Rate And Regulatory Matters	9 Months Ended
Sep. 30, 2014
Public Utilities, General Disclosures [Abstract]
RATE AND REGULATORY MATTERS	RATE AND REGULATORY MATTERS Below is a summary of updates to significant regulatory proceedings and related lawsuits. See also Note 2 - Rate and Regulatory Matters under Part II, Item 8, of the Form 10-K. We are unable to predict the ultimate outcome of these matters, the timing of the final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity. Missouri Rate Shift Complaint and Earnings Complaint Cases In February 2014, Noranda and 37 residential customers filed a rate shift complaint case and an earnings complaint case with the MoPSC. On August 20, 2014, the MoPSC issued an order that rejected Noranda’s and the residential customers’ request in the rate shift complaint case. On September 12, 2014, Noranda, the MoOPC, the MIEC, and other parties filed a rehearing request, which was subsequently denied by the MoPSC. In the earnings complaint case, Noranda and the residential customers asserted that Ameren Missouri’s electric service business is earning more than the 9.8% return on common equity authorized in the MoPSC's December 2012 electric rate order. The MoOPC, the MIEC, and other parties, participated in the earnings complaint case. On October 1, 2014, the MoPSC issued an order that rejected Noranda’s and the residential customers’ request in the earnings complaint case. On October 30, 2014, Noranda, the MoOPC, the MIEC, and other parties filed a rehearing request, which was subsequently denied by the MoPSC. 2014 Electric Rate Case In July 2014, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service by $264 million. The rate request seeks recovery of increased net energy costs and rebates provided for customer-installed solar generation, as well as recovery of, and a return on, additional electric infrastructure investments made for the benefit of Ameren Missouri’s customers. Plant additions to rate base since the last electric rate order are expected to total approximately $1.4 billion through the true-up date in this rate case and include electric infrastructure investments for upgrades to the electrostatic precipitators at the coal-fired Labadie energy center, the replacement of the nuclear reactor vessel head at the Callaway energy center, two new substations in St. Louis, and the O’Fallon solar energy center, among other additions. Approximately $127 million of the request relates to an increase in net energy costs above the current levels included in base rates previously authorized by the MoPSC in its December 2012 electric rate order, 95% of which, absent initiation of this general rate proceeding, would have been reflected in rate adjustments implemented under Ameren Missouri’s existing FAC. The electric rate increase request is based on a 10.4% return on common equity, a capital structure composed of 51.6% common equity, an electric rate base for Ameren Missouri of $7.3 billion, and a test year ended March 31, 2014, with certain pro-forma adjustments expected through the true-up date of December 31, 2014. As a part of its filing, Ameren Missouri also requested continued use of the FAC and the regulatory tracking mechanisms for storm costs, vegetation management/ infrastructure inspection costs, pension and postretirement benefits, and uncertain income tax positions that the MoPSC previously authorized in earlier electric rate orders. The MoPSC proceeding relating to the proposed electric service rate increase will take place over a period of up to 11 months and a decision by the MoPSC in such proceeding is expected by May 2015, with rates effective by June 2015. Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve, when any rate change may go into effect, or whether any rate increase that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the increase goes into effect. In October 2014, as part of this rate case proceeding, the MoOPC, the MIEC, and other parties, filed a rate shift request that seeks to reduce Noranda’s electric rates with an offsetting increase in electric rates for Ameren Missouri’s other customers. Ameren Missouri supplies electricity to Noranda’s aluminum smelter in southeast Missouri under a 15-year agreement, that is subject to termination as early as 2020 upon at least five years notice given by either party. Termination of the agreement by Ameren Missouri would require MoPSC approval. Accounting Authority Order In July 2011, Ameren Missouri filed a request with the MoPSC for an accounting authority order that would allow Ameren Missouri to defer fixed costs totaling $36 million that were not previously recovered from Noranda as a result of the loss of load caused by the severe 2009 ice storm for potential recovery in a future electric rate case. In November 2013, the MoPSC issued an accounting authority order that allowed Ameren Missouri to seek recovery of these fixed costs in an electric rate case. Ameren Missouri’s July 2014 electric rate case filing requested recovery of these fixed costs over five years. In February 2014, the MIEC and the MoOPC filed appeals of the MoPSC’s November 2013 accounting authority order with the Missouri Court of Appeals, Western District. Ameren Missouri has not recorded any potential revenue associated with this accounting authority order. Illinois IEIMA Under the provisions of the IEIMA, Ameren Illinois’ electric delivery service rates are subject to an annual revenue requirement reconciliation to its actual costs. Throughout each year, Ameren Illinois records a regulatory asset or a regulatory liability and a corresponding increase or decrease to operating revenues for any differences between the revenue requirement in effect for customer billings for that year and its estimate of the probable increase or decrease in the revenue requirement expected to ultimately be approved by the ICC based on that year's actual costs incurred. As of September 30, 2014, Ameren Illinois had recorded regulatory assets of $76 million and $64 million, respectively, to reflect its expected 2014 and 2013 revenue requirement reconciliation adjustments, with interest. As of September 30, 2014, Ameren Illinois had recorded a regulatory liability of $13 million to reflect its 2012 revenue requirement reconciliation adjustment, with interest, which is being refunded to customers during 2014. In December 2013, the ICC issued an order in Ameren Illinois' annual formula rate update filing, which was based on 2012 recoverable costs and expected net plant additions for 2013. The ICC order established rates for 2014. In February 2014, Ameren Illinois filed an appeal to the Appellate Court of the Fourth District of Illinois regarding the rate treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri electric assets located in Illinois to Ameren Illinois. In April 2014, Ameren Illinois filed with the ICC its annual electric delivery service formula rate update to establish the revenue requirement used to set rates for 2015. Pending ICC approval, Ameren Illinois’ update filing, as revised in July 2014, will result in a $205 million increase in Ameren Illinois’ electric delivery service revenue requirement beginning in January 2015. This update reflects an increase to the annual formula rate based on 2013 actual costs and expected net plant additions for 2014, an increase to include the annual reconciliation of the revenue requirement in effect for 2013 to the actual costs incurred in that year, and an increase resulting from the conclusion of a refund to customers in 2014 for the 2012 revenue requirement reconciliation. In August 2014, the ICC staff submitted its revised calculation of the revenue requirement. The ICC staff recommended a $205 million increase in Ameren Illinois’ electric delivery service revenue requirement. Other intervenors requested an electric delivery service revenue requirement up to $7 million lower than the revenue requirement recommended by the ICC staff. In October 2014, the administrative law judges issued a proposed order that reflected an increase to Ameren Illinois’ electric delivery service revenue requirement of $204 million. A final ICC decision on this April 2014 filing is expected by December 2014. 2013 Natural Gas Delivery Service Rate Case In December 2013, the ICC issued a rate order that approved an increase in revenues for natural gas delivery service of $32 million. The revenue increase was based on a 9.1% return on common equity, a capital structure composed of 51.7% common equity, and a rate base of $1.1 billion. The rate order was based on a 2014 future test year. The rate changes became effective January 1, 2014. In March 2014, Ameren Illinois filed an appeal of the allowed return on common equity included in the ICC's order and also appealed the rate treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri natural gas assets located in Illinois to Ameren Illinois with the Appellate Court of the Fourth District of Illinois. Ameren Illinois sought a 10.4% return on common equity in this rate case. ATXI Transmission Project The Spoon River project in northwest Illinois is a MISO-approved transmission line project. In August 2014, ATXI made a filing with the ICC requesting a certificate of public convenience and necessity and project approval for the Spoon River project. A decision is expected from the ICC in 2015. A certificate of public convenience and necessity is required before ATXI can proceed with right-of-way acquisition. Federal 2011 Wholesale Distribution Rate Case In January 2011, Ameren Illinois filed a request with FERC to increase its annual revenues for electric delivery service for its wholesale customers. These wholesale distribution revenues are treated as a deduction from Ameren Illinois’ revenue requirement in retail rate filings with the ICC with no material impact on net income. In March 2011, FERC issued an order authorizing the proposed rates to take effect, subject to refund when the final rates are determined. In November 2012, a FERC administrative law judge issued an initial decision finding that refunds were due to the wholesale customers. In September 2014, FERC issued an order affirming certain findings in the initial decision. Ameren and Ameren Illinois recognized in “Current regulatory liabilities” an estimate of $24 million and $13 million as of September 30, 2014, and December 31, 2013, respectively, for the refund due to the wholesale customers relating to billings since March 2011. In October 2014, Ameren Illinois refunded $24 million, including interest, to the wholesale customers and requested a rehearing on certain aspects of the order. Ameren Illinois Electric Transmission Rate Refund In July 2012, FERC issued an order concluding that Ameren Illinois improperly included acquisition premiums, including goodwill, in determining the common equity used in its electric transmission formula rate, and thereby inappropriately recovered a higher amount from its electric transmission customers. The order required Ameren Illinois to make refunds to customers for such improperly included amounts. In August 2012, Ameren Illinois filed a request for a rehearing of this order. Ameren Illinois submitted a refund report in November 2012 and concluded that no refund was warranted. Several wholesale customers filed a protest with FERC regarding Ameren Illinois’ conclusion that no refund was warranted. In June 2013, FERC issued an order that rejected Ameren Illinois' November 2012 refund report and provided guidance as to the filing of a new refund report. In July 2013, Ameren Illinois filed a revised refund report based on the guidance provided in the June 2013 order, as well as a request for a rehearing of that order. Ameren Illinois' July 2013 refund report also concluded that no refund was warranted. In June 2014, FERC issued an order that denied Ameren Illinois’ rehearing requests of the July 2012 order and the June 2013 order. Separately, in June 2014, FERC issued an order that established hearing and settlement procedures for Ameren Illinois’ July 2013 refund report. In July 2014, Ameren Illinois filed an appeal of FERC’s orders denying rehearing of the July 2012 and June 2013 orders with the United States Court of Appeals for the District of Columbia Circuit. Also in July 2014, Ameren Illinois separately filed a request for rehearing with FERC of its June 2014 order regarding the July 2013 refund report. Ameren Illinois estimates the maximum pretax charge to earnings for this possible refund obligation through December 31, 2014, would be $19 million, before interest charges. For the nine months ended September 30, 2014, Ameren and Ameren Illinois recorded a $4 million reduction to “Operating Revenues - Electric” with a corresponding increase to “Current regulatory liabilities” for its estimate of the refund due to electric transmission customers based on the June 2014 order. If Ameren Illinois were to determine that a refund to its electric transmission customers in excess of the amount already recorded is probable, an additional charge to earnings would be recorded in the period in which that determination is made. FERC Complaint Case In November 2013, a customer group filed a complaint case with FERC seeking a reduction in the allowed base return on common equity for FERC-regulated MISO transmission rate base to 9.15%, as well as a limit on the common equity ratio, under the MISO tariff. Currently, the FERC-allowed base return on common equity for MISO transmission owners is 12.38%. In October 2014, FERC issued an order establishing settlement procedures and, if necessary, hearing procedures regarding the allowed base return on common equity and denied all other aspects of the MISO complaint case. This complaint case could result in a reduction to Ameren Illinois' and ATXI's allowed base return on common equity, which would result in a refund for transmission service revenues earned from the refund effective date of November 12, 2013. In October 2014, FERC issued an order, which confirmed its June 2014 order, reducing the allowed base return on common equity for New England transmission owners from 11.14% to 10.57%, with rate incentives allowed up to 11.74%. The FERC orders in the New England transmission owners’ case applied observable market data from October 2012 to March 2013 to determine the allowed base return on common equity. FERC expects the evidence and the calculation used in the New England transmission owners’ case to guide its decision in the MISO complaint case. The calculation FERC will use to establish the allowed base return on common equity, which is based on a unique time period for each complaint case, will require multiple inputs based on observable market data specific to the utility industry and broader macroeconomic data. The unique time period of observable market data for the MISO complaint case has not been established by FERC. Due to the wide range of potential outcomes and significant uncertainty regarding the value of inputs required in FERC’s calculation, the Ameren Companies cannot reasonably estimate the impact, if any, that a resolution in the MISO complaint case could have on their allowed base return on common equity. On November 6, 2014, we filed a request with FERC to include an incentive adder of up to 50 basis points for participation in an RTO on the allowed base return on common equity. The filing requests a November 7, 2014 effective date and seeks authorization to defer collection of the incentive adder until after the issuance of the final order addressing the pending MISO complaint case discussed above. FERC is required to issue an order within 60 days of our filing. If MISO’s allowed base return on common equity was lowered to 10.57%, as established in the New England transmission owners’ case, with no additional rate incentives, the required refund for Ameren and Ameren Illinois would be $14 million and $11 million, respectively, from the refund effective date of November 12, 2013 through September 30, 2014. The estimated annual reduction in revenues if the MISO return on common equity was 10.57% for Ameren and Ameren Illinois would be $16 million and $12 million, respectively. Ameren Missouri would not expect that a reduction in the FERC-allowed base return on common equity for MISO transmission owners would be material to its results of operations, financial position or liquidity. If Ameren and Ameren Illinois were to determine that a refund to their electric transmission customers could be reasonably estimated, a charge to earnings would be recorded for the refund in the period in which that determination is made. Ameren Missouri Power Purchase Agreement with Entergy Beginning in 2005, FERC issued a series of orders addressing a complaint filed in 2001 by the Louisiana Public Service Commission against Entergy and certain of its affiliates. The complaint alleged unjust and unreasonable cost allocations. As a result of the FERC orders, Entergy began billing Ameren Missouri in 2007 for additional charges under a 165-megawatt power purchase agreement, which expired August 31, 2009. In May 2012, FERC issued an order stating that Entergy should not have included additional charges to Ameren Missouri under the power purchase agreement. Pursuant to the order, in June 2012, Entergy paid Ameren Missouri $31 million. In July 2012, Entergy filed an appeal of FERC's May 2012 order to the United States Court of Appeals for the District of Columbia Circuit, which was subsequently dismissed on a procedural issue. In November 2013, Entergy refiled the appeal of FERC's May 2012 order with the United States Court of Appeals for the District of Columbia Circuit. Ameren is not able to predict when or how the court will rule on Entergy's appeal. The Louisiana Public Service Commission appealed FERC’s orders regarding Louisiana Public Service Commission’s complaint against Entergy Services, Inc. to the United States Court of Appeals for the District of Columbia Circuit. In April 2008, that court ordered further FERC proceedings regarding Louisiana Public Service Commission’s complaint. The court ordered FERC to explain its previous denial of retroactive refunds and the implementation of prospective charges. Ameren Missouri is unable to predict when or how FERC will respond to the court’s decisions. Ameren Missouri estimates that it could incur an additional expense of up to $25 million if FERC orders retroactive application for the years 2001 to 2005. Ameren Missouri believes that the likelihood of incurring an expense is not probable, and therefore no liability has been recorded as of September 30, 2014. Combined Construction and Operating License In 2008, Ameren Missouri filed an application with the NRC for a COL for a new nuclear unit at Ameren Missouri's existing Callaway County, Missouri, energy center site. In 2009, Ameren Missouri suspended its efforts to build a new nuclear unit at its existing Missouri nuclear energy center site, and the NRC suspended review of the COL application. Ameren Missouri estimated the total cost required to obtain a small modular reactor COL to be $80 million to $120 million. As of September 30, 2014, Ameren Missouri had capitalized investments of $69 million for the development of a new nuclear energy center. Ameren Missouri is currently evaluating all potential nuclear technologies in order to maintain an option for nuclear power in the future. All of Ameren Missouri's capitalized investments for the development of a new nuclear energy center will remain capitalized while management pursues options to maximize the value of its investment. If efforts to license additional nuclear generation are abandoned or management concludes it is probable that the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination is made.

RATE AND REGULATORY MATTERS

Below is a summary of updates to significant regulatory proceedings and related lawsuits. See also Note 2 - Rate and Regulatory Matters under Part II, Item 8, of the Form 10-K. We are unable to predict the ultimate outcome of these matters, the timing of the final decisions of the various agencies and courts, or the impact on our results of operations, financial position, or liquidity.

Missouri

Rate Shift Complaint and Earnings Complaint Cases

In February 2014, Noranda and 37 residential customers filed a rate shift complaint case and an earnings complaint case with the MoPSC.

On August 20, 2014, the MoPSC issued an order that rejected Noranda’s and the residential customers’ request in the rate shift complaint case. On September 12, 2014, Noranda, the MoOPC, the MIEC, and other parties filed a rehearing request, which was subsequently denied by the MoPSC.

In the earnings complaint case, Noranda and the residential customers asserted that Ameren Missouri’s electric service business is earning more than the 9.8% return on common equity authorized in the MoPSC's December 2012 electric rate order. The MoOPC, the MIEC, and other parties, participated in the earnings complaint case. On October 1, 2014, the MoPSC issued an order that rejected Noranda’s and the residential customers’ request in the earnings complaint case. On October 30, 2014, Noranda, the MoOPC, the MIEC, and other parties filed a rehearing request, which was subsequently denied by the MoPSC.

2014 Electric Rate Case

In July 2014, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service by $264 million. The rate request seeks recovery of increased net energy costs and rebates provided for customer-installed solar generation, as well as recovery of, and a return on, additional electric infrastructure investments made for the benefit of Ameren Missouri’s customers. Plant additions to rate base since the last electric rate order are expected to total approximately $1.4 billion through the true-up date in this rate case and include electric infrastructure investments for upgrades to the electrostatic precipitators at the coal-fired Labadie energy center, the replacement of the nuclear reactor vessel head at the Callaway energy center, two new substations in St. Louis, and the O’Fallon solar energy center, among other additions. Approximately $127 million of the request relates to an increase in net energy costs above the current levels included in base rates previously authorized by the MoPSC in its December 2012 electric rate order, 95% of which, absent initiation of this general rate proceeding, would have been reflected in rate adjustments implemented under Ameren Missouri’s existing FAC. The electric rate increase request is based on a 10.4% return on common equity, a capital structure composed of 51.6% common equity, an electric rate base for Ameren Missouri of $7.3 billion, and a test year ended March 31, 2014, with certain pro-forma adjustments expected through the true-up date of December 31, 2014.

As a part of its filing, Ameren Missouri also requested continued use of the FAC and the regulatory tracking mechanisms for storm costs, vegetation management/ infrastructure inspection costs, pension and postretirement benefits, and uncertain income tax positions that the MoPSC previously authorized in earlier electric rate orders.

The MoPSC proceeding relating to the proposed electric service rate increase will take place over a period of up to 11 months and a decision by the MoPSC in such proceeding is expected by May 2015, with rates effective by June 2015. Ameren Missouri cannot predict the level of any electric service rate change the MoPSC may approve, when any rate change may go into effect, or whether any rate increase that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and earn a reasonable return on its investments when the increase goes into effect.

In October 2014, as part of this rate case proceeding, the MoOPC, the MIEC, and other parties, filed a rate shift request that seeks to reduce Noranda’s electric rates with an offsetting increase in electric rates for Ameren Missouri’s other customers. Ameren Missouri supplies electricity to Noranda’s aluminum smelter in southeast Missouri under a 15-year agreement, that is subject to termination as early as 2020 upon at least five years notice given by either party. Termination of the agreement by Ameren Missouri would require MoPSC approval.

Accounting Authority Order

In July 2011, Ameren Missouri filed a request with the MoPSC for an accounting authority order that would allow Ameren Missouri to defer fixed costs totaling $36 million that were not previously recovered from Noranda as a result of the loss of load caused by the severe 2009 ice storm for potential recovery in a future electric rate case. In November 2013, the MoPSC issued an accounting authority order that allowed Ameren Missouri to seek recovery of these fixed costs in an electric rate case. Ameren Missouri’s July 2014 electric rate case filing requested recovery of these fixed costs over five years. In February 2014, the MIEC and the MoOPC filed appeals of the MoPSC’s November 2013 accounting authority order with the Missouri Court of Appeals, Western District. Ameren Missouri has not recorded any potential revenue associated with this accounting authority order.

Illinois

IEIMA

Under the provisions of the IEIMA, Ameren Illinois’ electric delivery service rates are subject to an annual revenue requirement reconciliation to its actual costs. Throughout each year, Ameren Illinois records a regulatory asset or a regulatory liability and a corresponding increase or decrease to operating revenues for any differences between the revenue requirement in effect for customer billings for that year and its estimate of the probable increase or decrease in the revenue requirement expected to ultimately be approved by the ICC based on that year's actual costs incurred. As of September 30, 2014, Ameren Illinois had recorded regulatory assets of $76 million and $64 million, respectively, to reflect its expected 2014 and 2013 revenue requirement reconciliation adjustments, with interest. As of September 30, 2014, Ameren Illinois had recorded a regulatory liability of $13 million to reflect its 2012 revenue requirement reconciliation adjustment, with interest, which is being refunded to customers during 2014.

In December 2013, the ICC issued an order in Ameren Illinois' annual formula rate update filing, which was based on 2012 recoverable costs and expected net plant additions for 2013. The ICC order established rates for 2014. In February 2014, Ameren Illinois filed an appeal to the Appellate Court of the Fourth District of Illinois regarding the rate treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri electric assets located in Illinois to Ameren Illinois.

In April 2014, Ameren Illinois filed with the ICC its annual electric delivery service formula rate update to establish the revenue requirement used to set rates for 2015. Pending ICC approval, Ameren Illinois’ update filing, as revised in July 2014, will result in a $205 million increase in Ameren Illinois’ electric delivery service revenue requirement beginning in January 2015. This update reflects an increase to the annual formula rate based on 2013 actual costs and expected net plant additions for 2014, an increase to include the annual reconciliation of the revenue requirement in effect for 2013 to the actual costs incurred in that year, and an increase resulting from the conclusion of a refund to customers in 2014 for the 2012 revenue requirement reconciliation. In August 2014, the ICC staff submitted its revised calculation of the revenue requirement. The ICC staff recommended a $205 million increase in Ameren Illinois’ electric delivery service revenue requirement. Other intervenors requested an electric delivery service revenue requirement up to $7 million lower than the revenue requirement recommended by the ICC staff. In October 2014, the administrative law judges issued a proposed order that reflected an increase to Ameren Illinois’ electric delivery service revenue requirement of $204 million. A final ICC decision on this April 2014 filing is expected by December 2014.

2013 Natural Gas Delivery Service Rate Case

In December 2013, the ICC issued a rate order that approved an increase in revenues for natural gas delivery service of $32 million. The revenue increase was based on a 9.1% return on common equity, a capital structure composed of 51.7% common equity, and a rate base of $1.1 billion. The rate order was based on a 2014 future test year. The rate changes became effective January 1, 2014. In March 2014, Ameren Illinois filed an appeal of the allowed return on common equity included in the ICC's order and also appealed the rate treatment of accumulated deferred income taxes related to the transfer of former Ameren Missouri natural gas assets located in Illinois to Ameren Illinois with the Appellate Court of the Fourth District of Illinois. Ameren Illinois sought a 10.4% return on common equity in this rate case.

ATXI Transmission Project

The Spoon River project in northwest Illinois is a MISO-approved transmission line project. In August 2014, ATXI made a filing with the ICC requesting a certificate of public convenience and necessity and project approval for the Spoon River project. A decision is expected from the ICC in 2015. A certificate of public convenience and necessity is required before ATXI can proceed with right-of-way acquisition.

Federal

2011 Wholesale Distribution Rate Case

In January 2011, Ameren Illinois filed a request with FERC to increase its annual revenues for electric delivery service for its wholesale customers. These wholesale distribution revenues are treated as a deduction from Ameren Illinois’ revenue requirement in retail rate filings with the ICC with no material impact on net income. In March 2011, FERC issued an order authorizing the proposed rates to take effect, subject to refund when the final rates are determined. In November 2012, a FERC administrative law judge issued an initial decision finding that refunds were due to the wholesale customers. In September 2014, FERC issued an order affirming certain findings in the initial decision. Ameren and Ameren Illinois recognized in “Current regulatory liabilities” an estimate of $24 million and $13 million as of September 30, 2014, and December 31, 2013, respectively, for the refund due to the wholesale customers relating to billings since March 2011. In October 2014, Ameren Illinois refunded $24 million, including interest, to the wholesale customers and requested a rehearing on certain aspects of the order.

Ameren Illinois Electric Transmission Rate Refund

In July 2012, FERC issued an order concluding that Ameren Illinois improperly included acquisition premiums, including goodwill, in determining the common equity used in its electric transmission formula rate, and thereby inappropriately recovered a higher amount from its electric transmission customers. The order required Ameren Illinois to make refunds to customers for such improperly included amounts. In August 2012, Ameren Illinois filed a request for a rehearing of this order.

Ameren Illinois submitted a refund report in November 2012 and concluded that no refund was warranted. Several wholesale customers filed a protest with FERC regarding Ameren Illinois’ conclusion that no refund was warranted. In June 2013, FERC issued an order that rejected Ameren Illinois' November 2012 refund report and provided guidance as to the filing of a new refund report. In July 2013, Ameren Illinois filed a revised refund report based on the guidance provided in the June 2013 order, as well as a request for a rehearing of that order. Ameren Illinois' July 2013 refund report also concluded that no refund was warranted.

In June 2014, FERC issued an order that denied Ameren Illinois’ rehearing requests of the July 2012 order and the June 2013 order. Separately, in June 2014, FERC issued an order that established hearing and settlement procedures for Ameren Illinois’ July 2013 refund report. In July 2014, Ameren Illinois filed an appeal of FERC’s orders denying rehearing of the July 2012 and June 2013 orders with the United States Court of Appeals for the District of Columbia Circuit. Also in July 2014, Ameren Illinois separately filed a request for rehearing with FERC of its June 2014 order regarding the July 2013 refund report.

Ameren Illinois estimates the maximum pretax charge to earnings for this possible refund obligation through December 31, 2014, would be $19 million, before interest charges. For the nine months ended September 30, 2014, Ameren and Ameren Illinois recorded a $4 million reduction to “Operating Revenues - Electric” with a corresponding increase to “Current regulatory liabilities” for its estimate of the refund due to electric transmission customers based on the June 2014 order. If Ameren Illinois were to determine that a refund to its electric transmission customers in excess of the amount already recorded is probable, an additional charge to earnings would be recorded in the period in which that determination is made.

FERC Complaint Case

In November 2013, a customer group filed a complaint case with FERC seeking a reduction in the allowed base return on common equity for FERC-regulated MISO transmission rate base to 9.15%, as well as a limit on the common equity ratio, under the MISO tariff. Currently, the FERC-allowed base return on common equity for MISO transmission owners is 12.38%. In October 2014, FERC issued an order establishing settlement procedures and, if necessary, hearing procedures regarding the allowed base return on common equity and denied all other aspects of the MISO complaint case. This complaint case could result in a reduction to Ameren Illinois' and ATXI's allowed base return on common equity, which would result in a refund for transmission service revenues earned from the refund effective date of November 12, 2013.

In October 2014, FERC issued an order, which confirmed its June 2014 order, reducing the allowed base return on common equity for New England transmission owners from 11.14% to 10.57%, with rate incentives allowed up to 11.74%. The FERC orders in the New England transmission owners’ case applied observable market data from October 2012 to March 2013 to determine the allowed base return on common equity. FERC expects the evidence and the calculation used in the New England transmission owners’ case to guide its decision in the MISO complaint case. The calculation FERC will use to establish the allowed base return on common equity, which is based on a unique time period for each complaint case, will require multiple inputs based on observable market data specific to the utility industry and broader macroeconomic data. The unique time period of observable market data for the MISO complaint case has not been established by FERC. Due to the wide range of potential outcomes and significant uncertainty regarding the value of inputs required in FERC’s calculation, the Ameren Companies cannot reasonably estimate the impact, if any, that a resolution in the MISO complaint case could have on their allowed base return on common equity.

On November 6, 2014, we filed a request with FERC to include an incentive adder of up to 50 basis points for participation in an RTO on the allowed base return on common equity. The filing requests a November 7, 2014 effective date and seeks authorization to defer collection of the incentive adder until after the issuance of the final order addressing the pending MISO complaint case discussed above. FERC is required to issue an order within 60 days of our filing.

If MISO’s allowed base return on common equity was lowered to 10.57%, as established in the New England transmission owners’ case, with no additional rate incentives, the required refund for Ameren and Ameren Illinois would be $14 million and $11 million, respectively, from the refund effective date of November 12, 2013 through September 30, 2014. The estimated annual reduction in revenues if the MISO return on common equity was 10.57% for Ameren and Ameren Illinois would be $16 million and $12 million, respectively. Ameren Missouri would not expect that a reduction in the FERC-allowed base return on common equity for MISO transmission owners would be material to its results of operations, financial position or liquidity. If Ameren and Ameren Illinois were to determine that a refund to their electric transmission customers could be reasonably estimated, a charge to earnings would be recorded for the refund in the period in which that determination is made.

Ameren Missouri Power Purchase Agreement with Entergy

Beginning in 2005, FERC issued a series of orders addressing a complaint filed in 2001 by the Louisiana Public Service Commission against Entergy and certain of its affiliates. The complaint alleged unjust and unreasonable cost allocations. As a result of the FERC orders, Entergy began billing Ameren Missouri in 2007 for additional charges under a 165-megawatt power purchase agreement, which expired August 31, 2009. In May 2012, FERC issued an order stating that Entergy should not have included additional charges to Ameren Missouri under the power purchase agreement. Pursuant to the order, in June 2012, Entergy paid Ameren Missouri $31 million. In July 2012, Entergy filed an appeal of FERC's May 2012 order to the United States Court of Appeals for the District of Columbia Circuit, which was subsequently dismissed on a procedural issue. In November 2013, Entergy refiled the appeal of FERC's May 2012 order with the United States Court of Appeals for the District of Columbia Circuit. Ameren is not able to predict when or how the court will rule on Entergy's appeal.

The Louisiana Public Service Commission appealed FERC’s orders regarding Louisiana Public Service Commission’s complaint against Entergy Services, Inc. to the United States Court of Appeals for the District of Columbia Circuit. In April 2008, that court ordered further FERC proceedings regarding Louisiana Public Service Commission’s complaint. The court ordered FERC to explain its previous denial of retroactive refunds and the implementation of prospective charges. Ameren Missouri is unable to predict when or how FERC will respond to the court’s decisions. Ameren Missouri estimates that it could incur an additional expense of up to $25 million if FERC orders retroactive application for the years 2001 to 2005. Ameren Missouri believes that the likelihood of incurring an expense is not probable, and therefore no liability has been recorded as of September 30, 2014.

Combined Construction and Operating License

In 2008, Ameren Missouri filed an application with the NRC for a COL for a new nuclear unit at Ameren Missouri's existing Callaway County, Missouri, energy center site. In 2009, Ameren Missouri suspended its efforts to build a new nuclear unit at its existing Missouri nuclear energy center site, and the NRC suspended review of the COL application.

Ameren Missouri estimated the total cost required to obtain a small modular reactor COL to be $80 million to $120 million. As of September 30, 2014, Ameren Missouri had capitalized investments of $69 million for the development of a new nuclear energy center. Ameren Missouri is currently evaluating all potential nuclear technologies in order to maintain an option for nuclear power in the future.

All of Ameren Missouri's capitalized investments for the development of a new nuclear energy center will remain capitalized while management pursues options to maximize the value of its investment. If efforts to license additional nuclear generation are abandoned or management concludes it is probable that the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination is made.