Regulatory Matters	3 Months Ended
Mar. 31, 2019
Public Utilities, General Disclosures [Abstract]
Regulatory Matters	REGULATORY MATTERS 2017 Electric Rate Case Filing DTE Electric filed a rate case with the MPSC on April 19, 2017 requesting an increase in base rates of $231 million based on a projected twelve-month period ending October 31, 2018. 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. In March 2019, the MPSC approved the self-implementation refund of $27.2 million, including interest. The refund will be effective on a per kilowatt-hour basis for bills rendered May and June 2019. DTE Electric has a refund liability as of March 31, 2019. 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. On February 1, 2019, DTE Electric reduced its initial requested increase in base rates to $248.6 million, primarily reflecting the reduction in requested depreciation expense resulting from the MPSC's approval of new depreciation rates. A final MPSC order in this case is expected in May 2019. 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 composite depreciation rate 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 in May 2019. 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. In 2018, MPSC orders for the first two steps, Credit A and Credit B, were issued for DTE Electric and DTE Gas. 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.

REGULATORY MATTERS

2017 Electric Rate Case Filing

DTE Electric filed a rate case with the MPSC on April 19, 2017 requesting an increase in base rates of $231 million based on a projected twelve-month period ending October 31, 2018. 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. In March 2019, the MPSC approved the self-implementation refund of $27.2 million, including interest. The refund will be effective on a per kilowatt-hour basis for bills rendered May and June 2019. DTE Electric has a refund liability as of March 31, 2019.

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. On February 1, 2019, DTE Electric reduced its initial requested increase in base rates to $248.6 million, primarily reflecting the reduction in requested depreciation expense resulting from the MPSC's approval of new depreciation rates. A final MPSC order in this case is expected in May 2019.

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 composite depreciation rate 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 in May 2019.

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. In 2018, MPSC orders for the first two steps, Credit A and Credit B, were issued for DTE Electric and DTE Gas. 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.