Regulatory Matters	9 Months Ended
Sep. 30, 2012
Public Utilities, General Disclosures [Abstract]
REGULATORY MATTERS	REGULATORY MATTERS Detroit Edison Revenue Decoupling Mechanism (RDM) In May 2011, Detroit Edison filed an application with the MPSC for approval of its initial pilot RDM reconciliation for the period February 2010 through January 2011, requesting authority to refund to customers approximately $56 million, plus interest. This amount was accrued by Detroit Edison as of December 31, 2011. In addition, Detroit Edison accrued a pilot RDM liability for February 2011 through October 2011 of approximately $71 million. On April 10, 2012, the Michigan Court of Appeals (COA) issued a decision relating to an appeal of the January 2010 MPSC order in Detroit Edison's January 2009 rate case filing. The COA determined that the MPSC only had statutory authority to implement a RDM for gas providers, but not for electric providers, thereby reversing the MPSC's decision to authorize an RDM for Detroit Edison. No party appealed the COA decision regarding the RDM determination. On August 1, 2012, Detroit Edison filed an application for approval of accounting authority to defer for future amortization $127 million of gain resulting from the reversal of the Company's regulatory liability associated with the operation of the RDM. On August 14, 2012, the MPSC dismissed Detroit Edison's initial pilot RDM reconciliation case. On September 25, 2012, the MPSC issued an order approving the Company's accounting application. As described in the accounting application, Detroit Edison will amortize the new regulatory liability to income, at a monthly rate of approximately $10.6 million, beginning January 2014. It is currently anticipated that with this accounting treatment, along with other cost saving measures, Detroit Edison will not need to increase base rates until 2015. If Detroit Edison's base rates are increased prior to January 1, 2015, the Company will cease amortization and refund to customers the remaining unamortized balance of the new regulatory liability. Energy Optimization (EO) Plans In August 2012, Detroit Edison and MichCon filed amended EO plans with the MPSC. Detroit Edison's EO plan application proposed the recovery of EO expenditures for the period 2013-2015 of $224 million and further requested approval of surcharges to recover these costs. MichCon's EO plan application proposed the recovery of EO expenditures for the period 2013-2015 of $66 million and further requested approval of surcharges to recover these costs. Power Supply Cost Recovery (PSCR) Proceedings The PSCR process is designed to allow Detroit Edison to recover all of its power supply costs if incurred under reasonable and prudent policies and practices. Detroit Edison'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. 2013 Plan Year - In September 2012, Detroit Edison filed its 2013 PSCR plan case seeking approval of a levelized PSCR factor of 4.74 mills/kWh above the amount included in base rates for all PSCR customers. The filing supports a total power supply expense forecast of $1.5 billion. The plan also includes approximately $81 million for the recovery of its projected 2012 PSCR under-recovery. 2012 Gas Rate Case Filing MichCon filed a rate case on April 20, 2012 based on a projected test year for the twelve-month period ending October 31, 2013. The filing with the MPSC requested an increase in base rates of approximately $77 million that is required to recover higher costs associated with increased investments in plant, the impact of sales reductions due to customer losses and continuing conservation, and increasing operating costs, primarily pipeline integrity and leak remediation expenses. On September 28, 2012, MichCon filed testimony with the MPSC indicating that it intends to self-implement up to $34 million of rate relief beginning in November 2012. MichCon RDM Reconciliations In September 2011, MichCon filed an application with the MPSC for approval of its RDM reconciliation for the period July 1, 2010 through June 30, 2011. MichCon's RDM application proposed the recovery of approximately $20 million. On July 13, 2012, the MPSC approved a settlement agreement approving the 2011 RDM reconciliation and the implementation of a surcharge over a twelve-month period beginning in August 2012. As a result of the provisions of the settlement, during the nine months ended September 30, 2012, MichCon recognized an additional $5 million of revenue related to the 2010/2011 period and $3 million related to the 2011/2012 period. In October 2012, MichCon filed an application with the MPSC for approval of its RDM reconciliation for the period July 1, 2011 through June 30, 2012. MichCon's 2012 RDM application proposed the recovery of approximately $8.6 million. Gas Cost Recovery (GCR) Proceedings The GCR process is designed to allow MichCon to recover all of its gas supply costs if incurred under reasonable and prudent policies and practices. The MPSC reviews these costs, policies and practices for prudence in annual plan and reconciliation filings. 2010-2011 GCR Year - An MPSC order was issued on August 14, 2012 approving the GCR reconciliation for the 12-month period ended March 31, 2011. The MPSC authorized MichCon to include in its 2011-2012 GCR reconciliation beginning balance the net over-recovery of approximately $6 million. MichCon Uncollectible Expense True-up Mechanism (UETM) In March 2012, MichCon filed an application with the MPSC for approval of its UETM for 2011 requesting authority to refund approximately $7 million, consisting of a $19 million over-recovery related to 2011 uncollectible expense, partially offset by $12 million related to the 2010 UETM under-recovery. In September 2012, the MPSC approved a settlement agreement approving the 2011 UETM net refund of $7 million and the implementation of credits and surcharges over a twelve-month period beginning in November 2012. Other The Company is unable to predict the outcome of the unresolved regulatory matters discussed herein. Resolution of these matters is dependent upon future MPSC orders and appeals, which may materially impact the financial position, results of operations and cash flows of the Company.

REGULATORY MATTERS

Detroit Edison Revenue Decoupling Mechanism (RDM)

In May 2011, Detroit Edison filed an application with the MPSC for approval of its initial pilot RDM reconciliation for the period February 2010 through January 2011, requesting authority to refund to customers approximately $56 million, plus interest. This amount was accrued by Detroit Edison as of December 31, 2011. In addition, Detroit Edison accrued a pilot RDM liability for February 2011 through October 2011 of approximately $71 million. On April 10, 2012, the Michigan Court of Appeals (COA) issued a decision relating to an appeal of the January 2010 MPSC order in Detroit Edison's January 2009 rate case filing. The COA determined that the MPSC only had statutory authority to implement a RDM for gas providers, but not for electric providers, thereby reversing the MPSC's decision to authorize an RDM for Detroit Edison. No party appealed the COA decision regarding the RDM determination. On August 1, 2012, Detroit Edison filed an application for approval of accounting authority to defer for future amortization $127 million of gain resulting from the reversal of the Company's regulatory liability associated with the operation of the RDM. On August 14, 2012, the MPSC dismissed Detroit Edison's initial pilot RDM reconciliation case. On September 25, 2012, the MPSC issued an order approving the Company's accounting application. As described in the accounting application, Detroit Edison will amortize the new regulatory liability to income, at a monthly rate of approximately $10.6 million, beginning January 2014. It is currently anticipated that with this accounting treatment, along with other cost saving measures, Detroit Edison will not need to increase base rates until 2015. If Detroit Edison's base rates are increased prior to January 1, 2015, the Company will cease amortization and refund to customers the remaining unamortized balance of the new regulatory liability.

Energy Optimization (EO) Plans

In August 2012, Detroit Edison and MichCon filed amended EO plans with the MPSC. Detroit Edison's EO plan application proposed the recovery of EO expenditures for the period 2013-2015 of $224 million and further requested approval of surcharges to recover these costs. MichCon's EO plan application proposed the recovery of EO expenditures for the period 2013-2015 of $66 million and further requested approval of surcharges to recover these costs.

Power Supply Cost Recovery (PSCR) Proceedings

The PSCR process is designed to allow Detroit Edison to recover all of its power supply costs if incurred under reasonable and prudent policies and practices. Detroit Edison'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.

2013 Plan Year - In September 2012, Detroit Edison filed its 2013 PSCR plan case seeking approval of a levelized PSCR factor of 4.74 mills/kWh above the amount included in base rates for all PSCR customers. The filing supports a total power supply expense forecast of $1.5 billion. The plan also includes approximately $81 million for the recovery of its projected 2012 PSCR under-recovery.

2012 Gas Rate Case Filing

MichCon filed a rate case on April 20, 2012 based on a projected test year for the twelve-month period ending October 31, 2013. The filing with the MPSC requested an increase in base rates of approximately $77 million that is required to recover higher costs associated with increased investments in plant, the impact of sales reductions due to customer losses and continuing conservation, and increasing operating costs, primarily pipeline integrity and leak remediation expenses. On September 28, 2012, MichCon filed testimony with the MPSC indicating that it intends to self-implement up to $34 million of rate relief beginning in November 2012.

MichCon RDM Reconciliations

In September 2011, MichCon filed an application with the MPSC for approval of its RDM reconciliation for the period July 1, 2010 through June 30, 2011. MichCon's RDM application proposed the recovery of approximately $20 million. On July 13, 2012, the MPSC approved a settlement agreement approving the 2011 RDM reconciliation and the implementation of a surcharge over a twelve-month period beginning in August 2012. As a result of the provisions of the settlement, during the nine months ended September 30, 2012, MichCon recognized an additional $5 million of revenue related to the 2010/2011 period and $3 million related to the 2011/2012 period.

In October 2012, MichCon filed an application with the MPSC for approval of its RDM reconciliation for the period July 1, 2011 through June 30, 2012. MichCon's 2012 RDM application proposed the recovery of approximately $8.6 million.

Gas Cost Recovery (GCR) Proceedings

The GCR process is designed to allow MichCon to recover all of its gas supply costs if incurred under reasonable and prudent policies and practices. The MPSC reviews these costs, policies and practices for prudence in annual plan and reconciliation filings.

2010-2011 GCR Year - An MPSC order was issued on August 14, 2012 approving the GCR reconciliation for the 12-month period ended March 31, 2011. The MPSC authorized MichCon to include in its 2011-2012 GCR reconciliation beginning balance the net over-recovery of approximately $6 million.

MichCon Uncollectible Expense True-up Mechanism (UETM)

In March 2012, MichCon filed an application with the MPSC for approval of its UETM for 2011 requesting authority to refund approximately $7 million, consisting of a $19 million over-recovery related to 2011 uncollectible expense, partially offset by $12 million related to the 2010 UETM under-recovery. In September 2012, the MPSC approved a settlement agreement approving the 2011 UETM net refund of $7 million and the implementation of credits and surcharges over a twelve-month period beginning in November 2012.

Other

The Company is unable to predict the outcome of the unresolved regulatory matters discussed herein. Resolution of these matters is dependent upon future MPSC orders and appeals, which may materially impact the financial position, results of operations and cash flows of the Company.