| Significant Accounting Policies (Policies) | 12 Months Ended |
| Dec. 31, 2016 |
| Accounting Policies [Abstract] | |
| Basis of Presentation | Basis of Presentation The accompanying Consolidated Financial Statements of the Registrants are prepared using accounting principles generally accepted in the United States of America. These accounting principles require management to use estimates and assumptions that impact reported amounts of assets, liabilities, revenues and expenses, and the disclosure of contingent assets and liabilities. Actual results may differ from the Registrants' estimates. The information in these combined notes relates to each of the Registrants as noted in the Index of Combined Notes to Consolidated Financial Statements. However, DTE Electric does not make any representation as to information related solely to DTE Energy or the subsidiaries of DTE Energy other than itself. |
| Reclassification | Certain prior year balances for the Registrants were reclassified to match the current year's Consolidated Financial Statements presentation. |
| Principles of Consolidation | Principles of Consolidation The Registrants consolidate all majority-owned subsidiaries and investments in entities in which they have controlling influence. Non-majority owned investments are accounted for using the equity method when the Registrants are able to significantly influence the operating policies of the investee. When the Registrants do not influence the operating policies of an investee, the cost method is used. These Consolidated Financial Statements also reflect the Registrants' proportionate interests in certain jointly-owned utility plants. The Registrants eliminate all intercompany balances and transactions. The Registrants evaluate whether an entity is a VIE whenever reconsideration events occur. The Registrants consolidate VIEs for which they are the primary beneficiary. If a Registrant is not the primary beneficiary and an ownership interest is held, the VIE is accounted for under the equity method of accounting. When assessing the determination of the primary beneficiary, a Registrant considers all relevant facts and circumstances, including: the power, through voting or similar rights, to direct the activities of the VIE that most significantly impact the VIE's economic performance and the obligation to absorb the expected losses and/or the right to receive the expected returns of the VIE. The Registrants perform ongoing reassessments of all VIEs to determine if the primary beneficiary status has changed. Legal entities within DTE Energy's Power and Industrial Projects segment enter into long-term contractual arrangements with customers to supply energy-related products or services. The entities are generally designed to pass-through the commodity risk associated with these contracts to the customers, with DTE Energy retaining operational and customer default risk. These entities generally are VIEs and consolidated when DTE Energy is the primary beneficiary. In addition, DTE Energy has interests in certain VIEs through which control of all significant activities is shared with partners, and therefore are accounted for under the equity method. DTE Energy acquired a 55% interest in SGG in October 2016 . SGG owns and operates midstream natural gas assets. SGG has contracts through which certain construction risk is designed to pass-through to the customers, with DTE Energy retaining operational and customer default risk. SGG is a VIE with DTE Energy as the primary beneficiary. See Note 4 to the Consolidated Financial Statements, " Acquisitions and Exit Activities ," for more information. 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, 2016 , 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, 2016 , 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. For non-consolidated VIEs, the maximum risk exposure is generally limited to its investment, notes receivable, and future funding commitments. The following table summarizes the major Consolidated Statements of Financial Position items for consolidated VIEs as of December 31, 2016 and 2015 . 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. |
| Revenues | Revenues The Registrants' revenues from the sale and delivery of electricity, and DTE Energy's revenues from the sale, delivery, and storage of natural gas are recognized as services are provided. DTE Electric and DTE Gas record revenues for electricity and gas provided but unbilled at the end of each month. Rates for DTE Electric and DTE Gas include provisions to adjust billings for fluctuations in fuel and purchased power costs, cost of natural gas, and certain other costs. Revenues are adjusted for differences between actual costs subject to reconciliation and the amounts billed in current rates. Under or over recovered revenues related to these cost recovery mechanisms are included in Regulatory assets or liabilities on the Registrants' Consolidated Statements of Financial Position and are recovered or returned to customers through adjustments to the billing factors. For further discussion of recovery mechanisms authorized by the MPSC, see Note 9 to the Consolidated Financial Statements, " Regulatory Matters ." DTE Energy's non-utility businesses recognize revenues as services are provided and products are delivered. |
| Other Income | Other Income Other income for the Registrants is recognized for non-operating income such as equity earnings of equity method investees, allowance for equity funds used during construction, contract services, and gains (losses) from trading securities. DTE Energy's Power and Industrial Projects segment also recognizes Other income in connection with the sale of membership interests in reduced emissions fuel facilities to investors. In exchange for the cash received, the investors will receive a portion of the economic attributes of the facilities, including income tax attributes. The transactions are not treated as a sale of membership interests for financial reporting purposes. Other income is considered earned when refined coal is produced and tax credits are generated. |
| Accounting For ISO Transactions | Accounting for ISO Transactions DTE Electric participates in the energy market through MISO. MISO requires that DTE Electric submit hourly day-ahead, real-time, and FTR bids and offers for energy at locations across the MISO region. DTE Electric accounts for MISO transactions on a net hourly basis in each of the day-ahead, real-time, and FTR markets and net transactions across all MISO energy market locations. In any single hour DTE Electric records net purchases in Fuel, purchased power, and gas — utility and net sales in Operating Revenues — Utility operations on the Registrants' Consolidated Statements of Operations. The Energy Trading segment participates in the energy markets through various ISOs and RTOs. These markets require that Energy Trading submits hourly day-ahead, real-time bids and offers for energy at locations across each region. Energy Trading submits bids in the annual and monthly auction revenue rights and FTR auctions to the RTOs. Energy Trading accounts for these transactions on a net hourly basis for the day-ahead, real-time, and FTR markets. These transactions are related to trading contracts which, if derivatives, are presented on a net basis in Operating Revenues — Non-utility operations, and if non-derivatives, the realized gains and losses for sales are recorded in Operating Revenues — Non-utility operations and purchases are recorded in Fuel, purchased power, and gas — non-utility in the DTE Energy Consolidated Statements of Operations. DTE Electric and Energy Trading record accruals for future net purchases adjustments based on historical experience, and reconcile accruals to actual costs when invoices are received from MISO and other ISOs and RTOs. |
| Changes in Accumulated Other Comprehensive Income (Loss) | Changes in Accumulated Other Comprehensive Income (Loss) Comprehensive income (loss) is the change in common shareholders’ equity during a period from transactions and events from non-owner sources, including Net Income. The amounts recorded to Accumulated other comprehensive income (loss) for the Registrants include unrealized gains and losses on available-for-sale securities and changes in benefit obligations, consisting of deferred actuarial losses and prior service costs. The amounts recorded to Accumulated other comprehensive income (loss) relating solely to DTE Energy also include unrealized gains and losses from derivatives accounted for as cash flow hedges, DTE Energy's interest in other comprehensive income of equity investees which comprise the net unrealized gains and losses on investments, and foreign currency translation adjustments. |
| Cash, Cash Equivalents, and Restricted Cash | Cash, Cash Equivalents, and Restricted Cash Cash and cash equivalents include cash on hand, cash in banks, and temporary investments purchased with remaining maturities of three months or less. Restricted cash consists of funds held to satisfy requirements of certain debt and DTE Energy partnership operating agreements. Restricted cash designated for interest and principal payments within one year is classified as a Current Asset. |
| Receivables | 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 $814 million and $620 million , including $267 million and $237 million of DTE Electric unbilled revenues, are included in Customer Accounts receivable at December 31, 2016 and 2015 , respectively. Notes Receivable Notes receivable, or financing receivables, for DTE Energy are primarily comprised of capital lease receivables and loans and are included in Notes receivable and Other current assets on DTE Energy’s Consolidated Statements of Financial Position. Notes receivable, or financing receivables, for DTE Electric are primarily comprised of loans. Notes receivable are typically considered delinquent when payment is not received for periods ranging from 60 to 120 days. The Registrants cease accruing interest (nonaccrual status), consider a note receivable impaired, and establish an allowance for credit loss when it is probable that all principal and interest amounts due will not be collected in accordance with the contractual terms of the note receivable. Cash payments received on nonaccrual status notes receivable, that do not bring the account contractually current, are first applied to contractually owed past due interest, with any remainder applied to principal. Accrual of interest is generally resumed when the note receivable becomes contractually current. In determining the allowance for credit losses for notes receivable, the Registrants consider the historical payment experience and other factors that are expected to have a specific impact on the counterparty’s ability to pay. In addition, the Registrants monitor the credit ratings of the counterparties from which they have Notes receivable. |
| Inventories | Inventories Inventory related to utility operations is generally valued at average cost. Inventory related to non-utility operations is valued at the lower of cost or market. |
| Property, Retirement and Maintenance, and Depreciation and Amortization | Property, Retirement and Maintenance, and Depreciation and Amortization Property is stated at cost and includes construction-related labor, materials, overheads, and AFUDC for utility property. The cost of utility properties retired is charged to accumulated depreciation. Expenditures for maintenance and repairs are charged to expense when incurred, except for Fermi 2. Utility property at DTE Electric and DTE Gas is depreciated over its estimated useful life using straight-line rates approved by the MPSC. DTE Energy's non-utility property is depreciated over its estimated useful life using the straight-line method. Depreciation and amortization expense also includes the amortization of certain regulatory assets for the Registrants. The cost of nuclear fuel is capitalized. The amortization of nuclear fuel is included within Fuel, purchased power, and gas — utility in the DTE Energy Consolidated Statements of Operations, and Fuel and purchased power in the DTE Electric Consolidated Statements of Operations, and is recorded using the units-of-production method. Capitalized software costs are classified as Property, plant, and equipment and the related amortization is included in accumulated depreciation and amortization on the Registrants' Consolidated Financial Statements. The Registrants capitalize the costs associated with computer software developed or obtained for use in their businesses. The Registrants amortize capitalized software costs on a straight-line basis over the expected period of benefit, ranging from 3 to 15 years for DTE Energy and 4 to 15 years for DTE Electric. |
| Long-Lived Assets | Long-Lived Assets Long-lived assets are reviewed for impairment whenever events or changes in circumstances indicate the carrying amount of an asset may not be recoverable. If the carrying amount of the asset exceeds the expected discounted future cash flows generated by the asset, an impairment loss is recognized resulting in the asset being written down to its estimated fair value. Assets to be disposed of are reported at the lower of the carrying amount or fair value, less costs to sell. |
| Intangible Assets | DTE Energy amortizes customer relationship and contract intangible assets on a straight-line basis over the expected period of benefit. |
| Excise and Sales Taxes/ Income Taxes | Excise and Sales Taxes The Registrants record the billing of excise and sales taxes as a receivable with an offsetting payable to the applicable taxing authority, with no net impact on the Registrants’ Consolidated Statements of Operations. Deferred tax assets and liabilities are recognized for the estimated future tax effect of temporary differences between the tax basis of assets or liabilities and the reported amounts in the Consolidated Financial Statements. The federal income tax provisions or benefits of DTE Energy’s subsidiaries are determined on an individual company basis and recognize the tax benefit of tax credits and net operating losses, if applicable. The state and local income tax provisions of the utility subsidiaries are determined on an individual company basis and recognize the tax benefit of various tax credits and net operating losses, if applicable. The subsidiaries record federal, state, and local income taxes payable to or receivable from DTE Energy based on the federal, state, and local tax provisions of each company. |
| Deferred Debt Costs | Deferred Debt Costs The costs related to the issuance of long-term debt are deferred and amortized over the life of each debt issue. The deferred amounts are included as a direct deduction from the carrying amount of each debt issue in Mortgage bonds, notes, and other and Junior subordinated debentures on DTE Energy's Consolidated Statements of Financial Position and in Mortgage bonds, notes, and other on DTE Electric's Consolidated Statements of Financial Position. In accordance with MPSC regulations applicable to DTE Energy’s electric and gas utilities, the unamortized discount, premium, and expense related to utility debt redeemed with a refinancing are amortized over the life of the replacement issue. Discount, premium, and expense on early redemptions of debt associated with DTE Energy's non-utility operations are charged to earnings. |
| Investments in Debt and Equity Securities | Investments in Debt and Equity Securities The Registrants generally classify investments in debt and equity securities as either trading or available-for-sale and have recorded such investments at market value with unrealized gains or losses included in earnings or in Other comprehensive income or loss, respectively. Changes in the fair value of Fermi 2 nuclear decommissioning investments are recorded as adjustments to Regulatory assets or liabilities, due to a recovery mechanism from customers. The Registrants' equity investments are reviewed for impairment each reporting period. If the assessment indicates that the impairment is other than temporary, a loss is recognized resulting in the equity investment being written down to its estimated fair value. |
| Government Grants | Government Grants Grants are recognized when there is reasonable assurance that the grant will be received and that any conditions associated with the grant will be met. When grants are received related to Property, plant, and equipment, the Registrants reduce the cost of the assets on their Consolidated Statements of Financial Position, resulting in lower depreciation expense over the life of the associated asset. Grants received related to expenses are reflected as a reduction of the associated expense in the period in which the expense is incurred. |
| DTE Energy Foundation | DTE Energy Foundation DTE Energy's charitable contributions to the DTE Energy Foundation were $26 million , $12 million , and $25 million for the years ended December 31, 2016 , 2015 , and 2014 , 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 February 2015, the FASB issued ASU No. 2015-02, Amendments to the Consolidation Analysis , which changes the analysis that a reporting entity must perform to determine whether it should consolidate certain types of legal entities. The ASU affects (1) limited partnerships and similar legal entities, (2) evaluating fees paid to a decision maker or a service provider as a variable interest, (3) the effect of fee arrangements on the primary beneficiary determination, (4) the effect of related parties on the primary beneficiary determination, and (5) certain investment funds. It is effective for the Registrants for the first interim period within annual reporting periods beginning after December 15, 2015. The Registrants adopted this ASU at January 1, 2016. The implementation of this guidance is reflected in Note 1 of the Consolidated Financial Statements, " Organization and Basis of Presentation ." Certain entities are now deemed to be VIEs and are included in DTE Energy's non-consolidated VIE table. This implementation did not have a significant impact on the Registrants' Consolidated Financial Statements. In April 2015, the FASB issued ASU No. 2015-03, Simplifying the Presentation of Debt Issuance Costs . This ASU requires that debt issuance costs related to a recognized debt liability be presented in the balance sheet as a direct deduction from the carrying amount of that debt liability, consistent with debt discounts. This ASU is effective for reporting periods beginning after December 15, 2015 and interim periods therein. It is to be applied retrospectively. The Registrants adopted this ASU at January 1, 2016. The implementation of this guidance is reflected in Note 14 of the Consolidated Financial Statements, " Long-Term Debt ." The effect of the adoption decreased assets and liabilities on DTE Energy's and DTE Electric's Consolidated Statements of Financial Position by $75 million and $36 million , respectively, at December 31, 2015. In May 2015, the FASB issued ASU 2015-07, Fair Value Measurement (Topic 820): Disclosures for Investments in Certain Entities That Calculate Net Asset Value per Share (or Its Equivalent). This guidance removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value per share (or its equivalent) practical expedient. The guidance applies to investments for which there is not a readily determinable fair value (market quote) or the investment is in a mutual fund without a publicly available net asset value. It is effective for the Registrants for the first interim period within annual reporting periods beginning after December 15, 2015. It is to be applied retrospectively. The Registrants adopted this ASU at January 1, 2016. The implementation of this guidance is reflected in Notes 12 and 20 to the Consolidated Financial Statements, " Fair Value " and " Retirement Benefits and Trusteed Assets ," respectively. This implementation did not have a significant impact on the Registrants' Consolidated Financial Statements. In March 2016, the FASB issued ASU No. 2016-09, Compensation — Stock Compensation (Topic 718): Improvements to Employee Share-Based Payment Accounting. The ASU simplifies several aspects of the accounting for share-based payment transactions, including income tax consequences, classification of awards as either equity or liabilities, and classification on the Consolidated Statements of Cash Flows. Under the new standard, income tax benefits and deficiencies are to be recognized in the income statement and the tax effects of exercised or vested awards should be treated as discrete items in the reporting period in which they occur. This provision is to be applied prospectively. Excess tax benefits should be recognized regardless of whether the benefit reduces taxes payable in the current period, along with any valuation allowance, on a modified retrospective basis as a cumulative-effect adjustment to the retained earnings as of the date of adoption. Excess tax benefits should be classified along with other income tax cash flows as an operating activity. This provision can be applied prospectively or retrospectively for all periods presented. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. Effective July 1, 2016 DTE Energy elected to early adopt this standard, as permitted. As a result of the adoption, DTE Energy recognized $1 million of excess tax benefits on stock-based compensation expense in its Consolidated Statements of Operations as a component of the provision for income taxes on a prospective basis. DTE Energy also recognized a $3 million cumulative-effect adjustment to increase Retained earnings under the modified retrospective approach. While there was no impact to the current period, cash flows related to the excess tax benefits on DTE Energy's Consolidated Statements of Cash Flows will be classified as operating activities on a prospective basis. Due to the prospective election, prior period amounts have not been adjusted. In addition, cash paid on the employees’ behalf related to restricted shares withheld for tax purposes have been classified as a financing activity on a retrospective basis. For the year ended December 31, 2016 , the implementation resulted in an increase to Net cash from operating activities with a corresponding decrease to Net cash from financing activities of $4 million . This retrospective application resulted in an increase to Net cash from operating activities with a corresponding decrease to Net cash from financing activities of $5 million and $6 million for the years ended December 31, 2015 and 2014 , respectively. Finally, DTE Energy's stock compensation expense continues to reflect estimated forfeitures. Recently Issued Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), as amended . The objectives of this ASU are to improve upon revenue recognition requirements by providing a single comprehensive model to determine the measurement of revenue and timing of recognition. The core principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. This ASU also requires expanded qualitative and quantitative disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. The standard is effective for the first interim period within annual reporting periods beginning after December 15, 2017. The standard is to be applied retrospectively and early adoption is permitted in the preceding year. The Registrants do not plan to early adopt the standard. The Registrants are currently assessing the impact of the ASU, as amended, on their Consolidated Financial Statements as well as the transition method the Registrants will use to adopt the guidance. Specifically, the Registrants are considering whether the new guidance will affect accounting for certain contracts where collectibility is in question, contributions in aid of construction, and other utility industry-related areas. In July 2015, the FASB issued ASU No. 2015-11, Inventory (Topic 330), Simplifying the Measurement of Inventory . The ASU replaces the current lower of cost or market test with a lower of cost or net realizable value test when cost is determined on a first-in, first-out or average cost basis. The standard is effective for public entities for annual reporting periods beginning after December 15, 2016, and interim periods therein. It is to be applied prospectively and early adoption is permitted. The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments — Overall: Recognition and Measurement of Financial Assets and Financial Liabilities. The new guidance is intended to improve the recognition and measurement of financial instruments. The ASU 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. Under the new guidance, equity investments will generally be measured at fair value, with subsequent changes in fair value recognized in net income. The ASU is effective for fiscal years and interim periods within those years beginning after December 15, 2017. Upon adoption, entities will be required 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. Changes to the accounting for equity securities without a readily determinable fair value will be applied prospectively. The ASU will not have a significant impact on the Registrants' Consolidated Financial Statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), a replacement of Leases (Topic 840) . This guidance requires a lessee to account for leases as finance or operating leases. Both leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability on its balance sheet, with differing methodology for income statement recognition. For lessors, the standard modifies the classification criteria and the accounting for sales-type and direct financing leases. Entities will classify leases to determine how to recognize lease-related revenue and expense. This ASU is effective for public entities for fiscal years, and interim periods within those years, beginning after December 15, 2018, and early adoption is permitted. A modified retrospective approach is required for leases existing or entered into after the beginning of the earliest comparative period in the Consolidated Financial Statements. The Registrants expect an increase in assets and liabilities, however, they are currently 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 GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Entities will apply the new guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The ASU is effective for the Registrants beginning after December 15, 2019, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. In January 2017, the FASB issued ASU No. 2017-04, Intangibles — Goodwill and Other (Topic 350): Simplifying the Accounting for Goodwill Impairment . The guidance removes Step 2 of the goodwill impairment test, which requires a hypothetical purchase price allocation. A goodwill impairment will now be the amount by which a reporting unit’s carrying value exceeds its fair value, not to exceed the carrying amount of goodwill. The standard will be applied prospectively, and is effective for public entities that are SEC filers for annual or any interim goodwill impairment tests in fiscal years beginning after December 15, 2019. Early adoption is permitted for any impairment tests performed after January 1, 2017. |
| 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, 2016 and 2015 . The Registrants believe they use valuation techniques that maximize the use of observable market-based inputs and minimize the use of unobservable inputs. A fair value hierarchy has been established that prioritizes the inputs to valuation techniques used to measure fair value in three broad levels. The fair value hierarchy gives the highest priority to quoted prices (unadjusted) in active markets for identical assets or liabilities (Level 1) and the lowest priority to unobservable inputs (Level 3). In some cases, the inputs used to measure fair value might fall in different levels of the fair value hierarchy. All assets and liabilities are required to be classified in their entirety based on the lowest level of input that is significant to the fair value measurement in its entirety. Assessing the significance of a particular input may require judgment considering factors specific to the asset or liability, and may affect the valuation of the asset or liability and its placement within the fair value hierarchy. The Registrants classify fair value balances based on the fair value hierarchy defined as follows: • Level 1 — Consists of unadjusted quoted prices in active markets for identical assets or liabilities that the Registrants have the ability to access as of the reporting date. • Level 2 — Consists of inputs other than quoted prices included within Level 1 that are directly observable for the asset or liability or indirectly observable through corroboration with observable market data. • Level 3 — Consists of unobservable inputs for assets or liabilities whose fair value is estimated based on internally developed models or methodologies using inputs that are generally less readily observable and supported by little, if any, market activity at the measurement date. Unobservable inputs are developed based on the best available information and subject to cost-benefit constraints. |
| Nuclear Decommissioning Trust and Other Investments | Nuclear Decommissioning Trusts and Other Investments The nuclear decommissioning trusts and other investments hold debt and equity securities directly and indirectly through institutional mutual funds and commingled funds. Exchange-traded debt and equity securities held directly are valued using quoted market prices in actively traded markets. Non-exchange-traded fixed income securities are valued based upon quotations available from brokers or pricing services. The institutional mutual funds hold exchange-traded equity or debt securities (exchange and non-exchange traded) and are valued based on publicly available NAVs. The commingled funds hold exchange-traded equity or debt securities (exchange and non-exchange traded) and are valued based on a calculated NAV as a practical expedient. A primary price source is identified by asset type, class, or issue for each security. The trustee monitors prices supplied by pricing services and may use a supplemental price source or change the primary price source of a given security if the trustee determines that another price source is considered to be preferable. The Registrants have obtained an understanding of how these prices are derived, including the nature and observability of the inputs used in deriving such prices. Additionally, the Registrants selectively corroborate the fair value of securities by comparison of market-based price sources. Investment policies and procedures are determined by DTE Energy's Trust Investments Department which reports to DTE Energy's Vice President and Treasurer. |
| Derivative Assets and Liabilities | Derivative Assets and Liabilities Derivative assets and liabilities are comprised of physical and financial derivative contracts, including futures, forwards, options, and swaps that are both exchange-traded and over-the-counter traded contracts. Various inputs are used to value derivatives depending on the type of contract and availability of market data. Exchange-traded derivative contracts are valued using quoted prices in active markets. The Registrants consider the following criteria in determining whether a market is considered active: frequency in which pricing information is updated, variability in pricing between sources or over time, and the availability of public information. Other derivative contracts are valued based upon a variety of inputs including commodity market prices, broker quotes, interest rates, credit ratings, default rates, market-based seasonality, and basis differential factors. The Registrants monitor the prices that are supplied by brokers and pricing services and may use a supplemental price source or change the primary price source of an index if prices become unavailable or another price source is determined to be more representative of fair value. The Registrants have obtained an understanding of how these prices are derived. Additionally, the Registrants selectively corroborate the fair value of their transactions by comparison of market-based price sources. Mathematical valuation models are used for derivatives for which external market data is not readily observable, such as contracts which extend beyond the actively traded reporting period. The Registrants have established a Risk Management Committee whose responsibilities include directly or indirectly ensuring all valuation methods are applied in accordance with predefined policies. The development and maintenance of the Registrants' forward price curves has been assigned to DTE Energy's Risk Management Department, which is separate and distinct from the trading functions within DTE Energy. |
| Fair Value Transfer | Derivatives are transferred between levels primarily due to changes in the source data used to construct price curves as a result of changes in market liquidity. Transfers in and transfers out are reflected as if they had occurred at the beginning of the period. |
| Fair Value of Financial Instruments | Fair Value of Financial Instruments The fair value of financial instruments included in the table below is determined by using quoted market prices when available. When quoted prices are not available, pricing services may be used to determine the fair value with reference to observable interest rate indexes. The Registrants have obtained an understanding of how the fair values are derived. The Registrants also selectively corroborate the fair value of their transactions by comparison of market-based price sources. Discounted cash flow analyses based upon estimated current borrowing rates are also used to determine fair value when quoted market prices are not available. The fair values of notes receivable, excluding capital leases, and notes payable are generally estimated using discounted cash flow techniques that incorporate market interest rates as well as assumptions about the remaining life of the loans and credit risk. Depending on the information available, other valuation techniques may be used that rely on internal assumptions and models. Valuation policies and procedures for the Registrants are determined by DTE Energy's Treasury Department which reports to DTE Energy's Vice President and Treasurer and DTE Energy's Controller's Department which reports to DTE Energy's Vice President and Controller. |
| Derivatives | The Registrants recognize all derivatives at their fair value as Derivative assets or liabilities on their respective Consolidated Statements of Financial Position unless they qualify for certain scope exceptions, including the normal purchases and normal sales exception. Further, derivatives that qualify and are designated for hedge accounting are classified as either hedges of a forecasted transaction or the variability of cash flows to be received or paid related to a recognized asset or liability (cash flow hedge); or as hedges of the fair value of a recognized asset or liability or of an unrecognized firm commitment (fair value hedge). For cash flow hedges, the portion of the derivative gain or loss that is effective in offsetting the change in the value of the underlying exposure is deferred in Accumulated other comprehensive income (loss) and later reclassified into earnings when the underlying transaction occurs. Gains or losses from the ineffective portion of cash flow hedges are recognized in earnings immediately. For fair value hedges, changes in fair values for the derivative and hedged item are recognized in earnings each period. For derivatives that do not qualify or are not designated for hedge accounting, changes in fair value are recognized in earnings each period. The Registrants' primary market risk exposure is associated with commodity prices, credit, and interest rates. The Registrants have risk management policies to monitor and manage market risks. The Registrants use derivative instruments to manage some of the exposure. DTE Energy uses derivative instruments for trading purposes in its Energy Trading segment. Contracts classified as derivative instruments include electricity, natural gas, oil, certain coal forwards, futures, options, swaps, and foreign currency exchange contracts. Items not classified as derivatives include natural gas inventory, pipeline transportation contracts, renewable energy credits, and natural gas storage assets. |
| Derivatives, Offsetting Fair Value Amounts | Certain of DTE Energy's derivative positions are subject to netting arrangements which provide for offsetting of asset and liability positions as well as related cash collateral. Such netting arrangements generally do not have restrictions. Under such netting arrangements, DTE Energy offsets the fair value of derivative instruments with cash collateral received or paid for those contracts executed with the same counterparty, which reduces DTE Energy's Total Assets and Liabilities. Cash collateral is allocated between the fair value of derivative instruments and customer accounts receivable and payable with the same counterparty on a pro-rata basis to the extent there is exposure. Any cash collateral remaining, after the exposure is netted to zero, is reflected in Accounts receivable and Accounts payable as collateral paid or received, respectively. DTE Energy also provides and receives collateral in the form of letters of credit which can be offset against net Derivative assets and liabilities as well as Accounts receivable and payable. DTE Energy had issued letters of credit of approximately $2 million and $7 million outstanding at December 31, 2016 and 2015 , respectively, which could be used to offset net Derivative liabilities. Letters of credit received from third parties which could be used to offset net Derivative assets were $2 million at December 31, 2016 and 2015 . Such balances of letters of credit are excluded from the tables below and are not netted with the recognized assets and liabilities in DTE Energy's Consolidated Statements of Financial Position. For contracts with certain clearing agents, the fair value of derivative instruments is netted against realized positions with the net balance reflected as either 1) a Derivative asset or liability or 2) an Account receivable or payable. Other than certain clearing agents, Accounts receivable and Accounts payable that are subject to netting arrangements have not been offset against the fair value of Derivative assets and liabilities. Certain contracts that have netting arrangements have not been offset in DTE Energy's Consolidated Statements of Financial Position. The impact of netting these derivative instruments and cash collateral related to such contracts is not material. Only the gross amounts for these derivative instruments are included in the table below. |
| Derivatives, Methods of Accounting, Derivatives Not Designated or Qualifying as Hedges | Revenues and energy costs related to trading contracts are presented on a net basis in DTE Energy's Consolidated Statements of Operations. Commodity derivatives used for trading purposes, and financial non-trading commodity derivatives, are accounted for using the MTM method with unrealized and realized gains and losses recorded in Operating Revenues — Non-utility operations. Non-trading physical commodity sale and purchase derivative contracts are generally accounted for using the MTM method with unrealized and realized gains and losses for sales recorded in Operating Revenues — Non-utility operations and purchases recorded in Fuel, purchased power, and gas — non-utility. |
| Stock-Based Compensation | DTE Energy records compensation expense at fair value over the vesting period for all awards it grants. |
