New Accounting Pronouncements	9 Months Ended
Sep. 30, 2018
New Accounting Pronouncements and Changes in Accounting Principles [Abstract]
New Accounting Pronouncements	NEW ACCOUNTING PRONOUNCEMENTS Recently Adopted Pronouncements In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), as amended. The objectives of this ASU are to improve upon revenue recognition requirements by providing a single comprehensive model to determine the measurement of revenue and timing of recognition. The core principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. This ASU also required expanded qualitative and quantitative disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. The standard is to be applied retrospectively. The Registrants adopted the standard effective January 1, 2018, using the modified retrospective approach. Under the modified retrospective approach, the information for periods prior to the adoption date has not been restated and continues to be reported under the accounting standards in effect for those periods. As permitted under the standard, the Registrants have elected to apply the guidance only to those contracts that were not completed at January 1, 2018, and have elected not to restate the impacts of any contract modifications made prior to the earliest period presented. The adoption of the ASU did not have a significant impact on the Registrants' financial position or results of operations, but required additional disclosures for revenue. See Note 4 to the Consolidated Financial Statements, "Revenue." In March 2017, the FASB issued ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments in this update required that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside of income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The Registrants adopted the standard effective January 1, 2018. The standard has been applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. As permitted by the standard, the Registrants have used benefit cost amounts disclosed for prior periods as the basis for retrospective application in the income statement. As a result of regulatory mechanisms, the impact to the Consolidated Financial Statements was not material for the three and nine months ended September 30, 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 nine months ended September 30, 2018, DTE Energy and DTE Electric 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 $16 million was attributable to the regulated utilities and offset to Regulatory liabilities. The true-up adjustments were a result of further analysis for items subject to further consideration at December 31, 2017, under SAB 118 and primarily related to timing differences not recoverable from DTE Electric and DTE Gas customers. Additionally, during the three and nine months ended September 30, 2018, DTE Energy recorded a valuation allowance of $20 million against AMT credits that are expected to be subject to sequestration when refunded in accordance with TCJA. This adjustment increased Income Tax Expense and reduced the deferred tax asset related to AMT credits determined to be unrealizable. The valuation allowance adjustment was the result of further analysis for items subject to further consideration at December 31, 2017 under SAB 118. The Registrants will continue to analyze the amounts throughout 2018, which may result in additional changes. Recently Issued Pronouncements In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), as amended. This guidance requires a lessee to account for leases as finance or operating leases, and disclose key information about leasing arrangements. Both types of leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability on its balance sheet, with differing methodology for income statement recognition, depending on the lease classification. The Registrants will adopt the standard on January 1, 2019. 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 plan to apply the standard on a prospective basis. The Registrants expect to 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. The Registrants also plan to 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 is being implemented that will assist with the initial adoption and ongoing compliance of the standard. Preliminary system configuration has been completed and testing is in progress. The Registrants are continuing procedures to ensure all leases are captured, as well as, evaluating and implementing, new business processes, internal controls, and accounting policies. In addition, the Registrants are monitoring utility industry implementation issues for purchase power agreements, pipeline laterals, and other industry specific arrangements. While the Registrants expect an increase in assets and liabilities, as well as additional disclosures, they are still assessing the impact of this ASU on their Consolidated Financial Statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in this update replace the incurred loss impairment methodology in current generally accepted accounting principles with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Entities will apply the new guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The ASU is effective for the Registrants beginning after December 15, 2019, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. In February 2018, the FASB issued ASU No. 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The amendments in this update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA. The amendments in this update also require entities to disclose their accounting policy for releasing income tax effects from accumulated other comprehensive income. The ASU is effective for the Registrants for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements. 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.

NEW ACCOUNTING PRONOUNCEMENTS

Recently Adopted Pronouncements

In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606), as amended. The objectives of this ASU are to improve upon revenue recognition requirements by providing a single comprehensive model to determine the measurement of revenue and timing of recognition. The core principle is that an entity will recognize revenue to depict the transfer of goods or services to customers at an amount that the entity expects to be entitled to in exchange for those goods or services. This ASU also required expanded qualitative and quantitative disclosures regarding the nature, amount, timing, and uncertainty of revenues and cash flows arising from contracts with customers. The standard is to be applied retrospectively. The Registrants adopted the standard effective January 1, 2018, using the modified retrospective approach. Under the modified retrospective approach, the information for periods prior to the adoption date has not been restated and continues to be reported under the accounting standards in effect for those periods. As permitted under the standard, the Registrants have elected to apply the guidance only to those contracts that were not completed at January 1, 2018, and have elected not to restate the impacts of any contract modifications made prior to the earliest period presented.

The adoption of the ASU did not have a significant impact on the Registrants' financial position or results of operations, but required additional disclosures for revenue. See Note 4 to the Consolidated Financial Statements, "Revenue."

In March 2017, the FASB issued ASU No. 2017-07, Compensation — Retirement Benefits (Topic 715): Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost. The amendments in this update required that an employer report the service cost component in the same line item or items as other compensation costs arising from services rendered by the pertinent employees during the period. The other components of net benefit cost are required to be presented in the income statement separately from the service cost component and outside of income from operations. The amendments in this update also allow only the service cost component to be eligible for capitalization when applicable. The Registrants adopted the standard effective January 1, 2018. The standard has been applied retrospectively for the presentation of the service cost component and the other components of net periodic pension cost and net periodic postretirement benefit cost in the income statement and prospectively for the capitalization of the service cost component of net periodic pension cost and net periodic postretirement benefit in assets. As permitted by the standard, the Registrants have used benefit cost amounts disclosed for prior periods as the basis for retrospective application in the income statement. As a result of regulatory mechanisms, the impact to the Consolidated Financial Statements was not material for the three and nine months ended September 30, 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 nine months ended September 30, 2018, DTE Energy and DTE Electric 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 $16 million was attributable to the regulated utilities and offset to Regulatory liabilities. The true-up adjustments were a result of further analysis for items subject to further consideration at December 31, 2017, under SAB 118 and primarily related to timing differences not recoverable from DTE Electric and DTE Gas customers. Additionally, during the three and nine months ended September 30, 2018, DTE Energy recorded a valuation allowance of $20 million against AMT credits that are expected to be subject to sequestration when refunded in accordance with TCJA. This adjustment increased Income Tax Expense and reduced the deferred tax asset related to AMT credits determined to be unrealizable. The valuation allowance adjustment was the result of further analysis for items subject to further consideration at December 31, 2017 under SAB 118. The Registrants will continue to analyze the amounts throughout 2018, which may result in additional changes.

Recently Issued Pronouncements

In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), as amended. This guidance requires a lessee to account for leases as finance or operating leases, and disclose key information about leasing arrangements. Both types of leases will result in the lessee recognizing a right-of-use asset and a corresponding lease liability on its balance sheet, with differing methodology for income statement recognition, depending on the lease classification. The Registrants will adopt the standard on January 1, 2019. 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 plan to apply the standard on a prospective basis. The Registrants expect to 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. The Registrants also plan to 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 is being implemented that will assist with the initial adoption and ongoing compliance of the standard. Preliminary system configuration has been completed and testing is in progress. The Registrants are continuing procedures to ensure all leases are captured, as well as, evaluating and implementing, new business processes, internal controls, and accounting policies. In addition, the Registrants are monitoring utility industry implementation issues for purchase power agreements, pipeline laterals, and other industry specific arrangements. While the Registrants expect an increase in assets and liabilities, as well as additional disclosures, they are still assessing the impact of this ASU on their Consolidated Financial Statements.

In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. The amendments in this update replace the incurred loss impairment methodology in current generally accepted accounting principles with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. Entities will apply the new guidance as a cumulative-effect adjustment to retained earnings as of the beginning of the first reporting period in which the guidance is adopted. The ASU is effective for the Registrants beginning after December 15, 2019, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements.

In February 2018, the FASB issued ASU No. 2018-02, Income Statement — Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The amendments in this update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the TCJA. The amendments in this update also require entities to disclose their accounting policy for releasing income tax effects from accumulated other comprehensive income. The ASU is effective for the Registrants for fiscal years beginning after December 15, 2018, and interim periods therein. Early adoption is permitted. The Registrants are currently assessing the impact of this standard on their Consolidated Financial Statements.

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.