ 400	$ 1,120	$ 1,134	$ 868
Less: Allocation of earnings to net restricted stock awards									(2)	(2)	(2)
Net income available to common shareholders — diluted									$ 1,118	$ 1,132	$ 866
Average number of common shares outstanding — diluted (in shares)									181	179	179
Diluted Earnings per Common Share (in dollars per share)	$ 1.05	$ 1.84	$ 1.29	$ 2	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 6.17	$ 6.32	$ 4.83
Incremental common shares attributable to dilutive effect of equity units (in shares)									6.3	6.3

Fair Value (Assets and Liabilit

Fair Value (Assets and Liabilities Recorded at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivative assets
Derivative assets, gross	$ 663	$ 652
Derivative assets, netting	(530)	(498)
Derivative assets, net	133	154
Liabilities
Derivative liabilities, gross	(669)	(657)
Derivative liabilities, netting	513	511
Derivative liabilities, net	(156)	(146)
Current liabilities
Liabilities
Derivative liabilities, gross	(518)	(558)
Noncurrent liabilities
Liabilities
Derivative liabilities, gross	(151)	(99)
Natural Gas
Derivative assets
Derivative assets, gross	349	357
Derivative assets, netting	(277)	(256)
Derivative assets, net	72	101
Liabilities
Derivative liabilities, gross	(380)	(378)
Derivative liabilities, netting	272	263
Derivative liabilities, net	(108)	(115)
Electricity
Derivative assets
Derivative assets, gross	303	285
Derivative assets, netting	(252)	(241)
Derivative assets, net	51	44
Liabilities
Derivative liabilities, gross	(285)	(275)
Derivative liabilities, netting	240	246
Derivative liabilities, net	(45)	(29)
Other
Derivative assets
Derivative assets, gross	7	9
Derivative assets, netting	(1)	0
Derivative assets, net	6	9
Liabilities
Derivative liabilities, gross	(1)	(1)
Derivative liabilities, netting	1	1
Derivative liabilities, net	0	0
Interest rate contracts
Liabilities
Derivative liabilities, gross	(3)	0
Derivative liabilities, netting	0	0
Derivative liabilities, net	(3)	0
Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	4	1
Derivative assets, netting	0	(1)
Derivative assets, net	4	0
Liabilities
Derivative liabilities, gross	0	(3)
Derivative liabilities, netting	0	1
Derivative liabilities, net	0	(2)
Recurring
Assets
Cash equivalents	18	19
Derivative assets
Derivative assets, netting	(530)	(498)
Derivative assets, net	133	154
Total assets	1,712	1,859
Liabilities
Derivative liabilities, netting	513	511
Derivative liabilities, net	(156)	(146)
Net Assets (Liabilities) at end of period	1,556	1,713
Net Assets (Liabilities) at the end of the period, netting	(17)	13
Recurring | DTE Electric
Assets
Cash equivalents	10	11
Derivative assets
Total assets	1,404	1,523
Recurring | Current assets
Derivative assets
Derivative assets, netting	(461)	(437)
Total assets	120	122
Recurring | Current assets | DTE Electric
Derivative assets
Total assets	16	20
Recurring | Noncurrent assets
Derivative assets
Derivative assets, netting	(69)	(61)
Total assets	1,592	1,737
Recurring | Noncurrent assets | DTE Electric
Derivative assets
Total assets	1,388	1,503
Recurring | Current liabilities
Liabilities
Derivative liabilities, netting	451	459
Derivative liabilities, net	(67)	(99)
Recurring | Noncurrent liabilities
Liabilities
Derivative liabilities, netting	62	52
Derivative liabilities, net	(89)	(47)
Recurring | Cash and Cash equivalents
Assets
Cash equivalents	3
Recurring | Restricted cash
Assets
Cash equivalents	5	8
Recurring | Other
Assets
Cash equivalents	10	11
Recurring | Other | DTE Electric
Assets
Cash equivalents	10	11
Recurring | Natural Gas
Derivative assets
Derivative assets, netting	(277)	(256)
Derivative assets, net	72	101
Liabilities
Derivative liabilities, netting	272	263
Derivative liabilities, net	(108)	(115)
Recurring | Electricity
Derivative assets
Derivative assets, netting	(252)	(241)
Derivative assets, net	51	44
Liabilities
Derivative liabilities, netting	240	246
Derivative liabilities, net	(45)	(29)
Recurring | Other
Derivative assets
Derivative assets, netting	(1)	0
Derivative assets, net	6	9
Liabilities
Derivative liabilities, netting	1	1
Derivative liabilities, net	0	0
Recurring | Interest rate contracts
Liabilities
Derivative liabilities, netting	0	0
Derivative liabilities, net	(3)	0
Recurring | Foreign currency exchange contracts
Derivative assets
Derivative assets, netting	0	(1)
Derivative assets, net	4	0
Liabilities
Derivative liabilities, netting	0	1
Derivative liabilities, net	0	(2)
Recurring | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	6	9
Recurring | Cash equivalents
Assets
Nuclear decommissioning trusts	5	14
Other investments	4	4
Recurring | Cash equivalents | DTE Electric
Assets
Nuclear decommissioning trusts	5	14
Recurring | Private equity and other
Assets
Nuclear decommissioning trusts	20	5
Recurring | Private equity and other | DTE Electric
Assets
Nuclear decommissioning trusts	20	5
Recurring | Equity securities
Assets
Nuclear decommissioning trusts	851	978
Other investments	110	118
Recurring | Equity securities | DTE Electric
Assets
Nuclear decommissioning trusts	851	978
Other investments	10	11
Recurring | Fixed income securities
Assets
Nuclear decommissioning trusts	502	495
Other investments	69	72
Recurring | Fixed income securities | DTE Electric
Assets
Nuclear decommissioning trusts	502	495
Recurring | Level 1
Assets
Cash equivalents	16	16
Derivative assets
Derivative assets, gross	199	148
Total assets	1,266	1,368
Liabilities
Derivative liabilities, gross	(197)	(141)
Net Assets (Liabilities) at end of period	1,069	1,227
Recurring | Level 1 | DTE Electric
Assets
Cash equivalents	8	8
Derivative assets
Total assets	886	1,029
Recurring | Level 1 | Current assets
Derivative assets
Total assets	212	157
Recurring | Level 1 | Current assets | DTE Electric
Derivative assets
Total assets	8	8
Recurring | Level 1 | Noncurrent assets
Derivative assets
Total assets	1,054	1,211
Recurring | Level 1 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	878	1,021
Recurring | Level 1 | Current liabilities
Liabilities
Derivative liabilities, gross	(191)	(137)
Recurring | Level 1 | Noncurrent liabilities
Liabilities
Derivative liabilities, gross	(6)	(4)
Recurring | Level 1 | Natural Gas
Derivative assets
Derivative assets, gross	199	148
Liabilities
Derivative liabilities, gross	(197)	(141)
Recurring | Level 1 | Electricity
Derivative assets
Derivative assets, gross	0	0
Liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Other
Derivative assets
Derivative assets, gross	0	0
Liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Interest rate contracts
Liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
Liabilities
Derivative liabilities, gross	0	0
Recurring | Level 1 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	0	0
Recurring | Level 1 | Cash equivalents
Assets
Nuclear decommissioning trusts	5	14
Other investments	4	4
Recurring | Level 1 | Cash equivalents | DTE Electric
Assets
Nuclear decommissioning trusts	5	14
Recurring | Level 1 | Private equity and other
Assets
Nuclear decommissioning trusts	0	0
Recurring | Level 1 | Private equity and other | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Recurring | Level 1 | Equity securities
Assets
Nuclear decommissioning trusts	851	978
Other investments	110	118
Recurring | Level 1 | Equity securities | DTE Electric
Assets
Nuclear decommissioning trusts	851	978
Other investments	10	11
Recurring | Level 1 | Fixed income securities
Assets
Nuclear decommissioning trusts	12	18
Other investments	69	72
Recurring | Level 1 | Fixed income securities | DTE Electric
Assets
Nuclear decommissioning trusts	12	18
Recurring | Level 2
Assets
Cash equivalents	2	3
Derivative assets
Derivative assets, gross	338	356
Total assets	830	836
Liabilities
Derivative liabilities, gross	(302)	(359)
Net Assets (Liabilities) at end of period	528	477
Recurring | Level 2 | DTE Electric
Assets
Cash equivalents	2	3
Derivative assets
Total assets	492	480
Recurring | Level 2 | Current assets
Derivative assets
Total assets	273	298
Recurring | Level 2 | Current assets | DTE Electric
Derivative assets
Total assets	2	3
Recurring | Level 2 | Noncurrent assets
Derivative assets
Total assets	557	538
Recurring | Level 2 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	490	477
Recurring | Level 2 | Current liabilities
Liabilities
Derivative liabilities, gross	(251)	(313)
Recurring | Level 2 | Noncurrent liabilities
Liabilities
Derivative liabilities, gross	(51)	(46)
Recurring | Level 2 | Natural Gas
Derivative assets
Derivative assets, gross	87	112
Liabilities
Derivative liabilities, gross	(71)	(111)
Recurring | Level 2 | Electricity
Derivative assets
Derivative assets, gross	247	243
Liabilities
Derivative liabilities, gross	(227)	(245)
Recurring | Level 2 | Other
Derivative assets
Derivative assets, gross	0	0
Liabilities
Derivative liabilities, gross	(1)	0
Recurring | Level 2 | Interest rate contracts
Liabilities
Derivative liabilities, gross	(3)	0
Recurring | Level 2 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	4	1
Liabilities
Derivative liabilities, gross	0	(3)
Recurring | Level 2 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	0	0
Recurring | Level 2 | Cash equivalents
Assets
Nuclear decommissioning trusts	0	0
Other investments	0	0
Recurring | Level 2 | Cash equivalents | DTE Electric
Assets
Nuclear decommissioning trusts	0	0
Recurring | Level 2 | Private equity and other
Assets
Nuclear decommissioning trusts	0	0
Recurring | Level 2 | Private equity and other | 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	490	477
Other investments	0	0
Recurring | Level 2 | Fixed income securities | DTE Electric
Assets
Nuclear decommissioning trusts	490	477
Recurring | Level 3
Assets
Cash equivalents	0	0
Derivative assets
Derivative assets, gross	126	148
Total assets	126	148
Liabilities
Derivative liabilities, gross	(170)	(157)
Net Assets (Liabilities) at end of period	(44)	(9)
Recurring | Level 3 | DTE Electric
Assets
Cash equivalents	0	0
Derivative assets
Total assets	6	9
Recurring | Level 3 | Current assets
Derivative assets
Total assets	96	104
Recurring | Level 3 | Current assets | DTE Electric
Derivative assets
Total assets	6	9
Recurring | Level 3 | Noncurrent assets
Derivative assets
Total assets	30	44
Recurring | Level 3 | Noncurrent assets | DTE Electric
Derivative assets
Total assets	0	0
Recurring | Level 3 | Current liabilities
Liabilities
Derivative liabilities, gross	(76)	(108)
Recurring | Level 3 | Noncurrent liabilities
Liabilities
Derivative liabilities, gross	(94)	(49)
Recurring | Level 3 | Natural Gas
Derivative assets
Derivative assets, gross	63	97
Liabilities
Derivative liabilities, gross	(112)	(126)
Recurring | Level 3 | Electricity
Derivative assets
Derivative assets, gross	56	42
Liabilities
Derivative liabilities, gross	(58)	(30)
Recurring | Level 3 | Other
Derivative assets
Derivative assets, gross	7	9
Liabilities
Derivative liabilities, gross	0	(1)
Recurring | Level 3 | Interest rate contracts
Liabilities
Derivative liabilities, gross	0	0
Recurring | Level 3 | Foreign currency exchange contracts
Derivative assets
Derivative assets, gross	0	0
Liabilities
Derivative liabilities, gross	0	0
Recurring | Level 3 | Derivative assets — FTRs | DTE Electric
Derivative assets
Derivative assets, net	6	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 | Private equity and other
Assets
Nuclear decommissioning trusts	0	0
Recurring | Level 3 | Private equity and other | 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
Recurring | Other
Derivative assets
Total assets	20	5
Liabilities
Net Assets (Liabilities) at end of period	20	5
Recurring | Other | DTE Electric
Derivative assets
Total assets	20	5
Recurring | Other | Noncurrent assets
Derivative assets
Total assets	20	5
Recurring | Other | Noncurrent assets | DTE Electric
Derivative assets
Total assets	20	5
Recurring | Other | Private equity and other
Assets
Nuclear decommissioning trusts	20	5
Recurring | Other | Private equity and other | DTE Electric
Assets
Nuclear decommissioning trusts	$ 20	$ 5

Fair Value (Reconciliation of L

Fair Value (Reconciliation of Level 3 Assets and Liabilities at Fair Value on a Recurring Basis) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Purchases, issuances, and settlements:
Issuances	$ 0	$ 0
Natural Gas
Purchases, issuances, and settlements:
Issuances	0	0
Electricity
Purchases, issuances, and settlements:
Issuances	0	0
Other
Purchases, issuances, and settlements:
Issuances	0	0
Recurring
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	(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	(116)	82
Recorded in Regulatory liabilities	9	25
Purchases, issuances, and settlements:
Purchases	0	0
Settlements	75	(28)
Net Assets (Liabilities) as of December 31	(44)	(9)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	(120)	21
Recurring | Natural Gas
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	(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	(146)	(29)
Recorded in Regulatory liabilities	0	0
Purchases, issuances, and settlements:
Purchases	0	0
Settlements	129	96
Net Assets (Liabilities) as of December 31	(49)	(29)
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	(119)	(30)
Recurring | Electricity
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	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	29	109
Recorded in Regulatory liabilities	0	0
Purchases, issuances, and settlements:
Purchases	0	0
Settlements	(43)	(106)
Net Assets (Liabilities) as of December 31	(2)	12
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	15	50
Recurring | Other
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	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	1	2
Recorded in Regulatory liabilities	9	25
Purchases, issuances, and settlements:
Purchases	0	0
Settlements	(11)	(18)
Net Assets (Liabilities) as of December 31	7	8
The amount of total gains (losses) included in Net Income attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 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	(16)	1
Recurring | DTE Electric
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Net Assets (Liabilities) as of January 1	9	2
Total gains (losses)
Recorded in Regulatory liabilities	9	25
Purchases, issuances, and settlements:
Settlements	(12)	(18)
Net Assets (Liabilities) as of December 31	6	9
The amount of total gains (losses) included in Regulatory liabilities attributed to the change in unrealized gains (losses) related to assets and liabilities held at December 31, 2018 and 2017 and reflected in DTE Electric's Consolidated Statements of Financial Position	$ 6	$ 9

Fair Value (Unobservable Inputs

Fair Value (Unobservable Inputs related to Level 3 Assets and Liabilities) (Details) $ in Millions	Dec. 31, 2018USD ($)$ / MMBTU$ / MWh	Dec. 31, 2017USD ($)$ / MMBTU$ / MWh
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 663	$ 652
Derivative Liabilities	(669)	(657)
Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	349	357
Derivative Liabilities	(380)	(378)
Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	303	285
Derivative Liabilities	$ (285)	$ (275)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(2.15)	(1.10)
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	5.59	9.75
Level 3 | Discounted Cash Flow | Forward basis price | Natural Gas | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MMBTU	(0.10)	(0.03)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Minimum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	(7)	(5)
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Maximum
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	9	15
Level 3 | Discounted Cash Flow | Forward basis price | Electricity | Weighted Average
Unobservable Input Valuation Techniques [Line Items]
Forward basis price | $ / MWh	1	2
Recurring | Level 3
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	$ 126	$ 148
Derivative Liabilities	(170)	(157)
Recurring | Level 3 | Natural Gas
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	63	97
Derivative Liabilities	(112)	(126)
Recurring | Level 3 | Electricity
Unobservable Input Valuation Techniques [Line Items]
Derivative Assets	56	42
Derivative Liabilities	$ (58)	$ (30)

Fair Value (Fair Value of Finan

Fair Value (Fair Value of Financial Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	$ 40	$ 38
Dividends payable	172	158
Short-term borrowings	609	621
Notes payable — Other	41	12
Long-term debt	13,622	12,288
Carrying Amount | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	6	0
Short-term borrowings	149	238
Notes payable — Other	21	2
Long-term debt	6,538	6,017
Carrying Amount | DTE Electric | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	101	116
Fair Value | Level 1
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Dividends payable	172	158
Short-term borrowings	0	0
Notes payable — Other	0	0
Long-term debt	1,796	1,939
Fair Value | Level 1 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	0	0
Notes payable — Other	0	0
Long-term debt	0	0
Fair Value | Level 1 | DTE Electric | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	0	0
Fair Value | Level 2
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Dividends payable	0	0
Short-term borrowings	609	621
Notes payable — Other	0	0
Long-term debt	10,712	10,571
Fair Value | Level 2 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	0	0
Short-term borrowings	149	238
Notes payable — Other	0	0
Long-term debt	6,552	6,441
Fair Value | Level 2 | DTE Electric | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings		0
Fair Value | Level 3
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	40	38
Dividends payable	0	0
Short-term borrowings	0	0
Notes payable — Other	41	12
Long-term debt	1,317	764
Fair Value | Level 3 | DTE Electric
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Notes receivable, excluding capital leases	6	0
Short-term borrowings	0	0
Notes payable — Other	21	2
Long-term debt	161	171
Fair Value | Level 3 | DTE Electric | Affiliated entity
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Short-term borrowings	$ 101	$ 116

Fair Value (Fair Value of Nucle

Fair Value (Fair Value of Nuclear Decommissioning Trust Fund Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Nuclear decommissioning trust funds	$ 1,378	$ 1,492
DTE Electric
Debt Securities, Available-for-sale [Line Items]
Nuclear decommissioning trust funds	1,378	1,492
DTE Electric | Nuclear decommissioning trusts
Debt Securities, Available-for-sale [Line Items]
Nuclear decommissioning trust funds	1,378	1,492
DTE Electric | Nuclear decommissioning trusts | Fermi 2
Debt Securities, Available-for-sale [Line Items]
Nuclear decommissioning trust funds	1,372	1,475
DTE Electric | Nuclear decommissioning trusts | Fermi 1
Debt Securities, Available-for-sale [Line Items]
Nuclear decommissioning trust funds	3	3
DTE Electric | Nuclear decommissioning trusts | Low-level radioactive waste
Debt Securities, Available-for-sale [Line Items]
Nuclear decommissioning trust funds	$ 3	$ 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 trusts - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Securities, Available-for-sale [Line Items]
Realized gains	$ 65	$ 83	$ 74
Realized losses	(42)	(29)	(63)
Proceeds from sale of securities	$ 1,203	$ 1,240	$ 1,457

Fair Value (Fair Value and Unre

Fair Value (Fair Value and Unrealized Gains and Losses for the Nuclear Decommissioning Trust Funds) (Details) - DTE Electric - Nuclear decommissioning trusts - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Fair Value	$ 1,378	$ 1,492
Fixed income securities, fair value	502	495
Private equity securities, fair value	20	5
Cash equivalents, fair value	5	14
Unrealized gains	242	333
Fixed income securities, unrealized gain	7	13
Unrealized losses	(87)	(35)
Fixed income securities, unrealized loss	(8)	(3)
Equity securities
Debt Securities, Available-for-sale [Line Items]
Fair Value	851	978
Unrealized gains	235	320
Unrealized losses	$ (79)	$ (32)

Fair Value (Fair Value of Fixed

Fair Value (Fair Value of Fixed Income Securities Held in Nuclear Decommissioning Trust Funds (Details) - Nuclear decommissioning trusts - Fixed Income Securities $ in Millions	Dec. 31, 2018USD ($)
Debt Securities, Available-for-sale [Line Items]
Due within one year	$ 29
Due after one through five years	89
Due after five through ten years	113
Due after ten years	271
Fixed income securities total	$ 502

Fair Value (Details)

Fair Value (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Losses from trading securities	$ 11
Gains from trading securities		$ 26	$ 15

Financial and Other Derivativ_3

Financial and Other Derivative Instruments (Fair Value of Derivative Instruments) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivatives, Fair Value [Line Items]
Derivative Assets	$ 663	$ 652
Derivative Liabilities	(669)	(657)
Current derivative asset
Derivatives, Fair Value [Line Items]
Derivative Assets	563	540
Noncurrent derivative asset
Derivatives, Fair Value [Line Items]
Derivative Assets	100	112
Current derivative liability
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(518)	(558)
Noncurrent derivative liability
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(151)	(99)
Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Liabilities	(3)	0
Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	349	357
Derivative Liabilities	(380)	(378)
Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	303	285
Derivative Liabilities	(285)	(275)
Other
Derivatives, Fair Value [Line Items]
Derivative Assets	7	9
Derivative Liabilities	(1)	(1)
Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	4	1
Derivative Liabilities	0	(3)
Derivatives designated as hedging instruments | Interest rate contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	0	0
Derivative Liabilities	(3)	0
Derivatives not designated as hedging instruments
Derivatives, Fair Value [Line Items]
Derivative Assets	663	652
Derivative Liabilities	(666)	(657)
Derivatives not designated as hedging instruments | DTE Electric
Derivatives, Fair Value [Line Items]
Derivative Assets	6	9
Derivatives not designated as hedging instruments | Natural gas
Derivatives, Fair Value [Line Items]
Derivative Assets	349	357
Derivative Liabilities	(380)	(378)
Derivatives not designated as hedging instruments | Electricity
Derivatives, Fair Value [Line Items]
Derivative Assets	303	285
Derivative Liabilities	(285)	(275)
Derivatives not designated as hedging instruments | Other
Derivatives, Fair Value [Line Items]
Derivative Assets	7	9
Derivative Liabilities	(1)	(1)
Derivatives not designated as hedging instruments | FTRs — Other current assets | DTE Electric
Derivatives, Fair Value [Line Items]
Derivative Assets	6	9
Derivatives not designated as hedging instruments | Foreign currency exchange contracts
Derivatives, Fair Value [Line Items]
Derivative Assets	4	1
Derivative Liabilities	$ 0	$ (3)

Financial and Other Derivativ_4

Financial and Other Derivative Instruments (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Letters of credit that could be used to offset net derivative liabilities	$ 4,000,000	$ 4,000,000
Letters of credit that could be used to offset net derivative assets	8,000,000	4,000,000
Cash collateral received, net of cash collateral posted	13,000,000
Cash collateral posted, net of cash collateral received		28,000,000
Collateral adjustment on derivative assets	17,000,000	9,000,000
Collateral adjustment on derivative liabilities	0	22,000,000
Cash collateral paid	10,000,000	18,000,000
Cash collateral received	6,000,000	$ 3,000,000
Additional collateral, aggregate fair value	638,000,000
Derivative net liability position aggregate fair value	541,000,000
Collateral already posted fair value	0
Derivative, net asset position, fair value	495,000,000
Remaining amount of offsets to derivative net liability positions for hard and soft trigger provisions	$ 46,000,000

Financial and Other Derivativ_5

Financial and Other Derivative Instruments (Netting Offsets of Derivative Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Derivative assets
Gross Amounts of Recognized Assets (Liabilities)	$ 663	$ 652
Gross Amounts Offset in the Consolidated Statements of Financial Position	(530)	(498)
Derivative assets, net	133	154
Derivative liabilities
Gross Amounts of Recognized Assets (Liabilities)	(669)	(657)
Gross Amounts Offset in the Consolidated Statements of Financial Position	513	511
Derivative liabilities, net	(156)	(146)
Natural gas
Derivative assets
Gross Amounts of Recognized Assets (Liabilities)	349	357
Gross Amounts Offset in the Consolidated Statements of Financial Position	(277)	(256)
Derivative assets, net	72	101
Derivative liabilities
Gross Amounts of Recognized Assets (Liabilities)	(380)	(378)
Gross Amounts Offset in the Consolidated Statements of Financial Position	272	263
Derivative liabilities, net	(108)	(115)
Electricity
Derivative assets
Gross Amounts of Recognized Assets (Liabilities)	303	285
Gross Amounts Offset in the Consolidated Statements of Financial Position	(252)	(241)
Derivative assets, net	51	44
Derivative liabilities
Gross Amounts of Recognized Assets (Liabilities)	(285)	(275)
Gross Amounts Offset in the Consolidated Statements of Financial Position	240	246
Derivative liabilities, net	(45)	(29)
Other
Derivative assets
Gross Amounts of Recognized Assets (Liabilities)	7	9
Gross Amounts Offset in the Consolidated Statements of Financial Position	(1)	0
Derivative assets, net	6	9
Derivative liabilities
Gross Amounts of Recognized Assets (Liabilities)	(1)	(1)
Gross Amounts Offset in the Consolidated Statements of Financial Position	1	1
Derivative liabilities, net	0	0
Interest rate contracts
Derivative liabilities
Gross Amounts of Recognized Assets (Liabilities)	(3)	0
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	0
Derivative liabilities, net	(3)	0
Foreign currency exchange contracts
Derivative assets
Gross Amounts of Recognized Assets (Liabilities)	4	1
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	(1)
Derivative assets, net	4	0
Derivative liabilities
Gross Amounts of Recognized Assets (Liabilities)	0	(3)
Gross Amounts Offset in the Consolidated Statements of Financial Position	0	1
Derivative liabilities, net	$ 0	$ (2)

Financial and Other Derivativ_6

Financial and Other Derivative Instruments (Netting Offsets Reconciliation to Balance Sheet) (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Derivative Assets
Derivative Assets	$ 663,000,000	$ 652,000,000
Collateral adjustment	(17,000,000)	(9,000,000)
Derivative asset, current	102,000,000	103,000,000
Derivative assets, noncurrent	31,000,000	51,000,000
Derivative Liabilities
Derivative Liabilities	(669,000,000)	(657,000,000)
Collateral adjustment	0	22,000,000
Derivative liabilities, current	(67,000,000)	(99,000,000)
Derivative liabilities, noncurrent	(89,000,000)	(47,000,000)
Current derivative asset
Derivative Assets
Derivative Assets	563,000,000	540,000,000
Counterparty netting	(451,000,000)	(437,000,000)
Collateral adjustment	(10,000,000)	0
Derivative asset, current	102,000,000	103,000,000
Noncurrent derivative asset
Derivative Assets
Derivative Assets	100,000,000	112,000,000
Counterparty netting	(62,000,000)	(52,000,000)
Collateral adjustment	(7,000,000)	(9,000,000)
Derivative assets, noncurrent	31,000,000	51,000,000
Current derivative liability
Derivative Liabilities
Derivative Liabilities	(518,000,000)	(558,000,000)
Counterparty netting	451,000,000	437,000,000
Collateral adjustment	0	22,000,000
Derivative liabilities, current	(67,000,000)	(99,000,000)
Noncurrent derivative liability
Derivative Liabilities
Derivative Liabilities	(151,000,000)	(99,000,000)
Counterparty netting	62,000,000	52,000,000
Collateral adjustment	0	0
Derivative liabilities, noncurrent	$ (89,000,000)	$ (47,000,000)

Financial and Other Derivativ_7

Financial and Other Derivative Instruments (Effect of Derivatives not Designated as Hedging Instruments on the Consolidated Statement of Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	$ (81)	$ 128	$ (109)
Natural gas | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	(42)	(74)	(153)
Natural gas | Fuel, purchased power, and gas — non-utility
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	(94)	97	(2)
Electricity | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	49	105	43
Other | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	(1)	2	5
Foreign currency exchange contracts | Operating Revenues — Non-utility operations
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) Recognized in Income on Derivatives	$ 7	$ (2)	$ (2)

Financial and Other Derivativ_8

Financial and Other Derivative Instruments (Cumulative Gross Volume of Derivative Contracts Outstanding) (Details)	12 Months Ended
	Dec. 31, 2018CAD ($)MWhMMBTU
Natural Gas (MMBtu)
Derivative [Line Items]
Commodity | MMBTU	2,171,541,994
Electricity (MWh)
Derivative [Line Items]
Commodity | MWh	36,163,761
Foreign Currency Exchange (Canadian dollars)
Derivative [Line Items]
Foreign Currency Exchange (Canadian dollars) | $	$ 101,975,644

Long-Term Debt (Long Term Debt

Long-Term Debt (Long Term Debt Outstanding and Weighted Average Interest Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Long-term debt, excluding current maturities	$ 10,982	$ 11,039
Long-term debt, total	13,746
Other Long-Term Debt
Debt Instrument [Line Items]
Long-term debt, gross	1	7
Secured Debt, Unsecured Debt, Mortgage Notes and Other Debt
Debt Instrument [Line Items]
Long-term debt, gross	12,566	11,227
Unamortized debt discount and premium, net	(16)	(15)
Unamortized debt issuance costs	(73)	(69)
Long-term debt due within one year	(1,495)	(104)
Long-term debt, excluding current maturities	$ 10,982	11,039
Junior Subordinated Debentures
Debt Instrument [Line Items]
Interest rate	5.50%
Long-term debt, gross	$ 1,180	1,180
Unamortized debt issuance costs	(35)	(35)
Long-term debt, total	1,145	1,145
DTE Electric
Debt Instrument [Line Items]
Long-term debt, gross	6,590	6,065
Long-term debt, excluding current maturities	6,538	6,017
Long-term debt, total	$ 6,590
DTE Electric | Principally Secured
Debt Instrument [Line Items]
Interest rate	4.30%
Long-term debt, gross	$ 6,280	5,755
DTE Electric | Tax-Exempt Revenue Bonds
Debt Instrument [Line Items]
Interest rate	4.30%
Long-term debt, gross	$ 310	310
DTE Electric | Secured Debt, Unsecured Debt, Mortgage Notes and Other Debt
Debt Instrument [Line Items]
Unamortized debt discount and premium, net	(11)	(10)
Unamortized debt issuance costs	$ (41)	(38)
DTE Gas | Principally Secured
Debt Instrument [Line Items]
Interest rate	4.50%
Long-term debt, gross	$ 1,550	1,330
DTE Energy | Unsecured
Debt Instrument [Line Items]
Interest rate	3.20%
Long-term debt, gross	$ 4,425	$ 3,825

Long-Term Debt (Debt Issuances)

Long-Term Debt (Debt Issuances) (Details)	Dec. 31, 2018USD ($)
Debt Instrument [Line Items]
Amount	$ 1,445,000,000
DTE Energy | Senior Notes | August 2018 3.70% Senior Notes Maturing 2023
Debt Instrument [Line Items]
Interest Rate	3.70%
Amount	$ 600,000,000
DTE Electric | Mortgage Bonds | May 2018 4.05% Mortgage Bonds Maturing 2048
Debt Instrument [Line Items]
Interest Rate	4.05%
Amount	$ 525,000,000
DTE Gas | Mortgage Bonds | August 2018 3.81% Mortgage Bonds Maturing 2028
Debt Instrument [Line Items]
Interest Rate	3.81%
Amount	$ 195,000,000
DTE Gas | Mortgage Bonds | August 2018 4.14% Mortgage Bonds Maturing 2048
Debt Instrument [Line Items]
Interest Rate	4.14%
Amount	$ 125,000,000

Long-Term Debt (Debt Redemption

Long-Term Debt (Debt Redemptions) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Debt Instrument, Redemption [Line Items]
Amount	$ 105
DTE Energy | Other Long-Term Debt
Debt Instrument, Redemption [Line Items]
Amount	$ 5
DTE Gas | Senior Notes | April 2018 6.04% Senior Notes Maturing 2018
Debt Instrument, Redemption [Line Items]
Interest Rate	6.04%
Amount	$ 100

Long-Term Debt (Scheduled Debt

Long-Term Debt (Scheduled Debt Maturities) (Details) $ in Millions	Dec. 31, 2018USD ($)
Maturities of Long-term Debt [Abstract]
2,019	$ 1,495
2,020	682
2,021	462
2,022	616
2,023	1,177
2024 and Thereafter	9,314
Long-term debt, total	13,746
DTE Electric
Maturities of Long-term Debt [Abstract]
2,019	0
2,020	632
2,021	462
2,022	316
2,023	202
2024 and Thereafter	4,978
Long-term debt, total	$ 6,590

Long Term Debt (Junior Subordin

Long Term Debt (Junior Subordinated Debt and Interest Rates) (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Junior subordinated debentures	$ 1,145	$ 1,145
Junior Subordinated Debentures
Debt Instrument [Line Items]
Junior subordinated debentures	$ 1,180
Junior Subordinated Debentures | 5.25% junior subordinated debentures maturing 2062
Debt Instrument [Line Items]
Interest Rate	5.25%
Junior subordinated debentures	$ 200
Junior Subordinated Debentures | 5.375% junior subordinated debentures maturing 2076
Debt Instrument [Line Items]
Interest Rate	5.375%
Junior subordinated debentures	$ 300
Junior Subordinated Debentures | 6.00% junior subordinated debentures maturing 2076
Debt Instrument [Line Items]
Interest Rate	6.00%
Junior subordinated debentures	$ 280
Junior Subordinated Debentures | 5.25% junior subordinated debentures maturing 2077
Debt Instrument [Line Items]
Interest Rate	5.25%
Junior subordinated debentures	$ 400

Long-Term Debt (Details)

Long-Term Debt (Details) $ / shares in Units, shares in Millions	Jan. 01, 2017$ / shares	Oct. 05, 2016USD ($)	Oct. 31, 2016USD ($)day$ / shares	Dec. 31, 2018USD ($)shares	Dec. 31, 2016USD ($)	Oct. 31, 2019shares	Dec. 31, 2017USD ($)	Oct. 01, 2016
Debt Instrument [Line Items]
Face amount | $				$ 1,445,000,000
Junior subordinated debentures | $				1,145,000,000			$ 1,145,000,000
Equity units, percentage interest in attached debt instrument			0.005%
Financial instruments subject to mandatory redemption, settlement terms, share value, amount | $					$ 98,000,000
October series C 1.5% RSNs maturing 2024 | Other long-term debt
Debt Instrument [Line Items]
Face amount | $		$ 675,000,000	$ 675,000,000
Interest rate		1.50%	1.50%
Unsuccessful remarketing | October series C 1.5% RSNs maturing 2024 | Other long-term debt
Debt Instrument [Line Items]
Debt instrument, redemption price, percentage			100.00%
Equity units subject to mandatory redemption
Debt Instrument [Line Items]
Forward contract indexed to issuer's equity, forward rate per share (in dollars per share)			$ 50
Financial instruments subject to mandatory redemption, contract adjustment rate	5.00%	5.00%
Financial instruments subject to mandatory redemption, contract adjustment rate, annual amount (in dollars per share)	$ 2.50
Financial instruments subject to mandatory redemption, settlement terms, share value, amount | $				$ 98,000,000
Financial instruments subject to mandatory redemption, settlement terms, maximum number of shares (in shares) | shares				9
Equity units subject to mandatory redemption | Minimum | Scenario, Forecast
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, settlement terms, number of shares (in shares) | shares						5.8
Equity units subject to mandatory redemption | Maximum | Scenario, Forecast
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, settlement terms, number of shares (in shares) | shares						7.3
Equity units subject to mandatory redemption | Equal to or greater than $116.31, 0.4299 shares of common stock
Debt Instrument [Line Items]
Number of consecutive scheduled trading days | day			20
Financial instruments subject to mandatory redemption, anti-dilution provision, conversion ratio			0.4299
Equity units subject to mandatory redemption | Equal to or greater than $116.31, 0.4299 shares of common stock | Minimum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share)			$ 116.31
Equity units subject to mandatory redemption | Less than $116.31, but greater than $93.05, number of shares of common stock equal to $50 divided by the AMV rounded to the nearest 1/10,000th of a share | Minimum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share)			93.05
Equity units subject to mandatory redemption | Less than $116.31, but greater than $93.05, number of shares of common stock equal to $50 divided by the AMV rounded to the nearest 1/10,000th of a share | Maximum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share)			$ 116.31
Equity units subject to mandatory redemption | Less than or equal to $93.05, 0.5373 shares of common stock
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, conversion ratio			0.5373
Equity units subject to mandatory redemption | Less than or equal to $93.05, 0.5373 shares of common stock | Maximum
Debt Instrument [Line Items]
Financial instruments subject to mandatory redemption, anti-dilution provision, stock price threshold (in dollars per share)			$ 93.05
AGS | M3 Midstream | Midstream Natural Gas Assets
Debt Instrument [Line Items]
Percentage of voting interests acquired								100.00%
SGG | Midstream Natural Gas Assets
Debt Instrument [Line Items]
Percentage of voting interests acquired				55.00%				55.00%
SGG | M3 Midstream | Midstream Natural Gas Assets
Debt Instrument [Line Items]
Percentage of voting interests acquired								40.00%
SGG | Vega Energy Partners | Midstream Natural Gas Assets
Debt Instrument [Line Items]
Percentage of voting interests acquired								15.00%

Long-Term Debt (Equity Units an

Long-Term Debt (Equity Units and RSNs) (Details) - USD ($) shares in Millions	Jan. 01, 2017	Oct. 05, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Oct. 31, 2016
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Total Net Proceeds		$ 654,000,000	$ 0	$ 0	$ 654,000,000
Total Long-Term Debt			1,445,000,000
Equity units subject to mandatory redemption
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Units Issued (in shares)		13.5
Stock Purchase Contract Annual Rate	5.00%	5.00%
Stock Purchase Contract Liability		$ 98,000,000	33,000,000	66,000,000
Redemption of long-term debt			$ 33,000,000	$ 32,000,000
October series C 1.5% RSNs maturing 2024 | Other long-term debt
Financial Instruments Subject to Mandatory Redemption by Settlement Terms [Line Items]
Total Long-Term Debt		$ 675,000,000				$ 675,000,000
RSN Annual Interest Rate		1.50%				1.50%

Preferred and Preference Secu_3

Preferred and Preference Securities (Details)	Dec. 31, 2018$ / sharesshares
DTE Electric
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 100
Preferred stock, shares authorized (in shares) | shares	6,747,484
Preference stock, par value (in dollars per share) | $ / shares	$ 1
Preference stock shares authorized (in shares) | shares	30,000,000
DTE Gas
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 1
Preferred stock, shares authorized (in shares) | shares	7,000,000
Preference stock, par value (in dollars per share) | $ / shares	$ 1
Preference stock shares authorized (in shares) | shares	4,000,000
DTE Energy
Preferred and Preferenced Securities [Line Items]
Preferred stock, par value (in dollars per share) | $ / shares	$ 0
Preferred stock, shares authorized (in shares) | shares	5,000,000

Short-Term Credit Arrangement_3

Short-Term Credit Arrangements and Borrowings (Details)	Dec. 31, 2018USD ($)	Dec. 31, 2017USD ($)
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 777,000,000
Weighted average interest rate	2.90%	1.90%
Dividend restriction	$ 2,400,000,000
Retained earnings	6,112,000,000	$ 5,643,000,000
Effective limitations	0
Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 168,000,000
DTE Electric
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.50
Other outstanding letters of credit	$ 149,000,000
Weighted average interest rate	2.90%	1.50%
Retained earnings	$ 2,162,000,000	$ 1,956,000,000
DTE Electric | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
DTE Gas
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.48
Other outstanding letters of credit	$ 189,000,000
DTE Gas | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 0
DTE Energy
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.55
Other outstanding letters of credit	$ 439,000,000
DTE Energy | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	168,000,000
DTE Energy | Demand financing agreement
Short-term Debt [Line Items]
Maximum borrowing capacity	100,000,000
Additional margin financing	50,000,000
Amount outstanding	93,000,000	$ 56,000,000
DTE Energy | Demand financing agreement plus letter of credit
Short-term Debt [Line Items]
Maximum borrowing capacity	125,000,000
DTE Energy | Other outstanding letters of credit | Letters of credit
Short-term Debt [Line Items]
Other outstanding letters of credit	$ 9,000,000
Maximum
Short-term Debt [Line Items]
Total funded debt to capitalization ratio	0.65

Short-Term Credit Arrangement_4

Short-Term Credit Arrangements and Borrowings (Schedule of Borrowings) (Details)	Dec. 31, 2018USD ($)
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 2,120,000,000
Amounts outstanding	777,000,000
Net availability	1,343,000,000
DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	400,000,000
Amounts outstanding	149,000,000
Net availability	251,000,000
DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	300,000,000
Amounts outstanding	189,000,000
Net availability	111,000,000
DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,420,000,000
Amounts outstanding	439,000,000
Net availability	981,000,000
Letters of credit
Line Of Credit Facility [Line Items]
Amounts outstanding	168,000,000
Letters of credit | DTE Electric
Line Of Credit Facility [Line Items]
Amounts outstanding	0
Letters of credit | DTE Gas
Line Of Credit Facility [Line Items]
Amounts outstanding	0
Letters of credit | DTE Energy
Line Of Credit Facility [Line Items]
Amounts outstanding	168,000,000
Letters of credit | Unsecured letter of credit facility, expiring in February 2019
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	150,000,000
Letters of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in February 2019 | DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	150,000,000
Letters of credit | Unsecured letter of credit facility, expiring in September 2019
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	70,000,000
Letters of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	0
Letters of credit | Unsecured letter of credit facility, expiring in September 2019 | DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	70,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,900,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Electric
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	400,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Gas
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	300,000,000
Revolving credit facility | Unsecured revolving credit facility, expiring April 2022 | DTE Energy
Line Of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	1,200,000,000
Commercial paper issuances
Line Of Credit Facility [Line Items]
Amounts outstanding	609,000,000
Commercial paper issuances | DTE Electric
Line Of Credit Facility [Line Items]
Amounts outstanding	149,000,000
Commercial paper issuances | DTE Gas
Line Of Credit Facility [Line Items]
Amounts outstanding	189,000,000
Commercial paper issuances | DTE Energy
Line Of Credit Facility [Line Items]
Amounts outstanding	$ 271,000,000

Capital and Operating Leases (F

Capital and Operating Leases (Future Minimum Lease Payments under Non-Cancelable Leases) (Details) $ in Millions	Dec. 31, 2018USD ($)
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,019	$ 42
2,020	30
2,021	18
2,022	11
2,023	8
2024 and thereafter	45
Total minimum lease payments	154
DTE Electric
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2,019	17
2,020	12
2,021	10
2,022	7
2,023	5
2024 and thereafter	29
Total minimum lease payments	$ 80

Capital and Operating Leases _2

Capital and Operating Leases (Future Rental Revenue under Non-Cancelable Operating Leases) (Details) $ in Millions	Dec. 31, 2018USD ($)
Leases [Abstract]
2,019	$ 66
2,020	66
2,021	64
2,022	20
2,023	20
2024 and thereafter	196
Total minimum future rental revenue under non-cancelable operating leases	$ 432

Capital and Operating Leases (D

Capital and Operating Leases (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Leases [Abstract]
Contingent rental revenues	$ 107	$ 91	$ 101
Schedule of Lessor Capital Leases [Line Items]
Rent expense	$ 44	51	43
Pipeline System Lease
Schedule of Lessor Capital Leases [Line Items]
Lessor capital lease renewal terms	5 years
Percent ownership in pipeline	40.00%
DTE Electric
Schedule of Lessor Capital Leases [Line Items]
Rent expense	$ 18	$ 28	$ 28

Capital and Operating Leases (C

Capital and Operating Leases (Components of the Net Investment in the Capital Leases) (Details) $ in Millions	Dec. 31, 2018USD ($)
Capital Leases of Lessor [Abstract]
2,019	$ 10
2,020	9
2,021	0
2,022	0
2,023	0
2024 and thereafter	1
Total minimum future lease receipts	20
Residual value of leased pipeline	40
Less unearned income	(9)
Net investment in capital lease	51
Less current portion	(5)
Capital lease, noncurrent	$ 46

Commitments and Contingencies_2

Commitments and Contingencies (Details)	12 Months Ended
	Dec. 31, 2018USD ($)employeeplantfacilityNOVsite	Dec. 31, 2010	Dec. 31, 2017USD ($)	Jul. 31, 2009plant
Loss Contingencies [Line Items]
Sulfur dioxide ambient air quality standard finalized		1 hour
Utility capital expenditures, expenditures for non-utility businesses, and contributions to equity method investees estimated for next year	$ 3,900,000,000
Accounts receivable	1,789,000,000		$ 1,758,000,000
Reserve recorded related to pre-petition receivables	91,000,000		49,000,000
Long-lived assets used in producing electric output for sale	$ 21,650,000,000		20,721,000,000
Power and Industrial Projects
Loss Contingencies [Line Items]
Number of generating plants operated with ownership interests held | plant	5
Labor force concentration risk | Workforce subject to collective bargaining arrangements
Loss Contingencies [Line Items]
Approximate number of employees | employee	5,200
PG&E | Power and Industrial Projects
Loss Contingencies [Line Items]
Accounts receivable	$ 12,000,000
Reserve recorded related to pre-petition receivables	0
Long-lived assets used in producing electric output for sale	106,000,000
Impairment loss	0
Equity investments, including note receivable	77,000,000
Other than temporary decline in equity investments	$ 0
Synthetic fuel guarantees
Loss Contingencies [Line Items]
Number of days after expiration of statutes of limitations	90 days
Maximum potential liability	$ 400,000,000
Reduced emissions fuel guarantees
Loss Contingencies [Line Items]
Number of days after expiration of statutes of limitations	90 days
Maximum potential liability	$ 359,000,000
NEXUS Pipeline | DTE Gas
Loss Contingencies [Line Items]
Maximum potential liability	$ 242,000,000
Guarantee termination, minimum threshold, period following end of primary term of capacity lease agreements	2 months
NEXUS Pipeline | Texas Eastern Transmission, LP
Loss Contingencies [Line Items]
Maximum potential liability	$ 377,000,000
Percentage of all payment obligations due and payable	50.00%
Guarantee termination, minimum threshold, period following end of primary term of capacity lease agreements	2 months
NEXUS Pipeline | Vector
Loss Contingencies [Line Items]
Maximum potential liability	$ 7,000,000
Percentage of all payment obligations due and payable	50.00%
Guarantee termination, minimum threshold, period following end of primary term of capacity lease agreements	15 years
Other guarantees
Loss Contingencies [Line Items]
Maximum potential liability	$ 64,000,000
Performance surety bonds
Loss Contingencies [Line Items]
Performance bonds outstanding	$ 76,000,000
Reduction of Carbon Emissions by early 2020's
Loss Contingencies [Line Items]
Goal to reduce carbon emissions, percentage	30.00%
Reduction of Carbon Emissions by 2030
Loss Contingencies [Line Items]
Goal to reduce carbon emissions, percentage	45.00%
Reduction of Carbon Emissions by 2040
Loss Contingencies [Line Items]
Goal to reduce carbon emissions, percentage	75.00%
Reduction of Carbon Emissions by 2050
Loss Contingencies [Line Items]
Goal to reduce carbon emissions, percentage	80.00%
DTE Electric
Loss Contingencies [Line Items]
Number of power plants allegedly in violation | plant				5
Number of NOVs/FOVs currently being discussed with the EPA | NOV	2
Amount spent to comply with air pollution requirements	$ 2,400,000,000
Estimated capital expenditures	$ 0
Number of former MGP sites | site	3
Accrued for remediation related to the sites	$ 7,000,000		6,000,000
Number of permitted engineered coal ash storage facilities owned | facility	3
Time period to comply with coal combustion residual requirements and effluent limitations guidelines	6 years
Utility capital expenditures, expenditures for non-utility businesses, and contributions to equity method investees estimated for next year	$ 2,200,000,000
Accounts receivable	750,000,000		791,000,000
Reserve recorded related to pre-petition receivables	53,000,000		31,000,000
Long-lived assets used in producing electric output for sale	$ 15,437,000,000		14,988,000,000
DTE Electric | Labor force concentration risk | Workforce subject to collective bargaining arrangements
Loss Contingencies [Line Items]
Approximate number of employees | employee	2,800
DTE Electric | Coal combustion residual rule
Loss Contingencies [Line Items]
Estimated cost associated with building new facilities	$ 565,000,000
DTE Gas
Loss Contingencies [Line Items]
Number of former MGP sites | site	14
Accrued for remediation related to the sites	$ 25,000,000		$ 41,000,000
Amortization period for MGP costs (in years)	10 years
DTE Gas | NEXUS Pipeline | DTE Gas
Loss Contingencies [Line Items]
Percentage of all payment obligations due and payable	50.00%
DTE Gas | Cleanup completed and site closed
Loss Contingencies [Line Items]
Number of former MGP sites | site	6
DTE Gas | Partial closure completed
Loss Contingencies [Line Items]
Number of former MGP sites | site	6
NEXUS | NEXUS Pipeline | DTE Gas
Loss Contingencies [Line Items]
Capacity lease agreement term	15 years
NEXUS | NEXUS Pipeline | Texas Eastern Transmission, LP
Loss Contingencies [Line Items]
Capacity lease agreement term	15 years
NEXUS | NEXUS Pipeline | Vector
Loss Contingencies [Line Items]
Capacity lease agreement term	15 years

Commitments and Contingencies_3

Commitments and Contingencies (Purchase Commitments) (Details) $ in Millions	Dec. 31, 2018USD ($)
Purchase Obligation, Fiscal Year Maturity [Abstract]
2,019	$ 2,691
2,020	1,311
2,021	632
2,022	409
2,023	351
2024 and thereafter	1,953
Total purchase commitments	7,347
DTE Electric
Purchase Obligation, Fiscal Year Maturity [Abstract]
2,019	777
2,020	541
2,021	171
2,022	88
2,023	85
2024 and thereafter	737
Total purchase commitments	$ 2,399

Nuclear Operations (Details)

Nuclear Operations (Details) - DTE Electric $ in Millions	May 16, 2014kWh	May 15, 2014$ / MWh	Dec. 31, 2018USD ($)
Entity Information [Line Items]
Policy waiting period			84 days
Insurance coverage for extra expense when power plant unavailable			$ 490
Period of coverage of policy for extra expenses			3 years
Primary coverage for stabilization, decontamination, debris removal, repair and/or replacement of property, and decommissioning			$ 1,500
Excess coverage for stabilization, decontamination, debris removal, repair and/or replacement of property, and decommissioning			1,250
Combined coverage limit for total property damage			2,750
Total limit for property damage for non-nuclear events			2,000
Limit of coverage for aggregate extra expenses for non-nuclear events			$ 328
Period of coverage for extra expenses			2 years
Time period for TRIA after the first loss from terrorism			1 year
NEIL policies against terrorism loss, amount made available to all insured entities (up to)			$ 3,200
Maximum assessment if loss amount exceeds funds available			41
Public liability insurance for a nuclear incident			450
One industry aggregate limit of coverage arising from terrorist act outside scope of TRIA			300
Maximum deferred premium charges that could be levied against each licensed nuclear facility			138
Limit of deferred premium charges per year per facility			$ 20
Company obligated to pay DOE fee of Fermi 2 electricity generated and sold | $ / MWh		1
New DOE fee for Fermi 2 electricity generated and sold | kWh	0

Retirement Benefits and Trust_3

Retirement Benefits and Trusteed Assets (Pension Plan - Pension Cost Inclusions) (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 99	$ 92	$ 92
Interest cost	202	214	219
Expected return on plan assets	(329)	(311)	(309)
Amortization of:
Net actuarial loss	176	176	164
Prior service cost	0	1	1
Net pension cost/other postretirement credit	$ 148	$ 172	$ 167

Retirement Benefits and Trust_4

Retirement Benefits and Trusteed Assets (Pension Plan - Other Changes in Plan Assets and Benefit Obligations recognized in Reg Assets and OCI) (Details) - Pension plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other changes in plan assets and benefit obligations recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial loss	$ 125	$ 27
Amortization of net actuarial loss	(176)	(176)
Prior service credit	0	(11)
Amortization of prior service cost	0	(1)
Total recognized in Regulatory assets and Other comprehensive income (loss)	(51)	(161)
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	97	11
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	131	178
Prior service cost	$ 1	$ 0

Retirement Benefits and Trust_5

Retirement Benefits and Trusteed Assets (Pension Plan - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amounts recognized in Regulatory assets
Regulatory assets	$ 4,721	$ 3,778
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Accumulated benefit obligation, end of year	4,779	5,149
Change in projected benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	5,576	5,171
Service cost	99	92	$ 92
Interest cost	202	214	219
Plan amendments	0	(11)
Actuarial (gain) loss	(438)	391
Benefits paid	(315)	(281)
Projected/Accumulated postretirement benefit obligation, end of year	5,124	5,576	5,171
Change in plan assets
Plan assets at fair value, beginning of year	4,636	4,012
Actual return on plan assets	(233)	674
Company contributions	185	231
Benefits paid	(315)	(281)
Plan assets at fair value, end of year	4,273	4,636	$ 4,012
Funded status	(851)	(940)
Amount recorded as:
Current liabilities	(14)	(16)
Noncurrent liabilities	(837)	(924)
Defined benefit plans liabilities	(851)	(940)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial loss	152	163
Prior service cost	5	6
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	157	169
Amounts recognized in Regulatory assets
Net actuarial loss	1,973	2,014
Prior service credit	(12)	(14)
Regulatory assets	$ 1,961	$ 2,000

Retirement Benefits and Trust_6

Retirement Benefits and Trusteed Assets (Pension Plan - Contributions) (Details) - Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	$ 185	$ 231
Qualified Plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	175	223	$ 179
Qualified Plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Cash contributions to qualified pension plans	$ 175	$ 185	$ 145

Retirement Benefits and Trust_7

Retirement Benefits and Trusteed Assets (Pension Plan - Contributions to DTE Energy Company Affiliates Employee Benefit Plans Master Trust) (Details) - USD ($) $ / shares in Units, $ in Millions	Mar. 07, 2018	Dec. 31, 2018
Defined Contribution Plan Disclosure [Line Items]
Amount		$ 175
Pension Plan
Defined Contribution Plan Disclosure [Line Items]
Number of Shares (in shares)	1,751,401
Price per Share (in dollars per share)	$ 99.92
Amount	$ 175

Retirement Benefits and Trust_8

Retirement Benefits and Trusteed Assets (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized		$ 61	$ 57	$ 51
Annual contributions per employee, percentage		4.00%
DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized		$ 29	27	23
DTE Gas
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Annual contributions per employee, percentage		8.00%
Pension plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected return on plan assets for next fiscal year		7.30%
Pension plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Allocated pension benefit costs	$ 175	$ 120	136	136
Pension plan | Maximum
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions in next fiscal year		150
Pension plan | Maximum | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Estimated future employer contributions in next fiscal year		$ 100
Other postretirement benefit plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Expected return on plan assets for next fiscal year		7.75%
Retiree health care allowance will increase at lower of the rate of medical inflation or a set percentage		2.00%
Defined benefit plan, effect of one percentage point increase on service and interest cost components		$ 4
Defined benefit plan, effect of one percentage point increase on accumulated postretirement benefit obligation		72
Defined benefit plan, effect of one percentage point decrease on service and interest cost components		4
Defined benefit plan, effect of one percentage point decrease on accumulated postretirement benefit obligation		63
Other postretirement benefit plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined benefit plan, effect of one percentage point increase on service and interest cost components		3
Defined benefit plan, effect of one percentage point increase on accumulated postretirement benefit obligation		51
Defined benefit plan, effect of one percentage point decrease on service and interest cost components		3
Defined benefit plan, effect of one percentage point decrease on accumulated postretirement benefit obligation		45
Retiree healthcare plan
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized		11	8	6
Retiree healthcare plan | DTE Electric
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]
Defined contribution plan, cost recognized		$ 5	$ 5	$ 5

Retirement Benefits and Trust_9

Retirement Benefits and Trusteed Assets (Pension Plan - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) - Pension plan $ in Millions	Dec. 31, 2018USD ($)
Defined Benefit Plan, Expected Future Benefit Payment [Abstract]
2,019	$ 311
2,020	317
2,021	317
2,022	323
2,023	332
2024-2028	1,713
Total	$ 3,313

Retirement Benefits and Trus_10

Retirement Benefits and Trusteed Assets (Pension Plan - Assumptions used in Determining the PBO and Net Pension Costs) (Details) - Pension plan	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Projected benefit obligation
Discount rate	4.40%	3.70%	4.25%
Rate of compensation increase	4.98%	4.98%	4.65%
Net pension costs
Discount rate	3.70%	4.25%	4.50%
Rate of compensation increase	4.98%	4.65%	4.65%
Expected long-term rate of return on plan assets	7.50%	7.50%	7.75%

Retirement Benefits and Trus_11

Retirement Benefits and Trusteed Assets (Pension Plan - Target Allocations of Plan Assets) (Details) - Pension plan	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	100.00%
U.S. Large Capitalization (Cap) Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	16.00%
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	4.00%
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	15.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	42.00%
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	15.00%
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	8.00%

Retirement Benefits and Trus_12

Retirement Benefits and Trusteed Assets (Pension Plan - Fair Value Measurements) (Details) - Pension Plan - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 4,273	$ 4,636	$ 4,012
Assets valued at NAV	1,181	1,201
Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	27	114
U.S. Large Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	609	826
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	124	234
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	586	822
Assets valued at NAV	240	280
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,898	1,454
Assets valued at NAV	0	0
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	630	858
Assets valued at NAV	542	593
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	399	328
Assets valued at NAV	399	328
Securities Lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(30)	(66)
Securities Lending Collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	30	66
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,160	1,845
Level 1 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | U.S. Large Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	606	821
Level 1 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	123	229
Level 1 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	337	529
Level 1 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	6	1
Level 1 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	88	265
Level 1 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 1 | Securities Lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(22)	(53)
Level 1 | Securities Lending Collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	22	53
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,932	1,590
Level 2 | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	27	114
Level 2 | U.S. Large Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	3	5
Level 2 | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	5
Level 2 | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	9	13
Level 2 | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,892	1,453
Level 2 | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Level 2 | Securities Lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(8)	(13)
Level 2 | Securities Lending Collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 8	$ 13

Retirement Benefits and Trus_13

Retirement Benefits and Trusteed Assets (OPEB - Postretirement Cost Inclusions) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 27	$ 27	$ 27
Interest cost	69	73	80
Expected return on plan assets	(143)	(130)	(129)
Amortization of:
Net actuarial loss	11	13	30
Prior service credit	0	(14)	(118)
Other	0	0	(1)
Net pension cost/other postretirement credit	(36)	(31)	(111)
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Service cost	20	20	20
Interest cost	53	56	61
Expected return on plan assets	(98)	(90)	(90)
Amortization of:
Net actuarial loss	8	8	21
Prior service credit	0	(10)	(89)
Net pension cost/other postretirement credit	$ (17)	$ (16)	$ (77)

Retirement Benefits and Trus_14

Retirement Benefits and Trusteed Assets (OPEB - Other Changes in Plan Assets and APBO Recognized in Regulatory Assets and OCI) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial (gain) loss	$ (8)	$ (21)
Amortization of net actuarial loss	(11)	(13)
Prior service credit	(44)	(1)
Amortization of prior service (cost) credit	0	14
Total recognized in Regulatory assets and Other comprehensive income (loss)	(63)	(21)
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(99)	(52)
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	12	11
Prior service credit	(9)	(1)
DTE Electric
Other changes in plan assets and accumulated postretirement benefit obligation recognized in Regulatory assets and Other comprehensive income (loss)
Net actuarial (gain) loss	(46)	2
Amortization of net actuarial loss	(8)	(8)
Amortization of prior service (cost) credit	(35)	10
Total recognized in Regulatory assets and Other comprehensive income (loss)	(89)	4
Total recognized in net periodic pension cost, Regulatory assets, and Other comprehensive income (loss)	(106)	(12)
Estimated amounts to be amortized from Regulatory assets and Accumulated other comprehensive income (loss) into net periodic benefit cost during next fiscal year
Net actuarial loss	5	8
Prior service credit	$ (7)	$ 0

Retirement Benefits and Trus_15

Retirement Benefits and Trusteed Assets (OPEB - Reconciliation of Obligations, Assets and Funded Status of Plans) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Amounts recognized in Regulatory assets
Regulatory assets	$ 4,721	$ 3,778
Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,910	1,795
Service cost	27	27	$ 27
Interest cost	69	73	80
Plan amendments	(44)	0
Actuarial (gain) loss	(227)	101
Benefits paid	(90)	(86)
Projected/Accumulated postretirement benefit obligation, end of year	1,645	1,910	1,795
Change in plan assets
Plan assets at fair value, beginning of year	1,848	1,758
Actual return on plan assets	(75)	252
Benefits paid	(84)	(162)
Plan assets at fair value, end of year	1,689	1,848	1,758
Funded status	44	(62)
Amount recorded as:
Noncurrent assets	45	0
Current liabilities	(1)	(1)
Noncurrent liabilities	0	(61)
Defined benefit plans assets (liabilities)	44	(62)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial (gain) loss	1	(1)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	1	(1)
Amounts recognized in Regulatory assets
Net actuarial loss	257	279
Prior service credit	(44)	(1)
Regulatory assets	213	278
DTE Electric
Amounts recognized in Regulatory assets
Regulatory assets	3,977	3,055
DTE Electric | Other postretirement benefit plan
Change in accumulated postretirement benefit obligation
Projected/Accumulated postretirement benefit obligation, beginning of year	1,470	1,373
Service cost	20	20	20
Interest cost	53	56	61
Plan amendments	(35)	0
Actuarial (gain) loss	(196)	84
Benefits paid	(65)	(63)
Projected/Accumulated postretirement benefit obligation, end of year	1,247	1,470	1,373
Change in plan assets
Plan assets at fair value, beginning of year	1,272	1,218
Actual return on plan assets	(52)	172
Benefits paid	(62)	(118)
Plan assets at fair value, end of year	1,158	1,272	$ 1,218
Funded status	(89)	(198)
Amount recorded as:
Noncurrent assets	189	113
Current liabilities	0	0
Noncurrent liabilities	(278)	(311)
Defined benefit plans assets (liabilities)	(89)	(198)
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax
Net actuarial (gain) loss	0	0
Amounts recognized in Accumulated other comprehensive income (loss), pre-tax	0	0
Amounts recognized in Regulatory assets
Net actuarial loss	156	211
Prior service credit	(35)	0
Regulatory assets	$ 121	$ 211

Retirement Benefits and Trus_16

Retirement Benefits and Trusteed Assets (OPEB - Benefits related to Qualified and Nonqualified Pension Plans Expected to be paid in the Next Ten Years) (Details) - Other postretirement benefit plan $ in Millions	Dec. 31, 2018USD ($)
Defined Benefit Plan Disclosure [Line Items]
2,019	$ 88
2,020	92
2,021	96
2,022	100
2,023	102
2024-2028	532
Total	1,010
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
2,019	66
2,020	70
2,021	73
2,022	75
2,023	77
2024-2028	402
Total	$ 763

Retirement Benefits and Trus_17

Retirement Benefits and Trusteed Assets (OPEB - Assumptions used in Determining the PBO and Net Pension Costs) (Details)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accumulated postretirement benefit obligation
Ultimate health care trend rate			4.50%
Other postretirement benefit costs
Ultimate health care trend rate			4.50%
Other postretirement benefit plan
Accumulated postretirement benefit obligation
Discount rate	4.40%	3.70%	4.25%
Health care trend rate pre- 65	6.75%	6.75%	6.50%
Health care trend post- 65	7.25%	7.25%	6.75%
Ultimate health care trend rate	4.50%	4.50%	4.50%
Other postretirement benefit costs
Discount rate	3.70%	4.25%	4.50%
Expected long-term rate of return on plan assets	7.75%	7.75%	8.00%
Health care trend rate pre- 65	6.75%	6.50%	6.25%
Health care trend post- 65	7.25%	6.75%	6.75%
Ultimate health care trend rate	4.50%	4.50%	4.50%

Retirement Benefits and Trus_18

Retirement Benefits and Trusteed Assets (OPEB - Target Allocations of Plan Assets) (Details) - Other postretirement benefit plan	Dec. 31, 2018
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	100.00%
U.S. Large Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	16.00%
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	4.00%
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	19.00%
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	28.00%
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	19.00%
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Target allocation percentage of assets	14.00%

Retirement Benefits and Trus_19

Retirement Benefits and Trusteed Assets (OPEB - Fair Value Measurements) (Details) - Other postretirement benefit plan - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 1,689	$ 1,848	$ 1,758
Assets valued at NAV	681	660
Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	656	861
Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	352	327
Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	16	15
Short-term Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	14	13
Short-term Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	2	2
U.S. Large Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	225	284
U.S. Large Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	225	284
U.S. Large Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	75	131
U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	75	131
U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	301	366
Assets valued at NAV	67	77
Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	234	288
Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	1
Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	491	483
Assets valued at NAV	130	130
Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	11	29
Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	350	324
Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	300	335
Assets valued at NAV	203	219
Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	97	116
Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	281	234
Assets valued at NAV	281	234
Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
Securities Lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(22)	(40)
Securities Lending | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(21)	(39)
Securities Lending | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(1)	(1)
Securities Lending Collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	22	40
Securities Lending Collateral | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	21	39
Securities Lending Collateral | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	1
DTE Electric
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1,158	1,272	$ 1,218
Assets valued at NAV	471	457
DTE Electric | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	454	595
DTE Electric | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	233	220
DTE Electric | Short-term Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	11	10
DTE Electric | Short-term Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	10	9
DTE Electric | Short-term Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	1	1
DTE Electric | U.S. Large Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	154	195
DTE Electric | U.S. Large Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	154	195
DTE Electric | U.S. Large Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	52	91
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	52	91
DTE Electric | U.S. Small Cap and Mid Cap Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Non-U.S. Equity Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	208	253
Assets valued at NAV	45	52
DTE Electric | Non-U.S. Equity Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	163	200
DTE Electric | Non-U.S. Equity Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	1
DTE Electric | Fixed Income Securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	331	330
Assets valued at NAV	92	92
DTE Electric | Fixed Income Securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	7	20
DTE Electric | Fixed Income Securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	232	218
DTE Electric | Hedge Funds and Similar Investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	207	230
Assets valued at NAV	139	150
DTE Electric | Hedge Funds and Similar Investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	68	80
DTE Electric | Hedge Funds and Similar Investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Private Equity and Other
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	195	163
Assets valued at NAV	195	163
DTE Electric | Private Equity and Other | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Private Equity and Other | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	0
DTE Electric | Securities Lending
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(15)	(28)
DTE Electric | Securities Lending | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	(15)	(27)
DTE Electric | Securities Lending | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	0	(1)
DTE Electric | Securities Lending Collateral
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	15	28
DTE Electric | Securities Lending Collateral | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	15	27
DTE Electric | Securities Lending Collateral | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets at fair value	$ 0	$ 1

Stock-Based Compensation (Detai

Stock-Based Compensation (Details)	12 Months Ended
	Dec. 31, 2018USD ($)shares	Dec. 31, 2017USD ($)shares	Dec. 31, 2016USD ($)shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Authorized limit of common stock shares (in shares)	16,500,000
Performance units price per unit (in dollars per share)	1
Remaining contractual term (in years)	1 year 1 month 10 days
Options vested (in shares)	0
Options grants in period (in shares)	0	0
Options, exercises, intrinsic value | $	$ 4,000,000	$ 4,000,000	$ 4,000,000
Stock option expense | $	0	0	0
DTE Electric | DTE Energy
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation cost charged against income (in millions) | $	$ 38,000,000	34,000,000	38,000,000
Stock Options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	500,000
Award expiration period	10 years
Award vesting period	3 years
Restricted Stock Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	150,000
Award vesting period	3 years
Compensation cost charged against income (in millions) | $	$ 11,000,000	$ 11,000,000	$ 11,000,000
Performance Share Awards
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	300,000
Award vesting period	3 years
Performance Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum award per employee (in shares)	1,000,000

Stock-Based Compensation (Compo

Stock-Based Compensation (Components of Stock Based Compensation) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of stock based-compensation [Abstract]
Stock-based compensation expense	$ 64	$ 58	$ 61
Tax benefit	13	23	24
Stock-based compensation cost capitalized in Property, plant, and equipment	$ 11	$ 9	$ 10

Stock-Based Compensation (Stock

Stock-Based Compensation (Stock Option Activity) (Details) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)$ / sharesshares
Number of Options
Options outstanding beginning of the year (in shares) | shares	105,994
Exercised (in shares) | shares	(53,894)
Options outstanding end of the year (in shares) | shares	52,100
Weighted Average Exercise Price
Options outstanding beginning of the year (in dollars per share) | $ / shares	$ 42.95
Exercised (in dollars per share) | $ / shares	42.62
Options outstanding end of the year (in dollars per share) | $ / shares	$ 43.30
Options outstanding, Aggregate Intrinsic Value | $	$ 4

Stock-Based Compensation (Numbe

Stock-Based Compensation (Number, Weighted Average Exercise Price and Weighted Average Remaining Contractual Life of Options Outstanding) (Details)	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Number of Options (in shares) | shares	52,100
Weighted Average Exercise Price (in dollars per share)	$ 43.30
Weighted Average Remaining Contractual Life (Years)	1 year 1 month 10 days
$27.00 - $38.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 27
Range of Exercise Prices Upper Limit (in dollars per share)	$ 38
Number of Options (in shares) | shares	2,100
Weighted Average Exercise Price (in dollars per share)	$ 27.70
Weighted Average Remaining Contractual Life (Years)	1 month 28 days
$42.01 - $45.00
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Range of Exercise Prices Lower Limit (in dollars per share)	$ 42.01
Range of Exercise Prices Upper Limit (in dollars per share)	$ 45
Number of Options (in shares) | shares	50,000
Weighted Average Exercise Price (in dollars per share)	$ 43.95
Weighted Average Remaining Contractual Life (Years)	1 year 1 month 24 days

Stock-Based Compensation (Restr

Stock-Based Compensation (Restricted Stock Award Activity) (Details) - Restricted Stock Awards - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Fair value of awards vested	$ 11	$ 10	$ 9
Restricted common shares awarded (in shares)	109,393	136,825	145,240
Weighted average market price of shares awarded (in dollars per share)	$ 105.80	$ 99.53	$ 87.28
Compensation cost charged against income	$ 11	$ 11	$ 11

Stock Based-Compensation (Stock

Stock Based-Compensation (Stock Awards Activity Rollforward) (Details) - Restricted Stock - $ / shares	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restricted Stock
Balance at beginning of the period (in shares)	365,764
Grants (in shares)	109,393	136,825	145,240
Forfeitures (in shares)	(21,939)
Vested and issued (in shares)	(125,813)
Balance at end of period (in shares)	327,405	365,764
Weighted Average Grant Date Fair Value
Balance at beginning of period (in dollars per share)	$ 90.26
Grants (in dollars per share)	105.80	$ 99.53	$ 87.28
Forfeitures (in dollars per share)	98.59
Vested and issued (in dollars per share)	85.24
Balance at end of period (in dollars per share)	$ 96.79	$ 90.26

Stock-Based Compensation (Perfo

Stock-Based Compensation (Performance Share Awards Compensation Expense) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Compensation Expense Recorded [Line Items]
Compensation expense	$ 64	$ 58	$ 61
Performance Share Awards
Compensation Expense Recorded [Line Items]
Compensation expense	53	47	50
Cash settlements	13	15	7
Stock settlements	$ 39	$ 66	$ 38

Stock-Based Compensation (Per_2

Stock-Based Compensation (Performance Share Awards Activity) (Details) - Performance shares	12 Months Ended
	Dec. 31, 2018$ / sharesshares
Performance Shares
Balance at beginning of period (in shares) | shares	1,324,401
Grants (in shares) | shares	437,508
Forfeitures (in shares) | shares	(56,435)
Payouts (in shares) | shares	(418,788)
Balance at end of period (in shares) | shares	1,286,686
Weighted Average Grant Date Fair Value
Balance at beginning of period (in dollars per share) | $ / shares	$ 90.31
Grants (in dollars per share) | $ / shares	105.64
Forfeitures (in dollars per share) | $ / shares	96.02
Payouts (in dollars per share) | $ / shares	84.84
Balance at end of period (in dollars per share) | $ / shares	$ 97.17

Stock-Based Compensation (Unrec

Stock-Based Compensation (Unrecognized Compensation Costs) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2018USD ($)
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 71
Weighted Average to be Recognized	1 year 15 days
Stock awards
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 12
Weighted Average to be Recognized	1 year 11 days
Performance shares
Share Based Compensation Unrecognized and Non-Vested Cost [Line Items]
Unrecognized Compensation Cost	$ 59
Weighted Average to be Recognized	1 year 15 days

Segment and Related Informati_3

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

Segment and Related Informati_4

Segment and Related Information (Financial Data - Inter-Segment Billing) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ (3,750)	$ (3,550)	$ (3,159)	$ (3,753)	$ (3,271)	$ (3,245)	$ (2,855)	$ (3,236)	$ (14,212)	$ (12,607)	$ (10,630)
Electric
Segment Reporting Information [Line Items]
Revenues									(5,298)
Gas
Segment Reporting Information [Line Items]
Revenues									(1,436)
Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Revenues									(485)
Power and Industrial Projects
Segment Reporting Information [Line Items]
Revenues									(2,204)
Energy Trading
Segment Reporting Information [Line Items]
Revenues									(5,557)
Reclassifications and Eliminations
Segment Reporting Information [Line Items]
Revenues									771	704	704
Reclassifications and Eliminations | Electric
Segment Reporting Information [Line Items]
Revenues									52	48	43
Reclassifications and Eliminations | Gas
Segment Reporting Information [Line Items]
Revenues									12	8	9
Reclassifications and Eliminations | Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Revenues									36	42	9
Reclassifications and Eliminations | Power and Industrial Projects
Segment Reporting Information [Line Items]
Revenues									642	569	602
Reclassifications and Eliminations | Energy Trading
Segment Reporting Information [Line Items]
Revenues									27	35	39
Reclassifications and Eliminations | Corporate and Other
Segment Reporting Information [Line Items]
Revenues									$ 2	$ 2	$ 2

Segment and Related Informati_5

Segment and Related Information (Financial Data - Operating Revenues Including Inter-Segment Revenues) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									$ 6,670	$ 6,434	$ 6,497
Operating Revenues — Non-utility operations									7,542	6,173	4,133
Depreciation and amortization									1,124	1,030	976
Interest expense									559	536	472
Interest income									(12)	(12)	(20)
Equity in earnings of equity method investees									132	102	68
Income Tax Expense (Benefit)									98	175	271
Net Income (Loss) Attributable to DTE Energy Company	$ 191	$ 334	$ 234	$ 361	$ 287	$ 270	$ 177	$ 400	1,120	1,134	868
Investments in equity method investees	1,771				1,073				1,771	1,073	752
Capital expenditures and acquisitions									2,713	2,250	3,269
Goodwill	2,293				2,293				2,293	2,293	2,286
Total Assets	36,288				33,767				36,288	33,767	32,041
Effect of the Tax Cuts and Jobs Act of 2017					(105)				21	(105)	0
Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Investments in equity method investees	1,585				879				1,585	879
Operating Segments | Electric
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									5,298	5,102	5,225
Operating Revenues — Non-utility operations									0	0	0
Depreciation and amortization									836	753	750
Interest expense									283	274	264
Interest income									0	0	(8)
Equity in earnings of equity method investees									0	1	2
Income Tax Expense (Benefit)									193	321	353
Net Income (Loss) Attributable to DTE Energy Company									664	606	622
Investments in equity method investees	7				7				7	7	11
Capital expenditures and acquisitions									1,979	1,574	1,503
Goodwill	1,208				1,208				1,208	1,208	1,208
Total Assets	22,501				21,163				22,501	21,163	20,417
Operating Segments | Electric | Non-utility Entities
Segment Reporting Information [Line Items]
Effect of the Tax Cuts and Jobs Act of 2017										(5)
Operating Segments | Gas
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									1,436	1,388	1,324
Operating Revenues — Non-utility operations									0	0	0
Depreciation and amortization									133	123	106
Interest expense									70	65	60
Interest income									(6)	(7)	(6)
Equity in earnings of equity method investees									2	2	6
Income Tax Expense (Benefit)									67	78	77
Net Income (Loss) Attributable to DTE Energy Company									150	146	138
Investments in equity method investees	12				11				12	11	10
Capital expenditures and acquisitions									460	463	395
Goodwill	743				743				743	743	743
Total Assets	5,378				5,072				5,378	5,072	4,729
Operating Segments | Gas Storage and Pipelines
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									485	453	302
Depreciation and amortization									82	76	45
Interest expense									68	77	39
Interest income									(9)	(14)	(9)
Equity in earnings of equity method investees									123	90	60
Income Tax Expense (Benefit)									68	(30)	71
Net Income (Loss) Attributable to DTE Energy Company									235	275	119
Investments in equity method investees	1,585				879				1,585	879	538
Capital expenditures and acquisitions									176	137	1,322
Goodwill	299				299				299	299	292
Total Assets	3,161				2,594				3,161	2,594	2,417
Effect of the Tax Cuts and Jobs Act of 2017										(115)
Operating Segments | Power and Industrial Projects
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									2,204	2,089	1,906
Depreciation and amortization									67	72	72
Interest expense									31	29	32
Interest income									(9)	(7)	(8)
Equity in earnings of equity method investees									3	9	0
Income Tax Expense (Benefit)									(195)	(195)	(140)
Net Income (Loss) Attributable to DTE Energy Company									161	138	95
Investments in equity method investees	134				150				134	150	166
Capital expenditures and acquisitions									91	56	39
Goodwill	26				26				26	26	26
Total Assets	495				593				495	593	683
Effect of the Tax Cuts and Jobs Act of 2017										(21)
Operating Segments | Energy Trading
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									5,557	4,277	2,575
Depreciation and amortization									5	5	3
Interest expense									6	5	6
Interest income									(3)	(2)	(1)
Equity in earnings of equity method investees									0	0	0
Income Tax Expense (Benefit)									13	49	(29)
Net Income (Loss) Attributable to DTE Energy Company									39	72	(45)
Investments in equity method investees	0				0				0	0	0
Capital expenditures and acquisitions									5	7	7
Goodwill	17				17				17	17	17
Total Assets	909				725				909	725	660
Effect of the Tax Cuts and Jobs Act of 2017										2
Operating Segments | Corporate and Other
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									0	0	0
Operating Revenues — Non-utility operations									3	2	2
Depreciation and amortization									1	1	0
Interest expense									220	192	148
Interest income									(104)	(88)	(65)
Equity in earnings of equity method investees									4	0	0
Income Tax Expense (Benefit)									(48)	(48)	(61)
Net Income (Loss) Attributable to DTE Energy Company									(129)	(103)	(61)
Investments in equity method investees	33				26				33	26	27
Capital expenditures and acquisitions									2	13	3
Goodwill	0				0				0	0	0
Total Assets	6,153				5,324				6,153	5,324	4,648
Effect of the Tax Cuts and Jobs Act of 2017										34
Reclassifications and Eliminations
Segment Reporting Information [Line Items]
Operating Revenues — Utility operations									(64)	(56)	(52)
Operating Revenues — Non-utility operations									(707)	(648)	(652)
Depreciation and amortization									0	0	0
Interest expense									(119)	(106)	(77)
Interest income									119	106	77
Equity in earnings of equity method investees									0	0	0
Income Tax Expense (Benefit)									0	0	0
Net Income (Loss) Attributable to DTE Energy Company									0	0	0
Investments in equity method investees	0				0				0	0	0
Capital expenditures and acquisitions									0	0	0
Goodwill	0				0				0	0	0
Total Assets	$ (2,309)				$ (1,704)				$ (2,309)	$ (1,704)	$ (1,513)

Related Party Transactions (Det

Related Party Transactions (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Related Party Transaction [Line Items]
Dividends declared	$ 653,000,000	$ 602,000,000	$ 548,000,000
Dividends paid	620,000,000	592,000,000	531,000,000
DTE Electric
Related Party Transaction [Line Items]
Other services	(4,000,000)	(4,000,000)	(1,000,000)
Dividends declared	461,000,000	432,000,000	420,000,000
Dividends paid	461,000,000	432,000,000	420,000,000
DTE Electric | Energy sales
Related Party Transaction [Line Items]
Revenues	9,000,000	9,000,000	10,000,000
DTE Electric | Shared capital assets
Related Party Transaction [Line Items]
Revenues	43,000,000	39,000,000	33,000,000
DTE Electric | Fuel and purchased power
Related Party Transaction [Line Items]
Costs	7,000,000	6,000,000	10,000,000
DTE Electric | Other services and interest
Related Party Transaction [Line Items]
Costs	33,000,000	(2,000,000)	(1,000,000)
DTE Electric | Corporate expenses, net
Related Party Transaction [Line Items]
Costs	377,000,000	370,000,000	370,000,000
DTE Electric | DTE Energy
Related Party Transaction [Line Items]
Dividends declared	461,000,000	432,000,000	420,000,000
Dividends paid	461,000,000	432,000,000	420,000,000
Capital contribution from DTE Energy	325,000,000	100,000,000	120,000,000
DTE Electric | DTE Energy Foundation
Related Party Transaction [Line Items]
Charitable contributions to foundation	$ 0	$ 7,000,000	$ 0

Supplementary Quarterly Finan_3

Supplementary Quarterly Financial Information (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Entity Information [Line Items]
Operating Revenues	$ 3,750	$ 3,550	$ 3,159	$ 3,753	$ 3,271	$ 3,245	$ 2,855	$ 3,236	$ 14,212	$ 12,607	$ 10,630
Operating Income	332	429	329	504	372	434	320	585	1,594	1,711	1,486
Net Income	$ 191	$ 334	$ 234	$ 361	$ 287	$ 270	$ 177	$ 400	$ 1,120	$ 1,134	$ 868
Basic Earnings per Share (in dollars per share)	$ 1.05	$ 1.84	$ 1.29	$ 2.01	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 6.18	$ 6.32	$ 4.84
Diluted Earnings per Share (in dollars per share)	$ 1.05	$ 1.84	$ 1.29	$ 2	$ 1.60	$ 1.51	$ 0.99	$ 2.23	$ 6.17	$ 6.32	$ 4.83
Effect of the Tax Cuts and Jobs Act of 2017					$ (105)				$ 21	$ (105)	$ 0
DTE Electric
Entity Information [Line Items]
Operating Revenues	$ 1,296	$ 1,521	$ 1,276	$ 1,205	1,275	$ 1,434	$ 1,218	$ 1,175	5,298	5,102
Operating Income	168	444	269	253	281	395	272	217	1,134	1,165	1,204
Net Income	$ 56	$ 305	$ 163	$ 140	$ 138	$ 219	$ 138	$ 106	664	601	622
Effect of the Tax Cuts and Jobs Act of 2017									$ 7	$ 0	$ 0

Schedule II - Valuation and Q_2

Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	$ 49
Additions:
Balance at End of Period	91	$ 49
DTE Electric
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	31
Additions:
Balance at End of Period	53	31
Allowance for Doubtful Accounts
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	49	41	$ 49
Additions:
Charged to costs and expenses	140	80	78
Charged to other accounts	55	26	18
Deductions	(153)	(98)	(104)
Balance at End of Period	91	49	41
Allowance for Doubtful Accounts | DTE Electric
Allowance for Doubtful Accounts (shown as deduction from Accounts receivable in DTE Energy's Consolidated Statements of Financial Position)
Balance at Beginning of Period	31	25	28
Additions:
Charged to costs and expenses	85	55	49
Charged to other accounts	36	14	8
Deductions	(99)	(63)	(60)
Balance at End of Period	$ 53	$ 31	$ 25

Uncategorized Items - dte-20181

Label	Element	Value
Accounting Standards Update 2016-09 [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 3,000,000
Accounting Standards Update 2016-09 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ 3,000,000