Regulatory Matters	6 Months Ended
Jun. 30, 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. It is the Company's interpretation that the parties in this proceeding have until July 30, 2012 to appeal the decision to the Michigan Supreme Court. 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. If the Court of Appeals decision is not appealed, Detroit Edison is considering filing an application with the MPSC requesting authority to defer the gain that will arise from the reversal of the RDM liabilities by establishing a new regulatory liability to be refunded to customers through a deferral of base rate increases expected to be needed in future years. The Court found that the record of evidence in the 2009 rate case order was insufficient to support the MPSC's authorization to recover costs for the pilot advanced metering infrastructure (AMI) program and remanded this matter to the MPSC. 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 $90 million as of June 30, 2012, net of Department of Energy matching grant funds of $58 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 June 30, 2012. In light of the Court of Appeals decision, actions related to the RDM reconciliation periods have been suspended pending further appellate review. 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. On April 27, 2012, Detroit Edison and MichCon filed letters with the MPSC rejecting modifications to their EO plans. Accordingly, the amended 2010 EO plans remain in effect. In May 2012, Detroit Edison and MichCon both filed separate applications for approval of their respective reconciliations of their 2011 EO plan expenses. Detroit Edison's EO reconciliation included a cumulative $23 million net over-recovery and MichCon's EO reconciliation included a cumulative $11 million net over-recovery. Detroit Edison and MichCon proposed that the calculated cumulative over-recoveries for 2011 be carried forward into 2012 and used as beginning balances for the 2012 reconciliations. Vulnerable Household Warmth Fund 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. In May 2012, Detroit Edison and MichCon filed applications requesting approval of per customer monthly credits to remove the annualized funding for the VHWF from rates in the amount of $40 million and $5 million, respectively. On July 13, 2012, the MPSC approved the plans to remove the VHWF from rates beginning in August 2012. 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. MichCon RDM 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 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 quarter ended June 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. MichCon Depreciation Filing In June 2012, MichCon filed a depreciation study, as ordered by the MPSC, indicating an annual depreciation expense increase of $12.4 million. Depreciation rates remain unchanged pending the MPSC's consideration of the study. 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 GCR Year - In June 2012, MichCon filed its GCR reconciliation for the 12 months ending March 31, 2012. The net under-recovery of $6.4 million includes an over-recovery of $1 million for the 2010-2011 GCR year. 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. It is the Company's interpretation that the parties in this proceeding have until July 30, 2012 to appeal the decision to the Michigan Supreme Court. 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. If the Court of Appeals decision is not appealed, Detroit Edison is considering filing an application with the MPSC requesting authority to defer the gain that will arise from the reversal of the RDM liabilities by establishing a new regulatory liability to be refunded to customers through a deferral of base rate increases expected to be needed in future years.

The Court found that the record of evidence in the 2009 rate case order was insufficient to support the MPSC's authorization to recover costs for the pilot advanced metering infrastructure (AMI) program and remanded this matter to the MPSC. 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 $90 million as of June 30, 2012, net of Department of Energy matching grant funds of $58 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 June 30, 2012.

In light of the Court of Appeals decision, actions related to the RDM reconciliation periods have been suspended pending further appellate review. 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. On April 27, 2012, Detroit Edison and MichCon filed letters with the MPSC rejecting modifications to their EO plans. Accordingly, the amended 2010 EO plans remain in effect.

In May 2012, Detroit Edison and MichCon both filed separate applications for approval of their respective reconciliations of their 2011 EO plan expenses. Detroit Edison's EO reconciliation included a cumulative $23 million net over-recovery and MichCon's EO reconciliation included a cumulative $11 million net over-recovery. Detroit Edison and MichCon proposed that the calculated cumulative over-recoveries for 2011 be carried forward into 2012 and used as beginning balances for the 2012 reconciliations.

Vulnerable Household Warmth Fund

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. In May 2012, Detroit Edison and MichCon filed applications requesting approval of per customer monthly credits to remove the annualized funding for the VHWF from rates in the amount of $40 million and $5 million, respectively. On July 13, 2012, the MPSC approved the plans to remove the VHWF from rates beginning in August 2012.

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.

MichCon RDM

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 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 quarter ended June 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.

MichCon Depreciation Filing

In June 2012, MichCon filed a depreciation study, as ordered by the MPSC, indicating an annual depreciation expense increase of $12.4 million. Depreciation rates remain unchanged pending the MPSC's consideration of the study.

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 GCR Year - In June 2012, MichCon filed its GCR reconciliation for the 12 months ending March 31, 2012. The net under-recovery of $6.4 million includes an over-recovery of $1 million for the 2010-2011 GCR year.

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.