Regulatory Matters (Notes)	9 Months Ended
Sep. 30, 2013
Public Utilities, General Disclosures [Abstract]
Regulatory Matters	REGULATORY MATTERS 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, a 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. 2009 Electric Rate Case Filing - Court of Appeals Remand to MPSC In April 2012, the Michigan Court of Appeals (COA) issued a decision relating to an appeal of the January 2010 MPSC rate order in DTE Electric's January 2009 rate case filing. The COA found that the record of evidence in the January 2010 rate order was insufficient to support the MPSC's authorization to recover costs for the advanced metering infrastructure (AMI) program and remanded this matter to the MPSC. On October 17, 2013, the MPSC issued an order affirming the approximately $8 million rate increase authorized in the MPSC's January 2010 rate order for the AMI program and further concluded that the evidence presented after remand supports the authorized cost recovery. 2010 Electric Rate Case Filing - Court of Appeals Decision In July 2013, the COA issued a decision relating to an appeal of the October 2011 MPSC order in DTE Electric's October 2010 rate case filing. The COA found that the record of evidence in the 2010 rate case order was insufficient to support the MPSC's authorization to recover costs for the AMI program and remanded this matter to the MPSC. The MPSC had approved $55 million of the average rate base related to the AMI program in the October 2011 order. DTE Electric is currently operating its AMI program pursuant to the MPSC's approval set forth in the October 2011 order. On August 29, 2013, the MPSC reopened the 2010 electric rate case for the limited purpose of addressing the COA's opinion on AMI. The Company is unable to predict the outcome of this matter or the timing of its resolution. 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. 2012 PSCR Year - In March 2013, DTE Electric filed the 2012 PSCR reconciliation calculating a net under-recovery of approximately $87 million that includes an under-recovery of approximately $148 million for the 2011 PSCR year. The reconciliation includes approximately $30 million of purchased power costs related to the manual shutdown of our Fermi 2 nuclear power plant in June 2012 caused by the failure of one of the plant's two non-safety related feed-water pumps. The plant was restarted on July 30, 2012 which restored production to nominal 68% of full capacity. In September 2013, the repair to the plant was completed and production was returned to full capacity. We were able to purchase sufficient power from MISO to continue to provide uninterrupted service to our customers. Certain intervenors in the reconciliation case have challenged the recovery of some or all of the Fermi-related purchased power costs. Resolution of this matter is expected in 2014. Low Income Energy Assistance Fund (LIEAF) On July 1, 2013, Michigan Public Act 95 was signed into law and created the LIEAF. The legislation allows the use of a LIEAF funding factor to be determined by the MPSC and assessed on all customer classes of Michigan electric utilities to fund the LIEAF. On July 29, 2013, the MPSC adopted a funding factor of $0.99 per meter per month for all Michigan electric utilities that are participating in the program, including DTE Electric, effective with the September 2013 billing month. The surcharge billed by DTE Electric is remitted to the State of Michigan for subsequent distribution through a grant process to social service agencies and utilities to assist low income customers. DTE Gas Uncollectible Expense True-Up Mechanism (UETM) In March 2013, DTE Gas filed an application with the MPSC for approval of its UETM reconciliation for 2012 requesting authority to refund approximately $20 million. On September 10, 2013, the MPSC approved a settlement agreement approving the requested 2012 UETM refund over a twelve-month period beginning in October 2013.

REGULATORY MATTERS

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, a 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.

2009 Electric Rate Case Filing - Court of Appeals Remand to MPSC

In April 2012, the Michigan Court of Appeals (COA) issued a decision relating to an appeal of the January 2010 MPSC rate order in DTE Electric's January 2009 rate case filing. The COA found that the record of evidence in the January 2010 rate order was insufficient to support the MPSC's authorization to recover costs for the advanced metering infrastructure (AMI) program and remanded this matter to the MPSC. On October 17, 2013, the MPSC issued an order affirming the approximately $8 million rate increase authorized in the MPSC's January 2010 rate order for the AMI program and further concluded that the evidence presented after remand supports the authorized cost recovery.

2010 Electric Rate Case Filing - Court of Appeals Decision

In July 2013, the COA issued a decision relating to an appeal of the October 2011 MPSC order in DTE Electric's October 2010 rate case filing. The COA found that the record of evidence in the 2010 rate case order was insufficient to support the MPSC's authorization to recover costs for the AMI program and remanded this matter to the MPSC. The MPSC had approved $55 million of the average rate base related to the AMI program in the October 2011 order. DTE Electric is currently operating its AMI program pursuant to the MPSC's approval set forth in the October 2011 order. On August 29, 2013, the MPSC reopened the 2010 electric rate case for the limited purpose of addressing the COA's opinion on AMI. The Company is unable to predict the outcome of this matter or the timing of its resolution.

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.

2012 PSCR Year - In March 2013, DTE Electric filed the 2012 PSCR reconciliation calculating a net under-recovery of approximately $87 million that includes an under-recovery of approximately $148 million for the 2011 PSCR year. The reconciliation includes approximately $30 million of purchased power costs related to the manual shutdown of our Fermi 2 nuclear power plant in June 2012 caused by the failure of one of the plant's two non-safety related feed-water pumps. The plant was restarted on July 30, 2012 which restored production to nominal 68% of full capacity. In September 2013, the repair to the plant was completed and production was returned to full capacity. We were able to purchase sufficient power from MISO to continue to provide uninterrupted service to our customers. Certain intervenors in the reconciliation case have challenged the recovery of some or all of the Fermi-related purchased power costs. Resolution of this matter is expected in 2014.

Low Income Energy Assistance Fund (LIEAF)

On July 1, 2013, Michigan Public Act 95 was signed into law and created the LIEAF. The legislation allows the use of a LIEAF funding factor to be determined by the MPSC and assessed on all customer classes of Michigan electric utilities to fund the LIEAF. On July 29, 2013, the MPSC adopted a funding factor of $0.99 per meter per month for all Michigan electric utilities that are participating in the program, including DTE Electric, effective with the September 2013 billing month. The surcharge billed by DTE Electric is remitted to the State of Michigan for subsequent distribution through a grant process to social service agencies and utilities to assist low income customers.

DTE Gas Uncollectible Expense True-Up Mechanism (UETM)

In March 2013, DTE Gas filed an application with the MPSC for approval of its UETM reconciliation for 2012 requesting authority to refund approximately $20 million. On September 10, 2013, the MPSC approved a settlement agreement approving the requested 2012 UETM refund over a twelve-month period beginning in October 2013.