Regulatory Matters	3 Months Ended
Mar. 31, 2012
Public Utilities, General Disclosures [Abstract]
REGULATORY MATTERS	REGULATORY MATTERS 2009 Electric Rate Case Filing — Court of Appeals Decision On April 10, 2012, the Michigan Court of Appeals issued a decision relating to an appeal of the January 2010 MPSC order in Detroit Edison's January 2009 rate case filing. The order by the Court of Appeals is subject to further appellate review. The Court determined that the MPSC only had statutory authority to implement a Revenue Decoupling Mechanism (RDM) for gas providers, but not for electric providers, thereby reversing the MPSC's decision to authorize an RDM for Detroit Edison. As discussed below, Detroit Edison has accrued RDM refund liabilities of $56 million and $71 million for the 2010 and 2011 RDM reconciliation periods, respectively. If the Court of Appeals decision is not disturbed by further appellate review, then Detroit Edison's RDM liabilities will be reversed. Detroit Edison continues to retain the RDM liabilities until it is able to make a determination that the estimation of the liability should be revised. The Court also reversed the MPSC's order to approve the funding of the Low Income Energy Efficiency Fund (LIEEF) through customer rates consistent with the Court's July 2011 decision in an appeal of MichCon's June 2010 rate order. Please refer to discussion of LIEEF below. The Court found that the record of evidence in the January 2010 rate order was insufficient to support recovery of costs for the pilot advanced metering infrastructure (AMI) program and remanded this matter to the MPSC for further evidentiary hearing. The MPSC had approved $37 million of rate base related to the AMI program in the January 2010 order. Detroit Edison is currently operating its AMI program pursuant to the MPSC's approval set forth in its October 20, 2011 order, which was not reviewed by or subject to the Court of Appeal's April 10, 2012 decision. Detroit Edison will provide the necessary data and evidence to the MPSC supporting the AMI program expenditures at the remand hearing. Detroit Edison's AMI program expenditures are $83 million as of March 31, 2012, net of Department of Energy matching grant funds of $53 million. The Court affirmed the use of tracking mechanisms (restoration, line clearance, uncollectibles expense and choice incentive) and the peak demand computations approved in the January 2010 order. Detroit Edison 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 at December 31, 2011. There are various interpretations and alternative calculation methodologies relating to the pilot RDM refund calculation that could ultimately be adopted by the MPSC which may result in a range of customer refund amounts from $56 million to $140 million for this initial reconciliation filing under the pilot RDM. Detroit Edison accrued a pilot RDM liability for February 2011 through October 2011 of approximately $71 million , plus interest at December 31, 2011. Detroit Edison terminated the pilot RDM effective October 2011, and has requested a rehearing on this issue asserting that for reconciliation purposes, the pilot RDM should have been considered terminated in April 2011, when Detroit Edison self-implemented rates, consistent with prior MPSC orders. An April 2011 termination would result in a decrease to the liability. However, there can be no assurance that Detroit Edison will prevail in this matter. Similar to the initial reconciliation case, there are various interpretations and alternative calculation methodologies that could be adopted which may result in a range of refund obligations in excess of the amount accrued. Considering these variables, the potential customer refund amount could range from $10 million to $130 million for the second and final pilot RDM period. The primary uncertainties involved in the calculation methodologies of the pilot RDM for both reconciliation periods include customer class groupings and treatment of fixed customer charges. The Company believes that the calculation methodology used and the resulting refund estimates recorded follow the requirements and intent of the MPSC orders and represent the most probable amount of Detroit Edison's pilot RDM refund liability as of March 31, 2012. In light of the Court of Appeals decision, actions related to the RDM reconciliation periods have been suspended pending further appellate review. As noted above, Detroit Edison's RDM liabilities will be retained until Detroit Edison is able to make a determination that the estimation of the liability should be revised. Energy Optimization (EO) Plans In September 2011, Detroit Edison and MichCon filed biennial EO Plans with the MPSC as required. Detroit Edison's EO Plan application proposed the recovery of EO expenditures for the period 2012-2015 of $294 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 2012-2015 of $103 million and further requested approval of surcharges to recover these costs. On April 17, 2012, the MPSC approved the EO plans proposed by Detroit Edison and MichCon subject to the utilities' agreement to certain modifications. Detroit Edison and MichCon are currently reviewing the proposed modifications. If the MPSC proposed modifications are not accepted by Detroit Edison and MichCon, the amended 2010 EO plans will remain in effect. Detroit Edison Uncollectible Expense True-Up Mechanism (UETM) In February 2012, Detroit Edison filed an application with the MPSC for approval of its UETM for 2011 requesting authority to refund approximately $9 million consisting of costs related to 2011 uncollectible expense. Renewable Energy Plan (REP) In August 2010, Detroit Edison filed its reconciliation for the 2009 plan year indicating that the 2009 actual renewable plan revenues and costs approximated the related surcharge revenues and cost of the filed plan. In March 2012, the MPSC issued an order approving the 2009 REP cost reconciliation with the exception of approximately $3 million of capital expenditures that were deferred to a future rate case. Power Supply Cost Recovery 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. 2011 PSCR Year — In March 2012, Detroit Edison filed the 2011 PSCR reconciliation calculating a net under-recovery of $148 million that includes an under-recovery of $52.6 million for the 2010 PSCR year. In addition, the 2011 PSCR reconciliation includes an over-refund of $3.8 million for the 2011 refund of the self-implementation rate increase related to the 2009 electric rate case filing and a credit of $10.5 million related to the expiration of a wholesale power sales contract. Low Income Energy Efficiency Fund The Customer Choice and Electricity Reliability Act of 2000 authorized the creation of the LIEEF administered by the MPSC. The purpose of the fund is to provide shut-off and other protection for low income customers and to promote energy efficiency by all customer classes. Detroit Edison and MichCon collect funding for the LIEEF as part of their base rates and remit the funds to the State of Michigan monthly. In July 2011, the Michigan Court of Appeals issued a decision reversing the portion of MichCon's June 2010 MPSC rate order that permitted MichCon to recover funding for the LIEEF in base rates. In response to the Court of Appeals decision, Detroit Edison and MichCon ceased remitting payments for LIEEF funding to the State of Michigan. In October 2011, the MPSC issued orders directing Detroit Edison and MichCon to continue collecting funds for LIEEF in rates and to escrow the collected funds pending further order by the MPSC. Pursuant to a January 2012 MPSC order, in March 2012, Detroit Edison and MichCon filed plans for refunding previously escrowed LIEEF funds of $22 million and $3 million, respectively. In April 2012, the Michigan Court of Appeals issued a decision reversing the portion of Detroit Edison's January 2010 MPSC rate order that permitted Detroit Edison to recover funding for the LIEEF. On April 17, 2012, the MPSC issued orders approving the refund plans proposed by Detroit Edison and MichCon. In December 2011, The Vulnerable Household Warmth Fund (VHWF) was created under Michigan law. The purpose of the fund is to provide payment or partial payment of bills for electricity, natural gas, propane, heating oil, or any other type of fuel used to heat the primary residence of a vulnerable customer during the 2011-2012 heating season. Effective with the new law, Detroit Edison and MichCon are to contribute the amounts collected in their base rates, previously remitted for the LIEEF, to the new VHWF. The monthly payments into the VHWF will cease on the earlier of September 30, 2012 or when $48 million has been accumulated in the fund from payments by major Michigan electric and gas utilities. 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. MichCon proposed in the filing, starting in 2013, a five-year annual incremental Infrastructure Recovery Mechanism to recover costs associated with capital investment for the meter move-out, main renewal and pipeline integrity programs. MichCon also proposed a modified form of its RDM. Gas Cost Recovery 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. 2011-2012 Plan Year — In December 2010, MichCon filed its GCR plan case for the 2011-2012 GCR plan year. MichCon filed for a maximum base GCR factor of $5.89 per Mcf adjustable monthly by a contingency factor. An MPSC order was issued on April 17, 2012 approving the 2011-2012 plan. MichCon 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. 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

2009 Electric Rate Case Filing — Court of Appeals Decision

On April 10, 2012, the Michigan Court of Appeals issued a decision relating to an appeal of the January 2010 MPSC order in Detroit Edison's January 2009 rate case filing. The order by the Court of Appeals is subject to further appellate review.

The Court determined that the MPSC only had statutory authority to implement a Revenue Decoupling Mechanism (RDM) for gas providers, but not for electric providers, thereby reversing the MPSC's decision to authorize an RDM for Detroit Edison. As discussed below, Detroit Edison has accrued RDM refund liabilities of $56 million and $71 million for the 2010 and 2011 RDM reconciliation periods, respectively. If the Court of Appeals decision is not disturbed by further appellate review, then Detroit Edison's RDM liabilities will be reversed. Detroit Edison continues to retain the RDM liabilities until it is able to make a determination that the estimation of the liability should be revised.

The Court also reversed the MPSC's order to approve the funding of the Low Income Energy Efficiency Fund (LIEEF) through customer rates consistent with the Court's July 2011 decision in an appeal of MichCon's June 2010 rate order. Please refer to discussion of LIEEF below.

The Court found that the record of evidence in the January 2010 rate order was insufficient to support recovery of costs for the pilot advanced metering infrastructure (AMI) program and remanded this matter to the MPSC for further evidentiary hearing. The MPSC had approved $37 million of rate base related to the AMI program in the January 2010 order. Detroit Edison is currently operating its AMI program pursuant to the MPSC's approval set forth in its October 20, 2011 order, which was not reviewed by or subject to the Court of Appeal's April 10, 2012 decision. Detroit Edison will provide the necessary data and evidence to the MPSC supporting the AMI program expenditures at the remand hearing. Detroit Edison's AMI program expenditures are $83 million as of March 31, 2012, net of Department of Energy matching grant funds of $53 million.

The Court affirmed the use of tracking mechanisms (restoration, line clearance, uncollectibles expense and choice incentive) and the peak demand computations approved in the January 2010 order.

Detroit Edison 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 at December 31, 2011. There are various interpretations and alternative calculation methodologies relating to the pilot RDM refund calculation that could ultimately be adopted by the MPSC which may result in a range of customer refund amounts from $56 million to $140 million for this initial reconciliation filing under the pilot RDM.

Detroit Edison accrued a pilot RDM liability for February 2011 through October 2011 of approximately $71 million , plus interest at December 31, 2011. Detroit Edison terminated the pilot RDM effective October 2011, and has requested a rehearing on this issue asserting that for reconciliation purposes, the pilot RDM should have been considered terminated in April 2011, when Detroit Edison self-implemented rates, consistent with prior MPSC orders. An April 2011 termination would result in a decrease to the liability. However, there can be no assurance that Detroit Edison will prevail in this matter. Similar to the initial reconciliation case, there are various interpretations and alternative calculation methodologies that could be adopted which may result in a range of refund obligations in excess of the amount accrued. Considering these variables, the potential customer refund amount could range from $10 million to $130 million for the second and final pilot RDM period.

The primary uncertainties involved in the calculation methodologies of the pilot RDM for both reconciliation periods include customer class groupings and treatment of fixed customer charges. The Company believes that the calculation methodology used and the resulting refund estimates recorded follow the requirements and intent of the MPSC orders and represent the most probable amount of Detroit Edison's pilot RDM refund liability as of March 31, 2012.

In light of the Court of Appeals decision, actions related to the RDM reconciliation periods have been suspended pending further appellate review. As noted above, Detroit Edison's RDM liabilities will be retained until Detroit Edison is able to make a determination that the estimation of the liability should be revised.

Energy Optimization (EO) Plans

In September 2011, Detroit Edison and MichCon filed biennial EO Plans with the MPSC as required. Detroit Edison's EO Plan application proposed the recovery of EO expenditures for the period 2012-2015 of $294 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 2012-2015 of $103 million and further requested approval of surcharges to recover these costs. On April 17, 2012, the MPSC approved the EO plans proposed by Detroit Edison and MichCon subject to the utilities' agreement to certain modifications. Detroit Edison and MichCon are currently reviewing the proposed modifications. If the MPSC proposed modifications are not accepted by Detroit Edison and MichCon, the amended 2010 EO plans will remain in effect.

Detroit Edison Uncollectible Expense True-Up Mechanism (UETM)

In February 2012, Detroit Edison filed an application with the MPSC for approval of its UETM for 2011 requesting authority to refund approximately $9 million consisting of costs related to 2011 uncollectible expense.

Renewable Energy Plan (REP)

In August 2010, Detroit Edison filed its reconciliation for the 2009 plan year indicating that the 2009 actual renewable plan revenues and costs approximated the related surcharge revenues and cost of the filed plan. In March 2012, the MPSC issued an order approving the 2009 REP cost reconciliation with the exception of approximately $3 million of capital expenditures that were deferred to a future rate case.

Power Supply Cost Recovery 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.

2011 PSCR Year — In March 2012, Detroit Edison filed the 2011 PSCR reconciliation calculating a net under-recovery of $148 million that includes an under-recovery of $52.6 million for the 2010 PSCR year. In addition, the 2011 PSCR reconciliation includes an over-refund of $3.8 million for the 2011 refund of the self-implementation rate increase related to the 2009 electric rate case filing and a credit of $10.5 million related to the expiration of a wholesale power sales contract.

Low Income Energy Efficiency Fund

The Customer Choice and Electricity Reliability Act of 2000 authorized the creation of the LIEEF administered by the MPSC. The purpose of the fund is to provide shut-off and other protection for low income customers and to promote energy efficiency by all customer classes. Detroit Edison and MichCon collect funding for the LIEEF as part of their base rates and remit the funds to the State of Michigan monthly. In July 2011, the Michigan Court of Appeals issued a decision reversing the portion of MichCon's June 2010 MPSC rate order that permitted MichCon to recover funding for the LIEEF in base rates. In response to the Court of Appeals decision, Detroit Edison and MichCon ceased remitting payments for LIEEF funding to the State of Michigan. In October 2011, the MPSC issued orders directing Detroit Edison and MichCon to continue collecting funds for LIEEF in rates and to escrow the collected funds pending further order by the MPSC. Pursuant to a January 2012 MPSC order, in March 2012, Detroit Edison and MichCon filed plans for refunding previously escrowed LIEEF funds of $22 million and $3 million, respectively. In April 2012, the Michigan Court of Appeals issued a decision reversing the portion of Detroit Edison's January 2010 MPSC rate order that permitted Detroit Edison to recover funding for the LIEEF. On April 17, 2012, the MPSC issued orders approving the refund plans proposed by Detroit Edison and MichCon.

In December 2011, The Vulnerable Household Warmth Fund (VHWF) was created under Michigan law. The purpose of the fund is to provide payment or partial payment of bills for electricity, natural gas, propane, heating oil, or any other type of fuel used to heat the primary residence of a vulnerable customer during the 2011-2012 heating season. Effective with the new law, Detroit Edison and MichCon are to contribute the amounts collected in their base rates, previously remitted for the LIEEF, to the new VHWF. The monthly payments into the VHWF will cease on the earlier of September 30, 2012 or when $48 million has been accumulated in the fund from payments by major Michigan electric and gas utilities.

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. MichCon proposed in the filing, starting in 2013, a five-year annual incremental Infrastructure Recovery Mechanism to recover costs associated with capital investment for the meter move-out, main renewal and pipeline integrity programs. MichCon also proposed a modified form of its RDM.

Gas Cost Recovery 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.

2011-2012 Plan Year — In December 2010, MichCon filed its GCR plan case for the 2011-2012 GCR plan year. MichCon filed for a maximum base GCR factor of $5.89 per Mcf adjustable monthly by a contingency factor. An MPSC order was issued on April 17, 2012 approving the 2011-2012 plan.

MichCon 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.

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.