Regulatory Matters (Notes)	6 Months Ended
Jun. 30, 2013
Public Utilities, General Disclosures [Abstract]
REGULATORY MATTERS	REGULATORY MATTERS Energy Optimization (EO) Plans In May 2013, DTE Electric and DTE Gas filed separate applications for approval of their respective reconciliations of their 2012 EO plan expenses. DTE Electric's EO reconciliation includes a cumulative $26 million net over-recovery and DTE Gas's EO reconciliation includes a cumulative $7 million net over-recovery for their 2012 EO plans. DTE Electric and DTE Gas proposed that the calculated over-recoveries for 2012 be carried forward into 2013 and used as beginning balances for the 2013 reconciliations. In July 2013, DTE Electric and DTE Gas filed separate applications with the MPSC for the biennial review of their EO plans. Renewable Energy Plan (REP) In June 2013, DTE Electric filed an application for the biennial review and approval of its amended REP with the MPSC requesting authority to reduce its annual surcharge revenue recovery from approximately $100 million to $15 million. The proposed level is appropriate to continue to properly implement DTE Electric's 20-year REP, designed to deliver cleaner, renewable electric generation to its customers, to further diversify DTE Electric's and the State of Michigan's sources of electric supply, and to address the state and national goals of increasing energy independence. Transition of the City of Detroit's Public Lighting Department's (PLD) Customers to DTE Electric's Distribution System Accounting Authority On June 28, 2013, DTE Electric filed an application for accounting authority to defer certain costs associated with the transition of the City of Detroit's PLD customers to the DTE Electric distribution system over a five to seven year system conversion period. The Company requested authority to defer as a regulatory asset, all net incremental revenue requirement associated with the transition. The net incremental revenue requirement includes costs to install meters and attach customers; system and customer facility upgrades and repairs; and the difference between DTE Electric's tariff rates and any transitional rates approved in the future. On July 11, 2013, the MPSC approved DTE Electric's request to defer, for accounting purposes, the net incremental revenue requirement. The approval excludes the request to defer the difference between DTE Electric's tariff rates and any transitional rates that might be approved by the MPSC in the future. The MPSC will address proposed rates and recovery matters in a future contested proceeding. As the accounting order did not provide a regulatory recovery mechanism, the regulatory asset will not be recognized until a regulatory recovery mechanism is put into place and the recovery of the regulatory asset becomes probable. Transitional Reconciliation Mechanism (TRM) On July 19, 2013, DTE Electric filed its TRM application proposing a transitional tariff option for certain former PLD customers and a modified line extension provision. The application also proposes a recovery mechanism for the deferred incremental revenue requirement described above. The application further discusses that DTE Electric will be requesting recovery, in subsequent PSCR cases, of PLD transmission delivery service costs incurred while DTE Electric is temporarily relying upon PLD to operate and maintain PLD's system during the system conversion period. If the MPSC determines that the transmission costs are not recoverable in the PSCR, the Company requested recovery as part of the TRM. Power Supply Cost Recovery Proceedings The PSCR process is designed to allow DTE Electric to recover all of its power supply costs if incurred under reasonable and prudent policies and practices. DTE Electric's power supply costs include fuel and related transportation costs, purchased and net interchange power costs, nitrogen oxide and sulfur dioxide emission allowances costs, urea costs, transmission costs and MISO costs. The MPSC reviews these costs, policies and practices for prudence in annual plan and reconciliation filings. 2010 PSCR Year — In March 2011, DTE Electric filed the 2010 PSCR reconciliation calculating a net under-recovery of $52.6 million that includes an over-recovery of $15.6 million for the 2009 PSCR year. In addition, the 2010 PSCR reconciliation includes an under-recovery of $7.1 million for the reconciliation of the 2007-2008 Pension Equalization Mechanism, and an over-refund of $3.8 million for the 2011 refund of the self-implemented rate increase related to the 2009 electric rate case filing. On April 25, 2013, the MPSC approved the 2010 PSCR net under-recovery of $52.6 million and the recovery of this amount as part of the 2011 PSCR reconciliation. The order also approved DTE Electric's Pension Equalization Mechanism reconciliation and authorized a one month surcharge in June 2013 and approved the recovery of the over-refund of the self-implemented rate increase related to the 2009 electric rate case filing as part of the 2011 PSCR reconciliation. 2012 Plan Year — In September 2011, DTE Energy filed its 2012 PSCR plan case seeking approval of a levelized PSCR factor of 4.18 mills/kWh above the amount included in base rates for all PSCR customers. The filing supports a total power supply expense forecast of $1.4 billion. The plan also includes approximately $158 million for the recovery of its projected 2011 PSCR under-recovery. On June 28, 2013, the MPSC approved DTE Energy's 2012 PSCR plan. DTE Gas Revenue Decoupling Mechanism (RDM) In May 2013, DTE Gas filed an application with the MPSC for approval of its RDM reconciliation for the period July 1, 2012 through October 31, 2012. DTE Gas's RDM application proposed the recovery of a net under-recovery of approximately $5.2 million. DTE Gas Depreciation Filing In compliance with an MPSC order, DTE Gas filed a depreciation case in June 2012. On May 15, 2013, the MPSC approved a settlement agreement increasing DTE Gas's composite depreciation rates from 2.29% to 2.51%, effective on the same date as the MPSC-approved rates are effective in DTE Gas's next general rate case. The Company cannot predict when DTE Gas will file its next rate case.

REGULATORY MATTERS

Energy Optimization (EO) Plans

In May 2013, DTE Electric and DTE Gas filed separate applications for approval of their respective reconciliations of their 2012 EO plan expenses. DTE Electric's EO reconciliation includes a cumulative $26 million net over-recovery and DTE Gas's EO reconciliation includes a cumulative $7 million net over-recovery for their 2012 EO plans. DTE Electric and DTE Gas proposed that the calculated over-recoveries for 2012 be carried forward into 2013 and used as beginning balances for the 2013 reconciliations. In July 2013, DTE Electric and DTE Gas filed separate applications with the MPSC for the biennial review of their EO plans.

Renewable Energy Plan (REP)

In June 2013, DTE Electric filed an application for the biennial review and approval of its amended REP with the MPSC requesting authority to reduce its annual surcharge revenue recovery from approximately $100 million to $15 million. The proposed level is appropriate to continue to properly implement DTE Electric's 20-year REP, designed to deliver cleaner, renewable electric generation to its customers, to further diversify DTE Electric's and the State of Michigan's sources of electric supply, and to address the state and national goals of increasing energy independence.

Transition of the City of Detroit's Public Lighting Department's (PLD) Customers to DTE Electric's Distribution System

Accounting Authority

On June 28, 2013, DTE Electric filed an application for accounting authority to defer certain costs associated with the transition of the City of Detroit's PLD customers to the DTE Electric distribution system over a five to seven year system conversion period. The Company requested authority to defer as a regulatory asset, all net incremental revenue requirement associated with the transition. The net incremental revenue requirement includes costs to install meters and attach customers; system and customer facility upgrades and repairs; and the difference between DTE Electric's tariff rates and any transitional rates approved in the future. On July 11, 2013, the MPSC approved DTE Electric's request to defer, for accounting purposes, the net incremental revenue requirement.

The approval excludes the request to defer the difference between DTE Electric's tariff rates and any transitional rates that might be approved by the MPSC in the future. The MPSC will address proposed rates and recovery matters in a future contested proceeding. As the accounting order did not provide a regulatory recovery mechanism, the regulatory asset will not be recognized until a regulatory recovery mechanism is put into place and the recovery of the regulatory asset becomes probable.

Transitional Reconciliation Mechanism (TRM)

On July 19, 2013, DTE Electric filed its TRM application proposing a transitional tariff option for certain former PLD customers and a modified line extension provision. The application also proposes a recovery mechanism for the deferred incremental revenue requirement described above. The application further discusses that DTE Electric will be requesting recovery, in subsequent PSCR cases, of PLD transmission delivery service costs incurred while DTE Electric is temporarily relying upon PLD to operate and maintain PLD's system during the system conversion period. If the MPSC determines that the transmission costs are not recoverable in the PSCR, the Company requested recovery as part of the TRM.

Power Supply Cost Recovery Proceedings

The PSCR process is designed to allow DTE Electric to recover all of its power supply costs if incurred under reasonable and prudent policies and practices. DTE Electric's power supply costs include fuel and related transportation costs, purchased and net interchange power costs, nitrogen oxide and sulfur dioxide emission allowances costs, urea costs, transmission costs and MISO costs. The MPSC reviews these costs, policies and practices for prudence in annual plan and reconciliation filings.

2010 PSCR Year — In March 2011, DTE Electric filed the 2010 PSCR reconciliation calculating a net under-recovery of $52.6 million that includes an over-recovery of $15.6 million for the 2009 PSCR year. In addition, the 2010 PSCR reconciliation includes an under-recovery of $7.1 million for the reconciliation of the 2007-2008 Pension Equalization Mechanism, and an over-refund of $3.8 million for the 2011 refund of the self-implemented rate increase related to the 2009 electric rate case filing. On April 25, 2013, the MPSC approved the 2010 PSCR net under-recovery of $52.6 million and the recovery of this amount as part of the 2011 PSCR reconciliation. The order also approved DTE Electric's Pension Equalization Mechanism reconciliation and authorized a one month surcharge in June 2013 and approved the recovery of the over-refund of the self-implemented rate increase related to the 2009 electric rate case filing as part of the 2011 PSCR reconciliation.

2012 Plan Year — In September 2011, DTE Energy filed its 2012 PSCR plan case seeking approval of a levelized PSCR factor of 4.18 mills/kWh above the amount included in base rates for all PSCR customers. The filing supports a total power supply expense forecast of $1.4 billion. The plan also includes approximately $158 million for the recovery of its projected 2011 PSCR under-recovery. On June 28, 2013, the MPSC approved DTE Energy's 2012 PSCR plan.

DTE Gas Revenue Decoupling Mechanism (RDM)

In May 2013, DTE Gas filed an application with the MPSC for approval of its RDM reconciliation for the period July 1, 2012 through October 31, 2012. DTE Gas's RDM application proposed the recovery of a net under-recovery of approximately $5.2 million.

DTE Gas Depreciation Filing

In compliance with an MPSC order, DTE Gas filed a depreciation case in June 2012. On May 15, 2013, the MPSC approved a settlement agreement increasing DTE Gas's composite depreciation rates from 2.29% to 2.51%, effective on the same date as the MPSC-approved rates are effective in DTE Gas's next general rate case. The Company cannot predict when DTE Gas will file its next rate case.