Table of Contents

UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 10-K
(X) 
Annual report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934
for the fiscal year ended December 31, 2014.2017.
  
  OR
  
(   ) Transition report pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934 for the transition period from           to        .
Commission
File Number
 
Exact name of registrant as specified in its charter;
State of Incorporation;
Address and Telephone Number
 
IRS Employer
Identification No.
   
1-14756 Ameren Corporation 43-1723446
  (Missouri Corporation)  
  1901 Chouteau Avenue  
  St. Louis, Missouri 63103  
  (314) 621-3222  
   
1-2967 Union Electric Company 43-0559760
  (Missouri Corporation)  
  1901 Chouteau Avenue  
  St. Louis, Missouri 63103  
  (314) 621-3222  
   
1-3672 Ameren Illinois Company 37-0211380
  (Illinois Corporation)  
  6 Executive Drive  
  Collinsville, Illinois 62234  
  (618) 343-8150  
Securities Registered Pursuant to Section 12(b) of the Act:
The following security is registered pursuant to Section 12(b) of the Securities Exchange Act of 1934 and is listed on the New York Stock Exchange:
RegistrantTitle of each class
Ameren CorporationCommon Stock, $0.01 par value per share
Securities Registered Pursuant to Section 12(g) of the Act:
RegistrantTitle of each class
Union Electric CompanyPreferred Stock, cumulative, no par value, stated value $100 per share
Ameren Illinois Company
Preferred Stock, cumulative, $100 par value per share
Depositary Shares, each representing one-fourth of a share of 6.625% Preferred Stock, cumulative, $100 par value per share

Indicate by checkmark if each registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act.
Ameren CorporationYes(X)
ý

No( )
¨

Union Electric CompanyYes( )
¨

No(X)
ý

Ameren Illinois CompanyYes( )
¨

No(X)
ý

Indicate by checkmark if each registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act.
Ameren CorporationYes( )
¨

No(X)
ý

Union Electric CompanyYes( )
¨

No(X)
ý

Ameren Illinois CompanyYes( )
¨

No(X)
ý

Indicate by checkmark whether the registrants: (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) have been subject to such filing requirements for the past 90 days.
Ameren CorporationYes(X)
ý

No( )
¨

Union Electric CompanyYes(X)
ý

No( )
¨

Ameren Illinois CompanyYes(X)
ý

No( )
¨

Indicate by checkmark whether each registrant has submitted electronically and posted on its corporate website, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§ 232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files).
Ameren CorporationYes(X)
ý

No( )
¨

Union Electric CompanyYes(X)
ý

No( )
¨

Ameren Illinois CompanyYes(X)
ý

No( )
¨

Indicate by checkmark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K (§ 229.405 of this chapter) is not contained herein, and will not be contained, to the best of each registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K.
Ameren Corporation (X)
ý

Union Electric Company (X)
ý

Ameren Illinois Company (X)
ý

Indicate by checkmark whether each registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or a smaller reporting company, or an emerging growth company. See definitions of “large accelerated filer,” “accelerated filer,” and “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.
  
Large
Accelerated
Filer
 
Accelerated
Filer
 
Non-accelerated
Filer
 
Smaller
Reporting
Company
Emerging Growth Company
Ameren Corporation (X)ý ( )¨ ( )
¨

 ( )
¨

¨
Union Electric Company ( )
¨

 ( )
¨

 (X)
ý

 ( )¨¨
Ameren Illinois Company ( )
¨

 ( )
¨

 (X)
ý

 ( )¨¨
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.
Ameren Corporation¨
Union Electric Company¨
Ameren Illinois Company¨
Indicate by checkmark whether each registrant is a shell company (as defined in Rule 12b-2 of the Act).
Ameren CorporationYes( )
¨

No(X)
ý

Union Electric CompanyYes( )
¨

No(X)
ý

Ameren Illinois CompanyYes( )
¨

No(X)
ý

As of June 30, 20142017, Ameren Corporation had 242,634,798 shares of its $0.01 par value common stock outstanding. Thethe aggregate market value of these shares ofAmeren Corporation’s common stock, $0.01 par value, (based upon the closing price of the common stock on the New York Stock Exchange on June 30, 20142017) held by nonaffiliates was $9,918,910,542. The$13,230,607,078. All of the shares of common stock of the other registrants were held by Ameren Corporation as of June 30, 20142017.
The number of shares outstanding of each registrant’s classes of common stock as of January 30,31, 20152018, waswere as follows:
Ameren CorporationCommon stock, $0.01 par value per share: 242,634,798
  
Union Electric Company
Common stock, $5 par value per share, held by Ameren
Corporation (parent company of the registrant): 102,123,834
  
Ameren Illinois Company
Common stock, no par value, held by Ameren
Corporation (parent company of the registrant): 25,452,373
DOCUMENTS INCORPORATED BY REFERENCE
Portions of the definitive proxy statement of Ameren Corporation and portions of the definitive information statements of Union Electric Company and Ameren Illinois Company for the 20152018 annual meetings of shareholders are incorporated by reference into Part III of this Form 10-K.
 
This combined Form 10-K is separately filed by Ameren Corporation, Union Electric Company, and Ameren Illinois Company. Each registrant hereto is filing on its own behalf all of the information contained in this annual report that relates to such registrant. Each registrant hereto is not filing any information that does not relate to such registrant, and therefore makes no representation as to any such information.



TABLE OF CONTENTS
  Page
PART I  
Item 1.
 
 
 
 
 
 
 
 
 
Item 1A.
Item 1B.
Item 2.
Item 3.
Item 4.
   
PART II  
Item 5.
Item 6.
Item 7.
 
 
 
 
 
 
 
Item 7A.
Item 8.
 
Item 9.
Item 9A.
Item 9B.
   
PART III  
Item 10.
Item 11.
Item 12.
Item 13.
Item 14.
   
PART IV  
Item 15.
Item 16.
This report contains “forward-looking” statements within the meaning of Section 21E of the Securities Exchange Act of 1934, as amended. Forward-looking statements should be read with the cautionary statements and important factors under the heading “Forward-looking Statements.” Forward-looking statements are all statements other than statements of historical fact, including those statements that are identified by the use of the words “anticipates,” “estimates,” “expects,” “intends,” “plans,” “predicts,” “projects,” and similar expressions.



GLOSSARY OF TERMS AND ABBREVIATIONS
We use the words “our,” “we” or “us” with respect to certain information that relates to Ameren, Ameren Missouri, and Ameren Illinois, collectively. When appropriate, subsidiaries of Ameren Corporation are named specifically as their various business activities are discussed.
2006 Incentive Plan - The 2006 Omnibus Incentive Compensation Plan, provides for compensatory stock-based awards to eligible employees and directors. The 2006 Omnibus Incentive Compensation Plan was replaced prospectively for new grants by the 2014 Incentive Plan.
2012 Credit Agreements - The 2012 Illinois Credit Agreement and the 2012 Missouri Credit Agreement, collectively.
2012 Illinois Credit Agreement -Ameren's and Ameren Illinois' $1.1 billion multiyear senior unsecured credit agreement. The agreement was amended and restated in December 2014 and expires on December 11, 2019.
2012 Missouri Credit Agreement -Ameren's and Ameren Missouri's $1 billion multiyear senior unsecured credit agreement. The agreement was amended and restated in December 2014 and expires on December 11, 2019.
2014 Incentive Plan - The 2014 Omnibus Incentive Compensation Plan, which became effective in April 2014 and provides for compensatory stock-based awards to eligible employees and directors.
AER - Ameren Energy Resources Company, LLC, a former Ameren Corporation subsidiary that consisted of non-rate-regulated operations. In December 2013, AER contributed substantially all of its assets and liabilities, including its ownership interests in Genco, AERG,Ameren Energy Generating Company, Ameren Energy Resources Generating Company, and Ameren Energy Marketing Company, to New AER. Medina Valley was distributed from AER to Ameren in March 2013.
AERG - Ameren Energy Resources Generating Company, a former AER subsidiary that operated a merchant electric generation business in Illinois. In December 2013, AERG was included in the divestiture of New AER to IPH. Following the New AER divestiture, AERG became Illinois Power Resources Generating, LLC.
Ameren - Ameren Corporation and its subsidiaries on a consolidated basis. In references to financing activities, acquisition activities, or liquidity arrangements, Ameren is defined as Ameren Corporation, the parent.
Ameren Companies - Ameren Corporation, Ameren Missouri, and Ameren Illinois, collectively, which are individual registrants within the Ameren consolidated group.
Ameren Illinois or AICElectric Distribution – An Ameren Corporation and Ameren Illinois financial reporting segment consisting of the rate-regulated electric distribution business of Ameren Illinois.
Ameren Illinois Transmission -– An Ameren Illinois financial reporting segment consisting of the rate-regulated electric transmission business of Ameren Illinois.
Ameren Illinois Natural Gas – An Ameren Corporation and Ameren Illinois financial reporting segment consisting of the rate-regulated natural gas distribution business of Ameren Illinois.
Ameren Illinois Ameren Illinois Company, an Ameren Corporation subsidiary that operates rate-regulated electric and natural gas transmission and distribution businesses in Illinois, doing business as Ameren Illinois. Ameren Illinois is also defined as a financial reporting segment.
Ameren Illinois Merger - In 2010, CILCO and IP merged with and into CIPS, with the surviving corporation renamed Ameren Illinois Company.
Ameren Missouri or AMO - Union Electric Company, an Ameren Corporation subsidiary that operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas transmission and distribution business in Missouri, doing business as Ameren Missouri. Ameren Missouri is also defined as a financial reporting segment.segment of Ameren.
Ameren Services - Ameren Services Company, an Ameren
Corporation subsidiary that provides support services, such as accounting, legal, treasury, and asset management services, to Ameren and its subsidiaries.
Ameren Transmission – An Ameren Corporation financial reporting segment primarily consisting of the aggregated electric transmission businesses of Ameren Illinois and ATXI.
AMIL - The MISO balancing authority area operated by Ameren, which includes the load of Ameren Illinois and ATXI.
AMMO - The MISO balancing authority area operated by Ameren, which includes the load and energy centers of Ameren Missouri.
ARO - Asset retirement obligations.
ATXI - Ameren Transmission Company of Illinois, an Ameren Corporation subsidiary that is engaged in the construction and operation of electric transmission assets.
Baseload - The minimum amount of electric power delivered or required over a given period of time at a steady rate.
Btu - British thermal unit, a standard unit for measuring the quantity of heat energy required to raise the temperature of one pound of water by one degree Fahrenheit.
CAIR - Clean Air Interstate Rule.
CCR - Coal combustion residuals, which include fly ash, bottom ash, boiler slag, and flue gas desulfurization materials generated from burning coal to generate electricity.
CILCO - Central Illinois Light Company, a former Ameren Corporation subsidiary that operated rate-regulated electricwas merged with CIPS and natural gas transmission and distribution businesses in Illinois, before theIP to form Ameren Illinois Merger.Illinois.
CIPS - Central Illinois Public Service Company, ana predecessor to Ameren Corporation subsidiary, renamed Ameren Illinois Company upon the effectiveness of the Ameren Illinois Merger, which operates rate-regulated electric and natural gas transmission and distribution businesses in Illinois.
Clean Power Plan - “Carbon Pollution Emission Guidelines for Existing Stationary Sources: Electric Utility Generating Units,” a proposedan EPA rule, published bywhich would have established emission guidelines for states to follow in developing plans to reduce CO2 emissions from existing fossil-fuel-fired electric generating units. In October 2017, the EPA in June 2014.announced a proposal to repeal the Clean Power Plan.
CO2 - Carbon dioxide.
COL - Nuclear energy center combined construction and operating license.
Cooling degree-days - The summation of positive differences between the meanaverage daily temperature and a 65-degree Fahrenheit base. This statistic is useful as an indicator of electricity demand by residential and commercial customers for summer cooling.
Credit Agreements – The Illinois Credit Agreement and the Missouri Credit Agreement, collectively.
CSAPR - Cross-State Air Pollution Rule.
CSRA - Natural Gas Consumer, Safety and Reliability Act,Rule, an Illinois lawEPA rule that encourages natural gas utilitiesrequires states that contribute to accelerate modernization of the state's natural gas infrastructure through the use of a QIP rider.air pollution in downwind states to limit air emissions from fossil-fuel-fired electric generating units.
CT - Combustion turbine used primarily for peaking electric generation capacity.
Dekatherm - A standard unit of energy equivalent to one million Btus.
DOE - Department of Energy, a United States government agency.
DRPlus - Ameren Corporation’s dividend reinvestment and direct stock purchase plan.
DynegyElectric margins - Dynegy Inc.– Electric revenues less fuel and purchased power costs.
EEIEMANI - Electric Energy, Inc., a former 80%-owned Genco


1


subsidiary that operated merchant electric generation energy centers and FERC-regulated transmission facilities in Illinois. In December 2013, Genco's ownership interest in EEI was included in the divestiture of New AER to IPH.
Entergy -Entergy Arkansas, Inc.– European Mutual Association for Nuclear Insurance.
EPA - Environmental Protection Agency, a United States government agency.
ERISA - Employee Retirement Income Security Act of 1974, as amended.

Excess deferred taxes – The amount of income taxes previously collected from customers that will be returned to customers over periods of time determined by our regulators.
Exchange Act - Securities Exchange Act of 1934, as amended.
FAC - Fuel adjustment clause, a fuel and purchased power cost recovery mechanism that allows Ameren Missouri to recover or refund, through customer rates, 95% of changesthe variance in net energy costs greater or less thanfrom the amount set in base rates without a traditional rate proceeding, subject to MoPSC prudence reviews. Net energy costs include fuel and purchased power costs, including transportation charges and revenues, net of off-system sales.
FASB - Financial Accounting Standards Board, a rulemaking organization that establishes financial accounting and reporting standards in the United States.
FEJA – Future Energy Jobs Act,a 2016 Illinois law affecting electric distribution utilities. This law allows Ameren Illinois to earn a return on its electric energy-efficiency investments, decouples electric distribution revenues from sales volumes, offers customer rebates for installing distributed generation, and includes extensions and modifications of certain IEIMA performance-based framework provisions, among other things.
FERC - Federal Energy Regulatory Commission, a United States government agency.
Fitch - Fitch Ratings, a credit rating agency.
FTRs - Financial transmission rights, financial instruments that specify whether the holder shall pay or receive compensation for certain congestion-related transmission charges between two designated points.
GAAP - Generally accepted accounting principles in the United States.
Genco - Ameren Energy Generating Company, a former AER subsidiary that operated a merchant electric generation business in Illinois and held an 80% ownership interest in EEI. In December 2013, Genco was included in the divestiture of New AER to IPH. Following the New AER divestiture, Genco became Illinois Power Generating Company. 
Heating degree-days - The summation of negative differences between the meanaverage daily temperature and a 65-degree Fahrenheit base. This statistic is useful as an indicator of demand for electricity and natural gas for winter heating by residential and commercial customers.
IBEW - International Brotherhood of Electrical Workers, a labor union.
ICC - Illinois Commerce Commission, a state agency that regulates Illinois utility businesses, including Ameren Illinois and ATXI.
IEIMA - Illinois Energy Infrastructure Modernization Act, an Illinois law that established a performance-based formula process for determining electric deliverydistribution service rates. By its election to participate in this regulatory framework, Ameren Illinois is required to make incremental capital expenditures to modernize its electric distribution system, to meet performance standards, and to create jobs in Illinois, among other requirements.
Illinois Credit Agreement Ameren’s and Ameren Illinois’ $1.1 billion senior unsecured credit agreement, which expires in December 2021, unless extended.
IP - Illinois Power Company, a former Ameren Corporation subsidiary that operated rate-regulated electricmerged with CIPS and natural gas transmission and distribution businesses in Illinois, before theCILCO to form Ameren Illinois Merger.Illinois.
IPA - Illinois Power Agency, a state government agency that has broad authority to assist in the procurement of electric power for
residential and small commercial customers.
IPH - Illinois Power Holdings, LLC, an indirect wholly owned subsidiary of Dynegy.Dynegy Inc.
IRS - Internal Revenue Service, a United States government agency.
ISRS - Infrastructure system replacement surcharge, which is a cost recovery mechanism that allows Ameren Missouri to recover natural gas infrastructure replacement costs from utility customers without a traditional rate proceeding.
IUOE - International Union of Operating Engineers, a labor union.
Kilowatthour - A measure of electricity consumption equivalent to the use of 1,000 watts of power over one hour.
LIUNA - Laborers’ International Union of North America, a labor union.
Marketing Company - Ameren Energy Marketing Company, a former AER subsidiary that marketed power for Genco, AERG, and EEI. Marketing Company was included in the divestiture of New AER to IPH in December 2013. Following the New AER divestiture, Marketing Company became Illinois Power Marketing Company. 
MATS - Mercury and Air Toxics Standards.Standards, an EPA rule that limits emissions of mercury and other air toxics from coal- and oil-fired electric generating units.
Medina Valley - AmerenEnergy Medina Valley Cogen, LLC, an Ameren Corporation subsidiary. This company was distributed from AER to Ameren in March 2013.
MEEIA - Missouri Energy Efficiency Investment Act, a Missouri law that allows electric utilities to recover costs related to MoPSC-approved customer energy efficiencyenergy-efficiency programs.
MEEIA 2013 Ameren Missouri’s portfolio of customer energy-efficiency programs, net shared benefits, and performance incentive for 2013 through 2015, pursuant to the MEEIA, as approved by the MoPSC in August 2012.
MEEIA 2016 Ameren Missouri’s portfolio of customer energy-efficiency programs, throughput disincentive, and performance incentive for March 2016 through February 2019, pursuant to the MEEIA, as approved by the MoPSC in February 2016.
Megawatthour or MWh - One thousand kilowatthours.
Merchant Generation - A former financial reporting segment that, prior to the divestiture of New AER to IPH in December 2013, consisted primarily of the operations of AER, including Genco, AERG, Marketing Company and, through March 2013, Medina Valley.
MGP - Manufactured gas plant.
MIEC - Missouri Industrial Energy Consumers, an association of industrial companies.
MISO - Midcontinent Independent System Operator, Inc., an RTO.
Missouri Credit Agreement Ameren’s and Ameren Missouri’s $1 billion senior unsecured credit agreement, which expires in December 2021, unless extended.
Missouri Environmental Authority - Environmental Improvement and Energy Resources Authority of the state of Missouri, a governmental body authorized to finance environmental projects by issuing tax-exempt bonds and notes.
Mmbtu - One million Btus.
Money pool - Borrowing agreements among Ameren and its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements.
Moody’s - Moody’s Investors Service Inc., a credit rating agency.
MoOPC - Missouri Office of the Public Counsel.
MoPSC - Missouri Public Service Commission, a state agency that regulates Missouri utility businesses, including Ameren Missouri.
MTM - Mark-to-market.
MW - Megawatt.
Native load - End-use retail customers whom we are obligated to serve by statute, franchise, contract, or other regulatory requirement.

Natural gas margins – Natural gas revenues less natural gas purchased for resale.
NAV – Net asset value per share.
NEIL - Nuclear Electric Insurance Limited, which includes all of its affiliated companies.
NERC - North American Electric Reliability Corporation.


2


Net energy costs- Net energy costs, as defined in the FAC, which include fuel and purchased power costs, including transportation, charges and revenues, net of off-system sales. Substantially all transmission revenues and charges are excluded from net energy costs.
Net shared benefits – Ameren Missouri’s share of the present value of lifetime energy savings, net of program costs, designed to offset sales volume reductions resulting from MEEIA 2013 customer energy-efficiency programs.
New AER - New Ameren Energy Resources Company, LLC, a limited liability company formed as a direct wholly owned subsidiary of AER. New AER, acquired by IPH in December 2013, included substantially all of the assets and liabilities of AER, except for certain assets and liabilities retained by Ameren. Following the New AER divestiture, New AER became Illinois Power Resources, LLC. 
NONew Madrid Smelter 2 - Nitrogen dioxide.– A former aluminum smelter located in southeast Missouri.
NOx - Nitrogen oxides.
Noranda - Noranda Aluminum, Inc.
NPNS - Normal purchases and normal sales.
NRC - Nuclear Regulatory Commission, a United States government agency.
NSPS - New Source Performance Standards, a provisionprovisions under the Clean Air Act.
NSR - New Source Review provisions of the Clean Air Act, which include Nonattainment New Source Review and Prevention of Significant Deterioration regulations.
NWPA - Nuclear Waste Policy Act of 1982, as amended.
NYMEX - New York Mercantile Exchange.
NYSE - New York Stock Exchange, Inc.
OATT - Open Access Transmission Tariff.
OCI - Other comprehensive income (loss) as defined by GAAP.
Off-system sales revenues - Revenues from other than native load sales, including wholesale sales.
OTC - Over-the-counter.
PGA - Purchased Gas Adjustment tariffs, which permit prudently incurred natural gas costs to be recovered directly from utility customers without a traditional rate proceeding.
PJM - PJM Interconnection LLC., an RTO.
PUHCA 2005 - The Public Utility Holding Company Act of 2005.
QIP - Qualifying infrastructure plant. Costs of qualifying infrastructure natural gas plant that may beare included in aan Ameren Illinois recovery mechanism enacted as part of the CSRA.mechanism.
Rate base - The net value of propertybasis on which a public utility is permitted to earn an allowed rate of return. This basis is the net investment in assets used to provide utility service, which generally consists of in-service property, plant, and equipment, net of accumulated depreciation and accumulated deferred income taxes, inventories, and, depending on jurisdiction, construction work in progress.
Regulatory lag - The exposure to differences in costs incurred and actual sales volume levels as compared with the associated amounts included in customer rates. Rate increase requests in traditional regulatory rate case proceedingsreviews can take up to 11 months to be acted upon by the MoPSC and the ICC. As a result, revenue increases authorized by regulators will lag behind changing costs and sales volume levels when based on historical periods.
Revenue requirement - The cost of providing utility service to customers, which is calculated as the sum of a utility'sutility’s recoverable operating and maintenance expenses depreciation and amortization expense, taxes, and an allowed return on investment.rate base, including a return on invested capital, both debt and equity, and an amount for income taxes.
RFP - Request for proposal.
Rockland Capital - Rockland Capital, LLC, together with the special purpose entity affiliated with, and formed by, Rockland Capital, LLC, that acquired the Elgin, Gibson City, and Grand Tower gas-fired energy centers in January 2015.
RTO - Regional transmission organization.
S&P - Standard & Poor’s– S&P Global Ratings, Services, a credit rating agency.
SEC - Securities and Exchange Commission, a United States government agency.
SERC - SERC Reliability Corporation, one of the regional electric reliability councils organized for coordinating the planning and operation of the nation’s bulk power supply.
SO2- Sulfur dioxide.
TCJA – The Tax Cuts and Jobs Act of 2017, federal income tax legislation enacted in December 2017, which significantly changed the tax laws applicable to business entities; it includes specific provisions related to regulated public utilities. Substantially all of the provisions of the TCJA affecting the Ameren Companies, other than certain transition depreciation rules, are effective for taxable years beginning after December 31, 2017.
Test year - The selected period of time, typically a twelve-month12-month period, for which a utility'sutility’s historical or forecasted operating results are used to determine the appropriate revenue requirement.
UAThroughput disincentive Ameren Missouri’s reduced margin caused by the current period’s lower sales volume resulting from MEEIA 2016 customer energy-efficiency programs. Recovery of this disincentive is designed to make Ameren Missouri earnings neutral each period from the lost margins caused by its MEEIA 2016 customer energy-efficiency programs.
Westinghouse - United Association– Westinghouse Electric Company, LLC.
VBA – A volume balancing adjustment for Ameren Illinois’ natural gas operations. As a result of Plumbersthis adjustment, revenues from residential and Pipefitters, a labor union.small nonresidential customers will increase or decrease as billing determinants differ from filed amounts. This adjustment ensures that

changes in sales volumes, including deviations from normal weather conditions, do not result in an over- or under-collection of natural gas revenues for these rate classes.
Zero-emission credit – A credit that represents the environmental attributes of one MWh of energy produced from certain zero-emissions nuclear-powered generation facilities, which Illinois utilities are required to purchase pursuant to the FEJA.

 



3


FORWARD-LOOKING STATEMENTS
Statements in this report not based on historical facts are considered “forward-looking” and, accordingly, involve risks and uncertainties that could cause actual results to differ materially from those discussed. Although such forward-looking statements have been made in good faith and are based on reasonable assumptions, there is no assurance that the expected results will be achieved. These statements include (without limitation) statements as to future expectations, beliefs, plans, strategies, objectives, events, conditions, and financial performance. In connection with the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995, we are providing this cautionary statement to identify important factors that could cause actual results to differ materially from those anticipated. The following factors, in addition to those discussed underwithin Risk Factors under Part I, Item 1A, of this report, and elsewhere in this report and in our other filings with the SEC, could cause actual results to differ materially from management expectations suggested in such forward-looking statements:
regulatory, judicial, or legislative actions, includingand changes in regulatory policies and ratemaking determinations, such as Ameren Missouri’s July 2014 electric rate case filing; Ameren Missouri's December 2014 MEEIA filing; Ameren Illinois' appeal of the ICC's natural gas rate order issued in December 2013; Ameren Illinois' January 2015 natural gas delivery service rate case filing; FERC settlement procedures regarding a potential Ameren Illinois electric transmission rate refund;those that may result from the complaint case filed in February 2015 with the FERC seeking a reduction in the allowed base return on common equity under the MISO tariff;tariff, Ameren Missouri’s proceeding with the MoPSC to pass through to customer rates the effect of the reduction in the federal statutory corporate income tax rate enacted under the TCJA, Ameren Illinois’ natural gas regulatory rate review filed with the ICC in January 2018, Ameren Illinois’ proceeding filed with the ICC to pass through to its natural gas customer rates the effect of the reduction in the federal statutory corporate income tax rate enacted under the TCJA, the request filed by MISO participants, including Ameren Illinois and ATXI, with the FERC to allow revisions to 2018 electric transmission rates to reflect the impacts of the reduction in the federal statutory corporate income tax rate enacted under the TCJA, and future regulatory, judicial, or legislative actions that seek to change regulatory recovery mechanisms;
the effect of Ameren Illinois participatingIllinois’ participation in a performance-based formula ratemaking processframeworks under the IEIMA and the FEJA, including the direct relationship between Ameren Illinois'Illinois’ return on common equity and 30-year United States Treasury bond yields, the related financial commitments required by the IEIMA, and the resulting uncertain impact on the financial condition, results of operations, and liquidity of Ameren Illinois;
the potential extension of the IEIMA after its current sunset provision at the end of 2017, and any changes to the performance-based formula ratemaking process or requiredrelated financial commitments;
the effects of increased competitionchanges in the future due to, among other factors, deregulation of certain aspects of our business at either thefederal, state, or federal level;
changes inlocal laws and other governmental actions, including monetary, fiscal, tax, and energy policies;
the effects of changes in federal, state, or local tax laws or rates, including additional regulations, interpretations, amendments, or technical corrections to the TCJA, and any challenges to the tax positions taken by the Ameren Companies;
the effects on demand for our services resulting from technological advances, including advances in customer energy efficiencyenergy-efficiency and distributedprivate generation sources, which generate electricity at the site of consumption;consumption and are becoming more cost-competitive;
the effectiveness of Ameren Missouri'sMissouri’s customer energy efficiencyenergy-efficiency programs and the related revenues and performance incentives earned under its MEEIA plans;
Ameren Illinois’ ability to earn incentive awards underachieve the MEEIA;FEJA electric energy-efficiency goals and the resulting impact on its allowed return on program investments;
the timing of increasing capital expenditure and operating
expense requirements and our ability to align overall spending, both operating and capital, with frameworks established by our regulators and to recover these costs in a timely manner;manner in our attempt to earn our allowed returns on equity;
the cost and availability of fuel, such as ultra-low-sulfur coal, natural gas, and enriched uranium used to produce electricity; the cost and availability of purchased power, zero-emission credits, renewable energy credits, and natural gas for distribution; and the level and volatility of future market prices for such commodities, including our ability to recover the costs for such commodities and our customers'customers’ tolerance for any related price increases;
disruptions in the related rate increases;delivery of fuel, failure of our fuel suppliers to provide adequate quantities or quality of fuel, or lack of adequate inventories of fuel, including nuclear fuel assemblies from Westinghouse, Callaway energy center’s only NRC-licensed supplier of such assemblies, which is currently in bankruptcy proceedings;
the effectiveness of our risk management strategies and our use of financial and derivative instruments;
the ability to obtain sufficient insurance, including insurance for Ameren Missouri’s Callaway energy center, or, in the absence of insurance, the ability to recover uninsured losses from our customers;
business and economic conditions, including their impact on key customers, interest rates, bad debt expense,collection of our receivable balances, and demand for our products;
the effects of the TCJA on us and the resulting treatment by regulators will have on our results of operations, financial position, and liquidity;
disruptions of the capital markets, deterioration in credit metrics of the Ameren Companies, including as a result of the implementation of the TCJA, or other events that may have an adverse effect on the cost or availability of capital, including short-term credit and liquidity;
our assessment of our liquidity;
the impact of the adoption of new accounting guidance and the application of appropriate technical accounting rules and guidance;
actions of credit rating agencies and the effects of such actions;
the impact of adopting new accounting guidance and the application of appropriate accounting rules and guidance;

the impact of weather conditions and other natural phenomena on us and our customers, including the impact of system outages;
the construction, installation, performance, and cost recovery of generation, transmission, and distribution assets;
the effects of breakdowns or failures of equipment in the operation of natural gas transmission and distribution systems and storage facilities, such as leaks, explosions, and mechanical problems, and compliance with natural gas safety regulations;
the effects of our increasing investment in electric transmission projects, as well as potential wind and solar generation projects, our ability to obtain all of the necessary approvals to complete the projects, and the uncertainty as to whether we will achieve our expected returns in a timely fashion, if at all;
the extent to which Ameren Missouri prevails in its claim against an insurer in connection with the December 2005 breach of the upper reservoir at its Taum Sauk pumped-storage hydroelectric energy center;
the extent to which Ameren Missouri is permitted by its regulators to recover in rates the investments it made in connection with additional nuclear generation at its Callaway energy center;manner;
operation of Ameren Missouri'sMissouri’s Callaway energy center, including planned and unplanned outages, and decommissioning costs;
the effects of strategic initiatives, including mergers, acquisitions, and divestitures, and any related tax implications;divestitures;
the impact of current environmental regulations and new, more stringent, or changing requirements, including those related to greenhouse gases, other emissions and discharges, cooling water intake structures, CCR, and energy efficiency, that are enacted over time and that could limit or terminate the operation of certain of our energy centers, increase our costs or investment requirements, result in an impairment of our assets, cause us to sell our assets, reduce our customers'
the impact of current environmental regulations and new, more stringent, or changing requirements, including those related to CO2, other emissions and discharges, cooling water intake structures, CCR, and energy efficiency, that are enacted over time and that could limit or terminate the operation of certain of Ameren Missouri’s energy centers, increase our costs or investment requirements, result in an impairment of our assets, cause us to sell our assets, reduce our customers’ demand for electricity or natural gas, or otherwise have a negative financial effect;
the impact of negative opinions of us or our utility services that our customers, legislators, or regulators may have or develop, which could result from a variety of factors, including failures in system reliability, failure to implement our investment plans or protect sensitive customer information, increases in rates, or negative media coverage;
the impact of complying with renewable energy portfolio requirements in Missouri;Missouri and Illinois;


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labor disputes, work force reductions, future wage and employee benefits costs, including changes in discount rates, mortality tables, and returns on benefit plan assets;
the inability of our counterparties to meet their obligations with respect to contracts, credit agreements, and financial instruments;
the cost and availability of transmission capacity for the energy generated by Ameren Missouri'sMissouri’s energy centers or required to satisfy Ameren Missouri'sMissouri’s energy sales;
the inability of Dynegy and IPH to satisfy their indemnity and other obligations to Ameren in connection with the divestiture of New AER to IPH;
legal and administrative proceedings;
the impact of cyber attacks, which could, among other things, result in the loss of operational control of energy centers and electric and natural gas transmission and distribution systems and/or the loss of data, such as customer, employee, financial, and operating system information; and
acts of sabotage, war, terrorism, cyber attacks, or other intentionally disruptive acts.


New factors emerge from time to time, and it is not possible for management to predict all of such factors, nor can it assess the impact of each such factor on the business or the extent to which any factor, or combination of factors, may cause actual results to differ materially from those contained or implied in any forward-looking statement. Given these uncertainties, undue reliance should not be placed on these forward-looking statements. Except to the extent required by the federal securities laws, we undertake no obligation to update or revise publicly any forward-looking statements to reflect new information or future events.
PART I
ITEM 1.BUSINESS
GENERAL
Ameren, formed in 1997 and headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005, administered by the FERC. Ameren was formed in 1997 by the merger of Ameren Missouri and CIPSCO Inc., which was the parent company of CIPS. Ameren acquired CILCORP Inc., which was the parent company of CILCO, in 2003 and IP in 2004. CIPS, CILCO, and IP were merged to form Ameren Illinois in 2010. Ameren’swhose primary assets are its equity interests in its subsidiaries, including Ameren Missouri and Ameren Illinois.subsidiaries. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of other expenses by Ameren depend on distributions made to it by its subsidiaries.
Below is a summary description of Ameren’s principal subsidiaries, including Ameren Missouri, Ameren Illinois, and ATXI. Ameren Illinois.also has other subsidiaries that conduct other activities, such as the provision of shared services. Ameren evaluates competitive electric transmission investment opportunities as they arise. A more detailed description can be found in Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report.
Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas transmission and distribution business in Missouri.
Ameren Illinois operates rate-regulated electric transmission, electric distribution, and natural gas transmission and distribution businesses in Illinois.
Ameren has various other subsidiaries responsible for activities such as the provision of shared services. Ameren also has a subsidiary, ATXI that operates a FERC rate-regulated electric transmission business. ATXI is developing MISO-approved electric transmission projects, including the Illinois Rivers Spoon River, and Mark Twain projects. Ameren is also pursuing reliability projects, within Ameren Missouri's and Ameren Illinois'placed the Spoon River project in service territories as well as competitive electric transmission investment opportunities outside of these territories, including investments outside of MISO.in February 2018.
In December 2013, Ameren completed the divestiture of New AER to IPH. In January 2014, Medina Valley completed its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy

centers to Rockland Capital. In addition, in 2013, Ameren abandoned the Meredosia and Hutsonville energy centers upon the completion of the divestiture of New AER to IPH. Ameren has begun to demolish the Hutsonville energy center and expects to demolish the Meredosia energy center thereafter. As a result of these events, Ameren segregated the operating results, assets, and liabilities for New AER and for the Elgin, Gibson City, Grand Tower, Meredosia, and Hutsonville energy centers and presented them separately as discontinued operations for all periods presented in this report. Unless otherwise stated, the following information presented in Part I, Item 1, of this report excludes discontinued operations for all periods presented. See Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of this report for additional information.
The following table presents our total employees at December 31, 2014:2017:
Ameren Missouri3,9243,639
Ameren Illinois3,2083,423
Ameren Services and Other1,3951,553
Ameren8,5278,615
AsLabor unions at subsidiaries consist of January 1, 2015, the IBEW,International Brotherhood of Electrical Workers, the IUOE,International Union of Operating Engineers, the LIUNA,Laborer’s International Union of North America, the United Association of Plumbers and Pipefitters, and the UAUnited Government Security Officers of America. At December 31, 2017, these labor unions collectively represented about 55%52% of Ameren’s total employees. They represented 63%62% and 57% of the employees at Ameren Missouri and 60% at Ameren Illinois.Illinois, respectively. The collective bargaining agreements have terms ranging from two to six years, and expire between 20152018 and 2017.2020.
For additional information about the development of our businesses, our business operations, and factors affecting our results of operations, and financial position, and liquidity, see Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, of this report and Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report.


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BUSINESS SEGMENTS
Ameren has two reportablefour segments: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois. Ameren Missouri and Ameren Illinois each have one reportable segment.Transmission. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all the operations of Ameren Missouri. The Ameren Illinois segment for both Ameren and Ameren Illinois consists of all of the operations of Ameren Missouri. Ameren Illinois Electric Distribution consists of the electric distribution business of Ameren Illinois. SeeAmeren Illinois Natural Gas consists of the natural gas business of Ameren Illinois. Ameren Transmission is primarily composed of the aggregated electric transmission businesses of Ameren Illinois and ATXI.
Ameren Missouri has one segment. Ameren Illinois has three segments: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission.
An illustration of Ameren and Ameren Illinois’ reporting structures is provided below. For additional information on financial reporting segments, see Note 1 – Summary of Significant Accounting Policies and Note 1715 – Segment Information under Part II, Item 8, of this report for additional information on reporting segments.report.
(a)Ameren Transmission segment includes associated Ameren (parent) interest charges, Ameren Transmission Company, LLC, ATX East, LLC, and ATX Southwest, LLC.

RATES AND REGULATION
Rates
The rates that Ameren Missouri, Ameren Illinois, and ATXI are allowed to charge for their utility services significantly influence the results of operations, financial position, and liquidity of these companies and Ameren. The electric and natural gas utility industry is highly regulated. The utility rates charged to customers are determined in large part, by governmental entities, including the MoPSC, the ICC, and the FERC. Decisions by these entities are influenced by many factors, including the cost of providing service, the prudency of expenditures, the quality of service, regulatory staff knowledge and experience, customer intervention, and economic conditions, public policy, and
as well as social and political views. Decisions made by these governmental entities regarding rates are largely outside of our control. These decisions, as well as the regulatory lag involved in filing andthe process of getting new rates approved, could have a material adverse effect on the results of operations, financial position, and liquidity of the Ameren Ameren Missouri, and Ameren Illinois.Companies. The extent of the regulatory lag varies for each of Ameren'sAmeren’s electric and natural gas jurisdictions, with the FERC-regulated electricAmeren Transmission and Ameren Illinois electric distribution jurisdictionsElectric Distribution businesses experiencing the least amount of regulatory lag. Depending on the jurisdiction, the effects of regulatory lag are mitigated through a variety ofby various means, including the use of a future test year, the implementation of trackers and riders, the deferral of depreciation for assets not yet included in rate base, the level and timing of expenditures, and by regulatory frameworks that include annual revenue requirement reconciliations.reconciliations and decoupling of revenues from sales volumes.
The MoPSC regulates rates and other matters for Ameren Missouri. The ICC regulates rates and other matters for Ameren Illinois, as well asIllinois. The MoPSC and the ICC regulate non-rate utility matters for ATXI. ATXI does not have retail distribution customers; therefore, the MoPSC and the ICC doesdo not have authority to regulate itsATXI’s rates. The FERC regulates Ameren Missouri's,Missouri’s, Ameren Illinois'Illinois’, and ATXI'sATXI’s cost-based rates for the wholesale distributiontransmission and transmissiondistribution of energy in interstate commerce and various other matters discussed below under General Regulatory Matters.


The following table summarizes by rate jurisdiction, the key terms of the rate orders in effect for customer billings for each of Ameren'sAmeren’s rate-regulated utilities as of January 1, 2015.
2018:
RegulatorAllowed
Return on Equity
Percent of
 Common Equity
Rate Base (in billions)
Portion of Ameren's 2014 Operating Revenues(a)
Rate RegulatorAllowed
Return on Equity
Percent of
Common Equity
Rate Base
(in billions)
Portion of Ameren’s 2017 Operating Revenues(a)
Ameren Missouri  
Electric service(c)(b)
MoPSC9.8%52.3%$6.856%MoPSC
9.2% - 9.7%(c)
(c)54%
Natural gas delivery service(d)
MoPSC(d)52.9%$0.2  3%MoPSC(d)2%
Ameren Illinois  
Electric distribution delivery service(e)
ICC9.25%51.0%$2.123%ICC8.40%50.0%$2.725%
Natural gas delivery service(f)
ICC9.1%51.7%$1.116%ICC9.60%50.0%$1.212%
Electric transmission delivery service(g)
FERC12.38%53.8%$0.9  2%
Electric transmission service(g)
FERC10.82%51.6%$1.64%
ATXI  
Electric transmission delivery service(g)
FERC12.38%56.0%$0.5(h)
Electric transmission service(g)
FERC10.82%56.2%$1.33%
(a)Includes pass-through costs recovered from customers, such as purchased power for electric distribution delivery service and natural gas purchased for resale for natural gas delivery service, and intercompany eliminations.
(b)Ameren Missouri'sMissouri’s electric generation, transmission, and delivery service rates are bundled together and charged to retail customers under a combined electric service rate.
(c)Based on the MoPSC's December 2012MoPSC’s March 2017 rate order. This rate order which became effectivespecified that an implicit return on January 2, 2013. Ameren Missouri will have new electric service rates effective by June 2015, upon the completionequity was within a range of its9.2% to 9.7%. The rate case proceeding that was filed in July 2014.order did not specify a percent of common equity or rate base. The return on equity used for allowance for equity funds used during construction is 9.53%.
(d)Based on the MoPSC'sMoPSC’s January 2011 rate order, which became effective on February 20, 2011.order. This rate order did not specify the allowed return on equity.equity, the percent of common equity, or rate base. It includes the impacts on rate base and operating revenues relating to the ISRS for investments after the January 2011 rate order.
(e)Based on the ICC'sICC’s December 20142017 rate order, which becameorder. Ameren Illinois electric distribution delivery service rates are updated annually and become effective on January 1, 2015.each January. The December 20142017 rate order was based on 20132016 recoverable costs, expected net plant additions for 2014,2017, and the monthly yields during 20132016 of the 30-year United States Treasury bonds plus 580 basis points. Ameren Illinois' 2015Illinois’ 2018 electric distribution delivery service revenues will be based on its 20152018 actual recoverable costs, rate base, common equity percentage, and return on common equity, as calculated under the IEIMA'sIEIMA’s performance-based formula ratemaking framework.
(f)Based on the ICC'sICC’s December 20132015 rate order, which became effective on January 1, 2014.order. The rate order was based on a 20142016 future test year.
(g)Transmission rates are updated annually and become effective each January. They are determined by a company-specific, forward-looking rate formula ratemaking based on each year'syear’s forecasted information. The 12.38%10.82% return, iswhich includes the subject of two50 basis points incentive adder for participation in an RTO, could be lowered by a FERC complaint proceedingsproceeding filed in February 2015 that challengechallenged the allowed return on common equity for MISO transmission owners.owners and will require customer refunds if the FERC approves a return on equity lower than that previously collected through rates.
(h)Less than 1%.

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Ameren Missouri
Electric
Ameren Missouri’s electric operating revenues are subject to regulation by the MoPSC. If certain criteria are met, then Ameren Missouri’s electric rates may be adjusted without a traditional rate proceeding. TheFor example, Ameren Missouri’s MEEIA customer energy-efficiency program costs, net shared benefits or throughput disincentive, and any performance incentive are recoverable through a rider that may be adjusted without a traditional rate proceeding, subject to MoPSC prudence reviews. Likewise, the FAC permits Ameren Missouri to recover or refund, through customer rates, 95% of changesthe variance in net energy costs greater than or less thanfrom the amount set in base rates without a traditional rate proceeding, subject to MoPSC prudence reviews. Net energy costs, as defined in the FAC, include fuel and purchased power costs, including transportation charges and revenues, net of off-system sales. Similarly, all of Ameren Missouri's MEEIA costs, including customer energy efficiency program costs, lost revenues, and any incentive awards, are recovered through a rider that may be adjusted without a traditional rate proceeding.
In addition to the FAC and the MEEIA recovery mechanisms, Ameren Missouri employs other cost recovery mechanisms, including a vegetation management and infrastructure inspection cost tracker, a pension and postretirement benefit cost tracker, an uncertain tax position tracker, a renewable energy standards cost tracker, and a solar rebate program tracker, and a storm cost tracker. Each of these trackers allows Ameren Missouri to recorddefer the difference between the level ofactual costs incurred costs under GAAP and the level of such costs built intoincluded in customer rates as a regulatory asset or regulatory liability, whichliability. The difference will be included in base rates in a futuresubsequent MoPSC rate order.
Ameren Missouri is a member of MISO, and its transmission rate is calculated in accordance with the MISO OATT. The FERC regulates the rates charged and the terms and conditions for wholesale electric transmission services. Because Ameren Missouri is a member of MISO, its transmission rate is calculated in accordance with the MISO OATT.service. The transmission rate is updatedupdate each June is based on Ameren Missouri’s filings with the FERC. This rate is not directly charged to Missouri retail customers because, in Missouri, the MoPSC includesbundled retail rates include an amount for transmission-related costs and revenues in bundled retail rates. As discussed above, Ameren Missouri transportation charges and revenues are included in the FAC.
Natural Gasrevenues.
Ameren Missouri’s natural gas operating revenues are subject to regulation by the MoPSC. If certain criteria are met, then Ameren Missouri’s natural gas rates may be adjusted without a traditional rate proceeding. PGA clauses permit prudently incurred natural gas supply costs to be passed directly to customers. The ISRS also permits certain prudently incurred natural gas infrastructure replacement costs to be recovered from customers on a more timely basis between regulatory rate cases. The return on equity to be used byreviews. Ameren Missouri for purposes ofis not currently recovering any infrastructure replacement costs under the ISRS tariff is 10%.ISRS.
Ameren Illinois
Ameren Illinois Electric Distribution
Ameren Illinois'Illinois’ electric distribution delivery service operating revenues are regulated by the ICC, while its electric transmission delivery service operating revenues are regulated by the FERC.ICC. In 2014,2017, Ameren Illinois'Illinois’ electric distribution delivery service revenues accounted for 91% 88%of itsAmeren Illinois’ total electric operating revenues. The remainder were related to electric transmission delivery service.
Under Illinois law, electric customers may choose their own electric energy provider. However, Ameren Illinois is required to serve as the provider of last resort for electric customers within its territory who have not chosen an alternative retail electric supplier. In 2014, Ameren Illinois was the provider of last resort for approximately 26% of electric customers within its territory. Ameren Illinois’ obligation to provide this required electric service varies by customer size. Ameren Illinois is not required to offer fixed-priced electric service to customers with electric demands of 400 kilowatts or greater, as the market for service to this group of customers has been declared competitive. Power and related procurement costs incurred by Ameren Illinois are passed directly to its customers through a cost recovery mechanism.
Ameren Illinois participates in the performance-based formula ratemaking processframework established pursuant to the IEIMA.IEIMA and the FEJA. The IEIMA was designed to provideprovides for the recovery of actual costs of electric delivery service that are prudently incurred and to reflect the utility'suse of the utility’s actual regulated capital structure through a formula for calculating the return on equity component of the cost of capital. The return on equity component of the formula rate is equal to the average for the calendar year average of the monthly yields of the 30-year United States Treasury bonds plus 580 basis points. Ameren Illinois' actual return on equity relating to electric delivery service is subject to a collar adjustment on earnings in excess of 50 basis points greater or less than its allowed return. The IEIMA provides for an annual reconciliation of the revenue requirement necessary to reflect the actual costs incurred in a given year with the revenue requirement included in customer rates for that year, including an allowed return on equity. This annual revenue requirement reconciliation along with the collar adjustment if necessary, will be collected from, or refunded to, customers within the next two years.
The FEJA revised certain portions of the IEIMA, extending the IEIMA formula ratemaking framework through 2022, and clarifying that a common equity ratio up to and including 50% is prudent. Beginning in 2017, the FEJA allowed Ameren Illinois to recover, within the following two years, its electric distribution revenue requirement for a given year, independent of actual sales volumes. Prior to the FEJA, Ameren Illinois’ revenues were affected by the timing of sales volumes due to seasonal rates and changes in volumes resulting from, among other things, weather and energy efficiency. This portion of the law extends beyond the end of the IEIMA in 2022. Through 2022, revenue differences will be included in the annual IEIMA revenue requirement reconciliation. Additionally, this law implemented a customer surcharge relating to certain nuclear energy centers located in Illinois. The surcharge, like the cost of power purchased by Ameren Illinois on behalf of its customers, will be passed through to electric distribution customers with no effect on Ameren Illinois’ earnings.
Pursuant to the FEJA, and consistent with the energy-efficiency plan for 2018 through 2021 approved by the ICC, Ameren Illinois plans to invest up to $99 million in electric energy-efficiency programs per year. Ameren Illinois plans to make additional investments of a similar level in electric energy-efficiency programs per year that will earn a return through 2030. The electric energy-efficiency program investments and the return on those investments will be collected from customers through a rider; they will not be included in the IEIMA formula ratemaking framework.
Ameren Illinois is also subject to performance standards under the IEIMA.standards. Failure to achieve the standards would result in a reduction in the company'scompany’s allowed return on equity calculated under the formula.formulas. The performance standards applicable to electric distribution service include improvements in service reliability to reduce both the frequency and duration of outages, a reduction in the number of estimated bills, a reduction of consumption onfrom inactive meters, and a reduction in uncollectible accountsbad debt expense. The IEIMAregulatory framework applicable to electric

distribution service provides for return on equity penalties totaling up to 30 basis points in 2015, 34 basis points in 2016 through 2018, and up to 38 basis points in each year from 2019 through 2022, if thethese performance standards are not met. The formula ratemaking processBeginning in 2018, the regulatory framework applicable to electric energy-efficiency investments provides for increases or decreases of up to 200 basis points to the return on equity. Any adjustments to the return on equity for energy-efficiency investments will depend on annual performance of a historical period relative to energy savings goals.
Under the IEIMA, Ameren Illinois is currently effective until the end of 2017. Legislation passed by the Illinois General Assembly,


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which is awaiting the governor's approval, would extend the formula rate process until the end of 2019, with further extension possible through 2022.
also subject to minimum capital spending levels. Between 2012 and 2021, Ameren Illinois is required pursuant to the IEIMA, to invest a minimum of $625 million in capital projects to modernize its distribution system incremental to its average annual electric deliverydistribution service capital projects investments of $228 million for calendar years 2008 through 2010, to modernize its distribution system. Through 2014,2010. From 2012 through 2017, Ameren Illinois has invested $149$508 million in IEIMA capital projects toward its $625 million requirement. Such investments are expected to encourage economic development and to create an estimated 450 additional jobs within Illinois. Ameren Illinois is subject to monetary penalties if 450 additional jobs are not created during the peak program year.
Ameren Illinois employs cost recovery mechanisms for power procurement, customer energy efficiency programs,energy-efficiency program costs incurred before June 2017, and certain environmental costs andas well as bad debt expense and the costs of certain asbestos-related claims not recovered in base rates.
Ameren Illinois also has a tariff rider to recover the costs of certain asbestos-related claims.
Because Ameren Illinois is a member of MISO, its transmission rate is calculated in accordance with the MISO OATT. Currently, the FERC-allowed return on common equity in the ratemaking formula for MISO transmission owners is 12.38%. However, the 12.38% return is the subject of two FERC complaint proceedings that challenge the allowed return on common equity for MISO transmission owners. In January 2015, the FERC scheduled the initial case for hearing proceedings, requiring an initial decision to be issued no later than November 30, 2015. Also in January 2015, FERC approved an incentive adder of up to 50 basis points on the allowed base return on common equity for Ameren Illinois' participation in an RTO. Ameren Illinois will defer collection of this incentive adder until the issuance of the final order addressing the initial MISO complaint case. Ameren Illinois has received FERC approval to use a company-specific, forward-looking rate formula framework in setting its transmission rates. These forward-looking rates are updated each January with forecasted information. A reconciliation during the year, which adjusts for the actual revenue requirement and actual sales volumes, is used to adjust billing rates in a subsequent year. In Illinois, the AMIL pricing zone transmission rate is charged directly to wholesale customers and alternative retail electric suppliers, which serve unbundled retail load. The AMIL pricing zone transmission rate and other MISO-related costs are collected from retail customers who have not chosen an alternative retail electric supplier through a rider mechanism in Ameren Illinois' retail distribution tariffs.
Natural Gas
Ameren Illinois’ natural gas operating revenues are subject to regulationregulated by the ICC. In December 2015, the ICC issued a rate order that approved an increase in revenues for Ameren Illinois’ natural gas delivery service, based on a 2016 future test year. The rate order also approved the VBA for residential and small nonresidential customers. In January 2018, Ameren Illinois filed a request with the ICC seeking approval to increase its annual revenues for natural gas delivery service by $49 million, which included an estimated $42 million of annual revenues that would otherwise be recovered under a QIP rider, as explained in more detail below. The request was based on a 10.3% return on common equity, a capital structure composed of 50% common equity, and a rate base of $1.6 billion. If certain criteria are met, then Ameren Illinois’ natural gas rates may be adjusted without a traditional rate proceeding.proceeding, as PGA clauses permit prudently incurred natural gas costs to be passed directly to customers. Also, Ameren Illinois employs cost recovery mechanisms for customer energy efficiency programs,energy-efficiency program costs, certain environmental costs, and bad debt
expenses not recovered in base rates.
In July 2013, Illinois enacted the CSRA, whichhas a law that encourages Illinois natural gas utilities to accelerate modernization of the state'sstate’s natural gas infrastructure. The law allows natural gas utilities to file forinfrastructure through a QIP rider. AWithout legislative action, the QIP rider provides forwill expire in December 2023. Ameren Illinois’ QIP rider allows a surcharge to be added to customers'customers’ bills to recover depreciation expense forexpenses and to earn a return on qualifying natural gas investments that were not previously included in base rates. Recovery begins two months after the natural gas investments are placed in service and will continuecontinues until the investments are included in the base rates ofin a future natural gas rate case. order. Ameren Illinois’ QIP rider is subject to a rate impact limitation of a cumulative 4% per year since the most recent delivery service rate order, with no single year exceeding 5.5%. Upon issuance of the natural gas rate order, QIP recoveries will be included in base rates and the QIP rider will be reset to zero, which mitigates the risk that the QIP rider will exceed its statutory limitations in future years and ensures timely recovery of capital investment.
Ameren Illinois received ICC approvalTransmission
Ameren Illinois’ transmission operating revenues are regulated by the FERC. In 2017, Ameren Illinois’ transmission service operating revenues accounted for its QIP rider in January 2015, and subsequently began including qualified investments and recording revenue under this regulatory framework.12% of Ameren Illinois’ electric operating revenues. See Ameren Transmission below for additional information regarding Ameren Illinois’ transmission business.
In January 2015,Ameren Transmission
Ameren Transmission is primarily composed of the aggregated electric transmission businesses of Ameren Illinois filed a request with the ICC seeking approval to increase its annual revenues for natural gas delivery service. In an attempt to reduce regulatory lag, Ameren Illinois' request employed a 2016 future test year and also included a proposal to implement a decoupling rider mechanism for residential and small nonresidential customers. This decoupling rider is designed to ensure that changes in natural gas sales volumes do not affect Ameren Illinois' annual revenues for these rate classes. A decision by the ICC in this proceeding is required by December 2015.
ATXI
LikeATXI. Both Ameren Illinois and ATXI is a memberare members of MISO, and itstheir transmission rate isrates are calculated in accordance with the MISO OATT. Currently, the FERC-allowed return on common equity in the ratemaking formula for MISO transmission owners is 12.38%. However, as discussed above, the 12.38% return is the subject of two FERC complaint proceedings that challenge the allowed return on common equity for MISO transmission owners. In January 2015, the FERC scheduled the initial case for hearing proceedings, requiring an initial decision to be issued no later than November 30, 2015. Also in January 2015, FERC approved an incentive adder of up to 50 basis points on the allowed base return on common equity for ATXI's participation in an RTO.Ameren Illinois and ATXI will defer collection of this incentive adder until the issuance of the final order addressing the initial MISO complaint case. ATXI hashave received FERC approval to use a company-specific, forward-looking rate formula ratemaking framework in setting itstheir transmission rates. These forward-looking rates are updated each January with forecasted information. A reconciliation duringat the end of the year, which adjusts for the actual revenue requirement and for actual sales volumes, is used to adjust billing rates in a subsequent year. Additionally,Ameren Illinois Transmission earns revenue from transmission service provided to Ameren Illinois Electric Distribution and wholesale customers. The transmission expense for Illinois customers who have elected to purchase their power from Ameren Illinois is recovered through a cost recovery mechanism with no net effect on Ameren Illinois Electric Distribution earnings, as costs are offset by corresponding revenues. Transmission revenues from these transactions are reflected in Ameren Transmission’s and Ameren Illinois Transmission’s operating revenues.
The FERC-allowed return on common equity for MISO transmission owners of 12.38% was challenged by customer groups in two complaint cases filed in November 2013 and in February 2015. As a result of a FERC order issued in the November 2013 complaint case, a 10.82% total allowed return on common equity has been reflected in rates since September 2016, inclusive of the 50 basis point adder for participation in an RTO. In June 2016, an administrative law judge issued an initial decision in the February 2015 complaint case. If approved by the FERC, it would lower the allowed base return on common equity for the 15-month period of February 2015 to May 2016 to 9.70%, or a 10.20% total allowed return on equity with the inclusion of a 50 basis point incentive adder for participation in an RTO. It would also require

customer refunds, with interest, for that 15-month period. A final FERC order would also establish the allowed return on common equity that will apply prospectively from the effective date of such order, replacing the current 10.82% total return on common equity.In September 2017, MISO transmission owners, including Ameren Missouri, Ameren Illinois, and ATXI, filed a motion to dismiss the February 2015 complaint case with the FERC. The FERC is under no deadline to issue a final order in the February 2015 complaint case.
ATXI has three MISO-approved multi-value projects, the Illinois Rivers, Spoon River, and Mark Twain projects. As of December 31, 2017, ATXI’s expected remaining investment in all three projects was approximately $300 million, with the total investment expected to be more than $1.6 billion. The Illinois Rivers project involves the construction of a 345-kilovolt line from eastern Missouri across Illinois to western Indiana. ATXI has obtained a certificate of public convenience and necessity and project approvals from the ICC and the MoPSC for each state’s portion of the Illinois Rivers project. The last line segment of this project is expected to be completed by the end of 2019; however, delays associated with property acquisition could delay the completion date. As of December 31, 2017, all 10 substations and seven of the nine line segments for Illinois Rivers were complete and in-service. The Spoon River project is located in northwest Illinois. ATXI placed the Spoon River project in service in February 2018. The Mark Twain project is located in northeast Missouri and connects Iowa to the Illinois Rivers project. In January 2018, the MoPSC granted ATXI a certificate of convenience and necessity for the Mark Twain project. ATXI plans to complete the Mark Twain project by the end of 2019.
The FERC has approved transmission rate incentives relating to the three MISO-approved multi-value projects, discussed below, which allow construction work in progress to be included in rate base, thereby improving the timeliness of cash recovery.
The three MISO-approved multi-value projects being developed by ATXI are the Illinois Rivers, Spoon River, and Mark Twain projects. The first project, Illinois Rivers, involves the construction of a 345-kilovolt line from western Indiana across the


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state of Illinois to eastern Missouri. ATXI has obtained a certificate of public convenience and necessity and project approval from the ICC for the entire Illinois Rivers project. A full range of construction activities for the Illinois Rivers project began in 2014. The first sections of the Illinois Rivers project are expected to be completed in 2016. The last section of this project is expected to be completed in 2019. The Spoon River project is in northwest Illinois and the Mark Twain project is in northeast Missouri. In August 2014, ATXI filed a request for a certificate of public convenience and necessity and project approval from the ICC for the Spoon River project. A decision is expected from the ICC in 2015. ATXI expects to file a request for a certificate of public convenience and necessity and project approval from the MoPSC for the Mark Twain project in 2015. These two projects are expected to be completed in 2018. The total investment by ATXI in these three projects is expected to be more than $1.6 billion.
For additional information on Ameren Missouri, Ameren Illinois, and ATXI rate matters, including the FERC complaint casescase challenging the allowed return on common equity for MISO transmission owners, see Results of Operations and Outlook in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, Quantitative and Qualitative Disclosures About Market Risk under Part II, Item 7A, and Note 2 – Rate and Regulatory Matters and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.
General Regulatory Matters
Ameren Missouri, Ameren Illinois, and ATXI must receive FERC approval to enter into various transactions, such as issuing short-term debt securities and conducting certain acquisitions, mergers, and consolidations involving electric utility holding companies. In addition, Ameren Missouri, Ameren Illinois, and ATXI must receive authorization from the applicable state public utility regulatory agency to issue stock and long-term debt securities (with maturities of more than 12 months) and to conduct mergers, affiliate transactions, and various other activities.
Ameren Missouri, Ameren Illinois, and ATXI are also subject to mandatory reliability standards, including cybersecurity standards adopted by the FERC, to ensure the reliability of the bulk electric power electric system. These standards are developed and enforced by the NERC pursuant to authority givendelegated to it by the FERC. If any of Ameren Missouri, Ameren Illinois or its subsidiaries were determinedATXI is found not to be in compliance with any of these mandatory reliability standards, theyit could incur substantial monetary penalties and other sanctions.
Under PUHCA 2005, the FERC and any state public utility regulatory agency may access books and records of Ameren and its subsidiaries that are determinedfound to be relevant to costs incurred by Ameren’s rate-regulated subsidiaries that may affect jurisdictional rates. PUHCA 2005 also permits the MoPSC and the ICC to request that the FERC review cost allocations by Ameren Services to other Ameren companies.
Operation of Ameren Missouri’s Callaway energy center is subject to regulation by the NRC. Its facility operatingThe license for the Callaway energy center expires in October 2024. In December 2011, Ameren Missouri submitted an application to the NRC to extend the energy center's operating license to 2044. There is no date by which the NRC must act on this relicensing request. Ameren Missouri’s Osage hydroelectric energy center and Taum Sauk pumped-storage hydroelectric energy center, as licensed projects under the Federal Power Act, are subject to FERC regulations affecting, among other aspects, the general operation and maintenance of the projects. The licenselicenses for the Osage hydroelectric energy center expires in March 2047. The license forand the Taum Sauk pumped-storage hydroelectric energy center expiresexpire in June 2044.2047 and 2044, respectively. Ameren Missouri’s Keokuk energy center and its dam in the Mississippi River between Hamilton, Illinois, and Keokuk, Iowa, are operated under authority granted by an Act of Congress in 1905.
For additional information on regulatory matters, see Note 2 – Rate and Regulatory Matters, Note 109 – Callaway Energy Center, and Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report.
Environmental Matters
Certain of our operations are subject to federal, state, and local environmental statutes and regulations relating to the protection of the safety and health of our personnel, the public, and the environment. These environmental statutes and regulations include requirements relating to identification, generation, storage, handling, transportation, disposal, recordkeeping, labeling, reporting, and emergency response in connection with hazardous and toxic materials; safety and health standards; and environmental protection requirements, including standards and limitations relating to the discharge of air and water pollutants and the management of waste and byproduct materials. Failure to comply with these statutes or regulations could have material adverse effects on us. We could be subject to criminal or civil penalties by

regulatory agencies, or we could be ordered by the courts to pay private parties. Except as indicated in this report, we believe that we are in material compliance with existing statutes and regulations that currently apply to our operations.
The EPA is developing and implementinghas promulgated environmental regulations that will have a significant impact on the electric utility industry. Over time, compliance with these regulations could be costly for certain companies, including Ameren Missouri, that operatewhich operates coal-fired power plants. Significant new rules proposed or promulgatedAs of December 31, 2017, Ameren Missouri’s fossil fuel-fired energy centers represented 17% and 33% of Ameren’s and Ameren Missouri’s rate base, respectively. Regulations that apply to air emissions from the electric utility industry include the regulationNSPS, the CSAPR, the MATS, and the revised National Ambient Air Quality Standards, which are subject to periodic review for certain pollutants. Collectively, these regulations cover a variety of pollutants, such as SO2, particulate matter, NOx, mercury, toxic metals, and acid gases, and CO2 emissions from existing power plants through the proposed Clean Power Plan and from new power plants through the revised NSPS; revised national ambient air quality standards for ozone, fine particulates, SO2,plants. Water intake and NOx emissions; the CSAPR, which requires further reductions of SO2 emissions and NOx emissions from power plants; a regulation governing management of CCR and CCR impoundments; the MATS, which require reduction of emissions of mercury, toxic metals, and acid gases from power plants; revised NSPS for particulate matter, SO2, and NOx emissions from new sources; new effluent standards applicable to waste


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water discharges from power plants and new regulationsare regulated under the Clean Water Act thatAct. Such regulation could require significant capital expenditures, such as modifications to water intake structures or new cooling towersmore stringent limitations on wastewater discharges at Ameren Missouri’s energy centers, either of which could result in significant capital expenditures. The management and disposal of coal ash is regulated under the CCR rule, which will require the closure of surface impoundments and the installations of dry ash handling systems at several of Ameren Missouri’s energy centers. Certain of these new and proposed regulations, if adopted, are likely to be challenged through litigation, so their ultimate implementation, as well as the timing of any such implementation, is uncertain. Although many details of the future regulations are unknown, theThe individual or combined effects of the new and proposedexisting environmental regulations could result in significant capital expenditures, and increased operating costs, for Ameren and Ameren Missouri. Compliance with these environmental laws and regulations could be prohibitively expensive, result inor the closure or alteration of the operation ofoperations at some of Ameren Missouri’s energy centers, or require capital investment. centers.Ameren and Ameren Missouri expect thesethat such compliance costs would be recoverable through rates, subject to MoPSC prudence review, but the nature and timing of costs as well as the applicable regulatory framework,and their recovery could result inbe subject to regulatory lag. These new and proposed environmental regulations could also impactaffect the availability of, the cost of, and the demand for power and natural gas whichthat is acquired for Ameren Missouri'sMissouri’s natural gas customers and Ameren Illinois'Illinois’ electric and natural gas customers. Federal, state, and local authorities continually revise these regulations, which adds uncertainty to our planning process and to the ultimate implementation of these or other new or revised regulations.
For additional discussion of environmental matters, including NOx, and SO2, and mercury emission reduction requirements, proposed reductions toregulation of CO2 emissions, wastewater discharge standards, remediation efforts, CCR management regulations, and a discussion of the EPA’s allegations of violations of the Clean Air Act and Missouri law in connection with projects at Ameren Missouri'sMissouri’s Rush Island energy center, see Liquidity and Capital Resources in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, and Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report.
TRANSMISSION AND SUPPLY OF ELECTRIC POWER
Ameren owns an integrated transmission system that is comprisedcomposed of the transmission assets of Ameren Missouri, Ameren Illinois, and ATXI. Ameren also operates two balancing authority areas: AMMO and AMIL. During 2014,2017, the peak demand was 8,1997,814 megawatts in AMMO and 8,9138,877 megawatts in AMIL. The Ameren transmission system directly connects with 15 other balancing authority areas for the exchange of electric energy.
Ameren Missouri, Ameren Illinois, and ATXI are transmission-owning members of MISO. Ameren Missouri is authorized by the MoPSC to participate in MISO through May 2018.2020. The previously required cost-benefit study related to Ameren Missouri is required to file a study with the MoPSC in November 2017, as it has done periodically since it began participating in MISO in 2003, that evaluates the costs and benefits of Ameren Missouri'sMissouri’s continued participation in MISO, beyond May 2018.as required periodically by the MoPSC and originally expected to be filed in 2017, was deferred upon approval of the MoPSC. Ameren Missouri expects to file the periodic cost-benefit study in 2020, based on the deferral granted by the MoPSC.
The Ameren CompaniesMissouri, Ameren Illinois, and ATXI are members of the SERC. The SERC is responsible for ensuring the reliable operation of the bulk electric power system in all or portions of Missouri, Illinois, Arkansas, Kentucky, Tennessee, North Carolina, South Carolina, Georgia, Mississippi, Alabama,
Louisiana, Virginia, Florida, Oklahoma, Iowa,16 central and Texas. Ownerssoutheastern states. The Ameren Companies, like all owners and operators including the Ameren Companies, of the bulk electric power system, are subject to mandatory reliability standards that are promulgated by the NERC and its regional entities, such as the SERC, whichand are all enforced by the FERC.
SUPPLY OF ELECTRIC POWER
Ameren Missouri
Ameren Missouri’s electric supply is primarily generated from its energy centers. Factors that could cause Ameren Missouri to purchase power include, among other things, absence of sufficient owned generation, energy center outages, the fulfillment of renewable energy portfolio requirements, the failure of suppliers to meet their power supply obligations, extreme weather conditions, and the availability of power at a cost lower than its generation cost.cost, and absence of sufficient owned generation.
Ameren Missouri files a nonbinding 20-year integrated resource plan with the MoPSC every three years. The most recent integrated resource plan, filed in September 2017, includes Ameren Missouri’s preferred approach for meeting customers’ projected long-term energy needs in a cost-effective manner while maintaining system reliability. The plan targets cleaner and more diverse sources of energy generation, including solar, wind, natural gas, hydro, and nuclear power. It also includes expanding renewable generation by adding at least 700 megawatts of wind generation by 2020 in Missouri and neighboring states, adding 100 megawatts of solar generation over the next 10 years, retiring coal-fired energy centers as they reach the end of their useful lives, expanding customer energy-efficiency programs, and adding cost-effective demand response programs.

Ameren Missouri continues to evaluate its longer-term needs for new baseload capacity, including nuclear and peaking electric generationgenerating capacity. The potential need for a new energy center construction is dependent on several key factors, including continuation of and customer participation in energy efficiencyenergy-efficiency programs beyond 2015,and distributed generation, load growth, and the potential for more stringenttechnological advancements, costs of generation alternatives, environmental regulation of coal-fired power plants, and state renewable portfolio standards, which could lead to the retirement of current baseload assets before the end of their useful lives or alterations in the manner in whichway those assets operate. Because of the significant time required to plan, acquire permits for, and build a baseload energy center, Ameren Missouri continues to study alternatives and is takingto take steps to preserve options to meet future demand. Steps include evaluating the potential for further diversification of Ameren Missouri’s generation portfolio through renewable energy generation, including wind and solar generation, additional further customer energy-efficiency and demand response programs, distributed energy efficiency programsresources, and evaluating potential sites for natural-gas-fired generation. Additional steps include maintaining options for future nuclear generation and obtaining an operating license extension for the existing Callaway energy center from 2024 until 2044. Ameren Missouri is also exploring options to expand renewable generation and further diversify its generation portfolio.storage.
Ameren Missouri filed its integrated resource plan with the MoPSC in October 2014. The integrated resource plan is a 20-year plan that supports a more fuel-diverse energy portfolio in Missouri, including coal, solar, wind, natural gas and nuclear power. The plan includes expanding renewable generation, retiring coal-fired generation as energy centers reach the end of their useful lives, and adding natural-gas-fired combined cycle generation. Ameren Missouri continues to study alternatives, including additional customer energy efficiency programs, that could help defer new energy center construction.
See also Outlook in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, Note 2 – Rate and Regulatory Matters, Note 109 – Callaway Energy Center, and Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report.
Ameren Illinois
AnyIn Illinois, while electric transmission and distribution service rates are regulated, power supply prices are not. Although electric customers are allowed to purchase power from an alternative retail electric supplier, Ameren Illinois is required to be the provider of last resort for its electric distribution customers. In 2017, 2016, and 2015, Ameren Illinois procured power on behalf of its customers for 23%, 23%, and 26%, respectively, of its total kilowatthour sales. Power purchased by Ameren Illinois for its electric distribution customers who do not elect to purchase their power from an alternative retail customerselectric supplier comes either through procurement processes conducted by the IPA or through markets operated by MISO. The


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IPA administers an RFP process through which Ameren Illinois procures its expected supply obligation.supply. The power and related procurement costs incurred by Ameren Illinois are passed directly to its electric distribution customers through a cost recovery mechanism.
Under The costs are reflected in Ameren Illinois law,Electric Distribution’s results of operations, but do not affect Ameren Illinois Electric Distribution’s earnings, because these costs are offset by corresponding revenues. Ameren Illinois charges transmission and distribution service rates are regulated, whileto electric customers are allowed to purchase power from an alternative retail electric supplier. In 2014, approximately 741,000 retail customers representing 74% of Ameren Illinois' annual retail kilowatthour sales had elected to
purchase their electricity from alternative retail electric suppliers. Ameren Illinois continues to collect delivery charges for distribution and transmission services from customers who purchase electricity from alternative retail electric suppliers.suppliers, which does affect Ameren Illinois Electric Distribution’s earnings.
See Note 213 – Rate and Regulatory Matters, Note 14 – Related PartyRelated-party Transactions and Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report for additional information on power procurement in Illinois.

POWER GENERATION
Ameren Missouri owns energy centers that rely on a diverse fuel portfolio, including coal (Ameren Missouri’s primary fuel source), nuclear, and natural gas, as well as renewable sources of generation, which include hydroelectric, methane gas, and solar. All of Ameren Missouri’s coal-fired energy centers were constructed prior to 1978. The following table presents the sourceCallaway nuclear energy center began operation in 1984 and is licensed to operate until 2044. As of Ameren'sDecember 31, 2017, Ameren Missouri’s fossil fuel-fired energy centers represented 17% and 33% of Ameren’s and Ameren Missouri'sMissouri’s rate base, respectively. See Item 2 – Properties under Part I of this report for information regarding Ameren Missouri’s electric generation excluding purchased power, for the years ended December 31, 2014, 2013, and 2012:
energy centers.
 Coal Nuclear Natural Gas/Oil 
Renewables(a)
201476% 21%             (b) 3%
201377 19             (b) 3
201273 24 1 2
(a)Renewable power generation includes production from Ameren Missouri's hydroelectric, methane gas, and solar energy centers but excludes purchased renewable energy credits.
(b)Less than 1% of total fuel supply.
The following table presents the cost of fuels for electric generation for the years ended December 31, 2014, 2013, and 2012:
Cost of Fuels (dollars per mmbtu)
2014 2013 2012
Coal(a)
$2.151
 $2.050
 $1.925
Nuclear0.918
 0.942
 0.964
Natural gas(b)
11.226
 7.907
 4.517
Weighted average – all fuels(c)
$1.936
 $1.874
 $1.743
(a)Represents the cost of coal and the costs for transportation, which include hedges for railroad diesel fuel surcharges.
(b)Represents the cost of natural gas and fixed and variable costs for transportation, storage, balancing, and fuel losses for delivery to the energy center.
(c)Represents all costs, including transportation, for fuels used in our energy centers, including coal, nuclear, natural gas, methane gas, oil, and propane. Methane gas, oil, and propane are not individually listed in this table because their use is minimal.
Coal
Ameren Missouri has an ongoing need for coal as fuel for generation, so itand pursues a price-hedging strategy consistent with this requirement. Ameren Missouri has agreements in place to purchase and transport coal and to transport it toits energy centers. Coal supply agreements forAs of December 31, 2017, Ameren Missouri expire at the endhad price-hedged 88% of 2017. Coal transport agreementsits expected coal supply and 99% of its coal transportation requirements for Ameren Missouri expire at the end of 2019.generation in 2018. Ameren Missouri has additional coal supply under contract through 2021. The coal transport agreements that Ameren Missouri has with Union Pacific Railroad and Burlington Northern Santa Fe Railway. AsRailway are currently set to expire at the end of December 31, 2014, Ameren Missouri had price-hedged 100% of its expected coal supply and coal transportation requirements for generation in 2015.2019. Ameren Missouri burned 20approximately 18.6 million tons of coal in 2014.2017.
About 98%97% of Ameren Missouri’s coal is purchased from the Powder River Basin in Wyoming. The remaining coal is typically purchased from the Illinois Basin. InventoryInventories may be adjusted because of generation levels or uncertainties of supply due to potential work stoppages, delays in coal deliveries, equipment breakdowns, and other factors. Deliveries from the Powder River Basin have occasionally been restricted because of rail congestion and maintenance, derailments, and weather. As of December 31, 2014,2017, coal inventories for Ameren Missouri were belownear targeted levels due to delivery delays.levels. Disruptions in coal
deliveries could cause Ameren Missouri to pursue a strategy that could include reducing sales of power during low-margin periods, buying higher-cost fuels to generate required electricity, and purchasing power from other sources.

Nuclear
The production of nuclear fuel involves the mining and milling of uranium ore to produce uranium concentrates, the conversion of uranium concentrates to uranium hexafluoride gas, the enrichment of that gas, the conversion of the enriched uranium hexafluoride gas into uranium dioxide fuel pellets, and the fabrication into usable fuel assemblies. Ameren Missouri has entered into uranium, uranium conversion, uranium enrichment, and fabrication contracts to procure the fuel supply for its Callaway nuclear energy center.
The Callaway energy center requires refueling at 18-month intervals. The last refueling was completed in November 2014.December 2017. The next refueling is scheduled for the spring 2016. There is no refueling scheduled for 2015 and 2018.of 2019. As of December 31, 2017, Ameren Missouri currently hashad agreements or inventories to price-hedge approximately 97%, 71%, and 60%all of Callaway's 2016, 2017, andCallaway’s spring 2019 refueling requirements, respectively.requirements. Ameren Missouri has uranium (concentrateinventories and hexafluoride) inventories and


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supply contracts sufficient to meet all of its uranium (concentrate and hexafluoride), conversion, and enrichment requirements through at least 2017.through the 2022 refueling. Ameren Missouri has enriched uranium inventories and enrichment supply contracts sufficient to satisfy enrichment requirements through at least 2019 and fuel fabrication service contracts through at least 2019. Ameren Missouri expects to enter into additional contracts to purchase nuclear fuel. The nuclear fuel markets are competitive, and prices can be volatile; however, Ameren Missouri does not anticipate any significant problems in meeting its future supply requirements.2022.
Natural Gas Supply for Generation
To maintain deliveries to its natural-gas-fired energy centers throughout the year, especially during the summer peak demand, Ameren Missouri’s portfolio of natural gas supply resources includes firm transportation capacity and firm no-notice storage capacity leased from interstate pipelines. Ameren Missouri primarily uses the interstate pipeline systems of Panhandle Eastern Pipe Line Company, Trunkline Gas Company, Natural Gas Pipeline Company of America, and Mississippi River Transmission Corporation to transport natural gas to energy centers. In addition to physical transactions, Ameren Missouri uses financial instruments, including some in the NYMEX futures market and some in the OTC financial markets, to hedge the price paid for natural gas.
Ameren Missouri’s natural gas procurement strategy is designed to ensure reliable and immediate delivery of natural gas to its energy centers. This strategy is accomplished by optimizing transportation and storage options and by minimizing cost and price risk through various supply and price-hedging agreements that allow access to multiple natural gas pools, supply basins, and storage services. As of December 31, 2014,2017, Ameren Missouri had price-hedged about 3%73% of its expected natural gas supply requirements for generation in 2015.2018.
Renewable Energy
Missouri and Illinois and Missouri have enacted laws requiringrequire electric utilities to include renewable energy resources in their portfolios. Illinois required renewable energy resources to equal or exceed 2% of the total electricity that Ameren Illinois supplied to its eligible retail customers as of June 1, 2008, with that percentage increasing to 10% by June 1, 2015, and to 25% by June 1, 2025. For the 2014 plan year, Ameren Illinois met its requirement that 9% of its total electricity for eligible retail customers be procured from renewable energy resources. Based on current forecasts, Ameren Illinois has committed to procure sufficient renewable energy credits under the IPA-administered procurement process to meet the renewable energy portfolio requirement through at least May 2017. Ameren Illinois has entered into agreements through 2032 with renewable energy suppliers to obtain renewable energy credits. Approximately 65% of the 2015 plan year renewable energy requirement is expected to be met through these agreements. The remaining requirement will be met through IPA procurements, which resulted in contracts that have terms through December 2017.
In Missouri, utilities are required to purchase or generate electricity equal to at least 2%5% of native load sales from renewable energy sources with thatbeginning in 2017. That percentage increasingwill increase to at least 15% by 2021, subject to aan average 1% annual limitincrease on customer rate impacts.rates over any 10-year period. At least 2% of each renewable energy portfolio requirement must be derived from solar energy. In 2014,2017, Ameren Missouri met its requirement to purchase or generate at least 5% of its native load sales from renewable energy resources.requirements. Ameren Missouri expects to satisfy the nonsolar requirement intoin 2018 with its Keokuk energy center and its Maryland Heights energy center, and withthrough a 102-megawatt power purchase agreement through June 2024 with a wind farm operator in Iowa.operator. The Maryland Heights energy center generates electricity by burning methane gas collected from a landfill. Ameren Missouri is meeting the solar energy requirement through the purchase ofby purchasing solar-generated renewable energy credits from customer-installed systems and generation fromby generating its O'Fallonown solar energy center.at the O’Fallon energy center and at its headquarters building. See Supply of Electric Power above for renewable energy plans incorporated in Ameren Missouri’s integrated resource plan, filed with the MoPSC in September 2017.
UnderState law required renewable energy resources to equal or exceed 13% of the same Missouri statutetotal electricity that requires utilitiesAmeren Illinois supplied to purchase or generate electricity fromits eligible retail customers for the twelve months ended June 1, 2017. For the 2017 plan year, Ameren Illinois met the renewable sources,energy requirement. Starting June 1, 2017, Ameren MissouriIllinois is required to haveprocure renewable energy resources for all of its electric distribution customers, even if an alternative retail electric supplier provides power to the customer. The FEJA requires Ameren Illinois to procure zero-emission credits in an amount equal to approximately 16% of the actual amount of electricity delivered by Ameren Illinois to retail customers in Illinois during calendar year 2014. The zero-emission credit cost recovery mechanism, effective June 1, 2017, fully recovers or refunds, through customer rates, the variance in actual zero-emission credit costs incurred and the amounts collected from customers. Ameren Illinois defers the variance as a rebate programregulatory asset or liability, respectively. These requirements were, and will continue to provide an incentivebe, satisfied through ongoing IPA procurement events.
State law requires Ameren Illinois to offer rebates for customers to install solar generation on their premises. In accordance withcertain net metering customers. The cost of the statute and a 2013 MoPSC order, Ameren Missouri is required to provide $92 million of solar rebates by 2020, which was substantially completed by December 31, 2014. Also included in its 2013 order, the MoPSC authorized Ameren Missouri to employ a tracker to allow Ameren Missouri to record the costs it incurred under its solar rebate programare deferred as a regulatory asset. Ameren Missouri expects to recoverIt will be included in rate base and earn a return based on the costsutility’s weighted-average cost of capital. Customers that receive these rebates along withwill be allowed to net their supply service charges, but not their distribution service charges. Beginning in 2017, the estimated $9 million carrying cost ofFEJA decoupled the regulatory asset, overelectric distribution revenues established in a three-year period beginning withrate proceeding from the effective date of ratesactual sales volumes, which ensures that Ameren Illinois’ electric distribution earnings will not be affected by any reduction in its July 2014 electric rate case.sales volumes.
Energy Efficiency
Ameren Missouri and Ameren Illinois have implemented energy efficiencyenergy-efficiency programs to educate and to help their customers become more efficient users of energy. In Missouri, the MEEIA established a regulatory framework that, among other things, allows electric utilities to

recover costs relatedwith respect to MoPSC-approved customer energy efficiencyenergy-efficiency programs. The law requires the MoPSC to ensure that a utility’s financial incentives are aligned to help customers use energy more efficiently, to provide timely cost recovery, and to provide earnings opportunities associated with cost-effective energy efficiencyenergy-efficiency programs. Missouri does not have a law mandating energy efficiencyenergy-efficiency standards.
In February 2016, the MoPSC issued an order approving Ameren Missouri’s MEEIA 2016 plan. That plan included a portfolio of customer energy-efficiency programs along with a rider to collect the program costs, the throughput disincentive, and a performance incentive from customers. The MoPSC's December 2012 electric rate order approved Ameren Missouri's implementation ofthroughput disincentive recovery replaced the net shared benefits that were collected under the MEEIA megawatthour savings targets, customer energy efficiency programs, and associated cost recovery mechanisms and incentive awards. Ameren Missouri invested $76 million in these programs through 2014 and expects to invest an additional $71 million in 2015. A2013 plan. The MEEIA rider allows Ameren Missouri to collect from or refund to customers any annual difference in the actual amounts incurred and the amounts collectedthroughput disincentive without a traditional rate proceeding until lower volumes resulting from customers for the MEEIA programs are reflected in base rates. Customer rates, based upon both forecasted program costs and its lost revenues.


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Additionally, the MEEIA provides for incentive awards that would allow Ameren Missourithroughput disincentive, are reconciled annually to earn additional revenues by achieving certain energy efficiency goals. Under its current energy efficiency plan, which is effective for 2013 through 2015, Ameren Missouri can earn approximately $19 million if 100% of its energy efficiency goals are achieved during that time period, with the potential to earn more if energy savings exceed those goals. Ameren Missouri must achieve at least 70% of its energy efficiency goals before it can earn any incentive award. The recovery of the incentive award from customers, if the energy efficiency goals are achieved, is expected in 2017 through the above-mentioned rider.
In December 2014, Ameren Missouri filed an energy efficiency plan with the MoPSC under the MEEIA. This filing proposed a three-year plan that includes a portfolio of customer energy efficiency programs along with a cost recovery mechanism. If the plan is approved, beginning in January 2016,actual results. Ameren Missouri intends to invest $135$158 million over three years in the proposedMEEIA 2016 customer energy efficiencyenergy-efficiency programs. Ameren Missouri requested continued use of a MEEIA rider that allows itIn addition, similar to collect from or refund to customers any difference in the actual amounts incurred and the amounts collected from customers for the MEEIA program costs and its lost revenues. In addition, Ameren Missouri requested incentives to earn2013 plan, the MoPSC’s order included a performance incentive that provides for additional revenues by achievingif certain energy efficiencyMEEIA 2016 customer energy-efficiency goals are achieved, including approximately $25$27 million if 100% of its energy efficiencythe goals are achieved during the three-year period. See Note 2 – RateAmeren Missouri must achieve at least 25% of its energy efficiency-goals to be eligible for a MEEIA 2016 performance incentive, and Regulatory Matters under Part II, Item 8, of this report for additional information.can earn more if its energy savings exceed those goals.
Illinois has enacted aState law requiringrequires Ameren Illinois to offer customer energy efficiencyenergy-efficiency programs. The law also allows recovery mechanisms ofIn September 2017, the programs’ costs. The ICC has issued ordersan order approving Ameren Illinois’ electric and natural gas energy efficiencyenergy-efficiency plans, as well as cost recovery mechanisms by which program costs can be recovered from customers. The order authorized electric and natural gas energy-efficiency program expenditures of $394 million and $62 million, respectively, for the period 2018 through 2021. Additionally, as part of its IEIMA upgrades,capital project investments, Ameren Illinois expects to invest $360$439 million in smart gridsmart-grid infrastructure from 2012 to 2021, including smart meters that enable customers to improve their energy efficiency.
Historically, Ameren Illinois beganhas recovered the installationcost of smart metersits energy-efficiency programs as they were incurred. Since June 2017, the FEJA has allowed Ameren Illinois to earn a return on its electric energy-efficiency program investments. Ameren Illinois’ electric energy-efficiency investments are deferred as a regulatory asset, and such investments will earn a return at the company’s weighted-average cost of capital, with the equity return based on the monthly average yield of the 30-year United States Treasury bonds plus 580 basis points. The equity portion of Ameren Illinois’ return on electric energy-efficiency investments can be increased or decreased by up to 200 basis points, depending on the achievement of annual energy savings goals. The FEJA also increased the level of electric energy-efficiency saving targets through 2030. Ameren Illinois plans to invest up to $99 million per year in 2014.electric energy-efficiency programs from 2018 through 2021. Ameren Illinois plans to make similar yearly investments in electric energy-efficiency programs through 2030. The ICC can lower the electric energy-efficiency saving goals if sufficient cost-effective measures are not available. The electric energy-efficiency program investments and the return on those investments will be recovered through a rider; they will not be included in the IEIMA formula rate process.
NATURAL GAS SUPPLY FOR DISTRIBUTION
Ameren Missouri and Ameren Illinois are responsible for the purchase and delivery of natural gas to their utility customers. Ameren Missouri and Ameren Illinois each develop and manage a portfolio of natural gas supply resources. These resources include firm natural gas supply under termthrough agreements with producers, interstate and intrastate firm transportation capacity, firm no-notice storage capacity leased from interstate pipelines, and on-system storage facilities to maintain natural gas deliveries to customers throughout the year and especially during peak demand periods. Ameren Missouri and Ameren Illinois primarily use Panhandle Eastern Pipe Line Company, Trunkline Gas Company, Natural Gas Pipeline Company of America, Mississippi River Transmission Corporation, Northern Border Pipeline Company, and Texas Eastern Transmission Corporation interstate pipeline
systems to transport natural gas to their systems. In addition to transactions requiring physical delivery, certain financial instruments, including those entered into in the NYMEX futures market and in the OTC financial markets, are used to hedge the price paid for natural gas. Natural gas purchase costs are passed on to customers of Ameren Missouri and Ameren Illinois under PGA clauses, subject to prudence reviews by the MoPSC and the ICC. As of December 31, 2014,2017, Ameren Missouri had price-hedged 80% and Ameren Illinois had price-hedged 78%66% and 75%, respectively, of their expected 20152018 natural gas supply requirements.
For additional information on our fuel and purchased power supply, see Results of Operations and Liquidity and Capital Resources and Effects of Inflation and Changing Prices in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, of this report. Also see Note 1 – Summary of Significant Accounting Policies, Note 7 – Derivative Financial Instruments, Note 1013 – Callaway Energy Center, Note 14 – Related PartyRelated-party Transactions, and Note 1514 – Commitments and Contingencies under Part II, Item 8 of this report.
INDUSTRY ISSUES
We are facing issues common to the electric and natural gas utility industry. These issues include:
political, regulatory, and customer resistance to higher rates;
the potential for changes in laws, regulations, enforcement efforts, and policies at the state and federal levels;
changes to corporate income tax law changes that accelerate depreciation deductions, which reduce currentas a result of the enactment of the TCJA, as well as additional interpretations, regulations, amendments, or technical corrections related to the federal income tax payments but also result in rate base reductionscode, and limit the ability to claim other deductions and use carryforwardany state income tax benefits;reform;

cybersecurity risks, including loss of operational control of energy centers and electric and natural gas transmission and distribution systems and/or losstheft or inappropriate release of data, such as utilitycertain types of information, including sensitive customer, dataemployee, financial, and accountoperating system information;
the potential for more intense competition in generation, supply, and distribution, including new technologies;technologies and their declining costs;
net metering rules and other changes in existing regulatory frameworks and recovery mechanisms to address the allocation of costs to customers who own generation resources that enable them both to sell power to us and to purchase power from us through the use of our transmission and distribution assets;
legislation or programs to encourage or mandate energy efficiency and renewable sources of power, such as solar, and the lack of consensus as to who should pay for those programs;
pressure on customer growth and usage in light of economic conditions and energy efficiencyenergy-efficiency initiatives;
changes in the structure of the industry as a result of changes in federal and state laws, including the formation and growth of independent transmission entities;
pressure to reducea further reduction in the allowed return on common equity on FERC-regulated electric transmission assets;
the availability of fuel and fluctuations in fuel prices;
the availability of qualified labor and material, and rising costs;
the availability of a skilled workforce,work force, including retaining the specialized skills of those who are nearing retirement;
regulatory lag;
the influence of macroeconomic factors such ason yields onof United States Treasury securities, and on allowed rates of return on equity provided by regulators;
higher levels of infrastructure and technology investments couldand adjustments to customer rates associated with the TCJA that are expected to result in negative or decreased free cash flows,flow, which is defined as cash flows from operating activities less cash flows from investing


13


activities and dividends paid;
public concernconcerns about the siting of new facilities;
complex new and proposed environmental laws, regulations and requirements, including air and water quality standards, mercury emissions standards, CCR management requirements, and greenhouse gas limitations;
complex new and proposed environmental laws, regulations, and requirements, including air and water quality standards, mercury emissions standards, CCR management requirements, and potential CO2 limitations, which may reduce the frequency at which electric generating units are dispatched based upon their CO2 emissions;
public concernconcerns about the potential environmental impacts to the environment from the combustion of fossil fuels;fuels and some investors’ concerns about investing in energy companies that have fossil fuel-fired generation assets;
aging infrastructure and the need to construct new power generation, transmission, and distribution facilities, which have long time frames for completion, with littlelimited long-term ability to predict power and commodity prices, and regulatory requirements;
legislation or proposals for programs to encourage or mandate energy efficiency and renewable sources of power,
such as solar, and the macroeconomic debate over who should pay for those programs;
public concernconcerns about nuclear generation, and decommissioning and the disposal of nuclear waste; and
consolidation of electric and natural gas utility companies.
We are monitoring all these issues. Except as otherwise noted in this report, we are unable to predict what impact, if any, these issues will have on our results of operations, financial position, or liquidity. For additional information, see Risk Factors under Part I, Item 1A, and Outlook in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, and Note 2 – Rate and Regulatory Matters, Note 9 – Callaway Energy Center, and Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report.



14


OPERATING STATISTICS
The following tables present key electric and natural gas operating statistics for Ameren for the past three years:
Electric Operating Statistics – Year Ended December 31,
2014 2013 20122017 2016 2015
Electric Sales – kilowatthours (in millions):          
Ameren Missouri:          
Residential13,649
 13,562
 13,385
12,653
 13,245
 12,903
Commercial14,649
 14,634
 14,575
14,384
 14,712
 14,574
Industrial8,600
 8,709
 8,660
4,469
 4,790
 8,273
Street lighting and public authority117
 125
 126
Ameren Missouri retail load subtotal31,623
 32,872
 35,876
Off-system6,170
 6,128
 7,293
10,640
 7,125
 7,380
Other124
 125
 126
Ameren Missouri total43,192
 43,158
 44,039
42,263
 39,997
 43,256
Ameren Illinois:     
Ameren Illinois Electric Distribution(a):
     
Residential     10,985
 11,512
 11,554
Power supply and delivery service4,662
 5,474
 9,507
Delivery service only7,222
 6,310
 2,103
Commercial     12,382
 12,583
 12,280
Power supply and delivery service2,535
 2,606
 2,985
Delivery service only9,643
 9,541
 9,175
Industrial     11,359
 11,738
 11,863
Power supply and delivery service1,741
 1,667
 1,595
Delivery service only10,576
 10,861
 11,753
Other518
 522
 523
Ameren Illinois total36,897
 36,981
 37,641
Street lighting and public authority515
 521
 524
Ameren Illinois Electric Distribution total35,241
 36,354
 36,221
Eliminate affiliate sales(67) (82) 
(440) (520) (385)
Ameren total80,022
 80,057
 81,680
77,064
 75,831
 79,092
Electric Operating Revenues (in millions):          
Ameren Missouri:          
Residential$1,417
 $1,428
 $1,297
$1,416
 $1,421
 $1,464
Commercial1,203
 1,216
 1,088
1,207
 1,223
 1,258
Industrial475
 491
 435
305
 315
 469
Other, including street lighting and public authority115
 102
 84
Ameren Missouri retail load subtotal$3,043
 $3,061
 $3,275
Off-system173
 183
 208
370
 333
 195
Other120
 61
 104
Ameren Missouri total$3,388
 $3,379
 $3,132
$3,413
 $3,394
 $3,470
Ameren Illinois:     
Ameren Illinois Electric Distribution:     
Residential     $870
 $894
 $858
Power supply and delivery service$468
 $501
 $961
Delivery service only308
 282
 90
Commercial     527
 518
 474
Power supply and delivery service233
 215
 254
Delivery service only185
 184
 177
Industrial     113
 96
 124
Power supply and delivery service90
 70
 57
Delivery service only42
 44
 46
Other196
 165
 154
Ameren Illinois total$1,522
 $1,461
 $1,739
ATXI:     
Transmission services$33
 $19
 $9
Eliminate affiliate revenues(30) (27) (23)
Other, including street lighting and public authority58
 41
 76
Ameren Illinois Electric Distribution total$1,568
 $1,549
 $1,532
Ameren Transmission:     
Ameren Illinois Transmission(b)
$258
 $232
 $189
ATXI168
 123
 70
Ameren Transmission total$426
 $355
 $259
Other and intersegment eliminations(97) (102) (81)
Ameren total$4,913
 $4,832
 $4,857
$5,310
 $5,196
 $5,180

15


(a)Sales for which power was supplied by Ameren Illinois as well as alternative retail electric suppliers. In 2017, 2016, and 2015, Ameren Illinois procured power on behalf of its customers for 23%, 23%, and 26%, respectively, of its total kilowatthour sales.
(b)Includes $42 million, $45 million, and $38 million in 2017, 2016, and 2015, respectively, of electric operating revenues from transmission services provided to Ameren Illinois Electric Distribution.
Electric Operating Statistics – Year Ended December 31,
2014 2013 20122017 2016 2015
Electric Generation – Ameren Missouri – kilowatthours (in millions)43,474
 43,213
 44,658
Price per ton of delivered coal (average) – Ameren Missouri$37.36
 $36.19
 $34.21
Source of Ameren Missouri energy supply:          
Coal73.5% 74.1% 70.6%70.9% 66.2% 67.1%
Nuclear20.6
 18.6
 23.3
19.0
 22.8
 23.3
Hydroelectric2.2
 2.9
 2.1
3.4
 3.3
 3.6
Natural gas0.2
 0.4
 1.2
0.7
 0.7
 0.3
Methane gas0.1
 0.1
 0.1
Methane gas and solar0.1
 0.1
 0.2
Purchased – Wind0.8
 0.7
 0.7
0.7
 0.8
 0.7
Purchased – Other2.6
 3.2
 2.0
5.2
 6.1
 4.8
100.0% 100.0% 100.0%
Ameren Missouri total100.0% 100.0% 100.0%


Gas Operating Statistics – Year Ended December 31,
2014 2013 2012
Natural Gas Sales - dekatherms (in millions):     
Natural Gas Operating Statistics – Year Ended December 31,
2017 2016 2015
Natural Gas Sales – dekatherms (in millions):     
Ameren Missouri:          
Residential8
 8
 6
6
 6
 7
Commercial4
 4
 3
3
 3
 3
Industrial1
 1
 1
1
 1
 1
Transport7
 6
 6
8
 8
 7
Ameren Missouri total20
 19
 16
18
 18
 18
Ameren Illinois:     
Ameren Illinois Natural Gas:     
Residential66
 62
 49
50
 52
 55
Commercial23
 21
 17
15
 17
 18
Industrial3
 6
 5
3
 3
 3
Transport91
 87
 86
98
 94
 89
Ameren Illinois total183
 176
 157
Ameren Illinois Natural Gas total166
 166
 165
Ameren total203
 195
 173
184
 184
 183
Natural Gas Operating Revenues (in millions):          
Ameren Missouri:          
Residential$102
 $102
 $85
$77
 $77
 $84
Commercial40
 42
 36
31
 30
 34
Industrial7
 8
 8
4
 4
 5
Transport and other15
 9
 10
14
 17
 14
Ameren Missouri total$164
 $161
 $139
$126
 $128
 $137
Ameren Illinois:     
Ameren Illinois Natural Gas:     
Residential$675
 $611
 $547
$532
 $531
 $550
Commercial208
 185
 172
146
 153
 163
Industrial23
 26
 24
14
 12
 13
Transport and other70
 25
 43
51
 58
 57
Ameren Illinois total$976
 $847
 $786
Eliminate affiliate revenues
 (2) (1)
Ameren Illinois Natural Gas total$743
 $754
 $783
Other and intercompany eliminations(2) (2) (2)
Ameren total$1,140
 $1,006
 $924
$867
 $880
 $918
     
Rate Base Statistics At December 31,
2017 2016 2015
Rate Base (in billions):     
Coal generation$2.0
 $2.0
 $2.0
Natural gas generation0.4
 0.4
 0.5
Nuclear and renewables generation1.9
 1.8
 1.7
Electric and natural gas transmission and distribution10.1
 9.4
 8.2
Rate base total$14.4
 $13.6
 $12.4

16


AVAILABLE INFORMATION
The Ameren Companies make available free of charge through Ameren’s website (www.ameren.com) their annual reports on Form 10-K, quarterly reports on Form 10-Q, current reports on Form 8-K, eXtensible Business Reporting Language (XBRL) documents, and any amendments to those reports filed with or furnished to the SEC pursuant to Sections 13(a) or 15(d) of the Exchange Act as soon as reasonably possible after such reports are electronically filed with, or furnished to, the SEC. These documents are also available through an Interneta website maintained by the SEC (www.sec.gov). Ameren also uses itsAmeren’s own website as ais our channel of distribution for material information about the Ameren Companies. Financial and other material information regarding the Ameren Companies is routinely posted to, and accessible at, Ameren’s website.
The Ameren Companies also make available free of charge through Ameren’s website the charters of Ameren’s board of directors’ audit and risk committee, human resources committee, nominating and corporate governance committee, finance committee, and nuclear oversight and environmentaloperations committee; the corporate governance guidelines; a policy regarding communications to the board of directors; a policy and procedures document with respect to related-person transactions; a code of ethics for principal executive and senior financial officers; a code of business conduct applicable to all directors, officers and employees; and a director nomination policy that applies to the Ameren Companies. The information on Ameren’s website, or any other website referenced in this report, is not incorporated by reference into this report.
ITEM 1A.RISK FACTORS
Investors should review carefully the following material risk factors and the other information contained in this report. The risks that the Ameren Companies face are not limited to those in this section. There may be further risks and uncertainties that are not presently known or that are not currently believed to be material that may adversely affect the results of operations, financial position, and liquidity of the Ameren Companies.
REGULATORY AND LEGISLATIVE RISKS
We are subject to extensive regulation of our businesses, which could adversely affect our results of operations, financial position, and liquidity.
We are subject to extensive federal, state, and local regulation. This extensive regulatory framework, some but not all of which is more specifically identified in the following risk factors, regulates, among other matters, the electric and natural gas utility industries; the rate and cost structure of utilities; the operation of nuclear energy centers;power plants; the construction and operation of generation, transmission, and distribution facilities; the acquisition, disposal, depreciation and amortization of assets and facilities; the electric transmission system reliability; and present or prospective wholesale and retail competition. In the planning and management of our operations, we must address the effects of existing and proposed laws and regulations and potential changes in the regulatory
framework, including initiatives by federal and state legislatures, RTOs, utility regulators, and taxing authorities. Significant changes in the nature of the regulation of our businesses could require changes to our business planning and management of our businesses and could adversely affect our results of operations, financial position, and liquidity. Failure to obtain adequate rates or regulatory approvals in a timely manner; failure to obtain necessary licenses or permits from regulatory authorities; the impact of new or modified laws, regulations, standards, interpretations, or other legal requirements; or increased compliance costs could adversely affect our results of operations, financial position, and liquidity.
The electric and natural gas rates that we are allowed to charge are determined through regulatory proceedings, which are subject to intervention and appeal andappeal. Rates are also subject to legislative actions, which are largely outside of our control. Any events that prevent us from recovering our costs in a timely manner or from earning adequate returns on our investments could adversely affect our results of operations, financial position, and liquidity.
The rates that we are allowed to charge for our utility services significantly influence our results of operations, financial position, and liquidity. The electric and natural gas utility industries are extensivelyindustry is highly regulated. The utility rates charged to our customers are determined by governmental entities, including the MoPSC, the ICC, and the FERC. Many factors influence decisionsDecisions by these entities are influenced by many factors, including the cost of providing service, the prudency of expenditures, the quality of service, regulatory staff knowledge and experience, customer intervention, and economic conditions, public policy, as well as social and political views. Decisions made by these governmental entities regarding rates are largely outside of our control. We are exposed to regulatory lag and cost disallowances to varying degrees by jurisdiction, which, if unmitigated, could have a material adverse effect onadversely affect our results of operations, financial position, and liquidity. Rate orders are also subject to appeal, which creates additional uncertainty as to the rates that we will ultimately be allowed to charge for our services. From time to time, our regulators willmay approve trackers, riders, or other mechanisms that allow electric or natural gas rates to be adjusted without a traditional rate proceeding. These mechanisms are not permanent and could be changed or terminated.
Ameren Missouri'sMissouri’s electric and natural gas utility rates and Ameren Illinois'Illinois’ natural gas utility rates are typically established in regulatory proceedings that take up to 11 months to complete. RatesAmeren Missouri’s rates established in those proceedings for Ameren Missouri are primarily based on

historical costs and revenues. NaturalAmeren Illinois’ natural gas rates established in those proceedings for Ameren Illinois may beare based on historical or estimated future costs and revenues. Thus the rates that a utility iswe are allowed to charge for utility services may not match itsour actual costs at any given time.
Rates include an allowed rate of return on investments determinedestablished by the regulator.regulator, including a return on invested capital, both debt and equity, and an amount for income taxes. Although rate regulation is premised on providing an opportunity to earn a reasonable rate of return on invested capital, there can be no assurance that the regulator will


17


determine that our costs were prudently incurred or that the regulatory process will result in rates that will produce full recovery of such costs or provide for an adequateopportunity to earn a reasonable return on those investments.
InWith respect to Ameren Missouri’s electric and natural gas utility rates, in years when capital investments and operations costs rise or customer usage declines below those levels reflected in rates, we may not be able to earn the allowed return established by the regulator. This could result in the deferral or eliminationcancellation of planned capital investments, which could reduce the rate base investments on which we earnAmeren Missouri earns a rate of return. Additionally, increasing rates could result in regulatory andor legislative actions, as well as competitive andor political pressures, all of which could adversely affect our results of operations, financial position, and liquidity.
As a result of its participation in the performance-based formula ratemaking processframework established pursuant to the IEIMA and the FEJA, Ameren Illinois’ return on equity for its electric distribution businessservice and its electric energy-efficiency investments is directly correlated to yields on United States Treasury bonds. Additionally, Ameren Illinois is required to achieve certain performance objectives,standards and capital spending levels, and job creation targets.levels. Failure to meet these requirements could adversely affect Ameren'sAmeren’s and Ameren Illinois'Illinois’ results of operations, financial position, and liquidity.
Ameren Illinois is participatingparticipates in thea performance-based formula ratemaking processframework established pursuant to the IEIMA for its electric distribution business.service. Beginning in 2017, the FEJA allowed Ameren Illinois to recover its electric distribution revenue requirement for a given year, independent of actual sales volumes. Since June 2017, the FEJA has also allowed Ameren Illinois to earn a return on its electric energy-efficiency program investments, which is subject to performance-based formula ratemaking. The ICC annually reviews Ameren Illinois’ performance-based rate filings under the IEIMA for reasonableness and prudency. If the ICC were to conclude that Ameren Illinois’ incurred costs were not prudently incurred, the ICC would disallow recovery of such costs.
The return on equity component ofunder the formula rateIEIMA and the FEJA is equal to the average for the calendar year average of the monthly yields of 30-year United States Treasury bonds plus 580 basis points. Therefore, Ameren Illinois’ annual return on equity under the formula ratemaking processframeworks for both its electric distribution businessservice and its electric energy-efficiency investments is directly correlated to the yields on such bonds, which are outside of Ameren Illinois’ control. AWith respect to electric distribution service, a 50 basis point change in the average monthly yields of the 30-year United States Treasury bonds would result in an estimated $6$8 million change in Ameren'sAmeren’s and Ameren Illinois' 2015Illinois’ net income.income, based on its 2018 projected rate base.
Ameren Illinois is also subject to performance standards. Failure to achieve the standards would result in a reduction in the company’s allowed return on equity calculated under the formula.ratemaking formulas. The IEIMAperformance standards applicable to electric distribution service include improvements in service reliability to reduce both the frequency and duration of outages, a reduction in the number of estimated bills, a reduction of consumption from inactive meters, and a reduction in bad debt expense. The regulatory framework applicable to electric distribution service provides for return on equity penalties totaling 30 basis points in 2015,up to 34 basis points in each year from 2016 through 2018, and up to 38 basis points in each year from 2019 through 2022, if thethese performance standards are not met. Beginning in 2018, the regulatory framework applicable to electric energy-efficiency investments provides for increases or decreases of up to 200 basis points to the return on equity. Any adjustments to the return on equity for energy-efficiency investments will depend on annual performance of a historical period relative to energy savings goals.
Between 2012 and 2021, Ameren Illinois is required to invest a minimum of $625 million in capital projects to modernize its distribution system incremental to its average annual electric deliverydistribution service capital projects investments of $228 million for calendar years 2008 through 2010, in order to modernize its distribution system.2010. Through 2017, Ameren Illinois is subjecthas invested $508 million in IEIMA capital projects toward its $625 million minimum requirement. If Ameren Illinois does not meet its investment commitments under IEIMA, Ameren Illinois would no longer be eligible to monetary penalties if 450 additional jobs are not created in Illinois duringannually update its performance-based formula rates under IEIMA.
Without the peak program year.
Unless it is extended,extension of formula ratemaking, the IEIMA performance-based formula ratemaking process will expire in 2017. Whenframework expires at the performance-based formula rate process expires,end of 2022. Ameren Illinois would then be required to establish future rates through a traditional rate proceeding with the ICC, which might not result in rates that produce a full or timely recovery of costs or provide for an adequate return on investments. The decoupling provisions of the FEJA do not expire at the end of 2022.
Pursuant to the FEJA, Ameren Illinois plans to invest up to $99 million per year in electric energy-efficiency programs from 2018 through 2021 that will earn a return. Ameren Illinois plans to make similar yearly investments in electric energy-efficiency programs from 2022 through 2030. The ICC has the ability to reduce electric energy-efficiency savings goals if there are insufficient cost-effective programs available or if the savings goals would require investment levels that exceed amounts allowed by legislation.

We are subject to various environmental laws and regulations. Significant capital expenditures are required to achieve and to maintain compliance with these laws and regulations. Failure to comply with these laws and regulations could result in closurethe closing of facilities, alterations to the manner in which these facilities operate, increased operating costs, adverse impactsor exposure to fines and liabilities, all of which could adversely affect our results of operations, financial position, and liquidity, or exposure to fines and liabilities.liquidity.
We are subject to various environmental laws and regulations enforced by federal, state, and local authorities. From the beginning phases of sitingThe development and development to the operation of existing or new electric generation, transmission, and distribution facilities and natural gas storage, transmission, and distribution facilities our activities involvecan trigger compliance obligations with diverserespect to environmental laws and regulations. These laws and regulations address emissions;emissions, discharges to water, water usage, impacts to air, land, and water, and chemical and waste handling. Complex and lengthy processes are required to obtain and renew approvals, permits, orand licenses for new, existing or modified facilities. Additionally, the use and handling of various chemicals or hazardous materials require release prevention plans and emergency response procedures.
We are also subject to liability under environmental laws that address the remediation of environmental contamination ofon property currently or formerly owned by us or by our predecessors, as well as property contaminated by hazardous substances that we generated. Such properties include MGP sites and third-party sites, such as landfills. Additionally, private individuals may seek to enforce environmental laws and regulations against us. They could allege injury from exposure to hazardous materials, couldallege a failure to comply with environmental laws and regulations, seek to compel remediation of environmental contamination, or couldseek to recover damages resulting from that contamination.
The EPA is developing and implementinghas promulgated environmental regulations that will have a significant impact on the electric utility industry. Over time, compliance with these regulations could be costly for certain companies, including Ameren Missouri, that operatewhich operates coal-fired power plants. CertainAs of December 31, 2017, Ameren Missouri’s fossil fuel-fired energy centers represented 17% and 33% of Ameren’s and Ameren Missouri’s rate base, respectively. Regulations that apply to air emissions from the electric utility industry include the NSPS, the CSAPR, the MATS, and the revised National Ambient Air Quality Standards, which are subject to periodic review for certain pollutants. Collectively, these regulations cover a variety of pollutants, such as SO2, particulate matter, NOx, mercury, toxic metals, and acid gases, and CO2 emissions from new power plants. Water intake and proposeddischarges from power plants are regulated under the Clean Water Act. Such regulation could require modifications to water intake structures or more stringent limitations on wastewater discharges at Ameren Missouri’s energy centers, either of which could result in significant capital expenditures. The management and disposal of coal ash is regulated under the CCR rule, which will require the closure of surface impoundments and the installations of dry ash handling systems at several of Ameren Missouri’s energy centers. The individual or combined effects of existing environmental regulations if adopted, are likely to be challenged through litigation, so their ultimate implementation, as well ascould result in significant capital expenditures, increased operating costs, or the timingclosure or alteration of any such implementation, is uncertain.operations at some of Ameren Missouri’s energy centers.
Ameren is also subject to risks in connection withfrom changing or conflicting interpretations of existing laws and regulations. The EPA is engaged in an enforcement initiative to determine whether coal-fired power plants failed to comply with the requirements of the NSR and NSPS provisions under the Clean Air Act when the


18


power plants implemented modifications. In January 2011, the Department of Justice, on behalf of the EPA, filed a complaint against Ameren Missouri in the United States District Court for the Eastern District of Missouri. An outcomeThe complaint, as amended in October 2013, alleged that in performing projects at its Rush Island coal-fired energy center in 2007 and 2010, Ameren Missouri violated provisions of the Clean Air Act and Missouri law. The litigation has been divided into two phases: liability and remedy. In January 2017, the district court issued a liability ruling that the projects violated provisions of the Clean Air Act and Missouri law. The case then proceeded to the second phase to determine the actions required to remedy the violations found in the liability phase. The EPA previously withdrew all claims for penalties and fines. The ultimate resolution of this matter could have a material adverse effect on the results of operations, financial position, and liquidity of Ameren and Ameren Missouri. Among other things and subject to Ameren Missourieconomic and regulatory considerations, resolution of this matter could require substantialresult in increased capital expenditures for the installation of pollution control equipment, as well as increased operations and the payment of substantial penalties, neither of which can be determined at this time. Such expenditures could affect unit retirement and replacement decisions.maintenance expenses.
In January 2014,2015, the EPA published proposed regulations thatissued the Clean Power Plan, which would set revisedhave established CO2 emissions standards for new power plants. The proposed standards would establish separate emissions limits for new natural-gas-fired plants and new coal-fired plants. In June 2014, the EPA proposed the Clean Power Plan, which sets forth CO2 emissions standards that would be applicable to existing power plants. The proposed Clean Power Plan would require each state to develop plans to achieve CO2 emission standards thatUnited States Supreme Court stayed the rule in February 2016, pending various legal challenges. In October 2017, the EPA calculated for each state. The EPA believes thatannounced a proposal to repeal the Clean Power Plan would achieve a 30% reduction inPlan. In December 2017, the nation's existing power plantEPA issued an advanced notice of proposed rulemaking to solicit input from stakeholders as to how the EPA should regulate CO2 emissions from 2005 levels by 2030. The proposed rule also has interim goals of aggressively reducingexisting power plants under the Clean Air Act. Accordingly, we no longer expect the Clean Power Plan to take effect. However, the EPA may issue new requirements that would regulate CO2 emissions by 2020. The EPA expectsfrom existing power plants. We cannot predict the proposed rule will be finalized in 2015. Ameren Missouri’s integrated resource plan is projected to achieve the carbon emissions reductions proposed inoutcome of the EPA’s Clean Power Plan by 2035, rather thanfuture rulemaking or the EPA’s final target dateoutcome of 2030 or its interim target dates beginning in 2020. Ameren Missouri continuesany legal challenges relating to evaluate its potential compliance plans for the proposed Clean Power Plan. Preliminary studies suggest that if the proposed Clean Power Plan were to be finalized in its current form, Ameren Missouri may need to incur new or accelerated capital expenditures and increased fuel costs in order to achieve compliance. As proposed, the Clean Power Plan would require states, including Missouri and Illinois, to submit compliance plans as early as 2016. The states’ compliance plans might require Ameren Missouri to construct natural-gas-fired combined cycle generation and renewable generation, at a currently estimated costsuch future rulemakings, any of approximately $2 billion by 2020, that Ameren Missouri believes would otherwise not be necessary to meet the energy needs of its customers. Additionally, Missouri’s implementation of the proposed rules, if adopted, could result in the closure or alteration of the operation of some of Ameren Missouri’s coal and natural gas-fired energy centers, which could result in increased operating costs or impairmenthave an adverse effect on our results of assets. The Clean Power Plan may negatively impact electric system reliability for Ameren Missourioperations, financial position, and Ameren Illinois.liquidity.
Ameren and Ameren Missouri have incurred and expect to incur significant costs relatedwith respect to environmental compliance and site remediation. New or revised environmental regulations, enforcement initiatives, or legislation could result in a significant increase in capital expenditures and operating costs, decreased revenues, increased financing requirements, penalties or fines, or reduced operations of some of Ameren Missouri'sMissouri’s coal-fired energy centers, which, in turn, could lead to increased liquidity needs and higher financing costs. Actions required to ensure that ourAmeren Missouri’s facilities and operations are in compliance with environmental laws and regulations could be

prohibitively expensive for Ameren Missouri if the costs are not fully recovered through rates. Environmental laws could
require Ameren Missouri to close or to alter significantly the operationoperations of its energy centers. Moreover, ifIf Ameren Missouri requests recovery of these capital expenditures and costs for environmental compliance through rates, the MoPSC could deny recovery of all or a portion of these costs, prevent timely recovery, or make changes to the regulatory framework in an effort to minimize rate volatility and customer rate increases. Capital expenditures and costs to comply with future legislation or regulations that are not recoverable through rates might result in Ameren Missouri closing coal-fired energy centers earlier than planned, which wouldplanned. If these costs are not recoverable through rates, it could lead to an impairment of assets and reduced revenues. We are unableAny of the foregoing could have an adverse effect on our results of operations, financial positions, and liquidity.
The TCJA is complex and significantly affects the Ameren Companies. As a result of the TCJA, the Ameren Companies expect lower operating cash flows, driven by lower customer rates, which may need to predictbe funded through debt and/or equity issuances. Further, additional interpretations, regulations, amendments, and technical corrections to the ultimate impact of these matters onfederal income tax code, as well as the associated treatment by our regulators, may adversely affect our results of operations, financial position, and liquidity.
Government challengesThe TCJA, among other things, reduced the federal statutory corporate income tax rate from 35% to our21%, effective January 1, 2018. Additionally, the TCJA eliminated 50% accelerated depreciation tax positions,benefits for nearly all regulated utility capital investments made after September 27, 2017. As of December 31, 2017, Ameren recorded a noncash charge to earnings of $154 million as well asa result of the revaluation of deferred taxes, largely attributable to Ameren (parent). Ameren also reclassified deferred income tax law changesliabilities of $2.4 billion to regulatory liabilities. This reclassification is due to the reduction of the federal statutory corporate income tax rate, which reduced such income tax obligations, and the inherent difficultyexpected return of funds previously collected from customers. Our rate-regulated businesses recover income taxes in quantifying potentialcustomer rates based on the federal and state statutory corporate income tax rates in effect when the revenue requirements used to determine those rates were established. However, there is a timing difference between when we collect funds from our customers for income taxes and when we pay such taxes. Excess deferred taxes were created as the deferred income tax obligation decreased due to a reduction in the federal statutory corporate income tax rate.
The elimination of 50% accelerated tax depreciation on nearly all capital investments has caused an increase in Ameren’s near-term projected income tax liabilities. Ameren expects to largely offset its income tax obligations through about 2020 with existing net operating loss and tax credit carryforwards. Since we have been using existing net operating loss and tax credit carryforwards to largely offset income tax obligations, the effect of the reduced federal statutory corporate income tax rate is expected to be a decrease in operating cash flows. The decrease in operating cash flows results from reduced customer rates, reflecting the tax rate decrease, without a corresponding reduction in income tax payments until about 2021. Additionally, operating cash flows will be further reduced by lower customer rates, reflecting the return of excess deferred taxes previously collected from customers over periods of time determined by our regulators. The decrease in operating cash flows as a result of the TCJA is expected to be partially offset over time by increased customer rates due to higher rate base amounts, once approved by our regulators. We expect rate base amounts to be higher as a result of lower accumulated deferred income tax liabilities, due to the elimination of 50% accelerated tax depreciation, the reduced statutory income tax rate, and the return of excess deferred taxes to customers. Ameren expects a decrease in operating cash flows of approximately $1 billion from 2018 through 2022 (Ameren Missouri – $0.3 billion; Ameren Illinois – $0.4 billion) as a result of the TCJA, and expects an increase in rate base of approximately $1 billion over the same time period (Ameren Missouri – $0.3 billion; Ameren Illinois – $0.5 billion). Over the next five years, Ameren may be required to issue incremental debt and/or equity to fund this reduction in operating cash flows, with the long-term intent to maintain strong financial metrics and an equity ratio around 50%, as calculated in accordance with ratemaking frameworks. Ameren Missouri and Ameren Illinois expect to fund cash flows needs through debt issuances, adjustments of dividends to Ameren (parent), and/or capital contributions from Ameren (parent), with the intent to maintain strong financial metrics and an equity ratio around 50%, as calculated in accordance with ratemaking frameworks. As a result of the TCJA, financial metrics used by credit rating agencies may be negatively affected, primarily due to expected decreases in operating cash flows discussed above.
Most of the effects of business decisions,the TCJA will be reflected in adjusted customer electric and gas rates over time. The regulatory treatment of the effects of the TCJA will be subject to the discretion of the FERC, the MoPSC and the ICC. The period over which the return of excess deferred taxes will occur will ultimately be determined by our regulators.
Certain aspects of the TCJA are unclear. These aspects will require interpretations and regulations from the IRS and state taxing authorities, and the TCJA could be subject to potential amendments and technical corrections, any of which could adversely affect our results of operations, financial position, and liquidity.
We are required to make judgments in order to estimate tax obligations. These judgments include reserves for potential adverse outcomes for tax positions that The revaluation of deferred taxes recorded as of December 31, 2017, may be challenged bysubject to further adjustment in accordance with additional interpretations or as a result of the IRS audit of the 2017 income tax authorities. The obligations,return, either of which include income taxes and taxes other than income taxes, involve complex matters that ultimately could be litigated. We also estimate our ability to use tax benefits, including those in the form of carryforwards and tax credits that are recorded as deferred tax assets on our balance sheets. A disallowance of these tax benefits could have a material adverse impact onadversely affect our results of operation,operations, financial position, and liquidity. There may be other material adverse effects resulting from the TCJA that we have not yet identified, each of which could be material in any particular quarterly period.

Customers’, legislators’, and regulators’ opinions of us are affected by many factors, including system reliability, implementation of our investment plans, protection of customer information, rates, and media coverage. To the extent that customers, legislators, or regulators have or develop a negative opinion of us, our results of operations, financial position, and liquidity could be negativelyadversely affected.
Service interruptions can occur due to failures of equipment or facilities as a result of severe or destructive weather or other causes, and thecauses. The ability of Ameren Missouri and Ameren Illinois to respond promptly respond to such failures can affect customer satisfaction. In addition to system reliability issues, the success of modernization efforts, such as those plannedbeing undertaken for Ameren Illinois’ electric and natural gas delivery systems, our ability to safeguard sensitive customer information and protect our systems from cyber attacks, and other actions can affect customer satisfaction. The level of rates, the timing and magnitude of rate increases, and the volatility of rates can also affect customer satisfaction. Customers'Customers’, legislators'legislators’, and regulators'regulators’ opinions of us can also be affected by media coverage, including the proliferation of social media, which may include information, whether factual or not, that damages our brand and reputation.
If customers, legislators, or regulators have or develop a negative opinion of us and our utility services, this could result in increased costs associated with regulatory oversight and could impactaffect the returns on common equity we are allowed to earn. Additionally, negative opinions about us could make it more difficult for our utilities to achieve


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favorable legislative or regulatory outcomes. Negative opinions could also result in sales volume reductions andor increased use of distributed generation.generation by our customers. Any of these consequences could adversely affect our results of operations, financial position, and liquidity.
We are subject to federal regulatory compliance and proceedings, which increase our risk ofexposes us to the potential for regulatory penalties and other sanctions.
The FERC can impose civil penalties of $1approximately $1.2 million per violation per day for violation of FERC statutes,its regulations, rules, and orders, including mandatory NERC reliability standards. As owners and operators of bulk power transmission systems and electric energy centers, we are subject to mandatory NERC reliability standards, including cybersecurity standards. Compliance with these mandatory reliability standards may subject us to higher operating costs and may result in increased capital expenditures. If we were found not to be in compliance with these mandatory reliability standards, or the FERC statutes,regulations, rules, and orders, we could incur substantial monetary penalties and other sanctions, which could adversely affect our results of operations, financial position, and liquidity. The FERC also conducts audits and reviews of Ameren Missouri's,Missouri’s, Ameren Illinois'Illinois’, and ATXI'sATXI’s accounting records to assess the accuracy of its formula ratemaking process, and has the ability toit can require retroactive refunds to customers for previously billed amounts, with interest.
OPERATIONAL RISKS
The construction of, and capital improvements to, our electric and natural gas utility infrastructure involve substantial risks. These risks include escalating costs, unsatisfactory performance by the projects when completed, the inability to complete projects as scheduled, cost disallowances by regulators, and the inability to earn an adequate return on invested capital, any of which could result in higher costs and the closure of facilities.facility closures.
We expect to incur significant capital expenditures in order to make investments tomaintain and improve our electric and natural gas utility infrastructure and to comply with existing environmental regulations. We estimate that we will incurinvest up to $9.3$11.4 billion (Ameren Missouri - up to $3.9$4.5 billion; Ameren Illinois - up to $4.0$6.6 billion; ATXI - up to $1.4$0.3 billion) of capital expenditures duringfrom 2018 through 2022. These estimates do not reflect the period from 2015potential additional investments identified in Ameren Missouri’s integrated resource plan, which could represent incremental investments of approximately $1 billion through 2019.2020 and are subject to regulatory approval. They also do not reflect potential additional investments that Ameren Missouri could make if improvements in its regulatory frameworks were made. These estimates include allowance for equity funds used during construction.
Investments in Ameren’s rate-regulated operations are expected to be recoverable from ratepayers,customers, but they are subject to prudence reviews and depending on the jurisdiction,are exposed to regulatory lag.lag of varying degrees by jurisdiction.
Our ability to complete construction projects successfully within projected estimates is contingent upon many variables and subject to substantial risks. These variables include, but are not limited to, project management expertise, and escalating costs for materials and labor, the ability to obtain required project approvals, and environmental compliance.the ability to obtain necessary rights-of-way and easements. Delays in obtaining permits, shortages in materials and qualified labor, suppliers and contractors who do not perform as required under
their contracts, changes in the scope and timing of projects, the inability to raise capital on reasonable terms, or other events beyond our control that could occur may materially affect the schedule, cost, and performance of these projects. With respect to capital expenditures for pollution control equipment, thereThere is a risk that a power plant mayan energy center might not be permitted to continue to operate if pollution control equipment is not installed by prescribed deadlines or does not perform as expected. Should any such pollution control equipment not be installed on time or not perform as expected, Ameren Missouri could be subject to additional costs and to the loss of its investment in the project or facility. All of these project and construction risks could adversely affect our results of operations, financial position, and liquidity.
As of December 31, 2014, Ameren Missouri had capitalized $69 million of costs incurred to license additional nuclear generation at its existing Callaway energy center site. If efforts are abandoned or if management concludes that it is probable the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination was made. The NRC review of the COL application to license additional nuclear generation at the Callaway energy center site is currently suspended through the end of 2015.
Ameren and Ameren Illinois may not be able to execute their electric transmission investment plans or to realize the expected return on those investments.
Ameren, through ATXI and Ameren Illinois, is allocatinginvesting significant additional capital resources toin electric transmission investments. This allocation of capital resources istransmission. These investments are based on the FERC'sFERC’s regulatory framework and a rate of return on common equity that is currently higher than that allowed by our state commissions. However, the FERC regulatory framework and rate of return isare subject to change,changes, including changes as a result of third-party complaints and challenges at the FERC. The regulatory framework may not be asless favorable or the rate of return may be lower in the future. Currently, the FERC-allowed return on common equity for MISO transmission owners is 12.38%. In November 2013, aA pending complaint case was filed with the FERC seeking a reduction in February 2015 could reduce the allowed return on common equity under the MISO tariff. A second complaint case was filed in February 2015. These complaint casesand could negatively affect Ameren Illinois' and ATXI's allowed return. Any such reduction would also result in a refund of transmission service revenues earned since the filing of the initial complaint case in November 2013.require customer refunds. A 50 basis point reduction in the FERC-allowed return on common equity would reduce Ameren'sAmeren’s and Ameren Illinois' 2015Illinois’ earnings by an estimated $4$8 million and $2$4 million, respectively, based on each company’s 2018 projected rate base.
A significant portion of Ameren's plannedAmeren’s electric transmission investments consists of three separate ATXI projects, to be constructed by ATXI, which have been approved by MISO as multi-value projects. TheAs of December 31, 2017, ATXI’s expected remaining investment in all three projects was approximately $300 million, with the total investment by ATXI in these three projects is expected to be more than $1.6 billion.billion The last of these projects is expected to be completed in 2019. A failure by ATXI to complete these three projects on time and within projected cost estimates could adversely affect Ameren'sAmeren’s results


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of operations, financial position, and liquidity.
The FERC has issued multiple orders, which are subject to ongoing litigation, eliminating the right of first refusal for an electric utility to construct within its service territoryWithin MISO, certain new transmission projects for which there will beare eligible for regional cost sharing. If these orders are upheld by the courts,sharing may be subject to competition. Therefore, Ameren mightmay need to compete to build certain future electric transmission projects in its subsidiaries'subsidiaries’ service territories. Such competition could prevent Ameren from investing inlimit Ameren’s future electric transmission projects to the extent desired. Also, Ameren may not be successful in its efforts to build transmission assets outside of its subsidiaries' service territories or MISO.investment.
Our electric generation, transmission, and distribution facilities are subject to operational risks that could adversely affect our results of operations, financial position, and liquidity.
Our financial performance depends on the successful operation of electric generation, transmission, and distribution facilities. Operation of electric generation, transmission, and distribution facilities involves many risks, including:
facility shutdowns due to operator error, or a failure of equipment or processes;
longer-than-anticipated maintenance outages;
aging infrastructure that may require significant expenditures to operate and maintain;
disruptions in the delivery of fuel, failure of our fuel suppliers to provide adequate quantities or quality of fuel, or lack of adequate inventories of fuel, including ultra-low-sulfur coal used forby Ameren Missouri’s complianceMissouri to comply with environmental regulations;
lack of adequate water required for cooling plant operations;
labor disputes;
suppliers and contractors who do not perform as required under their contracts;
inability to comply with regulatory or permit requirements, including those relating to environmental laws;
disruptions in the delivery of electricity that impactto our customers;
handling, storage, and disposition of CCR;
unusual or adverse weather conditions or other natural disasters, including severe storms, droughts, floods, tornadoes, earthquakes, solar flares, and electromagnetic pulses;
accidents that might result in injury or loss of life, extensive property damage, or environmental damage;
cybersecurity risks, including loss of operational control of Ameren Missouri'sMissouri’s energy centers and our transmission and distribution systems and loss of data, such as utilityincluding sensitive customer, dataemployee, financial and accountoperating system information, through insider or outsider actions;
failure of other operators'operators’ facilities and the effect of that failure on our electric system and customers;
the occurrence of catastrophic events such as fires, explosions, acts of sabotage or terrorism, pandemic health events, or other similar occurrences;events;
limitations on amounts of insurance available to cover losses that might arise in connection with operating our electric generation, transmission, and distribution facilities;
inability to implement or maintain information systems;
failure to keep pace with rapid technological change; and
other unanticipated operations and maintenance expenses and liabilities.
The foregoing risks could affect the controls and operations of our facilities or impede our ability to meet regulatory requirements, which could increase operating costs, increase our capital requirements and costs, reduce our revenues or have an adverse effect on our liquidity.
Ameren Missouri’s ownership and operation of a nuclear energy center creates business, financial, and waste disposal risks.
Ameren Missouri’s ownership of the Callaway energy center subjects it to the risks ofassociated with nuclear generation, which include the following:including:

potential harmful effects on the environment and human health resulting from radiological releases associated with the operation of nuclear facilities and the storage, handling, and disposal of radioactive materials;
continued uncertainty inregarding the federal governmentgovernment’s plan to permanently store spent nuclear fuel and, as a result, the risk of being requiredneed to provide for long-term storage of spent nuclear fuel at the Callaway energy center;
limitations on the amounts and types of insurance available to cover losses that might arise in connection with the Callaway energy center or other United States nuclear facilities;facilities, including losses due to market performance and other economic factors that adversely affect the value of the securities in the nuclear decommissioning trust fund;
uncertainties with respect toabout contingencies and retrospective premium assessments relating to claims at the Callaway energy center or any other United States nuclear facilities;
public and governmental concerns about the safety and adequacy of security at nuclear facilities;
uncertainties with respect toabout the technological and financial aspects of decommissioning nuclear facilities at the end of their licensed lives;
limited availability of fuel supply;supply and our reliance on licensed fuel assemblies that are fabricated by Westinghouse, Callaway energy center’s only NRC-licensed supplier of such assemblies, which is currently in bankruptcy proceedings;
costly and extended outages for scheduled or unscheduled maintenance and refueling;
the adverse effect of poor market performance and other economic factors on the asset values of nuclear decommissioning trust funds and the corresponding increase, upon MoPSC approval, in customer rates to fund the estimated decommissioning costs; and
potential adverse effects of a natural disaster, or acts of sabotage or terrorism.terrorism, including cyber attack, or any accident leading to release of nuclear contamination.
The NRC has broad authority under federal law to impose licensing and safety requirements for nuclear facilities. In the event of noncompliance, the NRC has the authority to impose fines or to shut down a unit, or both, depending upon its assessment of the severity of the situation, until compliance is achieved. Revised safety requirements promulgated from time to time by the NRC could necessitate substantial capital expenditures at nuclear facilities such as Ameren Missouri’sthe Callaway energy center. In addition, if a serious nuclear incident were to occur, it could have a material but indeterminable adverse effect on Ameren'sadversely affect Ameren’s and Ameren Missouri’s results of operations, financial condition, and liquidity. A major incident at a nuclear facility anywhere in the world could cause the NRC to limit or prohibit the operation or relicensing of any domestic nuclear unit and could also cause the NRC to impose additional conditions or requirements on the industry, which could increase costs and result in additional capital expenditures. Under revisedNRC standards relating to seismic risk the NRC may require Ameren Missouri to further evaluate the impact of an earthquake on its Callaway energy center due to its proximity to a fault line, which could require the installation of additional capital equipment.
Our natural gas distribution and storage activities


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involve numerous risks that may result in accidents and otherincreased operating risks and costs that could adversely affect our results of operations, financial position, and liquidity.
Inherent in our natural gas distribution and storage activities are a variety of hazards and operating risks, such as leaks, accidental explosions, mechanical problems and cybersecurity risks, which could cause substantial financial losses. In addition, these hazards could result in serious injury, loss of human life, significant damage to property, environmental impacts, and impairment of our operations, which in turn could lead us to incur substantial losses. In accordance with customary industry practice, we maintain insurance against some, but not all, of these risks and losses. The location of distribution linesmains and storage facilities near populated areas, including residential areas, business centers, industrial sites, and other public gathering places, could increase the level of damages resulting from these risks. A major domestic incident involving natural gas systems could lead to additional capital expenditures, and increased regulation, ofand fines and penalties on natural gas utilities. The occurrence of any of these events could materially adversely affect our results of operations, financial position, and liquidity.
Significant portions of our electric generation, transmission, and distribution facilities and natural gas transmission and distribution facilities are aging. This aging infrastructure may require significant additional maintenance expenditures or may require replacement.replacement that could adversely affect our results of operations, financial position, and liquidity.
Our aging infrastructure may pose risks to system reliability and expose us to expedited or additional unplanned significant capital expenditures and operating costs. All of Ameren Missouri’s coal-fired energy centers were constructed prior to 1978, while itsand the Callaway nuclear energy center was constructed prior tobegan operating in 1984. The age of these energy centers increases the risks of unplanned outages, reduced generation output, and higher maintenance expense. If, at the end of its life, an energy center'scenter’s cost has not been fully recovered, Ameren Missouri may be negativelyadversely affected if the MoPSC does not allow such cost isto be recovered in rates. Ameren Missouri may also be adversely affected if the MoPSC does not allowed in rates byallow full or timely recovery of decommissioning costs associated with the MoPSC.retirement of an energy center. Aging transmission and distribution facilities are more prone to failure than new facilities, which results in higher maintenance expense and the need to replace these facilities with new infrastructure. Even if the system is properly maintained, its reliability may ultimately deteriorate and negatively affect our ability to serve our customers, which could result in additional oversight by our regulators.increased costs associated with regulatory oversight. The frequency and duration of customer outages are among the IEIMA performance standards. Any failure to achieve these standards will result in a reduction in Ameren Illinois’ allowed return on equity on electric distribution assets. The higher maintenance costs associated with aging infrastructure and capital expenditures for new or replacement infrastructure could cause additional rate volatility for our customers, resistance by our regulators to allow customer rate increases, and/or regulatory lag in some of our jurisdictions, any of which could adversely affect our results of operations, financial position, and liquidity.

Energy conservation, energy efficiency, distributed generation, energy storage, and other factors that reduce energy demand could adversely affect ourAmeren and Ameren Missouri’s results of operations, financial position, and liquidity.
Requirements and incentives to reduce energy consumption have been proposed by regulatory agencies and introduced by
legislatures. Conservation and energy efficiency programs are designed to reduce energy demand. Unless there isWithout a regulatory mechanism ensuringto ensure recovery, a declinedeclines in energy usage will result in an under-recovery of fixed costs at our rate-regulated businesses.Ameren Missouri’s revenue requirement. Such declines could occur due to a number of factors:
Conservation and energy-efficiency programs. Missouri allows for conservation and energy-efficiency programs that are designed to reduce energy demand.
Distributed generation and other energy-efficiency efforts. Ameren Missouri even with the implementation of customer energy efficiency programs under the MEEIA, is exposed to declining usage losses from energy efficiencyenergy-efficiency efforts not related to its specificenergy-efficiency programs, as well as from distributed generation sources, such as solar panels. Additionally, macroeconomic factors resulting in low economic growth or contraction within our service territories could reduce energy demand.
Technological advances could reduce customer electricity consumption.panels and other technologies. Ameren Missouri generates power at utility-scale energy centers to achieve economies of scale and to produce power at a competitive cost. Some distributed generation technologies have recently become more cost-competitive. It is possible that advancescost-competitive, with decreasing costs expected in technology and legislative or regulatory actions will continue to reduce the future. The costs of these alternative methods of producing powerdistributed generation technologies may decline over time to a level that is competitive with that of Ameren Missouri'sMissouri’s energy centers. Additionally, technological advances in energy storage may be coupled with distributed generation to reduce the demand for our electric utility services. Increased adoption of these technologies by customers could decrease our revenues asif customers might notcease to use our generation, transmission, and distribution services at current levels. Ameren Missouri and Ameren Illinois might incur stranded costs, which ultimately might not be recovered through rates.
Failure
Macroeconomic factors. Macroeconomic factors resulting in low economic growth or contraction within Ameren Missouri’s service territories could reduce energy demand.
We are subject to retain and attract key officers and other skilled professional and technical employeesemployee work force factors that could adversely affect our operations.
Our businesses depend upon our ability to employ and retain key officers and other skilled professional and technical employees. A significant portion of our work force is nearing retirement, including many employees with specialized skills, such as maintaining and servicing our electric and natural gas infrastructure and operating our energy centers. We are also party to collective bargaining agreements that collectively represent about 52% of Ameren’s total employees. Any work stoppage experienced in connection with negotiations of collective bargaining agreements could adversely affect our operations.
Our operations are subject to acts of sabotage, war, terrorism, cyber attacks, and other intentionally disruptive acts.
Like other electric and natural gas utilities, our energy centers, fuel storage facilities, transmission and distribution facilities, and information systems may be targets ofaffected by terrorist activities and other intentionally disruptive acts, including cyber attacks, which could disrupt our ability to produce or distribute some portion of our energy products. Within our industry, there have been attacks on energy infrastructure, such as substations and related assets, in the past, and there may be more attacks in the future. Any such incident could limit our ability to generate, purchase, or transmit power or natural gas and could have significant regional economic consequences. Any such disruption could result in a significant decrease in revenues, ora significant additionalincrease in costs including those for repair, or adversely impact economic activity in our service territory which, in turn, could adversely affect our results of operations, financial position, and liquidity.
Our industryThere has begun to seebeen an increase in volumethe number and sophistication of cybersecurity incidents from international activist organizations, countries, and individuals.cyber attacks across all industries worldwide. A security breach ofat our physical assets or in our information systems could affect the reliability of the transmission and distribution system, disrupt electric generation, including nuclear generation, and/or subject us to financial harm associated withresulting from theft or the inappropriate release of certain types of information, including sensitive customer, employee, financial, and operating system information. Many of our suppliers, vendors, contractors, and information technology providers have access to systems that support our operations and maintain customer and employee data. A breach of these third-party systems could adversely affect our business as if it was a breach of our own system. If a significant breach occurred, our reputation could be adversely affected,


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customer confidence could be diminished, and/or we could be subject to increased costs associated with regulatory oversight, fines or legal claims, any of which could result in a significant decrease in revenues or significant additional costs for remedying the impacts of such a breach. Our generation, transmission, and distribution systems are part of an interconnected system. Therefore, a disruption caused by a cybersecuritycyber incident at another utility, electric generator, RTO, or commodity supplier could also adversely affect our businesses. We maintain insurance against some, butInsurance might not all, ofbe adequate to cover losses that arise in connection with these risks and losses.events. In addition, new regulations could require changes in our security measures and result in increased costs. The occurrence of any of these events could adversely affect our results of operations, financial position, and liquidity.
Ameren Missouri may ultimately not collect its receivable from an insurance company that provided liability coverage at the time of the breach of the upper reservoir of its Taum Sauk pumped-storage hydroelectric energy center, which could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial condition, and liquidity.
In December 2005, there was a breach of the upper reservoir at Ameren Missouri’s Taum Sauk pumped-storage hydroelectric energy center. This breach resulted in significant flooding in the local area, which damaged a state park. Ameren Missouri had liability insurance coverage for the Taum Sauk incident, subject to certain limits and deductibles. Ameren’s and Ameren Missouri’s results of operations, financial position, and liquidity could be adversely affected if Ameren Missouri’s remaining liability insurance claim of $41 million as of December 31, 2014, is not paid. The insurance claim is currently subject to litigation.
FINANCIAL, ECONOMIC, AND MARKET RISKS
Our businesses are dependent on our ability to access the capital markets successfully. We maymight not have access to sufficient capital in the amounts and at the times needed.
We rely on short-term and long-term debt as significant sources of liquidity and funding for capital requirements not satisfied by our operating cash flow, as well as to refinance long-term debt. By the end of 2019, $951 million and $457 million of senior secured notes are scheduled to mature at Ameren Missouri and Ameren Illinois, respectively. Ameren Missouri and Ameren Illinois expect to refinance these

senior secured notes. In addition, the Ameren Companies may refinance a portion of their short-term debt with long-term debt in 2018 and 2019. The inability to raise debt or equity capital onat reasonable terms, or at all, could negatively affect our ability to maintain and to expand our businesses. Events beyond our control, such as a recession or extreme volatility in the debt, equity, or credit markets, maymight create uncertainty that could increase our cost of capital or impair or eliminate our ability to access the debt, equity, or credit markets, including our ability to draw on bank credit facilities. Any adverse change in our credit ratings could reduce access to capital and trigger additional collateral postings and prepayments. Such changes could also increase the cost of borrowing and the costs of fuel, power, and natural gas supply, among other things, which could have a material adverse effect onadversely affect our results of operations, financial position, and liquidity. Certain Ameren subsidiaries, such as ATXI, rely on Ameren for access to capital. Circumstances that limit Ameren’s access to capital could impair its ability to provide those subsidiaries with needed capital.
Ameren’s holding company structure could limit its ability to pay common stock dividends and to service its debt obligations.
Ameren is a holding company; therefore, its primary assets are its investments in the common stock of its subsidiaries, including Ameren Missouri, Ameren Illinois, and Ameren Illinois.ATXI. As a result, Ameren’s ability to pay dividends on its common stock depends on the earnings of its subsidiaries and the ability of its subsidiaries to pay dividends or otherwise transfer funds to Ameren. Similarly, Ameren’s ability to service its debt obligations is dependent upon the earnings of its operating subsidiaries and the distribution of those earnings and other payments, including payments of principal and interest under intercompanyaffiliate indebtedness. The payment of dividends to Ameren by its subsidiaries in turn depends on their results of operations, and available cash and other items affecting retained earnings.earnings, and available cash. Ameren’s subsidiaries are separate and distinct legal entities and have no obligation, contingent or otherwise, to pay any dividends or make any other distributions (except for payments required pursuant to the terms of intercompanyaffiliate borrowing arrangements and cash payments under the tax allocation agreement) to Ameren. Certain financing agreements, corporate organizational documents, and certain statutory and regulatory requirements may impose restrictions on the ability of Ameren Missouri, and Ameren Illinois, and ATXI to transfer funds to Ameren in the form of cash dividends, loans, or advances.
Dynegy’s or its subsidiaries' failure to satisfy certain of their indemnity and other obligations to Ameren in connection with the divestiture of New AER to IPH could have a material adverse effect on Ameren’s results of operations, financial position, and liquidity.
In December 2013, Ameren completed the divestiture of New AER to IPH. The transaction agreement between Ameren and IPH requires Ameren, until December 2, 2015, to maintain its financial obligations in existence as of December 2, 2013, under all credit support arrangements or obligations that pertain to New AER and its subsidiaries. Ameren must also provide any additional credit support that may be contractually required pursuant to any of the contracts of New AER, and its subsidiaries as of December 2, 2013. IPH, New AER and its subsidiaries, and Dynegy have agreed to indemnify Ameren for certain losses relating to this credit support. IPH’s indemnification obligations are secured by certain AERG and Genco assets. However, these indemnification obligations and security interests might not cover all losses that could be incurred by Ameren in connection with providing this credit support. As of December 31, 2014, the balance of the Marketing Company note to Ameren was $12 million. Additionally, as of December 31, 2014, Ameren provided $114 million in guarantees and $9 million in letters of credit relating to its credit support of New AER. Dynegy emerged from its Chapter 11 bankruptcy case in 2012. As of December 31, 2014, Dynegy’s credit ratings were sub-investment-grade. IPH, New AER and its subsidiaries also do not have investment-grade credit ratings. Dynegy, IPH, New AER, or their subsidiaries might not be able to satisfy their indemnity and other obligations under the transaction agreement, Marketing Company’s note to


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Ameren, or Dynegy’s limited guarantee to Ameren, which could have a material adverse impact on Ameren’s results of operations, financial position, and liquidity.
Increasing costs associated with our defined benefit retirement and postretirement plans, health care plans, and other employee benefits could adversely affect our financial position and liquidity.
We offerAmeren offers defined benefit retirementpension and postretirement benefit plans that covercovering substantially all of ourits union employees. Ameren offers defined benefit pension plans covering substantially all of its non-union employees and postretirement benefit plans covering non-union employees hired before October 2015. Assumptions related to future costs, returns on investments, interest rates, timing of employee retirements, and mortality, as well as other actuarial matters, have a significant impact on our customers'customers’ rates and our plan funding requirements. Ameren'sAmeren’s total unfunded obligation under its pension and postretirement benefit plans was $710$551 million as of December 31, 2014.2017. Ameren expects to fund its pension plans at a level equal to the greater of the pension expensecost or the legally required minimum contribution. ConsideringBased on Ameren’s assumptions at December 31, 2014,2017, its investment performance in 2014,2017, and its pension funding policy, Ameren expects to make annual contributions of $25less than $1 million to $115$60 million in each of the next five years, with aggregate estimated contributions of $290 million.$120 million. We expect Ameren Missouri’s and Ameren Illinois’ portionportions of the future funding requirements to be 41%35% and 40%55%, respectively. These amounts are estimates. They may change with actual investment performance, changes in interest rates, changes in our assumptions, changes in government regulations, and any voluntary contributions.
In addition to the costs of our retirement plans, the costs of providing health care benefits to our employees and retirees have increased in recent years. We believe that our employee benefit costs, including costs of health care plans for our employees and former employees, will continue to rise. Future legislative changes related to health care could also significantly change our benefit programs and costs. The increasing costs and funding requirements associated with our defined benefit retirement plans, health care plans, and other employee benefits could increase our financing needs and otherwise materially adversely affect our financial position and liquidity.
ITEM 1B.UNRESOLVED STAFF COMMENTS
None.



24


ITEM 2.PROPERTIES
ITEM 2.PROPERTIES
For information on our principal properties, see the energy center table below. See also Liquidity and Capital Resources and Regulatory Matters in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, of this report for a discussion of planned additions, replacements or transfers. See also Note 5 – Long-term Debt and Equity Financings and Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report.
The following table shows the anticipated capability of Ameren Missouri'sMissouri’s energy centers at the time of Ameren Missouri'sMissouri’s expected 20152018 peak summer electrical demand:
Primary Fuel SourceEnergy CenterLocation
Net Kilowatt Capability(a)
CoalLabadieFranklin County, Missouri2,372,000
 Rush IslandJefferson County, Missouri1,180,0001,178,000
 SiouxSt. Charles County, Missouri970,000972,000
 
Meramec(b)
St. Louis County, Missouri831,000591,000
Total coal  5,353,0005,113,000
NuclearCallawayCallaway County, Missouri1,193,0001,194,000
HydroelectricOsageLakeside, Missouri240,000
 KeokukKeokuk, Iowa140,000144,000
Total hydroelectric  380,000384,000
Pumped-storageTaum SaukReynolds County, Missouri440,000
Oil (CTs)FairgroundsJefferson City, Missouri55,000
MeramecSt. Louis County, Missouri54,000
FairgroundsJefferson City, Missouri54,00055,000
 MexicoMexico, Missouri53,00054,000
 MoberlyMoberly, Missouri53,00054,000
 MoreauJefferson City, Missouri53,00054,000
Total oil  267,000272,000
Natural gas (CTs)
Audrain(b)(c)
Audrain County, Missouri600,000608,000
 
Venice(c)(d)
Venice, Illinois487,000491,000
 Goose CreekPiatt County, Illinois432,000438,000
 PinckneyvillePinckneyville, Illinois316,000
 Raccoon CreekClay County, Illinois300,000304,000
Meramec(b)(d)(e)
St. Louis County, Missouri281,000
 
Kinmundy(c)(d)
Kinmundy, Illinois206,000208,000
 
Peno Creek(b)(c)(d)
Bowling Green, Missouri188,000
Meramec(c)
St. Louis County, Missouri44,000
KirksvilleKirksville, Missouri13,000192,000
Total natural gas  2,586,0002,838,000
Methane gas (CT)Maryland HeightsMaryland Heights, Missouri8,000
SolarO'FallonO’FallonO'Fallon,O’Fallon, Missouri3,000
Total Ameren and Ameren Missouri  10,230,00010,252,000
(a)Net kilowatt capability is the generating capacity available for dispatch from the energy center into the electric transmission grid.
(b)All coal-fueled kilowatts and 236,000 natural-gas-fueled kilowatts at the Meramec energy center are scheduled for retirement in 2022.
(c)There are economic development lease arrangements applicable to these CTs.
(c)(d)These CTs have the capability to operate on either oil or natural gas (dual fuel).
(e)Two of its three units are steam-powered.
The following table presents in-service electric and natural gas utility-related properties for Ameren Missouri and Ameren Illinois as of December 31, 2014:2017:
Ameren
Missouri
 
Ameren
Illinois
Ameren
Missouri
 
Ameren
Illinois
Circuit miles of electric transmission lines(a)
2,956
 4,558
2,970
 4,638
Circuit miles of electric distribution lines33,144
 46,071
33,414
 45,899
Circuit miles of electric distribution lines underground23% 15%
Percentage of circuit miles of electric distribution lines underground23% 15%
Miles of natural gas transmission and distribution mains3,334
 18,246
3,379
 18,393
Underground gas storage fields
 12
Total working capacity of underground gas storage fields in billion cubic feet
 24
Underground natural gas storage fields
 12
Total working capacity of underground natural gas storage fields in billion cubic feet
 24
(a)ATXI owns 29303 miles of transmission lines not reflected in this table.
Our other properties include office buildings, warehouses, garages, and repair shops.
With only a few exceptions, we have fee title to all principal
energy centers and other units of property material to the operation of our businesses, and to the real property on which such facilities are located (subject to mortgage liens securing our outstanding first mortgage bonds and to certain permitted liens and judgment liens). The exceptions are as follows:

A portion of Ameren Missouri’s Osage energy center reservoir, certain facilities at Ameren Missouri’s Sioux energy center, most of Ameren Missouri’s Peno Creek and Audrain CT energy centers, Ameren Missouri’s Maryland Heights energy center, certain substations, and most transmission and distribution lines and natural gas mains are situated on lands occupied under leases, easements, franchises, licenses, or permits. The United States or the state of Missouri may own or may have paramount rights with respect to certain lands lying in the bed of the Osage River or located between the inner and outer harbor lines of the Mississippi River on which certain of Ameren Missouri’s energy centers and other properties are located.
The United States, the state of Illinois, the state of Iowa, or the city of Keokuk, Iowa, may own or may have paramount


25


rights with respect to certain lands lying in the bed of the Mississippi River on which a portion of Ameren Missouri’s Keokuk energy center is located.
Substantially all of the properties and plant of Ameren Missouri and Ameren Illinois are subject to the first liens of the indentures securing their mortgage bonds.
Ameren Missouri has conveyed most of its Peno Creek CT energy center to the city of Bowling Green, Missouri, and leased the energy center back from the city through 2022. Under the terms of this capital lease, Ameren Missouri is responsible for all operation and maintenance for the energy center. Ownership of the energy center will transfer to Ameren Missouri at the expiration of the lease, at which time the property, plant, and plantequipment will become subject to the lien of any Ameren Missouri first mortgage bond indenture then in effect at such time.effect.
Ameren Missouri operates a CT energy center located in Audrain County, Missouri. Ameren Missouri has rights and obligations as lessee of the CT energy center under a long-term lease with Audrain County. The lease will expire onin December 1, 2023. Under the terms of this capital lease, Ameren Missouri is responsible for all operation and maintenance for the energy center. Ownership of the energy center will transfer to Ameren Missouri at the expiration of the lease, at which time the property, plant, and plantequipment will become subject to the lien of any Ameren Missouri first mortgage bond indenture then in effect.
ITEM 3.LEGAL PROCEEDINGS
We are involved in legal and administrative proceedings before various courts and agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in this report, will not have a material adverse effect on our results of operations, financial position, or liquidity. Risk of loss is mitigated, in some cases, by insurance or contractual or statutory indemnification. We believe that we have established appropriate reserves for potential losses. Material legal and administrative proceedings, which are discussed in Note 2 – Rate and Regulatory Matters, Note 9 – Callaway Energy Center, and Note 1514 – CommitmentCommitments and
Contingencies under Part II, Item 8, of this report and are incorporated herein by reference, include the following:
Ameren Missouri’s electric rate case filedproceeding with the MoPSC to investigate how the effect of the reduction in July 2014, including the federal statutory corporate income tax rate shift request filedenacted under TCJA should be reflected in rates paid by the MoOPC, the MIECelectric and other parties;natural gas customers;
Ameren Missouri's MEEIA filingIllinois’ proceeding with the MoPSCICC to pass through to its natural gas customers the effect of the reduction in December 2014;the federal statutory corporate income tax rate enacted under the TCJA;
Ameren Illinois' appeal of the ICC's December 2013Illinois’ natural gas regulatory rate order;
Ameren Illinois' natural gas rate casereview filed with the ICC in January 2015;2018;
the request filed by MISO participants, including Ameren Illinois’ request for rehearing of a September 2014Illinois and ATXI, with the FERC order requiring refunds to wholesale customers;
ATXI’s request for a certificate of public convenience and necessity and project approval fromallow revisions to 2018 electric transmission rates to reflect the ICC for the Spoon River project;
Entergy's appeal of a May 2012 FERC order requiring Entergy to refund to Ameren Missouri additional charges paid under an expired power purchase agreement;
Ameren Illinois' request for rehearingimpacts of the FERC's June 2014 orders,reduction in the appeal filed withfederal statutory corporate income tax rate enacted under the United States Court of Appeals for the District of Columbia Circuit, and settlement procedures regarding a potential electric transmission rate refund;TCJA;
the February 2015 complaint casescase filed with the FERC seeking a reduction in the allowed base return on common equity under the MISO tariff;
the EPA's Clean Air Act-related litigation against Ameren Missouri;Missouri with respect to the EPA Clean Air Act; and
remediation matters associated with former MGP and waste disposal sites of the Ameren Companies;Companies.
litigation associated with Ameren Missouri's liability insurance claim for the breach of the upper reservoir of its Taum Sauk pumped-storage hydroelectric energy center in December 2005; and
asbestos-related litigation associated with the Ameren Companies.
ITEM 4.MINE SAFETY DISCLOSURES
Not applicable.


EXECUTIVE OFFICERS OF THE REGISTRANTS (ITEM 401(b) OF REGULATION S-K):
The executive officers of the Ameren Companies, including major subsidiaries, are listed below, along with their ages as of December 31, 20142017, all their positions and offices held with the Ameren Companies as of February 23, 2015, tenure15, 2018, their tenures as officer,officers, and their business backgroundbackgrounds for at least the last five years. Some executive officers hold multiple positions within the Ameren Companies; their titles are given in the description of their business experience. References to “Ameren Illinois companies” below refers to CIPS, CILCO, and IP collectively prior to the Ameren Illinois Merger and to Ameren Illinois following the Ameren Illinois Merger.

26


AMEREN CORPORATION:
NameAge Positions and Offices Held
    
Warner L. Baxter5356
 Chairman, President and Chief Executive Officer, and Director
Baxter joined Ameren Missouri in 1995. BaxterHe was elected to the positions of executive vice president and chief financial officer of Ameren, Ameren Missouri, CIPS, CILCO,Ameren Illinois, and Ameren Services in 2003 and of IP in 2004.2003. He was elected chairman, president, chief executive officer, and chief financial officer of Ameren Services in 2007. In 2009, Baxterhe was elected chairman, president and chief executive officer of Ameren Missouri. In February 2014, Baxterhe was elected chairman, president, and chief executive officer of Ameren, and was appointed to the Ameren board. In April 2014, he relinquished his positions at Ameren Missouri and was elected chief executive officer of Ameren. In July 2014, Baxter was elected chairman of the Ameren board.Missouri.
    
Martin J. Lyons, Jr.4851
 Executive Vice President and Chief Financial Officer
Lyons joined Ameren Services in 2001. In 2008, Lyonshe was elected senior vice president and principalchief accounting officer of the Ameren Companies. In 2009, Lyonshe was also elected chief financial officer of the Ameren Companies. In 2013, Lyonshe was elected executive vice president and chief financial officer of the Ameren Companies, and relinquished his duties as principalchief accounting officer. In 2016, he was elected chairman and president of Ameren Services.
    
Gregory L. Nelson5760
 Senior Vice President, General Counsel, and Secretary
Nelson joined Ameren Missouri in 1995. NelsonHe was elected vice president and tax counsel of Ameren Services in 1999 and vice president of Ameren Missouri CIPS, and CILCOAmeren Illinois in 2003 and of IP in 2004.2003. In 2010, Nelsonhe was elected vice president, tax and deputy general counsel of Ameren Services. He remained vice president of Ameren Missouri and the Ameren Illinois companies.Illinois. In 2011, Nelsonhe was elected senior vice president, general counsel and secretary of the Ameren Companies.
    
Bruce A. Steinke5356
 Senior Vice President, Finance, and Chief Accounting Officer
Steinke joined Ameren Services in 2002. In 2008, he was elected vice president and controller of Ameren, the Ameren Illinois, companies, and Ameren Services. In 2009, Steinkehe relinquished his positions at the Ameren Illinois companies.Illinois. In 2013, Steinkehe was elected senior vice president, finance, and chief accounting officer of the Ameren Companies.

27


SUBSIDIARIES:
NameAge Positions and Offices Held
Mark C. Birk5053
 Senior Vice President, Corporate PlanningCustomer and OversightPower Operations (Ameren Services)Missouri)
Birk joined Ameren Missouri in 1986. In 2005, Birkhe was elected vice president, power operations, of Ameren Missouri. In 2012, Birkhe was elected senior vice president, corporate planning, of Ameren Services. In November 2014, he was also elected senior vice president, oversight, of Ameren Services.
Maureen A. Borkowski57
ChairmanServices, and President (ATXI)
Borkowski joined Ameren Missouri in 1981. She left the company in 2000 and rejoined Ameren in 2005 as vice president, transmission, of Ameren Services. In 2011, Borkowski was elected chairman and president of ATXI. In 2011, she was also elected senior vice president, transmission, of Ameren Services.
Daniel F. Cole61
Chairman and President (Ameren Services)
Cole joined Ameren Missouri in 1976. He2015, he was elected senior vice president, of Ameren Missouricorporate safety, planning and Ameren Services in 1999 and of CIPS in 2001. Heoperations oversight. In January 2017, he was elected senior vice president, of CILCO in 2003customer operations, at Ameren Missouri and of IP in 2004.relinquished his positions at Ameren Services. In 2009, ColeOctober 2017, he was elected chairman and president of Ameren Services; he remained senior vice president, ofcustomer and power operations, at Ameren Missouri and the Ameren Illinois companies.Missouri.
    
Fadi M. Diya5255
 Senior Vice President and Chief Nuclear Officer (Ameren Missouri)
Diya joined Ameren Missouri in 2005. In 2008, Diyahe was elected vice president, of nuclear operations, atof Ameren Missouri. In January 2014, Diyahe was elected senior vice president and chief nuclear officer of Ameren Missouri.
    
Mary P. Heger61
Senior Vice President and Chief Information Officer (Ameren Services)
Heger joined Ameren Missouri in 1976. In 2009, she was elected vice president, information technology, of Ameren Services, and in 2012, she was also elected chief information officer of Ameren Services. In 2015, she was elected senior vice president and chief information officer of Ameren Services.
Mark C. Lindgren50
Senior Vice President, Corporate Communications and Chief Human Resources Officer (Ameren Services)
Lindgren joined Ameren Services in 1998. In 2009, he was elected vice president, human resources, of Ameren Services, and in 2012, he was also elected chief human resources officer of Ameren Services. In 2015, he was elected senior vice president, corporate communications, and chief human resources officer of Ameren Services.
Richard J. Mark5962
 Chairman and President (Ameren Illinois)
Mark joined Ameren Services in 2002. He2002 as vice president, customer service. In 2003, he was elected vice president, governmental policy and consumer affairs, of Ameren Services. In 2005, he was elected senior vice president, customer operations, of Ameren Missouri in 2005.Missouri. In 2007, he relinquished his position at Ameren Services. In 2012, Markhe relinquished his position at Ameren Missouri and was elected chairman and president of Ameren Illinois.
    
Michael L. Moehn4548
 Chairman and President (Ameren Missouri)
Moehn joined Ameren Services in 2000. In 2004, he was elected vice president, corporate planning, of Ameren Services. In 2008, he was elected senior vice president, corporate planning and business risk management, of Ameren Services. In 2012, Moehn relinquished his position at Ameren Services and was elected senior vice president of customer operations of Ameren Illinois. Subsequently in 2012, Moehn relinquished his position at Ameren Illinois andhe was elected senior vice president, customer operations, of Ameren Missouri.Missouri, and relinquished his position at Ameren Services. In April 2014, Moehnhe was elected chairman and president of Ameren Missouri.
    
Charles D. NaslundShawn E. Schukar6256
 Executive ViceChairman and President (Ameren Missouri)(ATXI)
NaslundSchukar joined a predecessor company of Ameren MissouriIllinois in 1974.1984. In 2008,2005, he was elected vice president, commercial RTO operations, of Ameren Services. In 2013, he was elected senior vice president, transmission operations, construction and project management, of ATXI. In May 2017, he was elected chairman president and chief executive officer of AER. In 2011, Naslund assumed the position of senior vice president, generation and environmental projects, of Ameren Missouri and relinquished his positions of chairman, president, and chief executive officer of AER. In 2013, Naslund relinquished his position at Ameren Missouri and was elected executive vice president of Ameren Services. Subsequently in 2013, Naslund was elected executive vice president of Ameren Missouri. Naslund retired from each of his positions with Ameren effective March 1, 2015.ATXI.
Officers are generally elected or appointed annually by the respective board of directors of each company, following the election of board members at the annual meetings of shareholders. No special arrangement or understanding exists between any of the above-named executive officers and the Ameren Companies nor, to our knowledge, with any other person or persons pursuant to which any executive officer was selected as an officer. There are no family relationships among the executive officers or between theany executive officers and any directors of the Ameren Companies. All of the above-named executive officers have been employed by an Ameren company for more than five years in executive or management positions.

28


PART II
ITEM 5.MARKET FOR REGISTRANTS'REGISTRANTS’ COMMON EQUITY, RELATED STOCKHOLDER MATTERS, AND ISSUER PURCHASE OF EQUITY SECURITIES
Ameren’s common stock is listed on the NYSE (ticker symbol: AEE). Ameren common shareholders of record totaled 54,75547,748 on January 31, 20152018. The following table presents the price ranges, closing prices, and dividends declared per Ameren common share for each quarter during 20142017 and 20132016.:
High Low Close Dividends DeclaredHigh Low Close Dividends Declared
2014 Quarter Ended:       
2017 Quarter Ended:       
March 31$42.24
 $35.22
 $41.20
 $0.40
$56.57
 $51.35
 $54.59
 $0.44
June 3041.92
 37.67
 40.88
 0.40
57.21
 53.72
 54.67
 0.44
September 3040.96
 36.65
 38.33
 0.40
60.91
 53.54
 57.84
 0.44
December 3148.14
 38.25
 46.13
 0.41
64.89
 57.67
 58.99
 0.4575
2013 Quarter Ended:       
2016 Quarter Ended:       
March 31$35.12
 $30.64
 $35.02
 $0.40
$50.16
 $41.50
 $50.10
 $0.425
June 3036.74
 32.34
 34.44
 0.40
53.59
 46.29
 53.58
 0.425
September 3036.70
 32.61
 34.84
 0.40
54.08
 47.79
 49.18
 0.425
December 3137.31
 34.18
 36.16
 0.40
52.88
 46.84
 52.46
 0.44
There is no trading market for the common stock of Ameren Missouri and Ameren Illinois. Ameren holds all outstanding common stock of Ameren Missouri and Ameren Illinois.
The following table sets forth the quarterly common stock dividend payments made by Ameren and its registrant subsidiaries during 20142017 and 20132016:
2014 20132017 2016
(In millions)Quarter Ended Quarter EndedQuarter Ended Quarter Ended
RegistrantDecember 31 September 30 June 30 March 31 December 31 September 30 June 30 March 31December 31 September 30 June 30 March 31  December 31 September 30 June 30 March 31
Ameren Missouri$72
(a) 
$113
 $78
 $77
 $140
 $140
 $90
 $90
$30
 $160
 $112
 $60
  $70
 $75
 $70
 $140
Ameren Illinois
 
 
 
 65
 15
 15
 15

 
 
 
  15
 35
 30
 30
Ameren99
 97
 97
 97
 97
 97
 97
 97
111
 106
 107
 107
  107
 103
 103
 103
(a)Additionally, during the fourth quarter of 2014, Ameren Missouri returned capital of $215 million to Ameren (parent).
On February 13, 2015,9, 2018, the board of directors of Ameren declared a quarterly dividend on Ameren’s common stock of 4145.75 cents per share. The common share dividend is payable March 31, 2015,29, 2018, to shareholders of record on March 11, 2015.14, 2018.
For a discussion of restrictions on the Ameren Companies’ payment of dividends, see Liquidity and Capital Resources in Management’s Discussion and Analysis of Financial Condition and Results of Operations under Part II, Item 7, of this report.
Purchases of Equity Securities
The following table presents Ameren Corporation’s purchases of equity securities reportable under Item 703 of Regulation S-K:
Period
(a) Total Number
of Shares
(or Units)
Purchased
 
(b) Average Price
Paid per Share
(or Unit)
 
(c) Total Number of Shares
(or Units) Purchased as Part
of Publicly Announced Plans
or Programs
 
(d) Maximum Number
(or Approximate Dollar Value) of
Shares (or Units) that May Yet
Be Purchased Under the Plans or
Programs
October 1  October 31, 2017

 $
 
 
November 1  November 30, 2017(a)
5,232
 62.35
 
 
December 1  December 31, 2017

 
 
 
Total5,232
 $62.35
 
 
(a)The shares of Ameren common stock were purchased in open-market transactions in satisfaction of Ameren’s obligations for Ameren board of directors’ compensation awards issued under its stock-based compensation plans. Ameren does not have any publicly announced equity securities repurchase plans or programs.
Ameren Missouri and Ameren Illinois did not purchase any equity securities reportable under Item 703 of Regulation S-K during the period from October 1, 20142017, to December 31, 20142017.

Performance Graph
The following graph shows Ameren’s cumulative total shareholder return during the five years ended December 31, 20142017. The graph also shows the cumulative total returns of the S&P 500 Index and the Edison Electric Institute Index (EEI Index), which comprises most investor-owned electric utilities in the United States. The comparison assumes that $100 was invested on December 31, 20092012, in Ameren common stock and in each of the indices shown, and it assumes that all of the dividends were reinvested.




29



December 31,2009 2010 2011 2012 2013 20142012 2013 2014 2015 2016 2017
Ameren (AEE)$100.00
 $106.85
 $132.24
 $128.89
 $158.94
 $210.96
$100.00
 $123.31
 $163.67
 $159.79
 $200.79
 $232.84
S&P 500 Index100.00
 115.06
 117.49
 136.29
 180.43
 205.13
100.00
 132.39
 150.51
 152.59
 170.84
 208.14
EEI Index100.00
 107.04
 128.44
 131.12
 148.18
 191.02
100.00
 113.01
 145.68
 140.00
 164.42
 183.69
Ameren management cautions that the stock price performance shown in the graph above should not be considered indicative of potential future stock price performance.

30


ITEM 6.SELECTED FINANCIAL DATA
For the years ended December 31,
(In millions, except per share amounts)
2014 2013 2012 2011 2010
2017 2016 2015 2014 2013
Ameren(a):
                  
Operating revenues$6,053
 $5,838
 $5,781
 $6,148
 $6,188
$6,177
 $6,076
 $6,098
 $6,053
 $5,838
Operating income(b)
1,254
 1,184
 1,188
 1,033
 1,175
1,458
 1,381
 1,259
 1,254
 1,184
Income from continuing operations(c)593
 518
 522
 437
 523
529
 659
 585
 593
 518
Income (loss) from discontinued operations, net of taxes(c)(d)
(1) (223) (1,496) 89
 (372)
 
 51
 (1) (223)
Net income (loss) attributable to Ameren Corporation586
 289
 (974) 519
 139
Net income attributable to Ameren common shareholders523
 653
 630
 586
 289
Common stock dividends390
 388
 382
 375
 368
431
 416
 402
 390
 388
Continuing operations earnings per share – basic2.42
 2.11
 2.13
 1.79
 2.15
2.16
 2.69
 2.39
 2.42
 2.11
Continuing operations earnings per share – diluted2.40
 2.10
 2.13
 1.79
 2.15
2.14
 2.68
 2.38
 2.40
 2.10
Common stock dividends per share1.61
 1.60
 1.60
 1.555
 1.54
1.778
 1.715
 1.655
 1.61
 1.60
As of December 31:                  
Total assets(d)(e)
$22,676
 $21,042
 $22,230
 $23,723
 $23,511
$25,945
 $24,699
 $23,640
 $22,289
 $20,907
Long-term debt, excluding current maturities6,120
 5,504
 5,802
 5,853
 6,029
7,094
 6,595
 6,880
 6,085
 5,475
Total Ameren Corporation stockholders’ equity6,713
 6,544
 6,616
 7,919
 7,730
Total Ameren Corporation shareholders’ equity7,184
 7,103
 6,946
 6,713
 6,544
Ameren Missouri:                  
Operating revenues$3,553
 $3,541
 $3,272
 $3,383
 $3,197
$3,539
 $3,523
 $3,609
 $3,553
 $3,541
Operating income(b)
785
 803
 845
 609
 711
747
 745
 742
 785
 803
Net income available to common stockholder390
 395
 416
 287
 364
Net income available to common shareholder(c)
323
 357
 352
 390
 395
Dividends to parent340
 460
 400
 403
 235
362
 355
 575
 340
 460
As of December 31:                  
Total assets$13,541
 $12,904
 $13,043
 $12,757
 $12,504
$14,043
 $14,035
 $13,851
 $13,474
 $12,867
Long-term debt, excluding current maturities3,879
 3,648
 3,801
 3,772
 3,949
3,577
 3,563
 3,844
 3,861
 3,631
Total stockholders’ equity4,052
 3,993
 4,054
 4,037
 4,153
Total shareholders’ equity4,081
 4,090
 4,082
 4,052
 3,993
Ameren Illinois:                  
Operating revenues$2,498
 $2,311
 $2,525
 $2,787
 $3,014
$2,528
 $2,490
 $2,466
 $2,498
 $2,311
Operating income450
 415
 377
 458
 498
580
 544
 466
 450
 415
Net income available to common stockholder201
 160
 141
 193
 248
Net income available to common shareholder268
 252
 214
 201
 160
Dividends to parent
 110
 189
 327
 133

 110
 
 
 110
As of December 31:                  
Total assets$8,381
 $7,454
 $7,282
 $7,213
 $7,406
$10,345
 $9,474
 $8,903
 $8,204
 $7,397
Long-term debt, excluding current maturities2,241
 1,856
 1,577
 1,657
 1,657
2,373
 2,338
 2,342
 2,224
 1,844
Total stockholders’ equity2,661
 2,448
 2,401
 2,452
 2,576
Total shareholders’ equity3,310
 3,034
 2,897
 2,661
 2,448
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)
Includes regulatory disallowance associated witha $69 million provision recorded in 2015 for all of the Taum Sauk incident of $89 million recordedpreviously capitalized COL costs relating to the cancelled second nuclear unit at Ameren and Ameren Missouri for the year ended December 31, 2011.its Callaway energy center.
(c)Includes an increase to income tax expense of $154 million and $32 million recorded in 2017 as a result of the TCJA at Ameren and Ameren Missouri, respectively. See Note 1612Divestiture Transactions and Discontinued OperationsIncome Taxes under Part II, Item 8, of this report for additional information.
(d)See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report for additional information.
(e)Includes total assets from discontinued operations of $15 million, $165 million, $1,611 million, $3,721 million, and $3,825 million at December 31, 2014, 2013, 2012, 2011, and 2010, respectively.immaterial balances at December 31, 2017, 2016, 2015, and 2014. Total assets from discontinued operations are included in “Other current assets” on Ameren’s balance sheet.


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ITEM 7.MANAGEMENT'SMANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005, administered by the FERC. Ameren’swhose primary assets are its equity interests in its subsidiaries, including Ameren Missouri and Ameren Illinois. subsidiaries.Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of other expenses by Ameren depend on distributions made to it by its subsidiaries.
Below is a summary description of Ameren’s principal subsidiaries, including Ameren Missouri, Ameren Illinois, and ATXI. Ameren Illinois.also has other subsidiaries that conduct other activities, such as the provision of shared services. Ameren evaluates competitive electric transmission investment opportunities as they arise. A more detailed description can be found in Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report.
Ameren Missouri operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas transmission and distribution business in Missouri.
Ameren Illinois operates rate-regulated electric transmission, electric distribution, and natural gas transmission and distribution businesses in Illinois.
Ameren has various other subsidiaries responsible for activities such as the provision of shared services. Ameren also has a subsidiary, ATXI that operates a FERC rate-regulated electric transmission business. ATXI is developing MISO-approved electric transmission projects, including the Illinois Rivers Spoon River, and Mark Twain projects. projects, and placed the Spoon River project in service in February 2018.
Ameren is also pursuing reliability projects withinhas four segments: Ameren Missouri'sMissouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois' service territories as well as competitiveTransmission. The Ameren Missouri segment includes all of the operations of Ameren Missouri. Ameren Illinois Electric Distribution consists of the electric distribution business of Ameren Illinois. Ameren Illinois Natural Gas consists of the natural gas business of Ameren Illinois. Ameren Transmission is primarily composed of the aggregated electric transmission investment opportunities outsidebusinesses of these territories, including investments outsideAmeren Illinois and ATXI. See Note 15 – Segment Information under Part II, Item 8, of MISO.this report for further discussion of Ameren’s, Ameren Missouri’s, and Ameren Illinois’ Segments.
Unless otherwise stated, the following sections of Management'sManagement’s Discussion and Analysis of Financial Condition and Results of Operations exclude discontinued operations for all periods presented. See Note 161 – Divestiture Transactions and Discontinued OperationsSummary of Significant Accounting Policies under Part II, Item 8, of this report for additional information regarding that presentation.
TheAmeren’s financial statements of Ameren are prepared on a consolidated basis and therefore include the accounts of its majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren Missouri and Ameren Illinois have no subsidiaries, and therefore their financial statements are not prepared on a consolidated basis. All intercompany transactions have been eliminated.subsidiaries. All tabular dollar amounts are in millions, unless otherwise indicated.
In addition to presenting results of operations and earnings amounts in total, we present certain information in cents per share. These amounts reflect factors that directly affect Ameren’s earnings. We believe that this per share information helps readers to understand the impact of these factors on Ameren’s earnings per share. All references in this report to earnings per share are based on average diluted common shares outstanding.
outstanding for the relevant period.
OVERVIEW
In 2014, Ameren successfully executed its strategy to investAmeren’s strategic plan includes investing in, and to grow its utilities through investment in rate-regulated infrastructure while remaining focused on operational improvement and disciplined cost management, leading to an improved earned return on equity. During 2014, Ameren continued to make progress on the three elements of its strategy: (1) to invest in and to operateoperating its utilities in, a manner consistent with existing regulatory frameworks; (2) to enhance regulatoryframeworks, enhancing those frameworks, and to advocateadvocating for responsible energy policies; and (3) to create and to capitalize on opportunities for investment for the benefit of its customers and shareholders. These results, along with confidence in Ameren’s long-term outlook, led the board of directors to increase Ameren's quarterly dividend rate in October 2014.
In 2014, Ameren Missouri completed several key infrastructure projects, including a nuclear reactor vessel head replacement project at the Callaway energy center, electrostatic precipitator upgrades at the coal-fired Labadie energy center, a new substation in St. Louis, and the O’Fallon energy center. In July 2014, Ameren Missouri filed a request with the MoPSC seeking approval to increase its annual revenues for electric service. The request,economic policies, as amended in February 2015, seeks an annual revenue increase of approximately $190 million. In February 2015, the MoPSC staff recommended an increase in annual revenues of $89 million in this proceeding. A decision by the MoPSC is expected by May 2015, with new rates effective by June 2015. Additionally, in December 2014, Ameren Missouri filed a new proposed energy efficiency plan with the MoPSC under the MEEIA for 2016 through 2018.
Ameren Missouri continues to seek a modernized regulatory framework that reduces regulatory lag and supports increased investment to upgrade aging electric infrastructure and to advocate for responsible energy policies, notably in the environmental arena. In October 2014, Ameren Missouri filed its integrated resource plan with the MoPSC which targets to achieve the CO2 emissions reductions proposed in the EPA’s Clean Power Plan by 2035, rather than the EPA’s final target date of 2030 or its interim target dates beginning in 2020. Ameren Missouri's plan outlined its ongoing transition to a more fuel-diverse generation portfolio over the next 20 years, which it believes maximizes the use of its current generation fleet for the benefit of its customers while leveraging energy efficiency, environmental controls, renewable energy resources, and lower cost generation to meet future needs.
Ameren Illinois continued to implement its electric and natural gas distribution system modernization action plan, including the installation of advanced electric and upgraded natural gas meters. In December 2014, the ICC authorized an electric delivery service rate increase that was within $1 million of Ameren Illinois' revised request, which demonstrated that the formula ratemaking framework is workingwell as intended. In January 2015, Ameren Illinois filed a request with the ICC seeking


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approval to increase its annual revenues for natural gas delivery service by $53 million. A decision by the ICC in this proceeding is required by December 2015, with new rates expected to be effective in January 2016. Also in January 2015, Ameren Illinois received approval for its QIP rider under the CSRA and subsequently began including qualified investments and recording revenue under this regulatory framework. Ameren Illinois will start recovering costs from these investments in March 2015.
Ameren Illinois continues to seek enhancements to its regulatory frameworks. On this front, legislation was passed by the Illinois General Assembly, which is awaiting the governor's approval, that would extend the IEIMA's formula ratemaking framework until the end of 2019 with further extension possible through 2022. Additionally, in its January 2015 natural gas delivery service rate request, Ameren Illinois proposed to implement a decoupling rider mechanism for residential and small nonresidential customers that would ensure that changes in sales volumes do not affect Ameren Illinois’ annual natural gas revenues for these customers.
In addition to the Ameren Missouri investments discussed above, Ameren invested more than $1 billion in Ameren Illinois electric and natural gas delivery service infrastructure and FERC-regulated electric transmission service infrastructure in 2014. Ameren continues to focus on creating and capitalizing on opportunities for investment for the benefit of its customers and shareholders. To that end, Ameren identified needed reliability projects withinremains focused on disciplined cost management and strategic capital allocation. In 2017, Ameren Missouri's and Ameren Illinois' service territories while pursuing competitive electric transmission investment opportunities both within and outside of these service territories, including investments outside of MISO, leveraging past success as an experienced transmission developer and operator. Consistent with previous plans, Ameren intendscontinued to allocate significant and increasing amounts of discretionary capital to FERC-regulatedthose businesses that are supported by constructive regulatory frameworks. It invested $1.4 billion of capital expenditures in its FERC rate-regulated electric transmission service projects and Ameren Illinois electric and natural gas delivery service projects.distribution businesses.
In March 2017, the MoPSC issued an order approving a unanimous stipulation and agreement in Ameren plans to invest $2.3 billionMissouri’s July 2016 regulatory rate review. The electric rate order resulted in FERC-regulated electric transmission projects from 2015 through 2019, with $1.3 billion invested by ATXIa $92 million increase in Ameren Missouri’s revenue requirement, a $54 million decrease in the base level of net energy costs, and the remaining $1 billion by Ameren Illinois.
In November 2013, a customer group filed a complaint case with the FERC seeking a$26 million reduction in the 12.38%base level of certain tracked expenses, compared with the amounts in the MoPSC’s April 2015 rate order. The new rates and base level of expenses became effective on April 1, 2017. In September 2017, Ameren Missouri filed its nonbinding 20-year integrated resource plan with the MoPSC. This plan includes Ameren Missouri’s preferred approach for meeting customers’ projected long-term energy needs in a cost-effective manner while maintaining system reliability. The plan targets cleaner and more diverse sources of energy generation, including solar, wind, natural gas, hydro, and nuclear power. It also includes expanding renewable sources by adding at least 700 megawatts of wind generation by 2020 in Missouri and neighboring states, and adding 100 megawatts of solar generation over the next 10 years. These new renewable energy sources would support Ameren Missouri’s compliance with the state of Missouri’s requirement of achieving 15% of native load sales from renewable energy sources by 2021, subject to customer rate increase limitations. The plan also provides for expanding renewable generation, retiring coal-fired energy centers as they reach the end of their useful lives, expanding customer energy-efficiency programs, and adding cost-effective demand response programs. The new renewable energy sources identified in Ameren Missouri’s plan could represent incremental investments of approximately $1 billion through 2020. In connection with the integrated resource plan filing, Ameren Missouri established a goal of reducing CO2 emissions 80% by

2050 from a 2005 base level. To meet this goal, Ameren Missouri is targeting a 35% CO2 emission reduction by 2030 and a 50% reduction by 2040 from the 2005 level by retiring coal-fired generation at the end of its useful life.
In January 2017, Ameren Illinois implemented provisions of the FEJA that improved the constructive regulatory framework of its electric distribution business. The FEJA decoupled electric distribution revenues established in a rate proceeding from actual sales volumes. It provided that any revenue changes driven by actual electric distribution sales volumes differing from sales volumes that are reflected in that year’s rates be collected from, or refunded to, customers within two years. Also, since June 2017, the FEJA has allowed baseAmeren Illinois to defer the costs of its electric energy-efficiency program as a regulatory asset and earn a return on commonthose investments. The regulatory asset earns a return at the company’s weighted-average cost of capital, with the equity underreturn based on the MISO tariff.monthly average yield of the 30-year United States Treasury bonds plus 580 basis points. The equity portion of Ameren Illinois’ return on electric energy-efficiency program investments can also be increased or decreased by up to 200 basis points, depending on the achievement of annual energy savings goals. In January 2015, the FERC scheduled the case for hearings, requiring an initial decision to be issued no later than November 30, 2015. As the original 15-month refund period ended in February 2015, another customer complaint case was filed in February 2015, seeking a reduction in the allowed base return on common equity. In the fourth quarter of 2014,2018, Ameren recorded a reserve representing its estimate of the potential refund from November 2013 through December 31, 2014.
In November 2014, weIllinois filed a request with the FERCICC seeking approval to includeincrease its annual revenues for natural gas delivery service by $49 million, which included an incentive adderestimated $42 million of up to 50 basis pointsannual revenues that would otherwise be recovered under a QIP rider. The request was based on the allowed basea 10.3% return on common equity, a capital structure composed of 50% common equity, and a rate base of $1.6 billion.
In the third quarter of 2017, ATXI finalized an alternative project route and reached agreements with Ameren Missouri and an electric cooperative in northeast Missouri to locate almost all of the Mark Twain project on existing line corridors. It also received assents for participationroad crossings from the five affected counties in northeast Missouri. In January 2018, the MoPSC granted ATXI a certificate of convenience and necessity for the Mark Twain project. ATXI plans to begin construction in the second quarter of 2018 and to complete the project by the end of 2019.
In October 2017, Ameren’s board of directors increased the quarterly common stock dividend to 45.75 cents per share, resulting in an RTO. FERC approved the request to implement the incentive adder
prospectively from January 6, 2015, and to defer collectionannualized equivalent dividend rate of the incentive adder until the issuance of the final order addressing the initial MISO case.$1.83 per share.
Earnings
Ameren reported net income of $586 million, or $2.40 per diluted share, for 2014, and $289 million, or $1.18 per diluted share, for 2013. Net income attributable to Ameren Corporationcommon shareholders from continuing operations was $587$523 million, or $2.40$2.14 per diluted share, for 2014,2017, and $512$653 million, or $2.10$2.68 per diluted share, for 2013. Ameren’s earnings from continued operations increased2016. Net income was unfavorably affected in 2014,2017, compared with 2013,2016, by increased income tax expense due in part to increased electric delivery servicea noncash charge to earnings for the revaluation of deferred taxes primarily at Ameren Illinois and increased electric transmission earnings at Ameren Illinois and ATXI, which included a reserve for a potential reduction in the FERC-allowed return on equity for electric transmission services. Additionally, earnings from continuing operations were favorably affected by increased rates for Ameren Illinois’ natural gas delivery service, effective January 2014, as well as decreased interest charges resulting from higher-cost debt being replaced with lower-cost debt. Interest charges also declined in 2014, compared with 2013,(parent) as a result of the ICC's December 2014 order allowing partial recovery of certain previously disallowed debt premium costs, whichTCJA and the increase in the Illinois income tax rate. Earnings were chargedalso unfavorably affected in 2017, compared with 2016, by decreased demand, primarily at Ameren Missouri, due to earningsmilder temperatures in 2013. The2017, by the absence in 20142017 of a reduction in Ameren Missouri revenues resulting from a Julythe MEEIA 2013 MoPSC order that required a refund to customers for the earnings associated with certain long-term partial requirements sales recognized for the period from October 1, 2009, to May 31, 2011, also positively affected earnings comparisons. Ameren’s earnings from continuing operations were negatively affectedperformance incentive, and by increased depreciation and amortization expenses at Ameren Missouri. Net income was favorably affected in 2017, compared with 2016, by an increase in base rates, and lower base level of expenses at Ameren Missouri, pursuant to the MoPSC’s March 2017 electric rate order, and by increased investments in infrastructure at the Ameren Illinois Electric Distribution and Ameren Transmission segments, which reflect Ameren’s strategy to allocate incremental capital to those businesses.
After the application of jurisdictional regulatory recovery mechanisms, the effect of the revaluation of deferred taxes as a higher effectiveresult of the TCJA was a decrease to Ameren’s and Ameren Missouri’s net income tax rate,of $154 million and increased other operations and maintenance expenses.$36 million, respectively, while the effect on Ameren Illinois’ net income was immaterial.
Liquidity
Cash generated by operating activities associated with continuing operations of $1.6 billion, short-term borrowings, and available cash on hand were used to fund capital expenditures of $1.8 billion and to pay dividends to common stockholders of $390 million. At December 31, 2014,2017, Ameren, on a consolidated basis, had available liquidity in the form of cash on hand and amounts available under existing credit agreements,the Credit Agreements of $1.4$1.6 billion.
Capital SpendingExpenditures
In 2014,2017, Ameren madecontinued to make significant investmentsinvestment in its utilities. It expects that trend to continue into the future. From 2015utility businesses by making capital expenditures of $0.8 billion, $0.5 billion, $0.2 billion, and $0.6 billion in Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission, respectively. For 2018 through 2019, Ameren's2022, Ameren’s cumulative capital spending isexpenditures are projected to range between $8.6from $10.5 billion and $9.3to $11.4 billion. The projected spending by segment includes approximately $3.7up to $4.5 billion, $3.8$2.5 billion, $1.7 billion, and $1.3$2.7 billion for Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and ATXI,Ameren Transmission, respectively.
RESULTS OF OPERATIONS
Our results of operations and financial position are affected by many factors. Weather, economicEconomic conditions, energy-efficiency investments by our customers and by us, and the actions of key customers can significantly affect the demand for our


33


services. OurAmeren and Ameren Missouri results are also affected by seasonal fluctuations in winter heating and summer cooling demands.demands, as well as by nuclear refueling and other energy center maintenance outages. Additionally, fluctuations in interest rates and conditions in the capital and credit markets affect our cost of borrowing and our pension and postretirement benefits costs. Almost all of Ameren’s revenues are subject to state or federal regulation.

This regulation has a material impact on the prices we charge for our services. Our results of operations, financial position, and liquidity are affected by our ability to align our overall spending, both operating and capital, within the frameworks established by our regulators.
Ameren Missouri principally uses coal, nuclear fuel, and natural gas for fuel in its operations.electric operations and purchases natural gas for its customers. Ameren Illinois purchases power and natural gas for its customers. The prices for these commodities can fluctuate significantly because of the global economic and political environment, weather, supply, and demand, and many other factors. WeAs described below, we have natural gas cost recovery mechanisms for our Illinois and Missouri natural gas deliverydistribution service businesses, a purchased power cost recovery mechanism for Ameren Illinois'Illinois’ electric deliverydistribution service business, and a FAC for Ameren Missouri'sMissouri’s electric utility business.
Ameren Illinois' electric delivery service utility business, pursuantMissouri’s FAC cost recovery mechanism allows it to the IEIMA, conducts an annual reconciliationrecover or refund, through customer rates, 95% of the variance in net energy costs from the amount set in base rates without a traditional rate proceeding, subject to MoPSC prudence reviews, with the remaining 5% of changes retained by Ameren Missouri. Ameren Missouri accrues net energy costs that exceed the amount set in base rates (FAC under-recovery) as a regulatory asset. Net recovery of these costs through customer rates does not affect Ameren Missouri’s electric margins, as any change in revenue requirement necessaryis offset by a corresponding change in fuel expense to reflectreduce the previously recognized FAC regulatory asset. In addition, Ameren Missouri’s MEEIA customer energy-efficiency program costs, the throughput disincentive, and any performance incentive are recoverable through the MEEIA cost recovery mechanism without a traditional rate proceeding. Ameren Missouri also has a cost recovery mechanism for natural gas purchased on behalf of its customers. These pass-through purchased gas costs do not affect Ameren Missouri’s natural gas margins, as any change in costs is offset by a corresponding change in revenues. Ameren Missouri employs other cost recovery mechanisms, including a pension and postretirement benefit cost tracker, an uncertain tax position tracker, a renewable energy standards cost tracker, and a solar rebate program tracker. Each of these trackers allows Ameren Missouri to defer the difference between actual costs incurred in a given year with the revenue requirementand costs included in customer rates for that year, with recoveries fromas a regulatory asset or refunds to customers maderegulatory liability. The difference will be reflected in base rates in a subsequent year. IncludedMoPSC rate order.
Ameren Illinois’ electric distribution service business has cost recovery mechanisms for power purchased and transmission services incurred on behalf of its customers. The FEJA also provides Ameren Illinois with cost recovery of renewable energy credit compliance, zero-emission credits, and energy-efficiency investments as well as a return on those electric energy-efficiency investments. Ameren Illinois’ natural gas business has a cost recovery mechanism for natural gas purchased on behalf of its customers. These pass-through costs do not affect Ameren Illinois’ electric or natural gas margins, as any change in costs is offset by a corresponding change in revenues. Ameren Illinois'Illinois employs other cost recovery mechanisms for natural gas customer energy-efficiency program costs and certain environmental costs, as well as bad debt expense and costs of certain asbestos-related claims not recovered in base rates. Ameren Illinois’ natural gas business also has the QIP rider, which provides for recovery of, and a return on, qualifying infrastructure plant investments that are placed in service between regulatory rate reviews.
Ameren Illinois’ electric distribution service rates are reconciled annually to its actual revenue requirement reconciliation is a formula for theand allowed return on equity, whichunder a formula ratemaking process effective through 2022. If a given year’s revenue requirement varies from the amount collected from customers, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue requirement. The regulatory balance is then collected from, or refunded to, customers within two years.
Ameren Illinois’ electric distribution service revenue requirement is based on recoverable costs, year-end rate base, a capital structure of 50% common equity, and a return on equity. The return on equity component under the IEIMA and the FEJA is equal to the calendar year average of the monthly yields of 30-year United States Treasury bonds plus 580 basis points. Therefore, Ameren Illinois'Illinois’ annual return on equity under the formula ratemaking frameworks for both its electric distribution service and its electric energy-efficiency investments is directly correlated to the yields on United States Treasurysuch bonds. Beginning in 2017, the FEJA also provides that Ameren Illinois recovers, within the following two years, its electric distribution revenue requirement for a given year, independent of actual sales volumes.
FERC’s electric transmission formula rate framework provides for an annual reconciliation of the electric transmission service revenue requirement, which reflects the actual recoverable costs incurred and the 13-month average rate base for a given year, with the revenue requirement in customer rates, including an allowed return on equity. Ameren Illinois and ATXI have received FERC approval to use a company-specific, forward-looking rate formula ratemaking framework in setting their transmission rates. These forward-looking rates are updated each January with forecasted information. A reconciliation duringIf a given year’s revenue requirement varies from the year, which adjusts for theamount collected from customers, an adjustment is made to electric operating revenues with an offset to a regulatory asset or liability to reflect that year’s actual revenue requirementrequirement. The regulatory balance is collected from, or refunded to, customers within two years. The total return on equity currently allowed for Ameren Illinois’ and actual sales volumes,ATXI’s electric transmission service businesses is used10.82% and is subject to adjust billing rates in a subsequent year. Fluctuations in interest ratesFERC complaint case. See Note 2 – Rate and conditions in the capital and credit markets also affect our costRegulatory Matters under Part II, Item 8, of borrowing and our pension and postretirement benefits costs. this report for additional information.
We employ various risk management strategies to reduce our exposure to commodity risk and other risks inherent in our business. The reliability of Ameren Missouri'sMissouri’s energy centers and our transmission and distribution systems and the level and timing of purchased power costs, operations and maintenance costs and capital investment are key factors that we seek to manage in order to optimize our results of operations, financial position, and liquidity.

Earnings Summary
The following table presents a summary of Ameren'sAmeren’s earnings for the years ended December 31, 2014, 2013,2017, 2016, and 2012:
2015:
 2014 2013 2012
Net income (loss) attributable to Ameren Corporation$586
 $289
 $(974)
Earnings (loss) per common share – diluted2.40
 1.18
 (4.01)
      
Net income attributable to Ameren Corporation – continuing operations587
 512
 516
Earnings per common share – diluted – continuing operations2.40
 2.10
 2.13
 2017 2016 2015
Net income attributable to Ameren common shareholders$523
 $653
 $630
Earnings per common share – diluted2.14
 2.68
 2.59
Net income attributable to Ameren common shareholders – continuing operations523
 653
 579
Earnings per common share – diluted – continuing operations2.14
 2.68
 2.38
20142017 versus 20132016
Net income attributable to Ameren Corporationcommon shareholders from continuing operations in 2014 increased $752017 decreased $130 million, or $0.30$0.54 per diluted share, from 2013.2016. The increasedecrease was due to an increase in net loss of $125 million for activity not reported as part of a $41segment, primarily at Ameren (parent), and a net income decrease of $34 million at Ameren Missouri, both of which were primarily due to the enactment of the TCJA. The decrease was partially offset by a $23 million and a $5 million increase in net income from theAmeren Transmission and Ameren Illinois segment and a $39 million decrease in net loss from Ameren (parent) and nonregistrant subsidiaries partially offset by a $5 million decrease in net income from the Ameren Missouri segment.Electric Distribution, respectively.
Compared with 2016, 2017 earnings per share from continuing operations were unfavorably affected by:
an increase in income tax expense, primarily at Ameren (parent), due to the revaluation of deferred taxes, as a result of a decrease in the federal statutory corporate income tax rate resulting from enactment of the TCJA (63 cents per share), and an increase in the Illinois corporate income tax rate (6 cents per share), as discussed in Note 12 – Income Taxes under Part II, Item 8, of this report;
decreased demand primarily at Ameren Missouri due to milder winter and summer temperatures in 2017 (estimated at 15 cents per share);
the absence in 2017 of a MEEIA 2013 2014performance incentive at Ameren Missouri recognized in 2016 (7 cents per share);
increased depreciation and amortization expenses not subject to riders or regulatory tracking mechanisms at Ameren Missouri resulting from additional electric property, plant, and equipment (6 cents per share); and
increased transmission services charges at Ameren Missouri resulting from cost-sharing by all MISO participants of additional MISO-approved electric transmission investments made by other entities (2 cents per share).
Compared with 2016, 2017 earnings per share from continuing operations were favorably affected by:
an increase in base rates, net of increased revenues in 2016 from the suspension of operations at the New Madrid Smelter, and lower base level of expenses at Ameren Missouri pursuant to the MoPSC’s March 2017 electric rate order as discussed in Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report (32 cents per share);
increased Ameren Transmission earnings under formula ratemaking, primarily due to additional rate base, partially offset by a lower recognized return on equity (9 cents per share);
increased Ameren Illinois Electric Distribution earnings under formula ratemaking, primarily due to additional rate base investment as well as a higher recognized return on equity (4 cents per share); and
decreased income tax expense, excluding the effect of corporate income tax rate changes discussed above, primarily at Ameren (parent) resulting from changes in the valuation allowance for charitable contributions, tax benefits related to company-owned life insurance, and tax credits in 2017, partially offset by a lower income tax benefit in 2017 related to share-based compensation compared with 2016 (1 cent per share).
The cents per share information presented above is based on the diluted average shares outstanding in 2016. Pretax amounts have been presented net of income taxes, using Ameren’s 2016 statutory tax rate of 39%.
2016 versus 2015
Net income attributable to Ameren common shareholders from continuing operations in 2016 increased $74 million, or $0.30 per diluted share, from 2015. The increase was due to net income increases of $34 million, $22 million, $5 million, and $3 million at Ameren Transmission, Ameren Illinois Natural Gas, Ameren Missouri, and Ameren Illinois Electric Distribution, respectively. Additionally, the net loss from other businesses, primarily Ameren (parent), and intersegment eliminations decreased $10 million.
In 2015, net income attributable to Ameren common shareholders from discontinued operations was favorably affected by the recognition of a tax benefit resulting from the removal of a reserve for unrecognized tax benefits of $53 million recorded in 2013 related to the divestiture of New AER, based on the completion of the IRS audit of Ameren’s 2013 tax year.

Compared with 2015, 2016 earnings per share from continuing operations were favorably affected by:
increased Ameren Transmission earnings under formula ratemaking, primarily due to additional rate base investment. Ameren Transmission earnings also benefited from a temporarily higher allowed return on common equity, recognizing an allowed return on common equity of 12.38% for nearly four months in 2016 as a result of the expiration of the refund period in the February 2015 complaint case (19 cents per share);
the absence of a provision recognized in 2015, as a result of Ameren Missouri’s discontinued efforts to license and build a second nuclear unit at its Callaway energy center site (18 cents per share);
increased demand due to warmer summer temperatures in 2016, partially offset by milder winter temperatures (estimated at 15 cents per share);
higher natural gas distribution rates at Ameren Illinois pursuant to a December 20132015 order (8(11 cents per share);
an income tax benefit recorded at Ameren (parent) pursuant to the adoption of new accounting guidance related to share-based compensation (9 cents per share);
decreased interest expense, excluding the effects of the ICC's December 2014 order discussed below, primarily dueother operations and maintenance expenses not subject to the maturity of higher-cost debt replaced with issuances of lower-cost debt (8riders or regulatory tracking mechanisms at Ameren Missouri (7 cents per share);
the absence. This was due, in 2014 ofpart, to a reduction in energy center maintenance costs, excluding the cost of the Callaway energy center’s scheduled refueling and maintenance outage (discussed below), and reduced electric distribution maintenance expenditures; and
increased Ameren Missouri revenues resulting from a July 2013 MoPSC order that required a refund to customers associated with certain long-term partial requirements sales recognized from October 1, 2009, to May 31, 2011 (7 cents per share);
the ICC's December 2014 order allowing partial recovery of certain previously disallowed debt premium costs that were charged to earnings in 2013 (7 cents per share);
an increase in Ameren Illinois' and ATXI's electric transmissionIllinois Electric Distribution earnings under formula ratemaking, primarily due to additional rate base investment, partially offset by a reserve for a potential refund to customers due tolower return on equity resulting from a reduction in the FERC-allowed return on equity (630-year United States Treasury bond yields (2 cents per share). ATXI's net income was $13 million (5 cents per share) and $7 million (3 cents per share) in 2014 and 2013, respectively;
an increase in Ameren Illinois’ electric delivery service earnings under formula ratemaking pursuant to the IEIMA due to increased rate base investment (estimated at 5 cents per share);
higher revenues associated with Ameren Missouri's MEEIA lost revenue recovery mechanism (4 cents per share), which were partially offset by lower revenues resulting from reduced demand due to customer energy efficiency programs; and
increased electric and natural gas demand primarily resulting from colder winter temperatures in early 2014 and warmer early summer temperatures (estimated at 1 cent per share).
Compared with 2013, 20142015, 2016 earnings per share from continuing operations were unfavorably affected by:
the absence in 2016 of MEEIA net shared benefits due to the expiration of MEEIA 2013, partially offset by the recognition of a MEEIA 2013 performance incentive (15 cents per share);
decreased Ameren Missouri sales to the New Madrid Smelter resulting from a reduction in operations at the smelter (15 cents per share);
the cost of the Callaway energy center’s scheduled refueling and maintenance outage in 2016. There was no Callaway refueling and maintenance outage in 2015 (7 cents per share);
increased depreciation and amortization expenses not subject to riders or regulatory tracking mechanisms at Ameren Missouri, primarily resulting from additional electric distribution capital additions at Ameren Missouri (5property, plant, and equipment (4 cents per share);
an increasedecreased Ameren Illinois Electric Distribution earnings resulting from the absence in the effective tax rate2016 of a January 2015 ICC order regarding Ameren Illinois’ cumulative power usage cost and its purchased power rider mechanism (4 cents per share);
decreased Ameren Missouri electric margins resulting from increased transmission charges, net of transmission revenues (3 cents per share); and
increased other operations and maintenance expenses fornot subject to riders or regulatory tracking mechanisms at Ameren Missouri and for Ameren Illinois' natural gas business,Illinois Natural Gas, primarily due to increased laborrepairs and litigation costs, offset in part by decreased costs at Ameren (parent),


34


primarily resulting from the substantial elimination of costs previously incurred in support of the divested merchant generation business (3compliance expenditures (2 cents per share).
The cents per share information presented above is based on the diluted average shares outstanding in 2013.
2013 versus 2012
Net2015. Pretax amounts have been presented net of income attributable to Ameren Corporation from continuing operations in 2013 decreased $4 million, or $0.03 per diluted share, from 2012. The decrease was due to a $21 million decrease in net income from the Ameren Missouri segment and a $2 million increase in net loss from Ameren (parent) and nonregistrant subsidiaries, partially offset by a $19 million increase in net income from the Ameren Illinois segment.
Compared with 2012, 2013 earnings per share from continuing operations were unfavorably affected by:
the costtaxes, using Ameren’s 2015 statutory tax rate of the Callaway energy center's scheduled refueling and maintenance outage in 2013. There was no Callaway refueling and maintenance outage in 2012 (10 cents per share);
a reduction in Ameren Missouri revenues resulting from a July 2013 MoPSC order that required a refund to customers associated with certain long-term partial requirements sales recognized for the period from October 1, 2009, to May 31, 2011 (7 cents per share);
the absence in 2013 of a reduction in Ameren Missouri's purchased power expense and an increase in interest income, each as a result of a FERC-ordered refund received in 2012 from Entergy for a power purchase agreement that expired in 2009 (7 cents per share);
decreased electric demand resulting from summer temperatures in 2013 that were milder than the warmer-than-normal temperatures in 2012, partially offset by increased electric and natural gas demand resulting from winter temperatures in 2013 that were colder than winter temperatures in 2012 (estimated at 6 cents per share);
the ICC's December 2013 orders disallowing recovery of a portion of the premium paid by Ameren Illinois for a tender offer in August 2012 to repurchase senior secured notes (4 cents per share); and
increased depreciation primarily due to infrastructure additions at Ameren Missouri (3 cents per share)39%.
Compared with 2012, 2013 earnings per share from continuing operations were favorably affected by:
higher Ameren Missouri utility rates pursuant to an order issued by the MoPSC, which became effective in January 2013, partially offset by increased regulatory asset amortization as directed by the rate order. This excludes MEEIA impacts, which are discussed separately below (12 cents per share);
higher revenues associated with Ameren Missouri's MEEIA lost revenue recovery mechanism (9 cents per share), which were partially offset by lower revenues resulting from reduced demand due to customer energy efficiency programs;
higher electric transmission rates at Ameren Illinois and ATXI (8 cents per share); and
an increase in Ameren Illinois' electric delivery service earnings under formula ratemaking, favorably affected primarily by an increased rate base, a higher allowed return on equity, and lower required contributions pursuant to the IEIMA (estimated at 8 cents per share).
The cents per share information presented above is based on the diluted average shares outstanding in 2012.
For additional details regarding the Ameren Companies’ segment results of operations, including explanations of Margins, Other Operations and Maintenance Expenses, Provision for Callaway Construction and Operating License, Depreciation and Amortization, Taxes Other Than Income Taxes, Other Income and Expenses, Interest Charges, Income Taxes, and Income (Loss) from Discontinued Operations, Net of Taxes, see the major headings below.



35


Below is aAmeren’s table of income statement components by segment for the years ended December 31, 2014, 2013,2017, 2016, and 2012:2015:
2017Ameren Missouri 
Ameren
Illinois
Electric
Distribution
 
Ameren
Illinois
Natural Gas
 Ameren Transmission 
Other /
Intersegment
Eliminations
 Total
Electric margins$2,431
 $1,109
 $
 $426
 $(31) $3,935
Natural gas margins79
 
 479
 
 (2) 556
Other revenues
 1
 
 
 (1) 
Other operations and maintenance(902) (512) (224) (63) 41
 (1,660)
Depreciation and amortization(533) (239) (59) (60) (5) (896)
Taxes other than income taxes(328) (74) (60) (6) (9) (477)
Other income and (expenses)40
 3
 (3) 1
 (3) 38
Interest charges(207) (73) (36) (67) (8) (391)
Income taxes(254) (83) (36) (90) (113) (576)
Net income (loss)326
 132
 61
 141
 (131)
529
Noncontrolling interests – preferred stock dividends(3) (1) (1) (1) 
 (6)
Net income (loss) attributable to Ameren common shareholders$323
 $131
 $60
 $140
 $(131) $523
2016           
Electric margins$2,397
 $1,105
 $
 $355
 $(27) $3,830
Natural gas margins79
 
 462
 
 (2) 539
Other revenues1
 
 
 
 (1) 
Other operations and maintenance(893) (538) (215) (60) 30
 (1,676)
Depreciation and amortization(514) (226) (55) (43) (7) (845)
Taxes other than income taxes(325) (72) (58) (4) (8) (467)
Other income and (expenses)42
 8
 (1) 2
 (9) 42
Interest charges(211) (72) (34) (58) (7) (382)
Income taxes(216) (78) (39) (74) 25
 (382)
Net income (loss)360

127
 60
 118
 (6) 659
Noncontrolling interests – preferred stock dividends(3) (1) (1) (1) 
 (6)
Net income (loss) attributable to Ameren common shareholders$357
 $126
 $59
 $117
 $(6)
$653
2015           
Electric margins$2,481
 $1,074
 $
 $259
 $(26) $3,788
Natural gas margins80
 
 425
 
 (2) 503
Other revenues2
 
 
 
 (2) 
Other operations and maintenance(925) (532) (219) (56) 38
 (1,694)
Provision for Callaway construction and operating license(69) 
 
 
 
 (69)
Depreciation and amortization(492) (212) (52) (33) (7) (796)
Taxes other than income taxes(335) (72) (56) (2) (8) (473)
Other income and (expenses)41
 8
 (1) 2
 (6) 44
Interest charges(219) (71) (35) (35) 5
 (355)
Income taxes(209) (71) (24) (51) (8) (363)
Income (loss) from continuing operations355
 124
 38
 84
 (16)
585
Income from discontinued operations, net of taxes
 
 
 
 51
 51
Net income355
 124
 38
 84
 35
 636
Noncontrolling interests – preferred stock dividends(3) (1) (1) (1) 
 (6)
Net income attributable to Ameren common shareholders$352
 $123
 $37
 $83
 $35

$630











Below is Ameren Illinois’ table of income statement components by segment for the years ended December 31, 2017, 2016, and 2015:
2014
Ameren
Missouri
 
Ameren
Illinois
 
Other /
Intersegment
Eliminations
 Total
Electric margins$2,443
 $1,179
 $11
 $3,633
Natural gas margins82
 443
 
 525
Other revenues1
 
 (1) 
Other operations and maintenance(946) (771) 26
 (1,691)
Depreciation and amortization(473) (263) (9) (745)
Taxes other than income taxes(322) (138) (8) (468)
Other income48
 9
 
 57
Interest charges(211) (112) (18) (341)
Income taxes(229) (143) (5) (377)
Income (loss) from continuing operations393
 204
 (4) 593
Loss from discontinued operations, net of taxes
 
 (1) (1)
Net income (loss)393
 204
 (5) 592
Net income attributable to noncontrolling interests – continuing operations(3) (3) 
 (6)
Net income (loss) attributable to Ameren Corporation$390
 $201
 $(5) $586
2013       
2017Electric Distribution Natural Gas Transmission Total
Electric margins$2,407
 $1,081
 $(3) $3,485
$1,109
 $
 $258
 $1,367
Natural gas margins83
 399
 (2) 480

 479
  479
Other revenues1
 3
 (4) 
1
 
  1
Other operations and maintenance(915) (693) (9) (1,617)(512) (224) (53) (789)
Depreciation and amortization(454) (243) (9) (706)(239) (59) (43) (341)
Taxes other than income taxes(319) (132) (7) (458)(74) (60) (3) (137)
Other income and (expenses)47
 1
 (5) 43
3
 (3) 1
 1
Interest charges(210) (143) (45) (398)(73) (36) (35) (144)
Income (taxes) benefit(242) (110) 41
 (311)
Income (loss) from continuing operations398
 163
 (43) 518
Loss from discontinued operations, net of taxes
 
 (223) (223)
Net income (loss)398
 163
 (266) 295
Net income attributable to noncontrolling interests – continuing operations(3) (3) 
 (6)
Net income (loss) attributable to Ameren Corporation$395
 $160
 $(266) $289
2012       
Income taxes(83) (36) (47) (166)
Net income132
 61
 78
 271
Preferred stock dividends(1) (1) (1) (3)
Net income attributable to common shareholder$131
 $60
 $77
 $268
2016       
Electric margins$2,340
 $1,034
 $(11) $3,363
$1,105
 $
 $232
 $1,337
Natural gas margins75
 378
 (1) 452
 462
  462
Other revenues1
 
 (1) 
Other operations and maintenance(827) (684) 
 (1,511)(538) (215) (51) (804)
Depreciation and amortization(440) (221) (12) (673)(226) (55) (38) (319)
Taxes other than income taxes(304) (130) (9) (443)(72) (58) (2) (132)
Other income and (expenses)49
 (10) (6) 33
8
 (1) 2
 9
Interest charges(223) (129) (40) (392)(72) (34) (34) (140)
Income (taxes) benefit(252) (94) 39
 (307)
Income (loss) from continuing operations419
 144
 (41) 522
Loss from discontinued operations, net of taxes
 
 (1,496) (1,496)
Net income (loss)419
 144
 (1,537) (974)
Net income attributable to noncontrolling interests – continuing operations(3) (3) 
 (6)
Net loss attributable to noncontrolling interests – discontinued operations
 
 6
 6
Net income (loss) attributable to Ameren Corporation$416
 $141
 $(1,531) $(974)
Income taxes(78) (39) (41) (158)
Net income127
 60
 68
 255
Preferred stock dividends(1) (1) (1) (3)
Net income attributable to common shareholder$126
 $59
 $67
 $252
2015       
Electric margins$1,074
 $
 $189
 $1,263
Natural gas margins
 425
 
 425
Other operations and maintenance(532) (219) (46) (797)
Depreciation and amortization(212) (52) (31) (295)
Taxes other than income taxes(72) (56) (2) (130)
Other income and (expenses)8
 (1) 2
 9
Interest charges(71) (35) (25) (131)
Income taxes(71) (24) (32) (127)
Net income124
 38
 55
 217
Preferred stock dividends(1) (1) (1) (3)
Net income attributable to common shareholder$123
 $37
 $54
 $214



36


Margins
The following table presents the favorable (unfavorable) variations by segment for electric and natural gas margins from the previous year. Electric margins are definedin 2017 compared with 2016, as electric revenues less fuel and purchased power costs. Natural gas margins are definedwell as gas revenues less gas purchased for resale. The table covers the years ended December 31, 2014, 2013, and 2012.2016 compared with 2015. We consider electric and natural gas margins useful measures to analyze the change in profitability of our electric and natural gas operations between periods. We have included the analysis below as a complement to the financial information we provide in accordance with GAAP. However, these margins may not be a presentation defined under GAAP, and they may not be comparable to other companies’ presentations or more useful than the GAAP information we provide elsewhere in this report.

2014 versus 2013
Ameren
Missouri
 
Ameren
Illinois
 
Other(a)
 Ameren
Electric revenue change:       
Effect of weather (estimate)(b)
$8
 $(5) $
 $3
Base rates (estimate)
 56
 
 56
Off-system sales and transmission services revenues (included in base rates)(12) 
 
 (12)
Recovery of FAC under-recovery(c)
(14) 
 
 (14)
FAC prudence review charge in 201325
 
 
 25
MEEIA (energy efficiency) recovery mechanisms22
 
 
 22
Transmission services revenues
 35
 18
 53
Illinois pass-through power supply costs
 (38) 
 (38)
Reserve for potential transmission refunds
 (21) (4) (25)
Bad debt, energy efficiency programs, and environmental remediation cost riders
 25
 
 25
Sales volume (excluding the estimated effect of abnormal weather)(22) 3
 
 (19)
Other2
 6
 (3) 5
Total electric revenue change$9
 $61
 $11
 $81
Fuel and purchased power change:       
Energy costs included in base rates and other$18
 $
 $3
 $21
Effect of weather (estimate)(b)
(5) 
 
 (5)
Recovery of FAC under-recovery(c)
14
 
 
 14
Transmission services expenses
 (1) 
 (1)
Illinois pass-through power supply costs
 38
 
 38
Total fuel and purchased power change$27
 $37
 $3
 $67
Net change in electric margins$36
 $98
 $14
 $148
Natural gas revenue change:       
Effect of weather (estimate)(b)
$6
 $32
 $
 $38
Base rates (estimate)
 32
 
 32
Bad debt, energy efficiency programs, and environmental remediation cost riders
 4
 
 4
Gross receipts tax
 3
 
 3
Pass-through purchased gas costs(1) 57
 
 56
Sales volume (excluding the effect of abnormal weather) and other(2) 1
 2
 1
Total natural gas revenue change$3
 $129
 $2
 $134
Gas purchased for resale change:       
Effect of weather (estimate)(b)
$(5) $(28) $
 $(33)
Pass-through purchased gas costs1
 (57) 
 (56)
Total gas purchased for resale change$(4) $(85) $
 $(89)
Net change in natural gas margins$(1) $44
 $2
 $45
Electric and Natural Gas Margins
2017 versus 2016Ameren
Missouri
 Ameren Illinois Electric Distribution 
Ameren
Illinois
Natural Gas
 
Ameren Transmission(a)
 Other /
Intersegment
Eliminations
 Ameren
Electric revenue change:           
Effect of weather (estimate)(b)
$(65) $(5) $
 $
 $
 $(70)
Base rates (estimate)61
 42
 
 71
 
 174
Recovery of power restoration efforts provided to other utilities7
 1
 
 
 
 8
Sales volume (excluding the New Madrid Smelter and estimated effect of weather)(6) 
 
 
 
 (6)
Off-system sales and capacity revenues22
 
 
 
 
 22
MEEIA 2013 performance incentive(28) 
 
 
 
 (28)
Transmission services revenues11
 
 
 
 
 11
Other4
 (1) 
 
 5
 8
Cost recovery mechanisms – offset in fuel and purchased power(c)
(11) 18
 
 
 
 7
Other cost recovery mechanisms(d)
24
 (36) 
 
 
 (12)
Total electric revenue change$19
 $19
 $
 $71
 $5
 $114
Fuel and purchased power change:           
Energy costs (excluding the New Madrid Smelter and estimated effect of weather)$(22) $
 $
 $
 $
 $(22)
Effect of weather (estimate)(b)
13
 (1) 
 
 
 12
Effect of lower net energy costs included in base rates39
 
 
 
 
 39
Transmission services charges(16) 
 
 
 
 (16)
Other(10) 4
 
 
 (9) (15)
Cost recovery mechanisms – offset in electric revenue(c)
11
 (18) 
 
 
 (7)
Total fuel and purchased power change$15
 $(15) $
 $
 $(9) $(9)
Net change in electric margins$34
 $4
 $
 $71
 $(4) $105
Natural gas revenue change:           
Effect of weather (estimate)(b)
$(4) $
 $
 $
 $
 $(4)
QIP rider
 
 12
 
 
 12
Other
 
 (3) 
 
 (3)
Cost recovery mechanisms – offset in natural gas purchased for resale(c)
2
 
 (28) 
 
 (26)
Other cost recovery mechanisms(d)

 
 8
 
 
 8
Total natural gas revenue change$(2) $
 $(11) $
 $
 $(13)
Natural gas purchased for resale change:           
Effect of weather (estimate)(b)
$4
 $
 $
 $
 $
 $4
Cost recovery mechanisms – offset in natural gas revenue(c)
(2) 
 28
 
 
 26
Total natural gas purchased for resale change$2
 $
 $28
 $
 $
 $30
Net change in natural gas margins$
 $
 $17
 $
 $
 $17

37


2013 versus 2012
Ameren
Missouri
 
Ameren
Illinois
 
Other(a)
 Ameren
Electric revenue change:       
Effect of weather (estimate)(b)
$(29) $(20) $
 $(49)
Base rates (estimate)178
 57
 
 235
Off-system sales and transmission services revenues (included in base rates)11
 
 
 11
Transmission services revenue excluded from FAC until 2013(32) 
   (32)
Recovery of FAC under-recovery(c)
67
 
 
 67
FAC prudence review charge(25) 
 
 (25)
MEEIA (energy efficiency) recovery mechanisms72
 
 
 72
Transmission services revenues
 25
 10
 35
Gross receipts tax12
 
 
 12
Illinois pass-through power supply costs
 (316) 
 (316)
Hurricane Sandy relief recovery(7) (10) 
 (17)
Bad debt, energy efficiency programs, and environmental remediation cost riders
 (15) 
 (15)
Sales volume (excluding the estimated effect of abnormal weather)4
 2
 
 6
Other(4) (1) (4) (9)
Total electric revenue change$247
 $(278) $6
 $(25)
Fuel and purchased power change:       
Energy costs included in base rates and other$(88) $
 $2
 $(86)
Effect of weather (estimate)(b)
(1) 9
 
 8
Recovery of FAC under-recovery(c)
(67) 
 
 (67)
FERC-ordered power purchase settlement(24) 
 
 (24)
Illinois pass-through power supply costs
 316
 
 316
Total fuel and purchased power change$(180) $325
 $2
 $147
Net change in electric margins$67
 $47
 $8
 $122
Natural gas revenue change:       
Effect of weather (estimate)(b)
$29
 $110
 $
 $139
Base rates (estimate)
 2
 
 2
Hurricane Sandy relief recovery
 (3) 
 (3)
Gross receipts tax1
 7
 
 8
Pass-through purchased gas costs(12) (56) 
 (68)
Sales volume (excluding the effect of abnormal weather) and other

4
 1
 (1) 4
Total natural gas revenue change$22
 $61
 $(1) $82
Gas purchased for resale change:       
Effect of weather (estimate)(b)
$(26) $(96) $
 $(122)
Pass-through purchased gas costs12
 56
 
 68
Total gas purchased for resale change$(14) $(40) $
 $(54)
Net change in natural gas margins$8
 $21
 $(1) $28
2016 versus 2015Ameren
Missouri
 Ameren Illinois Electric Distribution 
Ameren
Illinois
Natural Gas
 
Ameren Transmission(a)
 Other /
Intersegment
Eliminations
 Ameren
Electric revenue change:           
Effect of weather (estimate)(b)
$57
 $15
 $
 $
 $
 $72
Base rates (estimate)48
 38
 
 102
 
 188
Sales volume (excluding the New Madrid Smelter and estimated effect of weather)

7
 
 
 
 
 7
New Madrid Smelter revenues(129) 
 
 
 
 (129)
Off-system sales and capacity revenues153
 
 
 
 
 153
MEEIA 2013 net shared benefits(85) 
 
 
 
 (85)
MEEIA 2013 performance incentive28
 
 
 
 
 28
Transmission services revenues3
 
 
 
 
 3
Purchased power rider order in 2015
 (15) 
 
 
 (15)
Other(1) (1) 
 (6) (21) (29)
Cost recovery mechanisms – offset in fuel and purchased power(c)
(118) (22) 
 
 
 (140)
Other cost recovery mechanisms(d)
(39) 2
 
 
 
 (37)
Total electric revenue change$(76) $17
 $
 $96
 $(21) $16
Fuel and purchased power change:           
Energy costs (excluding the New Madrid Smelter and estimated effect of weather)$(145) $
 $
 $
 $
 $(145)
New Madrid Smelter energy costs72
 
 
 
 
 72
Effect of weather (estimate)(b)
(9) (8) 
 
 
 (17)
Effect of higher net energy costs included in base rates(34) 
 
 
 
 (34)
Transmission services charges(16) 
 
 
 
 (16)
Other6
 
 
 
 20
 26
Cost recovery mechanisms – offset in electric revenue(c)
118
 22
 
 
 
 140
Total fuel and purchased power change$(8) $14
 $
 $
 $20
 $26
Net change in electric margins$(84) $31
 $
 $96
 $(1) $42
Natural gas revenue change:           
Effect of weather (estimate)(b)
$(7) $
 $13
 $
 $
 $6
Base rates (estimate)
 
 42
 
 
 42
Other
 
 2
 
 
 2
Cost recovery mechanisms – offset in natural gas purchased for resale(c)
(2) 
 (76) 
 
 (78)
Other cost recovery mechanisms(d)

 
 (10) 
 
 (10)
Total natural gas revenue change$(9) $
 $(29) $
 $
 $(38)
Natural gas purchased for resale change:           
Effect of weather (estimate)(b)
$6
 $
 $(10) $
 $
 $(4)
Cost recovery mechanisms – offset in natural gas revenue(c)
2
 
 76
 
 
 78
Total natural gas purchased for resale change$8
 $
 $66
 $
 $
 $74
Net change in natural gas margins$(1) $
 $37
 $
 $
 $36
(a)Primarily includes amounts for ATXIIncludes an increase in transmission margins of $26 million and intercompany eliminations.$43 million in 2017 and 2016, respectively, at Ameren Illinois. The 2017 increase in transmission margins at Ameren Illinois is the change in base rates (estimate) of $26 million. The 2016 increase in transmission margins at Ameren Illinois is the sum of the change in base rates (estimate) of $49 million and the change in Other of -$6 million.
(b)Represents the estimated variation resulting primarily from the effects of changes in cooling and heating degree-days on electric and natural gas demand compared with the prior year; this variation is based on temperature readings from the National Oceanic and Atmospheric Administration weather stations at local airports in our service territories.
(c)RepresentsIncludes amounts for power supply, renewable energy adjustment, zero-emission credits, transmission services, and purchased natural gas cost recovery mechanisms, as well as FAC recoveries. Electric and natural gas revenue changes are offset by corresponding changes in fuel, purchased power, and natural gas purchased for resale, resulting in no change to electric and natural gas margins.
(d)Includes amounts for bad debt, energy-efficiency programs, and environmental remediation cost recovery mechanisms, as well as gross receipts tax revenues. See Other Operations and Maintenance Expenses or Taxes Other Than Income Taxes in this section for the change in the net energy costs recovered under the FAC through customer rates, with corresponding offsetsrelated offsetting increase or decrease to fuel expense due to the amortization of a previously recorded regulatory asset.expense. These items have no overall impact on earnings.
20142017 versus 20132016
Ameren Corporation
Ameren'sAmeren’s electric margins increased $148$105 million, or 4%3%, in 20142017 compared with 2013. Ameren's2016, primarily because of increased margins at Ameren Transmission and Ameren Missouri. Ameren’s natural gas margins increased $45$17 million, or 9%3%, in 20142017 compared with 2013. These results were primarily driven by Ameren Missouri and2016, because of increased margins at Ameren Illinois results, as discussed below. Ameren's electricNatural Gas.

Ameren Transmission
Ameren Transmission’s margins also reflect the results of operations of ATXI. ATXI’s transmission revenues increased $14$71 million, or 20%, in 20142017 compared with 2013, reflecting2016. Margins were favorably affected by increased capital investment, as evidenced by an increase in rate base investment andof 23% in 2017 compared with 2016, as well as higher recoverable costs in 2017 compared with 2016 under forward-looking formula ratemaking.
Ameren Missouri
Ameren Missouri has Margins were unfavorably affected by the absence in 2017 of a FAC cost recovery mechanism that allows Ameren Missouri to recover, through customer rates, 95%temporarily higher allowed return on common equity of changes12.38% for nearly four months in net energy costs greater or less than the amount set in base rates without a traditional rate proceeding, subject to MoPSC prudence review. Net energy costs include fuel and purchased power costs, including transportation charges and revenues, net of off-system sales. Ameren Missouri accrues,2016 as a regulatory asset, net energy costs that exceedresult of the amount setexpiration of the refund period in base rates (FAC under-recovery). Net recovery of these costs through customer rates does not affect Ameren Missouri electric


38


margins, as increases in revenue are offset by a corresponding increase in fuel expense to reduce the previously recognized FAC regulatory asset.
Ameren Missouri's electric margins increased $36 million, or 1%, in 2014 compared with 2013. The following items had a favorable effect on Ameren Missouri's electric margins:
The absence in 2014 of a July 2013 MoPSC FAC prudence review order, which decreased 2013 revenues by $25 million. Ameren Missouri recorded a FAC prudence review charge in 2013 for its estimated obligation to refund to its electric customers the earnings associated with sales recognized by Ameren Missouri from October 1, 2009, to May 31, 2011.February 2015 FERC complaint case. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information regarding the FAC prudence review charge.
Higher revenues associated with the MEEIA energy efficiency program cost recovery mechanism and lost revenue recovery mechanism ($7 million and $15 million, respectively), which increased revenues by a combined $22 million. The higher revenues were driven by greater customer participation in the second year of the MEEIA program, which led to higher recovery of lost revenues. The lost revenue recovery mechanism helps compensate Ameren Missouriallowed return on common equity for lower sales volumes from energy-efficiency-related volume reductions in current and future periods. See Other Operations and Maintenance Expenses in this section for the related offsetting increase in customer energy efficiency program costs.
Winter temperatures in 2014 that were colder than in 2013, as heating degree-days increased 5%, which resulted in higher sales volumes and contributed to an estimated $3 million increase in margins. The change in weather margin is the sum of the effect of weather in electric revenues (+$8 million) and the effect of weather in fuel and purchased power (-$5 million) in the above table.
Ameren Missouri's electric margins were unfavorably affected by lower sales volumes primarily caused by the MEEIA
programs. Lower sales volumes from energy-efficiency-related volume reductions are offset by the MEEIA lost revenue recovery mechanism. Excluding the estimated effect of abnormal
weather, total retail sales volumes decreased 1%, which decreased revenues by an estimated $22 million, partially offset by a decrease in net energy costs of $6 million. The decrease in net energy costs is the sum of the change in energy costs included in base rates (+$18 million) and the change in off-system sales andFERC-regulated transmission services revenues (-$12 million) in the above table.rate base.
Ameren Missouri has a cost recovery mechanism for natural gas purchased on behalf of its customers. These pass-through purchased gas costs do not affect Ameren Missouri's natural gas margins as they are offset by a corresponding amount in revenues.
Ameren Missouri'sMissouri’s electric margins increased $34 million, or 1%, in 2017 compared with 2016. Ameren Missouri’s natural gas margins were comparable between the years.
Ameren Illinois
Ameren Illinois has a cost recovery mechanism for power purchased on behalf of its customers. These pass-through power supply costs do not affect Ameren Illinois' electric margins, as they are offset by a corresponding amount in revenues.
Ameren Illinois participates in the IEIMA's performance-based
formula ratemaking framework. The IEIMA provides for an annual reconciliation of the electric delivery service revenue requirement necessary to reflect the actual costs incurred in a given year with the revenue requirement included in customer rates for that year, including an allowed return on equity. See Other Operations and Maintenance Expenses in this section for additional information regarding the revenue requirement. If the current year's revenue requirement is greater than the revenue requirement reflected in that year's customer rates, an increase to electric operating revenues with an offset to a regulatory asset is recorded to reflect the expected recovery of those additional costs from customers within the next two years. If the current year's revenue requirement is less than the revenue requirement reflected in that year's customer rates, a reduction to electric operating revenues with an offset to a regulatory liability is recorded to reflect the expected refund to customers within the next two years. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information regarding Ameren Illinois' revenue requirement reconciliation pursuant to the IEIMA.
Ameren Illinois' electric margins increased $98 million, or 9%, in 2014 compared with 2013. The following items had a favorable effect on Ameren Illinois'Missouri’s electric margins:margins in 2017 compared with 2016:
Electric delivery service revenues that
Higher electric base rates, effective April 1, 2017, as a result of the March 2017 MoPSC electric rate order, which increased margins by an estimated $56 million, primarily caused by increased rate base and higher recoverable costs under formula ratemaking pursuant to the IEIMA.
Transmission services margin that increased by $34 million, largely due to a higher transmission services revenue requirement, driven primarily by increased rate base investment.$100 million. The change in transmission services marginelectric base rates is the sum of the change in base rates (estimate) (+$61 million) and the effect of lower net energy costs included in base rates (+$39 million) in the Electric and Natural Gas Margins table above. Higher electric base rates incorporated the effect of the suspension of operations at the New Madrid Smelter.
Increased transmission services revenues (+$35 million) and the change in transmission services expenses (-$1 million) in the above table.due to additional rate base investment, which increased margins by $11 million.
A net increase inThe recovery of bad debt charge-offs, customer energy efficiency programlabor and benefit costs and environmental remediation costs through rate-adjustment mechanisms,for crews assisting other utilities with power restoration efforts primarily caused by hurricane damage, which increased revenues by $25 million. See Other Operations and Maintenance Expenses in this section for the related offsetting net increase in bad debt, customer energy efficiency, and environmental remediation costs.
Excluding the estimated effect of abnormal weather, residential retail sales volumes that increased 1%, which increased revenues by $3$7 million.
The following items had an unfavorable effect on Ameren Illinois'Missouri’s electric margins in 20142017 compared with 2013:2016:
Reserves recorded for estimated refunds regarding FERC proceedings from a November 2013 complaint case seeking a reduction in the allowed base return on common equity for


39


the MISO tariff, a June 2014 order regarding acquisition premiums, and other matters, which decreased revenues by $21 million. See Note 2 - Rate and Regulatory Matters under Part II, Item 8, of this report for additional information.
Summer temperatures in 2014 that were milder than in 2013,2017 compared with 2016, as cooling degree-days decreased 6%, which resulted in lower sales volumes and contributed to an estimated $5 million reduction in revenues.
Ameren Illinois has a cost recovery mechanism for natural gas purchased on behalf10%. The effect of its customers. These pass-through purchased gas costs do not affect Ameren Illinois' natural gas margins as they are offset by a corresponding amount in revenues.
Ameren Illinois' natural gas delivery service margins increased $44 million, or 11%, in 2014 compared with 2013. The following items had a favorable effect on Ameren Illinois' natural gas margins:
Higher natural gas delivery service rates effective January 2014, which increased revenues by an estimated $32 million.
Winter temperatures in 2014 that were colder than in 2013 as heating degree-days increased 6%, which resulted in higher sales volumes and increasedweather decreased margins by an estimated $4$52 million. The change in margins due to weather margin is the sum of the effect of weather in(estimate) on electric revenues (+(-$3265 million) and the effect of weather in gas purchased for resale (-$28 million) in the above table.
Increased gross receipts taxes due to higher natural gas rates and higher sales volumes as a result of colder winter temperatures in 2014, which increased revenues by $3 million. See Taxes Other Than Income Taxes in this section for the related offsetting increase to gross receipts taxes.
A $4 million net increase in recovery of bad debt charge-offs, customer energy efficiency program costs, and environmental remediation costs through rate-adjustment mechanisms. See Other Operations and Maintenance Expenses in this section for the related offsetting net increase in bad debt, customer energy efficiency, and environmental remediation costs.
2013 versus 2012
Ameren Corporation
Ameren's electric margins increased $122 million, or 4%, in 2013 compared with 2012. Ameren's natural gas margins increased $28 million, or 6%, in 2013 compared with 2012. These results were primarily driven by Ameren Missouri and Ameren Illinois results, as discussed below. Ameren's electric margins also reflect the results of operations of ATXI. ATXI’s transmission revenues increased $10 million in 2013 compared with 2012, due to the inclusion of its 2013 rate base investment and recoverable costs under forward-looking formula ratemaking.
Ameren Missouri
Ameren Missouri's electric margins increased $67 million, or
3%, in 2013 compared with 2012. The following items had a favorable effect(estimate) on Ameren Missouri's electric margins:
Higher electric base rates effective January 2013 as a result of the December 2012 MoPSC electric rate order, which increased revenues by an estimated $178 million, partially offset by an increase in net energy costs of $78 million. The increase in net energy costs is the sum of the change in energy costs included in base rates (-$89 million) and the change in off-system sales and transmission services revenues (+$11 million) in the above table. Transmission services revenues were excluded from FAC until 2013 ($32 million).
Higher revenues associated with the MEEIA energy efficiency program cost recovery mechanism and lost revenue recovery mechanism ($35 million and $37 million, respectively), effective January 2013, which increased revenues by a combined $72 million. The lost revenue recovery mechanism helps compensate Ameren Missouri for lower sales from energy-efficiency-related volume reductions in current and future periods. See Other Operations and Maintenance Expenses in this section for the related offsetting increase in energy efficiency program costs.
Increased gross receipts taxes, due primarily to the higher base rates, which increased revenues by $12 million. See Taxes Other Than Income Taxes in this section for the related offsetting increase to gross receipts taxes.
Excluding the estimated effect of abnormal weather, total retail sales volumes that increased 1%, which increased revenues by an estimated $4 million.
The following items had an unfavorable effect on Ameren Missouri's electric margins in 2013 compared with 2012:
Summer temperatures in 2013 that were milder than the warmer-than-normal temperatures in 2012, as cooling degree-days decreased 22%, which resulted in lower sales volumes and contributed to an estimated $30 million decrease in margins. The change in weather margin is the sum of the effect of weather in electric revenues (-$29 million) and the effect of weather in fuel and purchased power (-(+$113 million) in the above table.Electric and Natural Gas Margins table above.
A reduction in revenues resulting from a JulyThe absence of the MEEIA 2013 MoPSC FAC order. Ameren Missouri recorded a FAC prudence review charge for its estimated obligation to refund to its electric customers the earnings associated with sales recognized by Ameren Missouri from October 1, 2009, to May 31, 2011,performance incentive, which decreased revenuesmargins by $25$28 million. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information regarding the FAC prudence review charge.MEEIA 2013 performance incentive.
The absence in 2013
Increased transmission services charges resulting from cost-sharing by all MISO participants of a reduction in purchased power expense as a result of a FERC-ordered refund received in 2012 from Entergy for a power purchase agreement that expired in 2009,additional MISO-approved electric transmission investments made by other entities, which decreased margins by $24$16 million.
Excluding the effect of reduced sales to the New Madrid Smelter, the estimated effect of weather, and the estimated effects of MEEIA 2016 customer energy-efficiency programs, total retail sales volumes decreased by less than 1%, which decreased revenues by $6 million. Lower sales volumes were due, in part, to the absence of the leap year benefit experienced in 2016, partially offset by growth. While MEEIA 2016 customer energy-efficiency programs reduced retail sales volumes, the throughput disincentive recovery ensured that electric margins were not affected.
Ameren Illinois
Ameren Illinois’ electric margins increased $30 million, or 2%, in 2017 compared with 2016, driven by increases in Ameren Illinois Electric Distribution ($4 million) and Ameren Illinois Transmission ($26 million) margins. Ameren Illinois Natural Gas’ margins increased $17 million, or 4%, in 2017 compared with 2016, primarily due to increased QIP rider recoveries, which increased margins by $12 million.
TheAmeren Illinois Electric Distribution
Ameren Illinois Electric Distribution’s margins increased $4 million, or less than 1%, in 2017 compared with 2016. Ameren Illinois Electric Distribution’s margins were favorably affected by an increase in rate base of 6% in 2017 compared with 2016 and a higher return on common equity due to an increase in 30-year United States Treasury bond yields of 29 basis points in 2017 compared with 2016, as well as higher recoverable expenses under formula ratemaking pursuant to the IEIMA, which collectively increased margins by $42 million. Ameren Illinois Electric Distribution’s margins were unfavorably affected by the absence of the impact of warmer-than-normal summer temperatures experienced in 2013 of recovery of labor and benefit costs for crews assisting with Hurricane Sandy power restoration in 2012,2016, which decreased margins by $7 million and was


40


fully offset by a related decrease in operations and maintenance costs, with no overall effect on net income. The costs related to storm assistancean estimated $6 million. Ameren Illinois Electric Distribution revenues were reimbursed by the utilities receiving the assistance.
Ameren Missouri's natural gas margins increased $8 million, or 11%, in 2013 compared with 2012. The following items had a favorable effect on Ameren Missouri's natural gas margins:
Excluding that the estimated effect of abnormal weather, revenues increased by $4 million, driven by 11% higher natural gas transportation sales and 2% higher retail sales.
Winter temperatures in 2013 that were colder than the warmer-than-normal temperatures in 2012, as heating degree-days increased 35%, which resulted in higherdecoupled from sales volumes and increased margins by an estimated $3 million.beginning in 2017. The change in margins due to weather margin is the sum of the effect of weather in(estimate) on electric revenues (+(-$295 million) and the effect of weather in gas(estimate) on fuel and purchased for resalepower (-$261 million) in the above table.Electric and Natural Gas Margins table above.
Increased gross receipts taxes due toAmeren Illinois Transmission
Ameren Illinois Transmission’s margins increased $26 million, or 11%, in 2017 compared with 2016. Margins were favorably affected by increased capital investment, as evidenced by an increase in rate base of 16% in 2017 compared with 2016, as well as higher salesrecoverable costs

in 2017 compared with 2016 under forward-looking formula ratemaking. Margins were unfavorably affected by the absence in 2017 of a temporarily higher allowed return on common equity of 12.38% for nearly four months in 2016 as a result of colder winter weatherthe expiration of the refund period in 2013 compared with 2012, which increased revenues by $1 million. See Taxes Other Than Income Taxes in this section for the related offsetting increase to gross receipts taxes.February 2015 FERC complaint case.
2016 versus 2015
Ameren Illinois
Ameren Illinois'Ameren’s electric margins increased $47$42 million, or 5%1%, in 20132016 compared with 2012. The following items had a favorable effect on2015, primarily because of increased margins at Ameren Illinois' electric margins:Transmission and Ameren Illinois Electric Distribution, partially offset by decreased margins at Ameren Missouri. Ameren’s natural gas margins increased $36 million, or 7%, in 2016 compared with 2015, primarily because of increased margins at Ameren Illinois Natural Gas.
Electric delivery service revenues thatAmeren Transmission
Ameren Transmission’s margins increased by an estimated $57$96 million, primarily causedor 37%, in 2016 compared with 2015. Margins were favorably affected by increased capital investment, as evidenced by a 42% increase in rate base used to calculate the revenue requirement, as well as higher recoverable costs in 2016 compared with 2015 under forward-looking formula ratemaking. Margins also benefited from a temporarily higher allowed return on common equity and higher recoverable costs under formula ratemaking pursuant toof 12.38% for nearly four months in 2016 as a result of the IEIMA.expiration of the refund period in the February 2015 FERC complaint case.
Transmission services revenues that increased by $25Ameren Missouri
Ameren Missouri’s electric margins decreased $84 million, due to the implementation of a 2013 forward-looking rate calculation which incorporated the rate base increaseor 3%, in 2013, pursuant to a 2012 FERC order. In 2012, rates2016 compared with 2015. Ameren Missouri’s natural gas margins were based on a historical period.comparable between years.
The following items had an unfavorable effect on Ameren Illinois'Missouri’s electric margins in 20132016 compared with 2012:2015:
A decrease
The suspension of the New Madrid Smelter operations in recoverythe first quarter of bad debt charge-offs, customer energy efficiency program costs, and environmental remediation costs through rate-adjustment mechanisms,2016, which decreased revenuesmargins by $15$57 million. See Other Operations and Maintenance Expenses in this section for the related offsetting decrease in bad debt, customer energy efficiency, and environmental remediation costs.
Summer temperatures in 2013 that were milder than the warmer-than-normal temperatures in 2012, as cooling degree-days decreased 21%, which resulted in lower sales volumes and contributed to an estimated $11 million decrease in margins. The change in weather marginmargins due to lower sales to the New Madrid Smelter is the sum of the effect of weather in electricNew Madrid Smelter revenues (-$20129 million) and the effect of weather in fuel and purchased powerNew Madrid Smelter energy costs (+$972 million) in the above table.Electric and Natural Gas Margins table above. New Madrid Smelter energy costs included the impact of a provision in the FAC tariff that, under certain circumstances, allowed Ameren Missouri to retain a portion of the revenues from any off-system sales it made as a result of reduced sales to the New Madrid Smelter.
The absence inexpiration of MEEIA 2013, of recovery of labor and benefit costs for crews assisting with Hurricane Sandy power restoration in 2012, which decreased margins by $10 million$57 million. The change in margins due to the expiration of MEEIA 2013 is the sum of MEEIA 2013 net shared benefits (-$85 million) and was fully offsetMEEIA 2013 performance incentive (+$28 million) in the Electric and Natural Gas Marginstable above. Net shared benefits compensated Ameren Missouri for lower sales volumes from energy-efficiency-related volume reductions in current and future periods. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for information regarding the MEEIA 2013 performance incentive.
Increased transmission services charges resulting from cost-sharing by a related decrease in operations and maintenance costs, with no overall effect on net income. The costs related to storm assistance were reimbursedall MISO participants of additional MISO-approved electric transmission investments made by the utilities receiving the assistance.other entities, which decreased margins by $16 million.
Ameren Illinois' natural gas margins increased $21 million, or 6%, in 2013 compared with 2012. The following items had a favorable effect on Ameren Illinois' natural gas margins:Missouri’s electric margins in 2016 compared with 2015:
Winter temperatures
Temperatures in 2013 that2016 were colder than warmer-than-normal temperatures in 2012,warmer compared with 2015, as cooling degree-days increased 16%, while heating degree-days decreased 6%. The net effect of weather increased 29%,margins by an estimated $48 million. The change in margins due to weather is the sum of the effect of weather (estimate) on electric revenues (+$57 million) and the effect of weather (estimate) on fuel and purchased power (-$9 million) in the Electric and Natural Gas Margins table above.
Higher electric base rates, effective May 30, 2015, as a result of the April 2015 MoPSC electric rate order, which resulted in higher sales volumes and increased margins by an estimated $14 million. The change in electric base rates is the sum of the change in base rates (estimate) (+$48 million) and the change in effect of higher net energy costs included in base rates (-$34 million) in the Electric and Natural Gas Margins table above.
Lower net energy costs as a result of the 5% of changes retained by Ameren Missouri through the FAC, primarily due to higher MISO capacity revenues, which increased margins by $8 million. The change in net energy costs is the sum of the change in off-system sales and capacity revenues (+$153 million) and the change in energy costs (excluding the New Madrid Smelter and estimated effect of weather) (-$145 million) in the Electric and Natural Gas Margins table above.
Excluding the effect of reduced sales to the New Madrid Smelter and the estimated effect of weather, margintotal retail sales volumes increased by less than 1%, which increased revenues by $7 million, due to an additional day as a result of the leap year and growth, partially offset by the carryover effect of MEEIA 2013 on sales volumes and the effect of MEEIA 2016 customer energy-efficiency programs. MEEIA 2016 customer energy-efficiency programs reduced retail sales volumes but the throughput disincentive recovery ensured that electric margins were not affected.

Ameren Illinois
Ameren Illinois’ electric margins increased $74 million, or 6%, in 2016 compared with 2015, driven by increases in Ameren Illinois Electric Distribution ($31 million) and Ameren Illinois Transmission ($43 million) margins. Ameren Illinois Natural Gas’ margins increased $37 million, or 9%, in 2016 compared with 2015.
Ameren Illinois Electric Distribution
Ameren Illinois Electric Distribution’s margins increased $31 million, or 3%, in 2016 compared with 2015. The following items had a favorable effect on Ameren Illinois Electric Distribution’s electric margins:
Revenues increased by $38 million, primarily because of an increase in rate base of 8% and higher recoverable costs in 2016 compared with 2015, under formula ratemaking pursuant to the IEIMA. These revenues were reduced by a lower return on equity due to a reduction in 30-year United States Treasury bond yields, which decreased 24 basis points in 2016 compared with 2015.
Temperatures in 2016 were warmer compared with 2015, as cooling degree-days increased 13%, while heating degree-days decreased 5%. The net effect of weather increased margins by an estimated $7 million. The change in margins due to weather is the sum of the effect of weather in(estimate) on electric revenues (+$11015 million) and the effect of weather in gas(estimate) on fuel and purchased for resalepower (-$968 million) in the above table.Electric and Natural Gas Margins table above.
Increased gross receipts taxes due to higher sales as a result of colder winter weather in 2013 compared with 2012, which increased revenues by $7 million. See Taxes Other Than Income Taxes in this section for the related offsetting increase to gross receipts taxes.
Higher natural gas delivery service rates effective in late January 2012, which increased revenues by an estimated $2 million.
Ameren Illinois' natural gasIllinois Electric Distribution’s margins were unfavorably affected by the absence in 20132016 of recoverya January 2015 ICC order regarding Ameren Illinois’ cumulative power usage cost and its purchased power rider mechanism, which increased margins by $15 million in 2015.
Ameren Illinois Natural Gas
Ameren Illinois Natural Gas’ margins increased $37 million, or 9%, in 2016 compared with 2015. The following items had a favorable effect on Ameren Illinois Natural Gas’ margins:
Higher natural gas base rates in 2016, which increased margins by an estimated $42 million.
The absence of laborwarmer-than-normal 2015 winter temperatures and benefit costs for crews assisting with Hurricane Sandy power restorationthe application of the VBA in 2012,2016, which decreasedincreased margins by $3 million. The VBA, which was approved by the ICC in December 2015, eliminated the impact of weather on natural gas margins for residential and small nonresidential customers in 2016. The change in margins due to weather is the sum of the effect of weather (estimate) on revenues (+$13 million) and the effect of weather (estimate) on natural gas purchased for resale (-$10 million) in the Electric and Natural Gas Margins table above.
Ameren Illinois Transmission
Ameren Illinois Transmission’s margins increased $43 million, and was fully offsetor 23%, in 2016 compared with 2015. Margins were favorably affected by increased capital investment, as evidenced by a related decrease27% increase in operations and maintenancerate base used to calculate the revenue requirement, as well as higher recoverable costs in 2016 compared with no overall effect2015 under forward-looking formula ratemaking. Margins also benefited from a temporarily higher allowed return on net income.common equity of 12.38% for nearly four months in 2016 as a result of the expiration of the refund period in the February 2015 FERC complaint case.
Other Operations and Maintenance Expenses
20142017 versus 20132016
Ameren
Other operations and maintenance expenses decreased $16 million in 2017 compared with 2016, because of items discussed below and an increase in intersegment eliminations of $14 million.
Ameren CorporationTransmission
Other operations and maintenance expenses increased $74$3 million in 20142017 compared with 2013. Other operations and maintenance expenses increased $31 million at Ameren Missouri and increased $78 million at Ameren Illinois. Partially offsetting the increases at Ameren Missouri and Ameren Illinois were decreased corporate expenses between years2016, primarily because of $35 million, primarilyan increase in labor costs due to the substantial elimination of businessincreased wages and administrative costs previously incurred in support of the divested merchant generation business.staffing additions.
Ameren Missouri
Other operations and maintenance expenses were $31$9 million higher in 20142017 compared with 2013.2016. The following items increased other operations and maintenance expenses between years:
MEEIA customer energy-efficiency program costs increased by $22 million.

Labor and benefit costs increased by $11 million due to increased wages, as well as assistance provided to other utilities to aid in storm recovery efforts, primarily caused by hurricane damage.
Energy center maintenance costs, excluding refueling and maintenance outage costs at the Callaway energy center, increased by $3 million, primarily due to higher coal handling charges.
The following items decreased other operations and maintenance expenses between years:
Employee benefit costs decreased by $21 million, primarily due to a reduction in the base level of pension and postretirement expenses allowed in rates as a result of the March 2017 MoPSC electric rate order, as well as changes in the market value of company-owned life insurance.
Solar rebate costs decreased by $8 million, primarily as a result of the March 2017 MoPSC electric rate order.
Ameren Illinois
Other operations and maintenance expenses decreased $15 million in 2017 compared with 2016, as discussed below. Other operations and maintenance expenses were comparable at Ameren Illinois Transmission in 2017 compared with 2016.
Ameren Illinois Electric Distribution
Other operations and maintenance expenses were $26 million lower in 2017 compared with 2016, primarily because of a $47 million decrease in customer energy-efficiency costs, which was partially offset by an $11 million increase in environmental remediation costs and a $3 million increase in labor costs resulting from increased wages.
Ameren Illinois Natural Gas
Other operations and maintenance expenses were $9 million higher in 2017 compared with 2016, primarily because of increased bad debt, customer energy-efficiency, and environmental remediation costs.
2016 versus 2015
Ameren
Other operations and maintenance expenses decreased $18 million in 2016 compared with 2015, as discussed below.
Ameren Transmission
Other operations and maintenance expenses increased $4 million in 2016 compared with 2015, primarily because of an increase in system operations and labor costs.
Ameren Missouri
Other operations and maintenance expenses were $32 million lower in 2016 compared with 2015. The following items decreased other operations and maintenance expenses between years:
MEEIA customer energy-efficiency program costs decreased by $34 million in 2016, primarily because of the expiration of MEEIA 2013, partially offset by costs incurred for MEEIA 2016.
Energy center maintenance costs, excluding refueling and maintenance outage costs at the Callaway energy center discussed below, decreased by $18 million, primarily because of reduced staffing costs and decreased routine maintenance costs, partially offset by higher coal handling charges.
Electric distribution maintenance expenditures decreased by $16 million, primarily related to reduced system repair and vegetation management work.
Employee benefit costs decreased by $15 million, primarily because of a $6 million reduction in the base level of pension and postretirement expenses allowed in rates, as a result of the April 2015 MoPSC electric rate order, and lower medical benefit costs, as well as a $4 million decrease due to changes in the market value of company-owned life insurance.
The following items increased other operations and maintenance expenses between years:
Refueling and maintenance outage costs at the Callaway energy center increased by $26 million, primarily because of costs for the 2016 scheduled refueling and maintenance outage. There was no Callaway refueling and maintenance outage in 2015.
Litigation costs increased by $11 million, primarily related to increases in estimated obligations for pending legal claims.
Solar rebate costs increased by $9 million, as a result of the April 2015 MoPSC electric rate order.
Storm-related repair costs increased by $7 million.

Ameren Illinois
Other operations and maintenance expenses increased $7 million in 2016 compared with 2015, as discussed below.
Ameren Illinois Electric Distribution
Other operations and maintenance expenses were $6 million higher in 2016 compared with 2015. The following items increased other operations and maintenance expenses between years:
Labor costs that increased $17by $6 million, primarily because of wage increases.


41


Litigationstaffing additions to meet enhanced standards and asbestos claim costs that increased $14 million due, in part,goals related to the proceedings discussed in Note 2 – Rate and Regulatory Matters and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.IEIMA.
An $8 million increase in disposalStorm-related repair costs for low-level radioactive nuclear waste at the Callaway energy center.increased by $3 million.
An increase of $7 million inBad debt, customer energy efficiency, programand environmental remediation costs dueincreased by $2 million.
Litigation costs increased by $2 million, primarily related to the MEEIA requirements. These costs were offset by increased electric revenues from customer billings, with no overall effect on net income.
A reduction of $3 millionincreases in unrealized net MTM gains, resulting from changes in the market value of investments used to support Ameren’s deferred compensation plans.estimated obligations for pending legal claims.
The following items decreased other operations and maintenance expenses between years:
A $13 million reduction in energy center costs, primarily related to coal handling.
A decrease of $7 million in storm-related costs due to fewer major storms in 2014.
A reduction of $2 million in refueling and maintenance costs associated with the scheduled Callaway outages. The 2014 outage costs were $36 million compared with 2013 outage costs of $38 million.
Ameren Illinois
Pursuant to the provisions of the IEIMA, recoverable electric delivery service costs that were incurred during the year but not recovered through riders are included in Ameren Illinois’ revenue requirement reconciliation, which results in a corresponding adjustment to electric operating revenues, with no overall effect on net income. These recoverable electric delivery service costs include other operations and maintenance expenses, depreciation and amortization, taxes other than income taxes, interest charges, and income taxes.
Other operations and maintenance expenses were $78 million higher in 2014 compared with 2013. The following items increased other operations and maintenance expenses between years:
An increase of $29 million in bad debt, customer energy efficiency, and environmental remediation costs. These expenses are recovered by Ameren Illinois' rider mechanisms through additional electric and natural gas revenues, resulting in no overall effect on net income.
Labor costs that increased $17 million, primarily because of staff additions to meet enhanced reliability standards and customer service goals related to the IEIMA and wage increases.
An increase of $13 million in electric distribution maintenance expenditures, primarily related to increased system repair and vegetation management work.
Asbestos claim costs that increased $8 million.
An increase of $7 million in information technology service expenses, partially related to the IEIMA
implementation.
An increase of $6 million in natural gas maintenance expenditures, primarily related to pipeline integrity compliance.
An increase of $4 million in rental expense, primarily related to software from affiliated companies.
A reduction of $2 million in unrealized net MTM gains, resulting from changes in the market value of investments used to support Ameren’s deferred compensation plans.
Other operations and maintenance expenses decreased between years because of a reduction in employeeEmployee benefit costs of $12decreased by $6 million, primarily due to lower pension and postretirement expenses caused by changes in actuarial assumptions and the performance of plan assets.
2013 versus 2012Electric distribution operations and maintenance expenditures decreased by $3 million, primarily related to reduced circuit maintenance work, partially offset by increased vegetation management work.
Ameren CorporationIllinois Natural Gas
Other operations and maintenance expenses increased $106were $4 million lower in 20132016 compared with 2012. Other2015. The following items decreased other operations and maintenance expenses increased $88between years:
Bad debt, customer energy-efficiency, and environmental remediation costs decreased by $10 million.
Employee benefit costs decreased by $5 million, at Ameren Missouriprimarily because of lower pension and increased $9 million at Ameren Illinois. In addition topostretirement expenses caused by changes in actuarial assumptions and the increases at Ameren Missouri and Ameren Illinois, corporate expenses increased $9 million between years, primarily due to business and administrative costs incurred in supportperformance of the divested merchant generation business.plan assets.
Ameren Missouri
Other operations and maintenance expenses increased $88 million in 2013 compared with 2012. The following items increased other operations and maintenance expenses between years:
An increase of $35 million in customer energy efficiency program costs due to the MEEIA requirements, which became effective in rates in January 2013. These costs were offsetRepairs and compliance expenditures increased by increased electric revenues from customer billings, with no overall effect on net income.
Energy center maintenance costs that increased $31$8 million, primarily duerelated to $38 million inincreased pipeline integrity and storage field maintenance.
Litigation costs for the scheduled 2013 Callaway energy center refueling and maintenance outage. There was no outage in 2012. The 2013 increase was partially offsetincreased by a $7 million reduction in costs due to fewer major boiler outages at coal-fired energy centers.
Employee benefit costs that increased $14$2 million, primarily duerelated to higher pension expense and increased amortization of prior-year pension deferrals from the pension and postretirement benefit cost tracker, each as a result of the 2012 MoPSC electric order. These costs were offset by increased electric revenues from customer billings, with no overall effect on net income.increases in estimated obligations for pending legal claims.
An increase of $9 million in storm-related repair costs, primarily due to major storms in 2013. A portion of these costs, $7 million, were offset by electric revenues from customer billings.
An increase of $6 million in bad debt expense due to


42


reduced customer collections and higher customer rates in 2013.Ameren Illinois Transmission
Other operations and maintenance expenses decreased between years because of the absencewere $5 million higher in 2013 of a $6 million charge recorded in 2012 for a canceled project.
Ameren Illinois
Other operations and maintenance expenses increased $9 million in 20132016 compared with 2012. The following items increased other operations and maintenance expenses between years:
Labor costs that increased $11 million,2015, primarily because of staff additions to comply with the requirements of the IEIMA.
Anan increase of $8 million in electric distribution maintenance expenditures, primarily related to increased vegetation management work.
An increase of $3 million in natural gas maintenance expenditures, primarily related to pipeline integrity compliance.
The following items decreased othersystem operations and maintenance expenses between years:labor costs.

Provision for Callaway Construction and Operating License
A decreaseAmeren Missouri discontinued its efforts to license and build a second nuclear unit at its existing Callaway energy center site in 2015, primarily because of $7changes in vendor support for licensing efforts at the NRC, Ameren Missouri’s assessment of long-term capacity needs, declining costs of alternative generation technologies, and the regulatory framework in Missouri. As a result of this decision, Ameren and Ameren Missouri recognized a $69 million noncash pretax provision in bad debt expense due to adjustments under2015 for the bad debt rider.
A decrease of $7 million in customer energy efficiency and environmental remediationpreviously capitalized COL costs.
Depreciation and Amortization
20142017 versus 2013
Ameren Corporation2016
Depreciation and amortization expenses increased $39$51 million, $19 million, and $22 million in 20142017 compared with 2013, primarily due to increased expenses2016 at Ameren, Ameren Missouri, and Ameren Illinois, as discussed below.respectively, primarily because of additional property, plant, and equipment across their respective segments.
Ameren Missouri2016 versus 2015
Depreciation and amortization expenses increased $19$49 million, $22 million, and $24 million in 20142016 compared with 2013, primarily because of electric system capital additions.
2015 at Ameren, Illinois
Depreciation and amortization expenses increased $20 million in 2014 compared with 2013, primarily because of electric system capital additions.
2013 versus 2012
Ameren Corporation
Depreciation and amortization expenses increased $33 million in 2013 compared with 2012, primarily because of increased expenses at Ameren Missouri, and Ameren Illinois, as discussed below.
Ameren Missouri
Depreciation and amortization expenses increased $14 million in 2013 compared with 2012,respectively, primarily because of a $6 million increase in depreciation expense related to electric system capital additionsadditional property, plant, and a $6 million increase in amortization expense related to the December 2012 MoPSC electric rate order resulting in higher amortization of pre-MEEIA customer energy efficiency program costs, which were reflected in electric rates effective in January 2013.
equipment across their respective segments. Additionally, Ameren Illinois
Depreciation and amortization expenses increased $22 million in 2013 compared with 2012, primarily because of new electricMissouri’s depreciation rates which increased depreciation expense by $17 million, as a result of a reduction in the useful lives of existingApril 2015 MoPSC electric meters that are being replaced with advanced metering infrastructure pursuant to the IEIMA. Additionally, electric system capital additions increased depreciation expense $6 million.rate order.

Taxes Other Than Income Taxes
20142017 versus 20132016
Ameren Corporation
Taxes other than income taxes increased $10 million in 20142017 compared with 2013, primarily because of increased expenses at Ameren Missouri and Ameren Illinois2016, as discussed below.
Ameren Missouri
Taxes other than income taxes increased $3 million, primarily because of an increase in property taxes resulting from higher tax rates and increased state and local assessments in 2014.
Ameren Illinois
Taxes other than income taxes increased $6 million because of a $3 million increase in gross receipts taxes, as a result of higher natural gas rates and higher sales volumes, and because of a $3 million increase in property taxes between years. The increased gross receipts taxes were offset by increased gross receipts tax revenues, with no overall effect on net income. See Excise Taxes in Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report for additional information.


43


2013 versus 2012
Ameren Corporation
Taxes other than income taxes increased $15 million in 2013 compared with 2012, primarily because of increased expensescomparable at Ameren Missouri and Ameren Illinois as discussed below.
Ameren Missouri
Taxes other than income taxes increased $15 million, primarily because of an increase of $13 million in gross receipts taxes as a result of increased sales. The increased gross receipts taxes were offset by increased gross receipts tax revenues, with no overall effect on net income.Transmission. See Excise Taxes in Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report for additional information.
Ameren Missouri
Taxes other than income taxes increased $3 million, primarily because of higher gross receipts taxes resulting from an increase in electric revenues.
Ameren Illinois
Taxes other than income taxes increased $2$5 million, primarily because of an increaseincreased property taxes at Ameren Illinois Electric Distribution and Ameren Illinois Natural Gas. Taxes other than income taxes were comparable at Ameren Illinois Transmission.
2016 versus 2015
Ameren
Taxes other than income taxes decreased $6 million in 2016 compared with 2015, primarily at Ameren Missouri, as discussed below. Taxes other than income taxes were comparable at Ameren Transmission, as well as at Ameren Illinois and its respective segments.
Ameren Missouri
Taxes other than income taxes decreased $10 million, primarily because of $7 million indecreased gross receipts taxes as a result of increased natural gas sales, partially offset by a decrease of $6 million in property taxes, primarily resulting from lower residential and commercial electric distribution tax credits received in 2013.revenues and because of decreased property taxes.
Other Income and Expenses
20142017 versus 20132016
Ameren Corporation
Other income, net of expenses, increased $14decreased $4 million in 20142017 compared with 2013,2016, primarily because of a $4 million reduction in charitable contributions at Ameren (parent) due to the timing of contributions, an increase in Ameren (parent) interestdecreased income from a note receivable with Marketing Company, and items at Ameren Illinois Electric Distribution, as discussed below.below, along with a decrease in the allowance for equity funds used during construction, partially offset by decreased donations in 2017. Other income, net of expenses, was comparable at the remaining Ameren segments. See Note 6 – Other Income and Expenses under Part II, Item 8, of this report for additional information.
Ameren MissouriIllinois
Other income, net of expenses, decreased $8 million, primarily because of lower interest income associated with a lower IEIMA revenue requirement reconciliation regulatory asset balance at Ameren Illinois Electric Distribution. Other income, net of expenses, was comparable at the remaining Ameren Illinois segments.
2016 versus 2015
Other income, net of expenses, was comparable between years.years at Ameren, Ameren Missouri, Ameren Illinois, and their respective segments.
Interest Charges
2017 versus 2016
Ameren
Interest charges increased $9 million in 2017 compared with 2016, as discussed below.

Ameren IllinoisTransmission
Other income, net of expenses,Interest charges increased $8$9 million, primarily because of increased income from customer-requested construction, and increased interest income on both the IEIMA 2013 and 2014 revenue requirement reconciliation regulatory assets. A decreasean increase in the equity portion of allowance for funds used during construction, primarily due to increased usage of short-termaverage outstanding debt to fund capital expenditures, reduced the favorable effect of the above items.
2013 versus 2012
Ameren Corporation
Other income, net of expenses, increased $10 million in 2013 compared with 2012, primarily because of items at Ameren Illinois discussed below.and ATXI.
Ameren Missouri
Other income, net of expenses,Interest charges decreased $2$4 million, primarily because of a decrease in the average interest income resulting from the absence in 2013rate of a 2012 interest payment received from Entergy as part of the FERC-ordered refund related to a power purchase agreement that expired in 2009, partially offset by decreased donations. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for more information about the Entergy refund received in 2012.debt.
Ameren Illinois
Other income, net of expenses,Interest charges increased $11$4 million, primarily because of decreased donations resulting from the absencean increase in 2013 of the one-time $7.5 million contribution in 2012 to the Illinois Science and Energy Innovation Trust pursuant to the IEIMA, in connection with participation in the formula ratemaking process. Additionally, interest income was higher, primarily causedaverage outstanding debt, partially offset by the IEIMA's 2013 revenue requirement reconciliation regulatory asset.
Interest Charges
2014 versus 2013
Ameren Corporation
Interest charges decreased $57 million in 2014 compared with 2013, primarily because of a $24 million reduction in interest charges at Ameren (parent), as a result of the maturity of $425 million of 8.875% senior unsecured notes in May 2014, which was replaced with lower cost debt, and a decrease in the average interest charges associated with uncertain tax positions at Ameren (parent). See Note 13 – Income Taxes under Part II, Item 8,rate of this report for additional information regarding uncertain tax positions. Additionally, interest charges were lower at Ameren Illinois as discussed below.
Ameren Missouri
debt. Interest charges were comparable between years. The absenceyears at each of the Ameren Illinois segments.
2016 versus 2015
Ameren
Interest charges increased $27 million in 20142016 compared with 2015, because of a 2013 reductionan approximately $475 million increase in average outstanding debt and an increase in the average interest rate of debt at Ameren (parent). Ameren (parent) issued senior unsecured notes in November 2015 to repay lower-cost short-term debt incurred primarily in connection with the funding of increasing ATXI investments. An increase in the average interest charges associated with uncertain tax positions resulted in higher interest charges. See Note 13 – Income Taxes under Part II, Item 8,rate of this report for information regarding uncertain tax positions. This increasedebt at Ameren Transmission was partially offset by a decrease in the effectaverage interest rate of refinancing activities that resulted in higher-cost debt being replaced with lower-cost debt.


44


Ameren Illinois
Interest charges decreased $31 million. There was a reduction in interest charges associated with the regulatory liability for the 2012 IEIMA revenue requirement reconciliation as the refund obligation was completed throughout 2014. The 2013 and 2014 IEIMA revenue requirement reconciliations were both regulatory assets, which, as discussed above under Other Income and Expenses, resulted in interest income. The favorable effect of refinancing activities that resulted in higher-cost debt being replaced with lower-cost debt also decreased interest charges. Additionally, the ICC issued an electric rate order in December 2014, which resulted in a partial reversal of a charge recorded in 2013 associated with a December 2013 ICC electric rate order that had disallowed the recovery from customers of certain debt premium costs. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information.
2013 versus 2012
Ameren Corporation
Interest charges increased $6 million in 2013 compared with 2012, primarily due to a $5 million increase in interest charges associated with uncertain tax positions at Ameren (parent). In addition, increases at Ameren Illinois more than offset decreases at Ameren Missouri, as discussed below. Interest charges were comparable between years at Ameren Illinois Electric Distribution and Ameren Illinois Natural Gas.
Ameren Transmission
Interest charges increased $23 million, because of an increase in ATXI’s and Ameren Illinois’ average outstanding debt and an increase in the average interest rate of debt.
Ameren Missouri
Interest charges decreased $13 million. Interest charges decreased$8 million, primarily because of changesa decrease in uncertain tax positions. Additionally, the favorable effect of refinancing activities that resulted in higher cost debt being replaced with lower cost debt lowered interest charges.average outstanding debt.
Ameren Illinois
Interest charges increased $14$9 million, primarily due to the charge recorded in 2013at Ameren Illinois Transmission, as a result of the ICC's December 2013 electric rate order discussed above. Also, interestbelow. Interest charges were comparable between years at Ameren Illinois Electric Distribution and Ameren Illinois Natural Gas.
Ameren Illinois Transmission
Interest charges increased $9 million, primarily because of interest applied toan increase in Ameren Illinois’ average outstanding debt and a decrease in the regulatory liabilityallowance for the 2012 revenue requirement reconciliation. Partially offsetting these increases was the favorable effectfunds used during construction because of refinancing activities that resulteda reduction in higher cost debt being replaced with lower cost debt.construction work in progress as more projects were placed in service in 2016.
Income Taxes

The following table presents effective income tax rates for the years ended December 31, 2014, 2013,2017, 2016, and 2012:
2015:
201420132012 2017 2016 2015 
Ameren39%38%37%Ameren52%
(a) 
37% 38% 
Ameren Missouri37%38%37%Ameren Missouri44%
(b) 
38% 37% 
Ameren Illinois41%40%Ameren Illinois38%
(c) 
38% 37% 
Ameren Illinois Electric DistributionAmeren Illinois Electric Distribution38%
(c) 
38% 36% 
Ameren Illinois Natural GasAmeren Illinois Natural Gas38%
(c) 
39% 40% 
Ameren Illinois TransmissionAmeren Illinois Transmission37%
(c) 
38% 37% 
Ameren TransmissionAmeren Transmission39%
(c) 
39% 38% 
(a)The net impact of the revaluation of deferred income taxes as a result of the TCJA and the increase in the Illinois corporate income tax rate increased the effective income tax rate for 2017 by 15 percentage points.
(b)The impact of the revaluation of deferred income taxes as a result of the TCJA increased the effective income tax rate for 2017 by 6 percentage points.
(c)The net impact of the revaluation of deferred income taxes as a result of the TCJA and the increase in the Illinois corporate income tax rate had no material effect on the effective income tax rate.

See Note 1312 – Income Taxes under Part II, Item 8, of this report for information regarding reconciliations of effective income tax rates.
rates for Ameren, Ameren Missouri, and Ameren Illinois, as well as a discussion of the effect of the TCJA and the revaluation of deferred taxes in 2017.
2017 versus 2016
Ameren
The effective income tax rate was higher in 2017 compared with 2016, primarily because of revaluation of deferred taxes due to enactment of the TCJA, which decreased the federal statutory corporate income tax rate from 35% to 21% for years after 2017. In addition, income tax expense increased due to the revaluation of deferred taxes as a result of an increase in the Illinois income tax rate in 2017 and due to a decrease in the recognition of tax benefits associated with share-based compensation, resulting from the difference between the deduction for tax purposes and the compensation cost recognized for financial reporting purposes. These items were partially offset by a reduction in the valuation allowance related to charitable contributions, due to higher-than-expected current-year taxable income.
Ameren Transmission
The effective income tax rate was comparable between years.
Ameren Missouri
The effective income tax rate was higher, primarily because of revaluation of deferred taxes due to the reduction in the federal statutory corporate income tax rate described above.
Ameren Illinois
The effective tax rate was comparable between years at Ameren Illinois and its respective segments.
2016 versus 2015
Ameren
The effective tax rate was comparable between years. The reduction in the 2016 effective tax rate, as compared with the 2015 effective tax rate, was primarily a result of the recognition of tax benefits associated with share-based compensation resulting from the difference between the deduction for tax purposes and the compensation cost recognized for financial reporting purposes. This reduction was partially offset by a higher effective tax rate in 2016 as compared with 2015 at Ameren Illinois Electric Distribution, as discussed below. The effective tax rate was comparable between years at the remaining Ameren segments.
Ameren Illinois
The effective tax rate was comparable between years. The effective tax rate was higher at Ameren Illinois Electric Distribution, primarily because of items detailed below. The effective tax rate was comparable between years at the remaining Ameren Illinois segments.
Ameren Illinois Electric Distribution
The effective tax rate was higher, primarily because of lower tax benefits from certain depreciation differences on property-related items.
Income (Loss) from Discontinued Operations, Net of Taxes
No material activity was recorded associated with discontinued operations in 2014. During2017 or 2016. In 2015, based on completion of the IRS audit of Ameren’s 2013 tax year, ended December 31, 2013,Ameren recognized a tax benefit of $53 million due to the lossresolution of an uncertain tax position from discontinued operations, net of taxes, was primarily related to the impairment loss and related income tax effects associated with the New AER divestiture. During 2012, AER's energy centers were impaired under held and used accounting guidance.operations. See Note 161 – Divestiture Transactions and Discontinued OperationsSummary of Significant Accounting Policies under Part II, Item 8, of this report for additional information.
In January 2014, Medina Valley completed the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital for a total purchase price of $168 million. Ameren did not recognize a gain from the sale to Rockland Capital for any value in excess of its $137.5 million carrying value for this disposal group, because any excess amount that Medina Valley may receive, net of taxes and other expenses, over the carrying value will ultimately be paid to Genco in January 2016, pursuant to Ameren's transaction agreement with IPH.
In December 2013, Ameren completed the divestiture of New AER to IPH. Ameren did not receive any cash proceeds from IPH for the divestiture of New AER. Ameren recorded a pretax charge to earnings related to the New AER divestiture of $201 million for the year ended December 31, 2013. In 2013, Ameren adjusted the accumulated deferred income taxes on its consolidated balance sheet to reflect the excess of tax basis over financial reporting basis of its stock investment in AER. This change in basis resulted in a discontinued operations deferred tax expense of $99 million, which was partially offset by the expected tax benefits of $86 million related to the pretax loss from discontinued operations, including the loss on disposal, for the year ended December 31, 2013. The final tax basis of the AER disposal group and the related tax benefit resulting from the transaction with IPH are dependent upon the resolution of tax matters under audit. It is reasonably possible in the next 12 months these tax audits will be completed. As a result, tax expense and benefits ultimately realized from the divestitures may differ materially from those recorded as of December 31, 2014, including the final resolution of Ameren's uncertain tax positions.
In 2012, Ameren recorded a $2.58 billion pretax noncash long-lived asset impairment charge to reduce the carrying value of AER’s energy centers to their estimated fair values under the accounting guidance for held and used assets.
LIQUIDITY AND CAPITAL RESOURCES
OurCollections from our tariff-based gross margins are our principal source of cash fromprovided by operating activities. A diversified retail customer mix, primarily consisting of rate-regulated residential, commercial, and industrial customers, provides us with a reasonably predictable source of cash. In addition to using cash generated fromprovided by operating activities, we use available cash, credit agreement borrowings under the Credit Agreements, commercial paper issuances, money pool borrowings, or, in the case of Ameren Missouri and Ameren


45


Illinois, other short-term affiliate borrowings from affiliates to support normal operations and temporary capital requirements. We may reduce our short-term borrowings with cash fromprovided by operations or, at our discretion, with long-term borrowings, or, in the case of Ameren Missouri and Ameren Illinois, with capital

contributions from Ameren (parent). The TCJA will benefit customers through lower rates for our services but is not expected to materially affect our earnings. However, our cash flows and rate base are expected to be materially affected in the near term. The TCJA eliminated 50% accelerated tax depreciation on nearly all capital investments, which has the effect of increasing Ameren’s near-term projected income tax liabilities. Ameren expects to largely offset its income tax obligations through about 2020 with existing net operating loss and tax credit carryforwards. Since we have been using existing net operating loss and tax credit carryforwards to largely offset income tax obligations, the effect of the reduced federal statutory corporate income tax rate is expected to be a decrease in operating cash flows. The decrease in operating cash flows results from reduced customer rates, reflecting the tax rate decrease, without a corresponding reduction in income tax payments until about 2021. Additionally, operating cash flows will be further reduced by lower customer rates, reflecting the return of excess deferred taxes previously collected from customers over periods of time determined by our regulators. The decrease in operating cash flows as a result of the TCJA is expected to be partially offset over time by increased customer rates due to higher rate base amounts, once approved by our regulators. We expect rate base amounts to be higher as a result of lower accumulated deferred income tax liabilities, due to the elimination of 50% accelerated tax depreciation, the reduced statutory income tax rate, and the return of excess deferred taxes to customers. We also expect to make significant capital expenditures over the next five years as we invest in our electric and natural gas utility infrastructure to support overall system reliability, environmental compliance, and other improvements. We intendAs part of its plan to fund thosethese capital expenditures, beginning in the first quarter of 2018, Ameren will use newly issued shares, rather than market-purchased shares, to satisfy requirements under its DRPlus and employee benefit plans and expects to do so over the next five years. Additionally, we may be required to issue incremental debt and/or equity, with available cash on hand, cash generated from operating activities,the long-term intent to maintain strong financial metrics and commercial paper and debt issuances so that we maintain an equity ratio around 50%, assuming constructive regulatory environments. We plan to implement our long-term financing
as calculated in accordance with ratemaking frameworks.
plans for debt, equity, or equity-linked securities to finance our operations appropriately, to fund scheduled debt maturities, and to maintain financial strength and flexibility.
The use of cash generated fromprovided by operating activities and short-term borrowings to fund capital expenditures and other long-term investments maywill periodically result in a working capital deficit, defined as current liabilities exceeding current assets, as was the case at December 31, 2014.2017, for the Ameren Companies. The working capital deficit as of December 31, 2014,2017, was primarily the result of increasedcurrent maturities of long-term debt and our decision to finance our businesses with lower-cost commercial paper issuances. With the 2012credit capacity available under the Credit Agreements, the Ameren hasCompanies had access to $2.1$1.6 billion of credit capacity, of which $1.4 billion was availableliquidity at December 31, 2014.2017.

The following table presents net cash provided by (used in) operating, investing and financing activities for the years ended December 31, 20142017, 20132016, and 20122015:
Net Cash Provided By (Used In)
Operating Activities
 
Net Cash Provided by (Used In)
Investing Activities
 
Net Cash Provided by (Used In)
Financing Activities
Net Cash Provided by (Used in)
Operating Activities
 
Net Cash Used in
Investing Activities
 
Net Cash Provided by (Used in)
Financing Activities
2014 2013 2012 2014 2013 2012 2014 2013 20122017 2016 2015 2017 2016 2015 2017 2016 2015
Ameren(a) – continuing operations
$1,557
 $1,636
 $1,404
 $(1,856) $(1,440) $(1,153) $141
 $(149) $(426)$2,104
 $2,124
 $2,035
 $(2,205) $(2,141) $(1,951) $102
 $(265) $232
Ameren(a) – discontinued operations
(6) 57
 286
 139
 (283) (157) 
 
 

 (1) (4) 
 
 (25) 
 
 
Ameren Missouri950
 1,143
 1,004
 (837) (687) (703) (113) (603) (354)1,016
 1,169
 1,247
 (685) (934) (724) (331) (434) (325)
Ameren Illinois445
 651
 519
 (828) (695) (437) 383
 45
 (103)815
 803
 763
 (1,070) (918) (913) 255
 44
 220
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
Cash Flows from Operating Activities
2014Our cash provided by operating activities is affected by fluctuations of trade accounts receivable, inventories, and accounts and wages payable, among other things, as well as the unique regulatory environment for each of our businesses. Substantially all expenditures related to fuel, purchased power, and natural gas purchased for resale are recovered from customers through rate adjustment mechanisms, which may be adjusted without a traditional rate proceeding. Similar regulatory mechanisms exist for certain operating expenses that can also affect the timing of cash provided by operating activities. The timing of cash payments for costs recoverable under our regulatory mechanisms differs from the recovery period of those costs. Additionally, the seasonality of our electric and natural gas businesses, primarily caused by changes in customer demand due to weather, significantly affect the amount and timing of our cash provided by operating activities. See Part 1, Item 1, and Note 1 – Summary of Significant Accounting Policies and Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for more information about our rate-adjustment mechanisms.
2017 versus 20132016
Ameren Corporation
Ameren’s cash from operating activities associated with continuing operations decreased $79$20 million in 2014,2017, compared with 2013.2016. The following items contributed to the decrease:
An $89A $48 million decrease in cash related to customer energy-efficiency program recovery mechanisms.
The absence of a $42 million insurance receipt received in 2016 at Ameren Missouri related to the Taum Sauk breach that occurred in December 2005.
A $36 million decrease in cash recoveries associated with Ameren Illinois’ IEIMA revenue requirement reconciliation adjustments. The

2015 revenue requirement reconciliation adjustment, which was recovered from customers in 2017, was less than the 2014 revenue requirement reconciliation adjustment, which was recovered from customers in 2016.
A $27 million decrease in net energy costs collected from Ameren Missouri customers under the FAC.
A $27 million decrease in cash related to Ameren Illinois’ power procurement cost recovery mechanism.
Refunds paid in 2017 of $21 million associated with the November 2013 FERC complaint case, as discussed in Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report.
A $17 million decrease in cash associated with Ameren Missouri’s under-recovered FAC costs. Deferrals and refunds exceeded recoveries in 2014 by $49 million, while recoveries exceeded deferrals in 2013 by $40 million.
Illinois’ transmission revenue requirement reconciliation adjustments. The 2014 refunds to Ameren Illinois customers of $67 million as required under the provisions of the IEIMA for the 20122015 transmission revenue requirement reconciliation adjustment, compared with no refundswhich was recovered from customers in 2013.2017, was less than the 2014 revenue requirement reconciliation adjustment, which was recovered from customers in 2016.
A $65 million difference in expenditures for customer energy efficiency programs compared with amounts collected from Ameren Missouri and Ameren Illinois customers.
A $50$14 million increase in coal purchasesthe cost of natural gas held in storage, caused primarily by increased volumes and prices. Ameren Missouri purchased less coal in 2013, due, in part, to delivery disruptions from flooding.reduced withdrawals as a result of milder winter temperatures compared with the prior year.
A $42 million difference in purchased power commodity costs incurred compared with amounts collected from Ameren Illinois customers.
A $39$13 million increase in rebateinterest payments, provided for customer-installed solar generationprimarily due to an increase in the average outstanding debt at Ameren Missouri, which will be collected from customers in a future period.
A $38 million decrease in natural gas commodity costs collected from customers under the PGAs, primarily related to Ameren Illinois.
A decrease of $26$10 million increase in labor costs at Ameren Missouri and Ameren Illinois, for storm restoration assistance provided to nonaffiliated utilities, primarily due to Hurricane Sandy in 2013.because of wage increases.
A $26$7 million increase in pension and postretirement benefit plan contributions.
A $4 million increase in payments to contractors at Ameren Illinois for additional reliability, maintenance, and IEIMA projects.increased natural gas compliance costs.
RefundsThe following items partially offset the decrease in Ameren’s cash from operating activities associated with continuing operations between years:
A $167 million increase resulting from electric and natural gas margins, as discussed in Results of $24Operations, excluding certain noncash items, as well as the change in customer receivable balances.
A $37 million increase in cash collected from Ameren Illinois customers related to customers as required by a September 2014 FERC order in Ameren Illinois' wholesale distribution rate case.zero-emission credits pursuant to the FEJA. In the first quarter of 2018, these funds will be used for the purchase of zero-emission credits pursuant to an IPA procurement event.
A $23 million increase in cash collected from Ameren Illinois’ alternative retail electric supplier customers for renewable energy credit compliance pursuant to the valueFEJA.
A $14 million decrease in coal inventory because of decreased market prices and decreased purchases at Ameren Missouri as a result of inventory reductions at its energy centers.
Ameren’s cash from operating activities associated with discontinued operations was immaterial in both 2017 and 2016.
Ameren Missouri
Ameren Missouri’s cash from operating activities decreased $153 million in 2017, compared with 2016. The following items contributed to the decrease:
An increase in income tax payments of $151 million to Ameren (parent) pursuant to the tax allocation agreement, primarily related to higher taxable income in 2017, because of significantly lower property-related deductions.
The absence of a $42 million insurance receipt received in 2016 related to the Taum Sauk breach that occurred in December 2005.
A $27 million decrease in net energy costs collected from customers under the FAC.
A $20 million decrease in cash related to customer energy-efficiency program recovery mechanisms.
The following items partially offset the decrease in Ameren Missouri’s cash from operating activities between years:
A $70 million increase resulting from electric and natural gas margins, as discussed in Results of Operations, excluding certain noncash items, as well as the change in customer receivable balances.
A $14 million decrease in coal inventory as a result of decreased market prices and decreased purchases as a result of inventory reductions at the energy centers.
Ameren Illinois
Ameren Illinois’ cash from operating activities increased $12 million in 2017, compared with 2016. The following items contributed to the increase:
A $75 million increase resulting from electric and natural gas margins, as discussed in Results of Operations, excluding certain noncash items, as well as the change in customer receivable balances.
A $37 million increase in cash collected from customers related to zero-emission credits pursuant to the FEJA. In the first quarter of 2018, these funds will be used for the purchase of zero-emission credits pursuant to an IPA procurement event.

A $30 million increase resulting from income tax refunds of $22 million in 2017, compared with income tax payments of $8 million in 2016, pursuant to the tax allocation agreement with Ameren (parent), primarily related to a larger taxable loss in 2017 as a result of higher property-related deductions and use of net operating losses.
A $23 million increase in cash collected from alternative retail electric supplier customers for renewable energy credit compliance pursuant to the FEJA.
The following items partially offset the increase in Ameren Illinois’ cash from operating activities between periods:
A $36 million decrease in cash recoveries associated with IEIMA revenue requirement reconciliation adjustments. The 2015 revenue requirement reconciliation adjustment, which was recovered from customers in 2017, was less than the 2014 revenue requirement reconciliation adjustment, which was recovered from customers in 2016.
A $28 million decrease in cash related to customer energy-efficiency program recovery mechanisms.
A $27 million decrease in cash related to the power procurement cost recovery mechanism.
A $17 million decrease in cash recoveries associated with the transmission revenue requirement reconciliation adjustments. The 2015 transmission revenue requirement reconciliation adjustment, which was recovered from customers in 2017, was less than the 2014 revenue requirement reconciliation adjustment, which was recovered from customers in 2016.
Refunds paid in 2017 of $17 million associated with the November 2013 FERC complaint case, as discussed in Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report.
A $14 million increase in the cost of natural gas held in storage, caused primarily by reduced withdrawals as a result of milder winter temperatures compared with the prior year.
A $13 million increase in interest payments, primarily due to an increase in the average outstanding debt.
2016 versus 2015
Ameren
Ameren’s cash from operating activities associated with continuing operations increased $89 million in 2016, compared with 2015. The following items contributed to the increase:
A $126 million increase resulting from electric and natural gas margins, as discussed in Results of Operations, excluding certain noncash items.
A $70 million decrease in pension and postretirement benefit plan contributions.
A $42 million insurance receipt at Ameren Illinois because of increased market prices and timing of injections and withdrawals.Missouri related to the Taum Sauk breach that occurred in 2005.
A $22$40 million increase in cash associated with the recovery of Ameren Illinois’ IEIMA revenue requirement reconciliation adjustments. The 2014 revenue requirement reconciliation adjustment, which was recovered from customers in 2016, was greater than the 2013 revenue requirement reconciliation adjustment, which was recovered from customers in 2015.
A $38 million increase in cash related to Ameren Illinois’ power procurement cost recovery mechanism.
A $37 million decrease in coal inventory purchases at Ameren Missouri, as additional coal was purchased in 2015 to compensate for delivery disruptions in 2014.
A $33 million increase in cash related to customer energy-efficiency program recovery mechanisms.
A $19 million increase in cash associated with stock-based compensation awards.the recovery of Ameren Illinois’ transmission revenue requirement reconciliation adjustments. The 2014 transmission revenue requirement reconciliation adjustment was recovered from customers in 2016, while the 2013 revenue requirement reconciliation adjustment was refunded to customers in 2015.
The following items partially offset the increase in Ameren’s cash from operating activities associated with continuing operations during 2016, compared with 2015:
A $21$166 million decrease resulting from the change in customer receivable balances.
A $94 million decrease in net energy costs collected from Ameren Missouri customers under the FAC.
A $23 million increase in interest payments, primarily due to an increase in the cost and amount of outstanding debt of Ameren (parent) and an increase in the average outstanding debt at Ameren Illinois.
A $20 million increase in payments for the refueling and maintenance outage at Ameren Missouri’s Callaway energy center. There was no refueling and maintenance outage in 2015.
A $9 million increase in labor costs at Ameren Illinois, primarily because of wage increases and staff additions to meet enhanced reliability and customer service goals related to the IEIMA.
A $21 million difference in transmission service costs incurred compared with amounts collected from customers primarily at Ameren Illinois.
A net $19 million decrease in returns of collateral posted with counterparties due to changes at Ameren Missouri and Ameren Illinois discussed below.


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A $17$7 million increase in the purchase of receivables from alternative retail electric suppliers compared with amounts collected frompayments to contractors at Ameren Illinois customers.for additional reliability, maintenance, and IEIMA projects.
A $16 million decrease in contributions received by Ameren Illinois from customers for future construction.
An $8 million increase in property tax payments at Ameren Missouri caused by higher assessed property tax values and increased property tax rates.
The following items partially offset the decrease in Ameren'sAmeren’s cash from operating activities associated with continuingdiscontinued operations during 2014,was immaterial in both 2016 and 2015.

Ameren Missouri
Ameren Missouri’s cash from operating activities decreased $78 million in 2016, compared with 2013:2015. The following items contributed to the decrease:
ElectricA $142 million decrease resulting from electric and natural gas margins, as discussed in Results of Operations, excluding certain noncash items, that increased by $166 million.
Income tax refunds of $41 millionas well as the change in 2014, primarily due to federal settlements for the tax years 2007 through 2011, compared with income tax payments in 2013 of $116 million. See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report for income tax payment (refund) information as it relates to continuing and discontinued operations.customer receivable balances.
A $76$94 million decrease in pension and postretirement benefit plan contributions. In addition to the Ameren Missouri and Ameren Illinois amounts discussed below, Ameren's nonregistrant subsidiaries' contributions to the pension and postretirement benefit plans decreased $30 million.
A $74 million increase in the collection of customer receivable balances compared to the prior year driven by the timing and amount of revenues in each period.
A $29 million decrease in interest payments, primarily due to refinancing activity at Ameren Missouri and Ameren (parent). See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report for interest payment information as it relates to continuing and discontinued operations.
A $27 million insurance receipt at Ameren Missouri related to the December 2005 breach of the upper reservoir at the Taum Sauk pumped-storage hydroelectricnet energy center.
Ameren’s cash from operating activities associated with discontinued operations decreased in 2014, compared with 2013. The 2013 activity related to the disposed New AER and the Elgin, Gibson City and Grand Tower energy centers. The 2014 activity related to transaction costs and tax payments associated with the Elgin, Gibson City and Grand Tower energy centers.
Ameren Missouri
Ameren Missouri’s cash from operating activities decreased $193 million in 2014, compared with 2013. The following items contributed to the decrease:
A $129 million increase in income tax payments paid to Ameren (parent) pursuant to the tax allocation agreement, resulting primarily from fewer deductions for capital
expenditures for tax years 2007 through 2013, which caused increased payments in 2014. The increase was partially offset by a reduction in payments due to the expected use of net operating loss carryforwards in 2014.
An $89 million decrease in the cash associated with Ameren Missouri’s under-recovered FAC costs. Deferrals and refunds exceeded recoveries in 2014 by $49 million, while recoveries exceeded deferrals in 2013 by $40 million.
A $50 million increase in coal purchases caused by increased volumes and prices. Ameren Missouri purchased less coal in 2013, due, in part, to delivery disruptions from flooding.
A $39 million increase in rebate payments provided for customer-installed solar generation, which will be collected from customers in a future period.
A $28 million difference in expenditures for customer energy efficiency programs compared with amounts collected from customers.
An $11 million decrease in natural gas commodity costs collected from customers under the PGA.FAC.
A decrease of $10 million for storm restoration assistance provided to nonaffiliated utilities, primarily due to Hurricane Sandy in 2013.
An $8$20 million increase in property tax payments caused by higher assessed property tax valuesfor the refueling and increased property tax rates.maintenance outage at the Callaway energy center. There was no refueling and maintenance outage in 2015.
The following items partially offset the decrease in Ameren Missouri'sMissouri’s cash from operating activities during 2014,2016, compared with 2013:2015:
A $76$45 million increasedecrease in the collection of customer receivable balances comparedincome tax payments, pursuant to the prior year driven by the timing and amount of revenuestax allocation agreement with Ameren (parent), primarily related to higher deductions related to increased capital expenditures in each period.2016.
A $27$42 million insurance receipt related to the December 2005 breach of the upper reservoir at the Taum Sauk pumped-storage hydroelectric energy center.breach that occurred in December 2005.
A $26$37 million decrease in coal inventory purchases, as additional coal was purchased in 2015 to compensate for delivery disruptions in 2014.
A $33 million decrease in pension and postretirement benefit plan contributions.
ElectricAn $11 million increase in cash related to customer energy-efficiency program recovery mechanisms.
Ameren Illinois
Ameren Illinois’ cash from operating activities increased $40 million in 2016, compared with 2015. The following items contributed to the increase:
A $58 million increase resulting from electric and natural gas margins, as discussed in Results of Operations, excluding certain noncash items, that increasedwhich was partially offset by $20 million.the change in customer receivable balances.
A net $10$40 million increase in returnscash associated with the recovery of collateral posted with counterparties primarily resultingIEIMA revenue requirement reconciliation adjustments. The 2014 revenue requirement reconciliation adjustment, which was recovered from changescustomers in 2016, was greater than the market prices of power and natural gas and2013 revenue requirement reconciliation adjustment, which was recovered from customers in contracted commodity volumes.2015.
A $9$38 million increase in cash related to the power procurement cost recovery mechanism.
A $22 million decrease in interest payments, primarily duepension and postretirement benefit plan contributions.
A $22 million increase in cash related to refinancing activity.customer energy-efficiency program recovery mechanisms.
Ameren IllinoisA $19 million increase in cash associated with the recovery of transmission revenue requirement reconciliation adjustments. The 2014 transmission revenue requirement reconciliation adjustment was recovered from customers in 2016, while the 2013 revenue requirement reconciliation adjustment was refunded to customers in 2015.
The following items partially offset the increase in Ameren Illinois’ cash from operating activities decreased $206during 2016, compared with 2015:
A $121 million decrease resulting from income tax payments of $8 million in 2014,2016, compared with 2013. The following items contributedincome tax refunds of $113 million in 2015, pursuant to the decrease:
The 2014 refunds to customers of $67 million as required under the provisions of the IEIMAtax allocation agreement with Ameren (parent). During 2015, Ameren Illinois used net operating loss carryforwards from prior years, resulting in a reduction in payments. Ameren Illinois also had higher deductions for the 2012 revenue


47


requirement reconciliation adjustment, compared with no refundsincreased capital expenditures in 2013.2015.
A $42 million difference in purchased power commodity costs incurred compared with amounts collected from customers.
A $37 million difference in expenditures for customer energy efficiency programs compared with amounts collected from customers.
A net $29 million decrease in returns of collateral posted with counterparties, primarily resulting from changes in the market prices of power and natural gas and in contracted commodity volumes.
A $27 million decrease in natural gas commodity costs collected from customers under the PGA.
A $26 million increase in payments to contractors for additional reliability, maintenance, and IEIMA projects.
Refunds to customers of $24 million as required by a September 2014 FERC order in the wholesale distribution rate case.
A $23 million increase in the value of natural gas held in storage because of increased market prices and the timing of injections and withdrawals.
A $21$9 million increase in labor costs primarily because of wage increases and staff additions to meet enhanced reliability and customer service goals related to the IEIMA.
A $20 million difference in transmission service costs incurred compared with amounts collected from customers.
A $17$7 million increase in the purchase of receivables from alternative retail electric suppliers compared with amounts collected from customers.payments to contractors for additional reliability, maintenance, and IEIMA projects.
A $16$7 million decrease in contributions received from customers for future construction.
The absence of $16 million received in 2013 for storm restoration assistance provided to nonaffiliated utilities, primarily due to Hurricane Sandy.
The following items partially offset the decrease in Ameren Illinois' cash from operating activities during 2014, compared with 2013:
Electric and natural gas margins, as discussed in Results of Operations excluding certain noncash items, that increased by $126 million.
A $21 million increase in income tax refunds from Ameren (parent) pursuant to the tax allocation agreement, resulting primarily from the expected use of net operating loss carryforwards in 2014.
A $20 million decrease in pension and postretirement benefit plan contributions.
2013 versus 2012
Ameren Corporation
Ameren’s cash from operating activities associated with continuing operations increased $232 million in 2013, compared with 2012. The following items contributed to the
increase:
The absence in 2013 of $138 million in premiums paid to debt holders in 2012 in connection with the repurchase of the tendered principal of multiple series of Ameren Missouri and Ameren Illinois senior secured notes.
A $115 million increase in the cash associated with Ameren Missouri’s under-recovered FAC costs. Recoveries outpaced deferrals in 2013 by $41 million, while deferrals and refunds outpaced recoveries in 2012 by $74 million.
Electric and natural gas margins, as discussed in Results of Operations excluding certain noncash items, that increased by $109 million.
A $94 million increase due to changes in Ameren Missouri coal inventory levels. In 2013, coal inventory levels decreased by $62 million because of delivery disruptions due to flooding, while in 2012, coal inventory levels increased by $32 million, primarily because additional tons were held in inventory when generation levels were lower than expected due to market conditions.
The absence in 2013 of $25 million in severance payments made in 2012 as a result of the voluntary separation offers extended to Ameren Missouri employees in the fourth quarter of 2011.
A $22 million decrease in interest payments, primarily due to 2012 refinancing activity and timing of payments on Ameren Missouri and Ameren Illinois senior secured notes.
The receipt of $16 million in 2013 for storm restoration assistance provided to nonaffiliated utilities in 2012 at Ameren Illinois.
A one-time $7.5 million contribution, in 2012, by Ameren Illinois to the Illinois Science and Energy Innovation Trust, as required by the IEIMA, which was not repeated in 2013.
The following items partially offset the increase in Ameren's cash from operating activities associated with continuing operations during 2013, compared with 2012:
A $106 million increase in income tax payments for continuing operations. As discussed below, income tax payments at Ameren Missouri increased $89 million, while income tax refunds at Ameren Illinois increased $1 million. Considering both Ameren's continuing and discontinued operations, Ameren made immaterial federal income tax payments in 2013.
A $91 million decrease in the collection of customer receivable balances compared with the prior year, driven by the timing and amount of revenues in each period.
A $27 million increase in payments for the 2013 scheduled nuclear refueling and maintenance outage at the Callaway energy center. There was no refueling and maintenance outage in 2012.
The absence in 2013 of court registry receipts and payments. In 2012, Ameren Missouri received $19 million from the Circuit Court of Stoddard County's registry and the Circuit Court of Cole County's registry, net of


48


payments into those registries, as a result of a Missouri Court of Appeals ruling upholding the MoPSC's January 2009 electric rate order.
A $13 million increase in property tax payments, primarily at Ameren Missouri, caused by the timing of payments.
A $12 million increase in major storm restoration costs.
An $11 million increase in labor costs primarily related to increased staffing levels associated with IEIMA at Ameren Illinois.
An $8 million increase in pension and postretirement benefit plan contributions, primarily caused by an increase in funding requirements in 2013 compared with 2012, partially offset by an additional postretirement contribution in 2012 at Ameren Illinois. In addition to the Ameren Missouri and Ameren Illinois amounts discussed below, Ameren's nonregistrant subsidiaries increased their contributions to the pension and postretirement benefit plans by $19 million.
Ameren’s cash from operating activities associated with discontinued operations decreased in 2013, compared with 2012, primarily because of a $277 million decrease in electric margins, excluding impacts of noncash unrealized MTM activity. The decrease was partially offset by a $99 million increase in income tax refunds in 2013 due to a reduction in pretax book income partially offset by a reduction in accelerated depreciation deductions. Ameren’s discontinued operations entities received these income tax refunds through the tax allocation agreement with Ameren’s continuing operations entities.
Ameren Missouri
Ameren Missouri’s cash from operating activities increased $139 million in 2013, compared with 2012. The following items contributed to the increase:
A $115 million increase in the cash associated with under-recovered FAC costs. Recoveries exceeded deferrals in 2013 by $41 million, while deferrals and refunds exceeded recoveries in 2012 by $74 million.
A $94 million increase due to changes in coal inventory levels. In 2013, coal inventory levels decreased by $62 million because of delivery disruptions due to flooding, while in 2012, coal inventory levels increased by $32 million, primarily because additional tons were held in inventory when generation levels were lower than expected due to market conditions.
Electric and natural gas margins, as discussed in Results of Operations excluding certain noncash items, that increased by $91 million.
The absence in 2013 of $62 million in premiums paid toaverage outstanding debt, holders in 2012 in connection with the repurchase of the tendered principal of multiple series ofincluding senior secured notes.
The absencenotes issued in 2013 of $25 million in severance payments made in 2012 as a result of the voluntary separation offers extended to employees in the fourth quarter of 2011.
An $8 million decrease in interest payments, primarily due to 2012 refinancing activity and timing of payments on senior secured notes.
The following items partially offset the increase in Ameren Missouri's cash from operating activities during 2013, compared with 2012:
Income tax payments that totaled $86 million in 2013, resulting primarily from a reduction in accelerated depreciation deductions, while income tax refunds were $3 million in 2012. Payments and refunds were made between Ameren Missouri and Ameren (parent) pursuant to the tax allocation agreement.
A $60 million decrease in the collection of customer receivable balances compared with the prior year, driven by the timing and amount of revenues in each period.
A $27 million increase in payments for scheduled nuclear refueling and maintenance outages at the Callaway energy center. There was no refueling and maintenance outage in 2012.
A $20 million increase in property tax payments caused by the timing of payments.
The absence in 2013 of court registry receipts and payments. In 2012, Ameren Missouri received $19 million from the Circuit Court of Stoddard County's registry and the Circuit Court of Cole County's registry, net of payments into those registries, as a result of a Missouri Court of Appeals ruling upholding the MoPSC's January 2009 electric rate order.
A $9 million increase in pension and postretirement benefit plan contributions primarily caused by an increase in funding requirements in 2013 compared with 2012.
An $8 million increase in major storm restoration costs.
Ameren Illinois
Ameren Illinois’ cash from operating activities increased $132 million in 2013, compared with 2012. The following items contributed to the increase:
The absence in 2013 of $76 million in premiums paid to debt holders in 2012 in connection with the repurchase of the tendered principal of multiple series of senior secured notes.
A $20 million decrease in pension and postretirement benefit plan contributions, primarily caused by an additional postretirement contribution in 2012.
The receipt of $16 million in 2013 for storm restoration assistance provided to nonaffiliated utilities in 2012.
A $13 million decrease in interest payments, primarily due to 2012 refinancing activity and timing of payments on senior secured notes.
Electric and natural gas margins, as discussed in Results of Operations excluding certain noncash items, that increased by $11 million.
A one-time $7.5 million contribution, in 2012, to the Illinois Science and Energy Innovation Trust as required by the IEIMA.


49


A $7 million decrease in property tax payments due to two electricity distribution tax credit refunds received in 2013.
The following items partially offset the increase in Ameren Illinois' cash from operating activities during 2013, compared with 2012:
A $29 million decrease in the collection of customer receivable balances compared with the prior year, driven by the timing and amount of revenues in each period.
An $11 million increase in labor costs primarily related to increased staffing levels associated with IEIMA.December 2015.
Pension Plans
Ameren’s pension plans are funded in compliance with income tax regulations, and federal funding, orand other regulatory requirements. As a result, Ameren expects to fund its pension plans at a level equal to the greater of the pension expensecost or the legally required minimum contribution. ConsideringBased on Ameren’s assumptions at December 31, 2014,2017, its investment performance in 2014,2017, and its pension funding policy, Ameren expects to make annual contributions of $25less than $1 million to $115$60 million in each of the next five years, with aggregate estimated contributions of $290 million.$120 million. We expect Ameren Missouri’s and Ameren Illinois’ portions of the future funding requirements to be 41%35% and 40%55%, respectively. These amounts are estimates. The estimatesThey may change withbased on actual investment performance, changes in interest rates, changes in our assumptions, changes in government regulations, orand any voluntary contributions. In 2014,2017, Ameren contributed $99$64 million to its pension plans. See Note 1110 – Retirement Benefits under Part II, Item 8, of this report for additional information.

Cash Flows from Investing Activities
20142017 versus 20132016
Ameren'sAmeren’s cash used in investing activities associated with continuing operations increased by $416$64 million during 2014,2017, compared with 2013.2016. Capital expenditures increased $406$56 million primarily becauseas a result of increased transmission expenditures, which included a $150activity at Ameren Missouri and Ameren Illinois, discussed below. The $187 million increase for ATXI'sin capital expenditures at Ameren Missouri and Ameren Illinois was partially offset by a $127 million decrease in capital expenditures at ATXI due to reduced spending on the Illinois Rivers project. In addition, capital expenditures for energy center, reliability and IEIMA projects increased cash used in investing activities and are discussed below.
During 2014, cash provided by investing activities associated with Ameren’s discontinued operations consisted of $152 million received from Rockland Capital for the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers in January 2014,project, partially offset by payment of $13 million to IPH foran increase in spending on the final working capital adjustmentSpoon River project. During 2017 and a portion of certain contingent liabilities associated with the New AER divestiture. In comparison,2016, there was no cash used in investing activities associated with discontinued operations during 2013 was $283 million, primarily because of the requirement to leave $235 million with New AER upon divestiture, pursuant to the transaction agreement with IPH.operations.
Ameren Missouri’s cash used in investing activities
increased decreased by $150$249 million during 2014,2017, compared with 2013. Capital2016, primarily because of net money pool advances. During 2017, Ameren Missouri received $161 million in returns of net money pool advances compared with investing $125 million in net money pool advances in 2016. This decrease was partially offset by a $35 million increase in capital expenditures, increased $99 million, primarily forrelated to electric distribution and transmission system reliability and energy center projects, including the nuclear reactor vessel head replacement project at its Callaway energy center, the electrostatic precipitator upgrades at the Labadie energy center, a new substation in St. Louis, and investment in the O’Fallon energy center, offset by a reduction in storm restoration expenditures. Nuclear fuel expenditures increased by $29 million due to timing of purchases in 2014 compared to 2013. In addition, cash used in investing activities increased in 2014 because of the absence in 2014 of $24 million in net receipts related to money pool advances received in 2013.projects.
Ameren Illinois’ cash used in investing activities increased by $133$152 million during 2014,2017, compared with 2013,2016, because of increased capital expenditures, primarily forrelated to electric transmission system reliability projects and IEIMAnatural gas infrastructure projects.
20132016 versus 20122015
Ameren'sAmeren’s cash used in investing activities associated with continuing operations increased by $287$190 million during 2013,2016, compared with 2012.2015. Capital expenditures increased $316$159 million, primarily because of increased transmission expenditures, for transmission inwhich included a $41 million increase at ATXI primarily related to the Illinois reliability projects,Rivers project, and storm restoration costs. The increase inincreased Ameren Missouri and Ameren Illinois capital expenditures.
During 2016, there was no cash flows used in investing activities was partially offset by a $46 million decrease in nuclear fuel expenditures due to timing of purchases.
Cash used in investing activities associated with Ameren’s discontinued operations increased $126 million during 2013, compared with 2012, primarily because of the requirement to leave $235 million with New AER upon divestiture, pursuant to the transaction agreement with IPH. This use of cash was partially offset by reduced capital expenditures in 2013 as a result of the deceleration of the scrubber construction project at the previously-owned Newton energy center.
Ameren Missouri'soperations. During 2015, Ameren’s cash used in investing activities decreased $16 million during 2013, comparedassociated with 2012, primarily due to changes in money pool advances and a $46 million decrease in nuclear fuel expenditures due to timing of purchases. The decrease in cash used in investing activities was partially offset by increased capital expenditures and the absence in 2013discontinued operations consisted of a 2012 receipt of $18$25 million payment for federal tax grants related to renewable energy construction projects. Capital expenditures increased $53 million, primarily because of increased expenditures for reliability projects and an increase in storm restoration costs.a liability associated with the New AER divestiture.
Ameren Illinois'Missouri’s cash used in investing activities increased $258by $210 million during 2013,2016, compared with 2012.2015. Capital expenditures increased $259$116 million, primarily related to electric distribution system reliability and energy center projects. Additionally, there was an increase in net advances to the money pool of $89 million.
Ameren Illinois’ cash used in investing activities increased by $5 million during 2016, compared with 2015, because of increased capital expenditures, of $164 million for transmission and reliability projects, $18 million forprimarily related to qualified investments in natural gas infrastructure under the QIP rider, storm restoration costs, and $12 million for IEIMA projects.reliability.
Capital Expenditures
The following table presents the capital expenditures by the


50


Ameren Companies for the years ended December 31, 2014, 2013,2017, 2016, and 2012:2015:
 2014 2013 2012
Ameren(a)
$1,785
 $1,379
 $1,063
Ameren Missouri747
 648
 595
Ameren Illinois835
 701
 442
 2017 2016 2015
Ameren Missouri$773
 $738
 $622
Ameren Illinois Electric Distribution476
 470
 491
Ameren Illinois Natural Gas245
 181
 133
Ameren Illinois Transmission355
 273
 294
ATXI289
 416
 375
Other (a)
(6) (2) 2
Ameren$2,132
 $2,076
 $1,917
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries and the elimination of intercompany transfers.
Ameren’s 20142017 capital expenditures consisted primarily of the following expenditures made by its subsidiaries. Ameren Missourisubsidiaries, including ATXI, which spent $101$289 million for electrostatic precipitator upgrades at its Labadie energy center, $33 million forprimarily on the replacement of the nuclear reactor vessel head at its Callaway energy center,Illinois Rivers and $16 million for the construction of the O’Fallon energy center.Spoon River projects. Ameren Illinois spent $284$355 million on transmission initiativesprojects, $153 million on projects that are recovered under the QIP rider, and $89$123 million on IEIMA projects. Other capital expenditures were made principally to maintain, upgrade, and improve the reliability of the transmission and distribution systems of Ameren Missouri and Ameren Illinois by investing in substation upgrades, energy center projects, and smart-grid technology. Additionally, the Ameren Companies invested in various software projects.
Ameren’s 2016 capital expenditures consisted of expenditures made by its subsidiaries, including ATXI, which spent $201$416 million primarily on the Illinois Rivers project. Ameren Illinois spent $273 million on transmission projects and $109 million on IEIMA projects. Other

capital expenditures were made principally to maintain, upgrade, and improve the reliability of the transmission and distribution systems of Ameren Missouri and Ameren Illinois as well as to fund various Ameren Missouri energy center upgrades.
Ameren’s 20132015 capital expenditures consisted primarily of the following expenditures made by its subsidiaries. Ameren Missourisubsidiaries, including ATXI, which spent $53$375 million for electrostatic precipitator upgrades at the Labadie energy center, $30 million on storm restoration, and $29 million on the replacement of the nuclear reactor vessel head at its Callaway energy center which was installed during the 2014 refueling and maintenance outage. Ameren Illinois spent $269 million on transmission initiatives, $33 million on IEIMA projects, and $23 million on storm restoration. ATXI spent $51 millionprimarily on the Illinois Rivers project. Other capital expenditures were made principally to maintain, upgrade, and improve the reliability of the transmission and distribution systems of Ameren Missouri and Ameren Illinois as well as to fund various Ameren Missouri energy center upgrades.
Ameren’s 2012 capital expenditures consisted primarily of the following expenditures by its subsidiaries. Ameren Missouri spent $30 million on the replacement of the nuclear reactor vessel head at its Callaway energy center which was installed during the 2014 refueling and maintenance outage, and $23 million on a boiler upgrade project. Ameren Illinois spent $27$294 million on transmission projects and $134 million on IEIMA projects. Other capital expenditures were made principally to maintain, upgrade, and improve the reliability of the transmission and distribution systems of Ameren Missouri and Ameren Illinois as well as to fund various Ameren Missouri energy center upgrades.
The following table presents Ameren'sAmeren’s estimate of capital expenditures that will be incurred from 20152018 through 2019,2022, including construction expenditures, allowance for funds used during construction, and expenditures for compliance with existing environmental regulations. Ameren expects to continue to allocate more of its discretionary capital expenditures to Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and ATXIAmeren Transmission based, in part, on the more constructive regulatory frameworks within which they operate.
2015 2016 - 2019 Total2018 2019-2022 Total
Ameren Missouri$710
 $2,875
-$3,180
 $3,585
-$3,890
$845
 $3,310
-$3,660
 $4,155
-$4,505
Ameren Illinois905
 2,775
-3,065
 3,680
-3,970
Ameren Illinois Electric Distribution465
 1,815
-2,005
 2,280
-2,470
Ameren Illinois Natural Gas330
 1,220
-1,350
 1,550
-1,680
Ameren Illinois Transmission470
 1,765
-1,950
 2,235
-2,420
ATXI345
 945
-1,045
 1,290
-1,390
70
 215
-240
 285
-310
Other5
 15
-15
 20
-20
Ameren$1,960
 $6,595
-$7,290
 $8,555
-$9,250
$2,185
 $8,340
-$9,220
 $10,525
-$11,405
Ameren Missouri’s estimated capital expenditures include transmission, distribution, and generation-related investments, as well as expenditures for compliance with environmental regulations. The estimates above do not reflect the potential additional investments identified in Ameren Missouri’s integrated resource plan, which could represent incremental investments of approximately $1 billion through 2020 and are subject to regulatory approval. They also do not reflect potential additional investments that Ameren Missouri could make if improvements in its regulatory frameworks were made. Ameren Illinois’ estimated capital expenditures are primarily for electric and natural gas transmission and distribution-related investments, capital expenditures incremental to historical average electric delivery capital expenditures to modernize its distribution system pursuant to the IEIMA, and capital expenditures for qualified investments in natural gas infrastructure under the QIP rider. ATXI'sATXI’s estimated capital expenditures include expenditures for the three MISO-approved multi-value transmission projects. For additional information regarding the IEIMA capital expenditure requirements, the QIP rider, and ATXI'sATXI’s transmission projects, see Business under Part I, Item 1, of this report.
Ameren Missouri continually reviews its generation portfolio and expected power needs. As a result, Ameren Missouri could modify its plan for generation capacity, the type of generation asset technology that will be employed, and whether capacity or power may be purchased, among other changes. Additionally, we continually review the reliability of our transmission and distribution systems, expected capacity needs, and opportunities for transmission investments. The timing and amount of investments could vary because of changes in expected capacity, the condition of transmission and distribution systems, and our ability and willingness to pursue transmission investments, among other factors. Any changes in future generation, transmission, or distribution needs could result in significant capital expenditures or losses, which could be material. Compliance with environmental regulations could also have significant impacts on the level of capital expenditures.
Environmental Capital Expenditures
Ameren Missouri will continue to incur significant costs in future years to comply with federal and state regulations, including those requiring the reduction of SO2, NOx, and mercury emissions from its coal-fired energy centers. See Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report for a discussion of existing and proposed environmental laws and regulations that affect, or may affect, our facilities and capital expenditures to comply with such laws and regulations.
Cash Flows from Financing Activities
2014Cash provided by, or used in, financing activities is a result of our financing needs, which depend on the level of cash provided by operating activities, the level of cash used in investing activities, the dividends declared by Ameren’s board of directors, and our long-term debt maturities, among other things.
2017 versus 20132016
Ameren'sAmeren’s financing activities associated with continuing operations provided net cash of $141$102 million in 2014,2017, compared with 2013 when Ameren usedusing net cash of $149 million.$265 million in 2016. During 2014,2017, Ameren and its registrant subsidiaries issued lower-costutilized net proceeds from the issuance of $1,345 million of long-term and short-term debtindebtedness to fund the maturities and redemptions


51


repay $681 million of higher-cost long-term debt, including the maturityindebtedness, to repay $74 million of Ameren (parent)’s $425 million senior unsecured notes. In 2014, Ameren also used cash from financing activitiesnet commercial paper issuances, and to fund, in part, investing activities that were not funded by cash generated from operating activities. In comparison, during 2013,2016, Ameren utilized net proceeds from the issuance of $646 million of long-term indebtedness

and its registrant subsidiaries issued lower-cost long-term and short-term debtnet commercial paper issuances to fund the maturities and redemptionsrepay $395 million of higher-cost long-debtlong-term indebtedness and to fund, the $235in part, investing activities. Additionally, during 2017, Ameren made $431 million that Ameren was requiredin dividend payments to leaveshareholders, compared with New AER upon its divestiture$416 million in December 2013, pursuant to the transaction agreement with IPH. In 2013, Ameren used cash on hand to fund investing and financing activities that were not funded by cash generated from operating activities.

dividend payments in 2016. No cash from financing activities was used for discontinued operations during 2014.

2017.
Ameren Missouri’s cash used in financing activities used net cash of $113decreased by $103 million in 2014,2017, compared with $6032016. During 2017, Ameren Missouri utilized net proceeds from the issuance of $438 million in 2013. During 2014,of long-term indebtedness and net commercial paper issuances to repay $431 million of higher-cost long-term indebtedness. In comparison, during 2016, Ameren Missouri issued $350 million of senior secured notes and a net $97 million of short-term debt, repaid at maturity $104$149 million of long-term debt, repaid $105 million toindebtedness and used the money pool, and paid common stock dividends of $340 million. Ameren Missouri used cash generated from its operating activities to fund investing and financing activities in 2014. In comparison, during 2013, Ameren Missouri redeemed $244 million of long-term debt, paid common stock dividends of $460 million, and received $105 million from the money pool. In 2013, Ameren Missouri usedproceeds, along with cash on hand, to fund investing andrepay $266 million of higher-cost long-term indebtedness. In 2017, Ameren Missouri paid $362 million in dividends to Ameren (parent), compared with $355 million dividends paid in 2016. Additionally, during 2017, Ameren Missouri received $30 million in capital contributions from Ameren (parent) associated with the tax allocation agreement, compared to $44 million received in 2016.
Ameren Illinois’ cash provided by financing activities that were not fundedincreased by cash generated from operating activities.

Ameren Illinois' financing activities provided net cash of $383$211 million in 2014,2017, compared with $452016. During 2017, Ameren Illinois utilized net proceeds from the issuance of $507 million in 2013. During 2014,of long-term indebtedness and net commercial paper issuances to repay at maturity $250 million of higher-cost long-term indebtedness. In comparison, during 2016, Ameren Illinois issued $550 million in senior secured notes and a net $32 million of short-term debt, redeemed existing long-term debt of $163 million, and repaid $41 million to the money pool. In comparison, during 2013, Ameren Illinois issued $280 million in senior secured debt, repaid at maturity $150$291 million of long-term debt,indebtedness and net commercial paper issuances and utilized the proceeds to repay at maturity $129 million of higher-cost long-term indebtedness. Additionally, in 2017, no dividends were paid common stock dividends ofto Ameren (parent) compared to $110 million. During both years, Ameren Illinois used cash from financing activities to fund investing activities that were not funded by cash generated from operating activities.million paid in 2016.
20132016 versus 20122015
Ameren used net cash of $149 million in 2013, compared with $426 million in 2012 related toAmeren’s financing activities associated with continuing operations.operations used net cash of $265 million in 2016, compared with providing net cash of $232 million in 2015. During 2013,2016, Ameren utilized net proceeds from the issuance of $646 million of long-term indebtedness and its registrant subsidiaries issued lower-cost long-term and short-term debtnet commercial paper issuances to fund the maturities and redemptionsrepay $395 million of higher-cost long-term debtindebtedness and to fund, in part, investing activities. In comparison, during 2015, Ameren utilized net proceeds from the $235issuance of $1,197 million that Ameren was required
of long-term indebtedness to leave with New AER upon its divestiture in December 2013, pursuant to the transaction agreement with IPH. During 2012, Ameren and its registrant subsidiaries issued lower-cost long-term debt to fund the maturities and redemptionsrepay $413 million of net commercial paper issuances, $120 million of higher-cost long-term debtindebtedness, and repay short-term debt. During both years, Ameren used cash on hand to fund, in part, investing and financing activities that were not funded by cash generated from operating activities.

No cash from financing activities was used for discontinued operations during 2013.

2016.
Ameren Missouri’s cash used in financing activities used net cash of $603increased by $109 million in 2013,2016, compared with $354 million in 2012.2015. During 2013,2016, Ameren Missouri redeemed $244utilized net proceeds from the issuance of $149 million of long-term debt, paid common stock dividends of $460 million, and received $105 million from the money pool. In comparison, during 2012, Ameren Missouri issued $485 million of senior secured notes, redeemed or repaid of $422 million of long-term debt, and paid common stock dividends of $400 million. During both years, Ameren Missouri usedindebtedness, along with cash on hand, to fund investingrepay $266 million of higher-cost long-term indebtedness. In comparison, during 2015, Ameren Missouri utilized net proceeds from the issuance of $249 million of long-term indebtedness to repay $120 million of higher-cost long-term indebtedness and $97 million of net commercial paper issuances. Additionally, during 2016, Ameren Missouri paid $355 million in dividends to Ameren (parent), compared with $575 million dividends paid in the year-ago period. Also, in 2016, Ameren Missouri received $44 million as a capital contribution from Ameren (parent) compared to $224 million received in 2015.
Ameren Illinois’ cash provided by financing activities that were not fundeddecreased by cash generated from operating activities.

Ameren Illinois' financing activities provided net cash of $45$176 million in 2013,2016, compared with 2012 when Ameren Illinois’ financing activities used net cash of $103 million.2015. During 2013,2016, Ameren Illinois issued $280 million in senior secured debt, repaid at maturity $150$291 million of long-term debt,indebtedness and paid common stock dividendsnet commercial paper issuances and utilized the proceeds to repay at maturity $129 million of $110 million. Ameren Illinois used cash from financing activities to fund investing activities that were not funded by cash provided by operating activities.higher-cost long-term indebtedness. In comparison, during 2012,2015, Ameren Illinois issued $400 millionutilized proceeds from the issuance of senior secured notes, redeemed or repaid $333$248 million of long-term debtindebtedness to repay $32 million of net commercial paper issuances and paid common stock dividends of $189 million. In 2012,to fund, in part, investing activities. Additionally, in 2016 Ameren Illinois used cash on handpaid $110 million in dividends to fund investing and financing activities that were not funded by cash generated from operating activities.Ameren (parent) compared to no dividends paid in the year-ago period.
Credit Facility Borrowings and Liquidity
The liquidity needs of Ameren, Ameren Missouri, and Ameren Illinois are typically supported through the use of available cash, or proceeds from short-term intercompanyaffiliate borrowings, drawings under committed bank credit agreements,the Credit Agreements, or commercial paper issuances. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for additional information on credit agreements, short-term affiliate borrowing activity, commercial paper issuances, relevant interest rates, and borrowings under Ameren’s money pool arrangements.



52


The following table presents the committed 2012 Credit Agreements of Ameren, Ameren Missouri, and Ameren Illinois and the credit capacity available under such agreements, considering reductions for commercial paper issuances and letters of credit,Ameren’s consolidated liquidity as of December 31, 20142017:
 Expiration Borrowing Capacity Credit Available
Ameren and Ameren Missouri:     
2012 Missouri Credit AgreementDecember 2019 $1,000
 $1,000
Less: Commercial paper outstanding  (a)
 438
Subtotal    562
Ameren and Ameren Illinois:     
2012 Illinois Credit AgreementDecember 2019 1,100
 1,100
Less: Commercial paper outstanding  (a)
 276
     Less: Letters of credit(b)
  (a)
 13
Subtotal    811
Ameren total  $2,100
 $1,373
  
Available at
December 31, 2017
Ameren (parent) and Ameren Missouri (a):
  
Missouri Credit Agreement  borrowing capacity
 $1,000
Less: Ameren (parent) commercial paper outstanding 224
Less: Ameren Missouri commercial paper outstanding 39
Missouri Credit Agreement  credit available
 737
Ameren (parent) and Ameren Illinois(b):
  
Illinois Credit Agreement  borrowing capacity
 1,100
Less: Ameren (parent) commercial paper outstanding 159
Less: Ameren Illinois commercial paper outstanding 62
Less: Letters of credit 1
Illinois Credit Agreement  credit available
 878
Total Credit Available $1,615
Cash and cash equivalents 10
Total Liquidity $1,625
(a)Not applicable.
(b)As of December 31, 2014, $9The maximum aggregate amount available to Ameren (parent) and Ameren Missouri under the Missouri Credit Agreement is $700 million of the letters of credit relate to Ameren's ongoing credit support obligations to New AER.and $800 million, respectively. See Note 164 – Divestiture TransactionsShort-term Debt and Discontinued OperationsLiquidity under Part II, Item 8, of this report for additional information.further discussion of the Credit Agreements.
(b)The maximum aggregate amount available to Ameren (parent) and Ameren Illinois under the Illinois Credit Agreement is $500 million and $800 million, respectively. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for further discussion of the Credit Agreements.
In December 2014, Ameren (parent), Ameren Missouri and Ameren Illinois amended, restated, and extended the maturity dates of their 2012The Credit Agreements from November 14, 2017, toprovide $2.1 billion of credit cumulatively through maturity in December 11, 2019.2021. The maturity date may be extended for two additional one-year periods upon mutual consent of the borrowers and lenders. Borrowings by Ameren (parent) under either of the 2012 Credit Agreements are due and payable no later than the maturity date, while borrowings by Ameren Missouri and Ameren Illinois are due and payable no later than the earlier of the maturity date or 364 days after the date of such borrowing (subject to the right of each borrower to re-borrow in accordance with the terms of the applicable 2012 Credit Agreement). The 2012 Credit Agreements are used to borrow cash, to issue letters of credit, and to support issuances under Ameren’s,Ameren (parent)’s, Ameren Missouri’s, and Ameren Illinois’ commercial paper programs. Both of the 2012 Credit Agreementscredit agreements are available to Ameren (parent) to support issuances under Ameren’sAmeren (parent)’s commercial paper program, subject to borrowing sublimits.available credit capacity under the agreements. The 2012 Missouri Credit Agreement is available to support issuances under Ameren Missouri’s commercial paper program. The 2012 Illinois Credit Agreement is available to support issuances under Ameren Illinois’ commercial paper program. During 2013 and 2014, issuancesIssuances under the Ameren (parent), Ameren Missouri, and Ameren Illinois commercial paper programs were available at lower interest rates than the interest rates availableof borrowings under the 2012 Credit Agreements. As such, commercialCommercial paper issuances were thus preferred to credit facility borrowings as a preferred source of third-party short-term debt relative to credit facility borrowings.debt.
The maximum aggregate amount available to each borrower under each facility is shown in the following table (the amount being the borrower’s “Borrowing Sublimit”):
 
2012 Missouri
Credit Agreement
 
2012 Illinois
Credit Agreement
Ameren$700
 $500
Ameren Missouri800
 (a)
Ameren Illinois(a)
 800
(a)Not applicable.
Subject to applicable regulatory short-term borrowing authorizations, these credit arrangements are also available to Ameren's other subsidiaries through direct short-term borrowings
from Ameren including, but not limited to, Ameren Services, throughhas a money pool agreement. Ameren has money pool agreementsagreement with and among its utility subsidiaries to coordinate and to provide for certain short-term cash and working capital requirements. As short-term capital needs arise, and based on availability of funding sources, Ameren Missouri and Ameren Illinois will access funds from the utility money pool, the Credit Agreements, or the commercial paper programs depending on which option has the lowest interest rates. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for a detailed explanation of the utility money pool arrangements.arrangement.
The issuance of short-term debt securities by Ameren'sAmeren’s utility subsidiaries is subject to approval by the FERC under the Federal Power Act. In February 2014,June 2017, the FERC issued an order authorizing ATXI to issue up to $300 million of short-term debt securities through July 2019. In 2016, the FERC issued orders authorizing Ameren Missouri and Ameren Illinois to each issue up to $1 billion of short-term debt securities through March 16, 2016. In September 2014, the FERC issued an order authorizing Ameren Illinois to issue up to $1 billion of short-term debt securities2018 and through September 15, 2016.2018, respectively.
The Ameren Companies continually evaluate the adequacy and appropriateness of their liquidity arrangements givenfor changing business conditions. When business conditions warrant, changes may be made to existing credit agreements or to other short-term borrowing arrangements.


53


Long-term Debt and Equity
The following table presents theour issuances (net of issuance premiums or discounts), redemptions, repurchases, and maturities of long-term debt (net of any issuance discounts) for the years ended December 31, 20142017, 20132016, and 20122015 for the Ameren Companies.. The Ameren Companies did not issue any common stock or redeem or repurchase any preferred stock during the years ended 20142017, 20132016, and 20122015. In 2017, 2016, and 2015, Ameren Missouri received cash capital contributions as a result of the tax allocation agreement from Ameren (parent). In 2017 and 2015, Ameren Illinois received cash capital contributions from Ameren (parent). For additional information related to the terms and uses of these issuances and effective registration statements, see Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report.

 
Month Issued, Redeemed,
Repurchased, or Matured
 2014 2013 2012
Issuances       
Ameren Missouri:       
3.90% Senior secured notes due 2042September $
 $
 $482
3.50% Senior secured notes due 2024April 350
 
 
Ameren Illinois:       
2.70% Senior secured notes due 2022August 
 
 400
4.80% Senior secured notes due 2043December 
 278
 
4.30% Senior secured notes due 2044June 248
 
 
3.25% Senior secured notes due 2025December 300
 
 
Total Ameren long-term debt issuances  $898
 $278
 $882
Redemptions, Repurchases and Maturities       
Ameren (Parent):       
8.875% Senior unsecured notes due 2014May $425
 $
 $
Ameren Missouri:       
City of Bowling Green capital lease (Peno Creek CT)Various 5
 5
 5
5.25% Senior secured notes due 2012September 
 
 173
6.00% Senior secured notes due 2018September 
 
 71
6.70% Senior secured notes due 2019September 
 
 121
5.10% Senior secured notes due 2018September 
 
 1
5.10% Senior secured notes due 2019September 
 
 56
1993 5.45% Series pollution control revenue bonds due 2028October 
 44
 
4.65% Senior secured notes due 2013October 
 200
 
5.50% Senior secured notes due 2014May 104
 
 
Ameren Illinois:       
9.75% Senior secured notes due 2018August 
 
 87
6.25% Senior secured notes due 2018August 
 
 194
5.50% 2000 Series A pollution control revenue bonds due 2014August 
 
 51
6.20% Series 1992B due 2012November 
 
 1
8.875% Senior secured notes due 2013December 
 150
 
5.90% Series 1993 due 2023(a)
January 32
 
 
5.70% 1994A Series due 2024(a)
January 36
 
 
5.95% 1993 Series C-1 due 2026January 35
 
 
5.70% 1993 Series C-2 due 2026January 8
 
 
5.40% 1998A Series due 2028January 19
 
 
5.40% 1998B Series due 2028January 33
 
 
Total Ameren long-term debt redemptions, repurchases and maturities  $697
 $399
 $760
 Month Issued, Redeemed, Repurchased, or Matured 2017 2016 2015
Issuances of Long-term Debt       
Ameren (parent)       
2.70% Senior unsecured notes due 2020November $
 $
 $350
3.65% Senior unsecured notes due 2026November 
 
 350
Ameren Missouri:       
3.65% Senior secured notes due 2045April 
 
 249
3.65% Senior secured notes due 2045June 
 149
 
2.95% Senior secured notes due 2027June 399
 
 
Ameren Illinois:       
3.70% First mortgage bonds due 2047November 496
 
 
4.15% Senior secured notes due 2046December 
 240
 248
ATXI:       
3.43% Senior notes due 2050June 150
 
 
3.43% Senior notes due 2050August 300
 
 
Total long-term debt issuances  $1,345
 $389
 $1,197
Redemptions, Repurchases, and Maturities of Long-term Debt       
Ameren Missouri:       
5.40% Senior secured notes due 2016February 
 260
 
4.75% Senior secured notes due 2015April 
 
 114
6.40% Senior secured notes due 2017June 425
 

City of Bowling Green capital lease (Peno Creek CT)December 6
 6
 6
Ameren Illinois:       
6.20% Senior secured notes due 2016June 
 54
 
6.25% Senior secured notes due 2016June 
 75
 
6.125% Senior secured notes due 2017November 250
 
 
Total long-term debt redemptions, repurchases, and maturities  $681
 $395
 $120
(a)    Less than $1In June 2017, Ameren Missouri issued $400 million of 2.95% senior secured notes due June 2027, with interest payable semiannually on June 15 and December 15 of each year, beginning December 15, 2017. Ameren Missouri received proceeds of $396 million, which were used, in conjunction with other available funds, to repay at maturity $425 million of Ameren Missouri’s 6.40% senior secured notes in June 2017.
In June 2017, pursuant to a note purchase agreement, ATXI agreed to issue $450 million principal amount of 3.43% senior unsecured notes, due 2050, with interest payable semiannually on the last day of February and August of each year, beginning February 28, 2018, through a private placement offering exempt from registration under the Securities Act of 1933, as amended. ATXI issued $150 million principal amount of the notes in June 2017 and the remaining $300 million principal amount of the notes in August 2017. ATXI received proceeds of $449 million from the notes, which were used by ATXI to repay existing short-term and long-term affiliate debt owed to Ameren (parent).
In November 2017, Ameren Illinois issued $500 million of 3.70% first mortgage bonds remaindue December 2047, with interest payable semiannually on June 1 and December 1 of each year, beginning June 1, 2018. Ameren Illinois received proceeds of $492 million, which were used to repay outstanding after redemption.short-term debt, including short-term debt that Ameren Illinois incurred in connection with the repayment of $250 million of its 6.125% senior secured notes that matured in November 2017.
In December 2017, Ameren, Ameren Missouri, and Ameren Illinois filed a Form S-3 shelf registration statement with the SEC, registering the issuance of an indeterminate amount of certain types of securities. The registration statement became effective immediately upon filing and expires in December 2020.
Ameren filed a Form S-3 registration statement with the SEC in May 2017, which expires in May 2020, authorizing the offering of 6 million additional shares of its common stock under DRPlus. Shares of common stock sold under DRPlus are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated transactions.
The Ameren Companies may sell securities registered under their effective registration statements if market conditions and capital requirements warrant such sales. Any offer and sale will be made only by means of a prospectus that meets the requirements of the Securities Act of 1933 and the rules and regulations thereunder.

54


Indebtedness Provisions and Other Covenants
At December 31, 2014,2017, the Ameren Companies were in compliance with the provisions and covenants contained within their credit agreements, indentures, and articles of incorporation.incorporation, as applicable, and ATXI was in compliance with the provisions and covenants contained in its note purchase agreement. See Note 4 – Short-term Debt and Liquidity and Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report for a discussion of covenants and provisions (and applicable cross-default provisions) contained in our bank credit agreements, and in certain of the Ameren Companies’ indentures and articles of incorporation.incorporation, and ATXI’s note purchase agreement.
We consider access to short-term and long-term capital markets to be a significant source of funding for capital requirements not satisfied by cash generated fromprovided by our operating activities. Inability to raise capital on reasonable terms, particularly during times of uncertainty in the capital markets, could negatively affect our ability to maintain and expand our businesses. After assessing its current operating performance, liquidity, and credit ratings (see Credit Ratings below), Ameren, Ameren Missouri, and Ameren Illinois each believes that it will continue to have access to the capital markets. However, events beyond Ameren's,Ameren’s, Ameren Missouri's,Missouri’s, and Ameren Illinois'Illinois’ control may create uncertainty in the capital markets or make access to the capital markets uncertain or limited. Such events could increase our cost of capital and adversely affect our ability to access the capital markets.
Dividends and Return of Capital
Ameren paid to its shareholders common stock dividends totaling $390$431 million,, or $1.61$1.778 per share, in 2014, $3882017, $416 million,, or $1.60$1.715 per share, in 2013,2016, and $382$402 million,, or $1.60$1.655 per share, in 2012.2015.
The amount and timing of dividends payable on Ameren’s common stock are within the sole discretion of Ameren’s board of directors. TheAmeren’s board of directors has not set specific targets or payout parameters when declaring common stock dividends, but it considers various issues,factors, including Ameren’s overall payout ratio, payout ratios of our peers, projected cash flow and potential future cash flow requirements, historical earnings and cash flow, projected earnings, impacts of regulatory orders or legislation, and other key business considerations. Ameren expects its dividend payout ratio to be between 55% and 70% of earnings over the next few years. On February 13, 2015,9, 2018, the board of
directors of Ameren declared a quarterly dividend on Ameren’s common stock of 4145.75 cents per share, payable on March 31, 2015,29, 2018, to shareholders of record on March 11, 2015.14, 2018.
Certain of our financial agreements and corporate organizational documents contain covenants and conditions that, among other things, restrict the Ameren Companies’ payment of dividends in certain circumstances.
Ameren Illinois’ articles of incorporation require its dividend payments on common stock to be based on ratios of common stock to total capitalization and other provisions relatedwith respect to certain operating expenses and accumulations of earned surplus. Additionally, Ameren has committed to the FERC to maintain a minimum of 30% equity in its capital structure at Ameren Illinois.
Ameren Missouri and Ameren Illinois, as well as certain other nonregistrant Ameren subsidiaries, are subject to Section 305(a) of the Federal Power Act, which makes it unlawful for any officer or director of a public utility, as defined in the Federal Power Act, to participate in the making or paying of any dividend from any funds “properly included in capital account.” The FERC has consistently interpreted the provision to allow dividends to be paid as long as (1) the source of the dividends is clearly disclosed, (2) the dividends are not excessive, and (3) there is no self-dealing on the part of corporate officials. At a minimum, Ameren believes that dividends can be paid by its subsidiaries that are public utilities from net income and from retained earnings. In addition, under Illinois law, Ameren Illinois may not pay any dividend on its stock unless, among other things, its earnings and earned surplus are sufficient to declare and pay a dividend after provision is made for reasonable and proper reserves, or unless Ameren Illinois has specific authorization from the ICC.
Ameren has committed to the FERC to maintain a minimum of 30% equity in its capital structure at Ameren Illinois.
At December 31, 2014, Ameren, Ameren Missouri, and Ameren Illinois were not restricted from paying dividends.
At December 31, 2014,2017, the amount of restricted net assets of wholly ownedAmeren’s subsidiaries of Ameren that may not be distributed to Ameren in the form of a loan or dividend was $2.3 billion.


The following table presents common stock dividends paid by Ameren Corporation to its common shareholders and by Ameren Missouri and Ameren Illinois to their parent, Ameren.Ameren:
2014 2013 20122017 2016 2015
Ameren$431
 $416
 $402
Ameren Missouri$340
(a) 
$460
 $400
362
 355
 575
Ameren Illinois
 110
 189

 110
 
Ameren390
 388
 382
(a)Additionally, during the fourth quarter of 2014, Ameren Missouri returned capital of $215 million to Ameren (parent).
Certain of the Ameren CompaniesMissouri and Ameren Illinois each have issued preferred stock, which provides for cumulative preferred stock dividends. Each company’s board of directors considers the declaration of the preferred stock dividends to shareholders of record on a
certain date, stating the date on which the dividend is payable and the amount to be paid. See Note 5 – Long-term Debt and Equity Financings under Part II, Item 8, of this report for further detail concerning the preferred stock issuances.



55


Contractual Obligations
The following table presents our contractual obligations as of December 31, 20142017. See Note 1110 – Retirement Benefits under Part II, Item 8, of this report for information regarding expected minimum funding levels for our pension plans. These expected pension funding amounts are not included in the table below. In addition, routine short-term purchase order commitments are not included.
Less than
1 Year
 1 - 3 Years 3 - 5 Years 
After 5
Years
 Total
Less Than
1 Year
 
 3 Years
 3 – 5 Years 
After 5
Years
 Total
Ameren:(a)
                  
Long-term debt and capital lease obligations(b)
$120
 $1,076
 $1,421
 $3,634
 $6,251
$841
 $1,023
 $514
 $5,617
 $7,995
Interest payments(c)
339
 613
 429
 2,387
 3,768
464
 855
 814
 5,018
 7,151
Operating leases(d)
13
 24
 23
 38
 98
Other obligations(e)
1,317
 1,978
 660
 1,231
 5,186
Operating leases10
 17
 12
 14
 53
Other obligations(d)
981
 964
 206
 254
 2,405
Total cash contractual obligations$1,789
 $3,691
 $2,533
 $7,290
 $15,303
$2,296
 $2,859
 $1,546
 $10,903
 $17,604
Ameren Missouri:                  
Long-term debt and capital lease obligations(b)
$120
 $697
 $964
 $2,224
 $4,005
$384
 $673
 $64
 $2,867
 $3,988
Interest payments(c)
220
 390
 289
 1,580
 2,479
331
 592
 575
 3,208
 4,706
Operating leases(d)
11
 22
 20
 37
 90
Other obligations(e)
898
 1,613
 476
 525
 3,512
Operating leases8
 15
 12
 14
 49
Other obligations(d)
628
 654
 163
 194
 1,639
Total cash contractual obligations$1,249
 $2,722
 $1,749
 $4,366
 $10,086
$1,351
 $1,934
 $814
 $6,283
 $10,382
Ameren Illinois:                  
Long-term debt(b)
$
 $379
 $457
 $1,410
 $2,246
$457
 $
 $400
 $2,000
 $2,857
Interest payments(c)
118
 224
 139
 807
 1,288
106
 188
 185
 1,584
 2,063
Operating leases(d)
1
 2
 2
 1
 6
Other obligations(e)
381
 347
 184
 706
 1,618
Operating leases1
 
 
 1
 2
Other obligations(d)
352
 310
 43
 40
 745
Total cash contractual obligations$500
 $952
 $782
 $2,924
 $5,158
$916
 $498
 $628
 $3,625
 $5,667
(a)Includes amounts for registrant and nonregistrant Ameren subsidiaries and intercompany eliminations.
(b)
Excludes unamortized discount and premium and debt issuance costs of $11$60 million, $627 million, and $5$27 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively. See Note 5 – Long-term Debt and Equity Financings under Part II, Item 8 of this report, for discussion of items included herein.
(c)
The weighted-average variable-rate debt has been calculated using the interest rate as of December 31, 20142017.
(d)
Amounts for certain land-related leases have indefinite payment periods. The annual obligation of $2 million, $1 million, and $1 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, for these items is included in the Less than 1 Year, 1 - 3 Years, and 3 - 5 Years columns.
(e)See Other Obligations in Note 1514 – Commitments and Contingencies under Part II, Item 8 of this report, for discussion of items included herein.
As of December 31, 2014, the amounts of2017, Ameren, Ameren Missouri, and Ameren Illinois had no unrecognized tax benefits (detriments) for uncertain tax positions were $54 million, $- million, and $(1) million for Ameren, Ameren Missouri, and Ameren Illinois, respectively. It is reasonably possible to expect that the settlement of an unrecognized tax benefit will result in an underpayment or overpayment of tax and related interest. However, there is a high degree of uncertainty with respect to the timing of cash payments or receipts associated with unrecognized tax benefits. The amount and timing of certain payments or receipts is not reliably estimable or determinable at this time. See Note 13 – Income Taxes under Part II, Item 8, of this report for information regarding the Ameren Companies’ unrecognized tax benefits and related liabilities for interest expense.positions.
Off-Balance-Sheet Arrangements
At December 31, 2014,2017, none of the Ameren Companies had any significant off-balance-sheet financing arrangements, other than operating leases entered into in the ordinary course of business. None of the Ameren Companies expect to engage in any significant off-balance-sheet financing arrangements in the near future. See Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of this report for Ameren (parent) guarantees andbusiness, letters of credit, issued to support New AER basedand Ameren (parent) guarantee arrangements on the transaction agreement with IPH.behalf of its subsidiaries.
Credit Ratings
Our credit ratings affect our liquidity, our access to the
capital markets and credit markets, our cost of borrowing under our credit facilities and our commercial paper programs, and our collateral posting requirements under commodity contracts.

The following table presents the principal credit ratings of the Ameren Companies by Moody’s and S&P and Fitch effective on the date of this report:
 Moody’sS&PFitch
Ameren:
Issuer/corporate credit ratingBaa2BBB+BBB+
Senior unsecured debtBaa2BBBBBB+
Commercial paperP-2A-2F2
Ameren Missouri:  
Issuer/corporate credit ratingBaa1BBB+BBB+
Secured debtA2AA
Senior unsecured debtBaa1BBB+A-BBB
Commercial paperP-2A-2F-2
Ameren Illinois:Missouri:  
Issuer/corporate credit ratingBaa1BBB+BBB
Secured debtA2AA-
Senior unsecured debtBaa1BBB+BBB+
Commercial paperP-2A-2
F-2Ameren Illinois:
Issuer/corporate credit ratingA3BBB+
Secured debtA1A
Senior unsecured debtA3BBB+
Commercial paperP-2A-2
ATXI:
Issuer credit ratingA2Not Rated
Senior unsecured debtA2Not Rated
The cost of borrowing under our credit facilities can also fluctuate depending upon the credit ratings of the borrower. A credit rating is not a recommendation to buy, sell, or hold securities. It should be evaluated independently of any other


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rating. Ratings are subject to revision or withdrawal at any time by the rating organization.
Collateral Postings
Any adverse change inweakening of our credit ratings may reduce access to capital and trigger additional collateral postings and prepayments. Such changes may also increase the cost of borrowing, resulting in a potential negative impactan adverse effect on earnings. Cash collateral postings and prepayments made with external parties, including postings related to exchange-traded contracts, at December 31, 2014, were $7 million, $7 million, and less than $1 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively. Cashcash collateral posted by external counterparties with Ameren and Ameren Illinois was $2 million and $2 million, respectively,parties were immaterial at December 31, 2014. Sub-investment-grade2017. A sub-investment-grade issuer or senior unsecured debt ratings (lower thanrating (whether below “BBB-” from S&P or below “Baa3”) from Moody’s) at December 31, 2014,2017, could have resulted in Ameren, Ameren Missouri, or Ameren Illinois being required to post additional collateral or other assurances for certain trade obligations amounting to $159$82 million, $88$44 million, and $71$38 million, respectively.
Changes in commodity prices could trigger additional collateral postings and prepaymentsprepayments. Based on credit ratings at current credit ratings. IfDecember 31, 2017, if market prices were 15% higher or lower than December 31, 2014,2017, levels in the next 12 months and 20% higher thereafter through the end of the term of the commodity contracts, then Ameren, Ameren Missouri, or Ameren Illinois would not be required to post additional collateral or other assurances for certain trade obligations. If market prices were 15% lower than December 31, 2014 levels in the next 12 months and 20% lower thereafter through the end of the term of the commodity contracts, then Ameren, Ameren Missouri, or Ameren Illinois could be required to post additionalan immaterial amount, compared to each company’s liquidity, of collateral or provide other assurances for certain trade obligations up to $25 million, $14 million, and $11 million, respectively.obligations.
The balance of Marketing Company’s note payable to Ameren for cash collateral requirements was $12 million at December 31, 2014. This balance will vary until December 2, 2015, as cash collateral requirements caused by changes in commodity prices could trigger additional collateral postings and prepayments for New AER and thus affect the balance of the note. Ameren’s obligation to provide credit support on behalf of New AER will cease on December 2, 2015. If market prices were 15% higher than their December 31, 2014 levels in the next 12 months and 20% higher thereafter through the end of the term of the commodity contracts, then Ameren could be required to provide additional credit support to IPH, up to $26 million. If market prices were 15% lower than their December 31, 2014 levels in the next 12 months and 20% lower thereafter through the end of the term of the commodity contracts, then Ameren could be required to provide IPH with additional credit support up to $31 million. If, on December 31, 2014, Ameren's credit ratings had been below investment grade, Ameren could have been required to post additional cash collateral in support of New AER in the amount of $26 million.
See Note 16 – Divestiture Transactions and Discontinued
Operations under Part II, Item 8, of this report for information regarding Ameren (parent) guarantees.
OUTLOOK
We seek to earn competitive returns on investments in our businesses. We are seekingseek to improve our regulatory frameworks and cost recovery mechanisms and are simultaneously pursuing constructive regulatory outcomes within existing frameworks.frameworks, while also advocating for responsible energy policies. We are seeking to align our overall spending, both operating and capital, with economic conditions and cash flows providedwith the frameworks established by our regulators. Consequently, we are focusedregulators and to create and capitalize on investment opportunities for the benefit of our customers and shareholders. We focus on minimizing the gap between allowed and earned returns on equity. We intend to allocateequity and allocating capital resources to our business opportunities that we expect will offer the most attractive risk-adjusted return potential.
As part of Ameren’s strategic plan, we pursue projects to meet our customer energy needs and to improve electric and natural gas system reliability, safety, and security within our service territories. Ameren also evaluates competitive electric transmission investment opportunities as they arise. Additionally, Ameren Missouri expects to make investments over time that will enable it to transition to a more diverse energy generation portfolio.
Below are some key trends, events, and uncertainties that aremay reasonably likely to affect the Ameren Companies'our results of operations, financial condition, or liquidity, as well as theirour ability to achieve strategic and financial objectives, for 20152018 and beyond.
Operations
Our strategy for earning competitive returns on our investments involves meeting customer energy needs in an efficient fashion, working to enhance regulatory frameworks, making timely and well-supported rate case filings, and aligning overall spending with those rate case outcomes, economic conditions, and return opportunities.
Ameren continues to pursue its plans to invest in FERC-regulated electric transmission. MISOATXI has approved three electric transmissionMISO-approved multi-value projects, to be developed by ATXI. The first project,the Illinois Rivers, Spoon River, and Mark Twain projects. The Illinois Rivers project involves the construction of a 345-kilovolttransmission line from western Indianaeastern

Missouri across the state of Illinois to eastern Missouri. The first sections ofwestern Indiana. Construction activities for the Illinois Rivers project are expected to be completed in 2016. Thecontinuing on schedule, and the last section of this project is expected to be completed by the end of 2019. The Spoon River project, located in northwest Illinois, was placed in service in February 2018. The Mark Twain project, located in northeast Missouri and connecting the Illinois Rivers project to Iowa, is expected to be completed by the end of 2019. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for information regarding the Mark Twain project in northeast Missouri areand its approval process and the other two MISO-approved projects to be constructed by ATXI. These two projects areIllinois Rivers project. As of December 31, 2017, ATXI’s expected to be completed in 2018. The totalremaining investment in theseall three projects is expectedapproximately $300 million, with the total investment to be more than $1.4 billion during 2015 through 2019. This total includes over $100 million of investment by Ameren Illinois to construct connections to its existing transmission system. Separate from the three projects discussed above,$1.6 billion. In addition, Ameren Illinois expects to invest approximately $900 million$2.3 billion in electric transmission assets during 2015from 2018 through 20192022 to address load growthreplace aging infrastructure and reliability requirements.improve reliability.
In November 2013, a customer group filed a complaint case with the FERC seeking a reduction in the allowed base return on common equity for the FERC-regulated MISO transmission rate base under the MISO tariff to 9.15%. Currently, the FERC-allowed base return on common equity for MISO transmission owners is 12.38%. However, the 12.38% return is the subject of two FERC complaint proceedings that challenge the allowed return on common


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equity for MISO transmission owners. In January 2015, the FERC scheduled the initial case for hearing proceedings, requiring an initial decision to be issued no later than November 30, 2015. A 50 basis point reduction in the FERC-allowed return on common equity would reduce Ameren's and Ameren Illinois' 2015 earnings by an estimated $4 million and $2 million, respectively, based on projected rate base. The final outcome of these proceedings could result in a refund to customers retroactive to November 2013 and have a material impact on the results of operations, financial position, and liquidity of Ameren and Ameren Illinois.
In January 2015, FERC approved our request to implement an incentive adder of up to 50 basis points on the allowed base return on common equity prospectively from January 6, 2015, and to defer collection of the incentive adder until the issuance of the final order addressing the initial MISO complaint case discussed above.
Both Ameren Illinois and ATXI have FERC authorization to employuse a forward-looking rate calculation with an annual revenue requirement reconciliation for each company’s electric transmission business. UsingBased on expected rate base growth and the currently allowed 10.82% return on common equity, the 2018 revenue requirements for Ameren Illinois’ and ATXI’s electric transmission businesses are $270 million and $174 million, respectively. These revenue requirements represent an increase in Ameren Illinois' and ATXI's revenue requirements of $11 million and $4 million, respectively, primarily because of the rate base growth described above, partially offset by a decrease due to the lower federal statutory corporate income tax rates enacted under the TCJA.
The return on common equity for MISO transmission owners, including Ameren Illinois and ATXI, was the subject of a FERC complaint case filed in February 2015 which challenged the allowed base return on common equity. Ameren Illinois and ATXI currently use the FERC authorized total allowed return on common equity of 10.82% in customer rates. A final FERC order would establish the allowed return on common equity to be applied to the 15-month period from February 2015 to May 2016 and also establish the return on common equity to be included in customer rates prospectively from the effective date of such order, replacing the current 10.82% total return on common equity. The timing and amount of any adjustment to the total allowed return on common equity that may be ordered as a result of the complaint case is uncertain. A 50 basis point reduction in the FERC-allowed base return on common equity would reduce Ameren’s and Ameren Illinois’ annual earnings by an estimated $8 million and $4 million, respectively, based on each company’s 2018 projected rate base. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for information regarding FERC complaint cases.
In March 2017, the MoPSC issued an order approving a unanimous stipulation and agreement in Ameren Missouri’s July 2016 regulatory rate review. The order resulted in a $3.4 billion revenue requirement, which is a $92 million increase in Ameren Missouri’s annual revenue requirement for electric service, compared with the prior revenue requirement established in the MoPSC’s April 2015 electric rate order. The new rates, base level of expenses, and amortizations became effective on JanuaryApril 1, 2017. Excluding cost reductions associated with reduced sales volumes, the base level of net energy costs decreased by $54 million from the base level established in the MoPSC’s April 2015 electric rate order. Changes in amortizations and an assumed 12.38% return on equity, Ameren Illinois expects that the base level of expenses for the other regulatory tracking mechanisms, including extending the amortization period of certain regulatory assets, reduced expenses by $26 million from the base levels established in the MoPSC’s April 2015 revenue requirement for its electric transmission business to be $199 million, which represents a $40 million increase over the 2014 revenue requirement because of rate base growth. These rates also reflect a capital structure composed of approximately 54% common equity and a rate base of $890 million. Using the rates that became effective on January 1, 2015, and an assumed 12.38% return on equity, ATXI expects that the 2015 revenue requirement for its electric transmission business to be $80 million, which represents a $46 million increase over the 2014 revenue requirement because of rate base growth, primarily relating to the Illinois Rivers project. These rates also reflect a capital structure composed of approximately 56% common equity, and a rate base of $536 million.order.
In February 2015, Ameren Missouri filed an amended request with the MoPSC seeking approval to increase its annual revenues for electric service by approximately $190 million. The MoPSC proceedings relating to the proposed electric service rate increase are ongoing and a decision by the MoPSC is expected by May 2015, with new rates effective by June 2015.
Ameren Missouri's current MEEIA plan provides for a cumulative investment in customer energy efficiency programs of $147 million during 2013 through 2015. In December 2014,2017, the ICC issued an order in Ameren Missouri filedIllinois’ annual update filing that approved a new proposed energy efficiency plan with the MoPSC under the MEEIA. This plan includes a portfolio of customer energy efficiency programs along with a cost recovery mechanism. If the plan is approved, $17 million decrease in Ameren Illinois’ electric delivery service revenue requirement beginning in January 2016, Ameren Missouri intends to invest $135 million over three years for the proposed customer energy efficiency programs.
In January 2015, Ameren2018. However, Illinois filed a request with the ICC seeking approval to increase its annual revenues for natural gas delivery service by $53 million. A decision by the ICC in this proceeding is required by December 2015 and new rates are expected to be effective in January 2016.
The IEIMAlaw provides for an annual reconciliation of the electric distribution revenue requirement as is necessary to reflect the actual costs incurred and investment return in a given year with the revenue requirement that was reflected in customer rates for that year. Consequently, Ameren Illinois' 2015Illinois’ 2018 electric deliverydistribution service revenues will be based on its 20152018 actual recoverable costs, rate base, and return on common equity as calculated under the IEIMA'sIllinois performance-based formula ratemaking framework. The 20152018 revenue requirement is expected to be higher thancomparable to the 20142017 revenue requirement due tobecause of an expected increase in recoverable costs, andexpected rate base growth.growth of approximately 5%, and an expected increase in the monthly average yield of 30-year United States Treasury bonds, partially offset by a decrease due to the lower federal statutory corporate income tax rates enacted under the TCJA. The 2018 revenue requirement reconciliation is expected to result in a regulatory asset that will be collected from customers in 2020. A 50 basis point change in the average monthly yields of the 30-year United States Treasury bonds would result in an estimated $6$8 million change in Ameren'sAmeren’s and Ameren Illinois' 2015Illinois’ net income.
In December 2014, the ICC issued an order with respect toincome, based on Ameren Illinois’ annual update filing. 2018 projected year-end rate base.
The ICC approvedFEJA allows Ameren Illinois to earn a $204 million increase inreturn on its electric energy-efficiency program investments. Ameren Illinois’ electric delivery service revenue requirement, beginning in January 2015. These rates have affected and will continue to affect Ameren Illinois' cash receipts during 2015, but will not be the sole determinant of its electric delivery service operating revenues, which will instead be largely determined by the IEIMA's 2015 revenue requirement reconciliation. The 2015 revenue requirement reconciliation,energy-efficiency investments are deferred as discussed above, is expected to result in a regulatory asset and earn a return at the company’s weighted-average cost of capital, with the equity return based on the monthly average yield of the 30-year United States Treasury bonds plus 580 basis points. The equity portion of Ameren Illinois’ return on electric energy-efficiency investments can be increased or decreased by up to 200 basis points, depending on the achievement of annual energy savings goals.Pursuant to the FEJA, Ameren Illinois plans to invest up to $99 million per year in electric energy-efficiency programs from 2018 through 2021 that will earn a return.Ameren Illinois plans to make similar yearly investments in electric energy-efficiency programs from 2022 through 2030. The ICC has the ability to reduce electric energy-efficiency savings goals if there are insufficient cost-effective programs available or if the savings goals would require investment levels that exceed amounts allowed by legislation. The electric energy-efficiency program investments and the return on those investments will be collected from customers through a rider; they will not be included in 2017.the IEIMA formula ratemaking framework. See Note 2 – Rate and

Regulatory Matters under Part II, Item 8, of this report for information regarding Ameren Illinois’ approved energy-efficiency program for 2018 through 2021.
In January 2018, Ameren Illinois filed a request with the ICC seeking approval to increase its annual revenues for natural gas delivery service by $49 million, which included an estimated $42 million of annual revenues that would otherwise be recovered under a QIP rider. The request was based on a 10.3% return on common equity, a capital structure composed of 50% common equity, and a rate base of $1.6 billion. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for information regarding Ameren Illinois’ Natural Gas Delivery Service Regulatory Rate Review.
Ameren Missouri'sMissouri’s next scheduled refueling and maintenance outage at its Callaway energy center will be inis scheduled for the spring of 2016.2019. During the 20142017 refueling, Ameren Missouri incurred maintenance expenses of $36$35 million. During a scheduled outage, which occurs every 18 months, maintenance expenses increase relative to non-outage years. Additionally, depending on the availability of its other generation sources and the market prices for power, Ameren Missouri'sMissouri’s purchased power costs may increase and the amount of excess power available for sale may decrease versus non-outage years. Changes in purchased power costs and excess power available for sale are included in the FAC, resultingwhich results in limited impacts to earnings.
As of December 31, 2014, In addition, Ameren Missouri had capitalized $69may incur increased nonnuclear energy center maintenance costs in non-outage years.
Ameren and Ameren Missouri expect an approximately $15 million decrease in annual interest charges as a result of the repayment of $425 million of costs incurred to license additional nuclear generationAmeren Missouri’s 6.40% senior secured notes at its Callaway energy site.maturity and issuance of $400 million 2.95% senior secured notes in 2017. In 2009,2018, Ameren Missouri suspended its effortsexpects to build a new nuclear unit at the Callaway site, and the NRC suspended review of the COL application. The suspended status of the COL application currently extends through the end of 2015. If efforts to license additional nuclear generation are abandoned, the NRC does not extend the COL application suspended status, or if management concludes that it is probable the costs incurred will be disallowed in rates, a charge to earningsrefinance maturing long-term debt with lower-cost long-term debt, which would be recognized in the period in which that determination was made.
Ameren Missouri is engaged in litigation with an insurer to recover an unpaid liability insurance claim for the December 2005 breach of the upper reservoir at Ameren Missouri's Taum Sauk pumped-storage hydroelectric energy center.further reduce Ameren’s and Ameren Missouri’s results of operations, financial position, and liquidity could be adversely affected ifannual interest charges.


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Ameren Missouri’s remaining liability insurance claim of $41 million as of December 31, 2014, is not paid by the insurer.
Under the provisions of the CSRA, Ameren Illinois received ICC approval for its QIP rider in January 2015 and subsequently began including qualified investments and recording revenue under this regulatory framework. Ameren Illinois will start recovering costs from these investments in March 2015.
As we continue to experience cost increases and to make infrastructure investments, Ameren Missouri and Ameren Illinois expect to seek regular electric and natural gas rate increases and timely cost recovery and tracking mechanisms from their regulators. Ameren Missouri and Ameren Illinois will also seek, as necessary, legislative solutions to address cost recovery pressures and to support investment in their energy infrastructure. These pressures include limited economic growth in their service territories, customer conservation efforts, the impacts of additional customer energy efficiency programs, increased investments and expected future investments for environmental compliance, system reliability improvements, and new generation capacity, including renewable energy requirements. Increased investments also result in higher depreciation and financing costs. Increased costs are also expected from rising employee benefit costs and higher property and income taxes, among others.
As we continue to make infrastructure investments and to experience cost increases, Ameren Missouri and Ameren Illinois expect to seek regular electric and natural gas rate increases and timely cost recovery and tracking mechanisms from their regulators. Ameren Missouri and Ameren Illinois will also seek legislative solutions, as necessary, to address regulatory lag and to support investment in their utility infrastructure for the benefit of their customers. Ameren Missouri and Ameren Illinois continue to face cost recovery pressures, including limited economic growth in their service territories, customer conservation efforts, the impacts of additional customer energy-efficiency programs, and increased customer use of increasingly cost-effective technological advances, including private generation and storage. However, we expect the decreased demand to be partially offset by increased demand resulting from increased electrification of the economy as a means to address CO2 emission concerns. Increased investments, including expected future investments for environmental compliance, system reliability improvements, and potential new generation sources, result in rate base earnings growth but also higher depreciation and financing costs. Increased costs are also expected from rising employee benefit costs, higher property taxes, and higher state income taxes, among other costs.
For additional information regarding recent rate orders, lawsuits, and related appeals, pending requests filed with state and federal regulatory commissions, Taum Sauk matters, and separate FERC orders affecting Ameren Missouri and Ameren Illinois, see Note 2 – Rate and Regulatory Matters Note 10 – Callaway Energy Center, and Note 15 – Commitments and Contingencies under Part II, Item 8, of this report.
Liquidity and Capital Resources
We
In September 2017, Ameren Missouri filed its nonbinding 20-year integrated resource plan with the MoPSC. This plan includes Ameren Missouri’s preferred approach for meeting customers’ projected long-term energy needs in a cost-effective manner while maintaining system reliability. The plan targets cleaner and more diverse sources of energy generation, including solar, wind, natural gas, hydro, and nuclear power. It also includes expanding renewable sources by adding at least 700 megawatts of wind generation by 2020 in Missouri and neighboring states, and adding 100 megawatts of solar generation over the next 10 years. The new wind generation facilities are expected to be located in Missouri and neighboring states. The source, location, and cost of the new wind generation, among other items, remain subject to reaching agreements with developers. Based on current and projected market prices for energy, and for wind and solar generation technologies, among other factors, Ameren Missouri expects its ownership of these renewable resources would represent the lowest-cost option for customers. The plan also provides for the expected implementation of continued customer energy-efficiency programs. Ameren Missouri’s plan for the addition of renewable resources could be affected by, among other factors: the availability of federal production and investment tax credits related to renewable energy and Ameren Missouri’s ability to use such credits; the cost of wind and solar generation technologies, as well as energy prices; Ameren Missouri’s ability to obtain timely interconnection agreements with MISO or other RTOs, including the cost of such interconnections; and Ameren Missouri’s ability to obtain a certificate of convenience and necessity from the MoPSC for projects located in Missouri, and any other required project approvals.
In connection with the integrated resource plan filing, discussed above, Ameren Missouri established a goal of reducing CO2 emissions 80% by 2050 from a 2005 base level. To meet this goal, Ameren Missouri is targeting a 35% CO2 emission reduction by 2030 and a 50% reduction by 2040 from the 2005 level by retiring coal-fired generation at the end of its useful life.

Through 2022, we expect to incurmake significant capital expenditures in order to make investments to improve our electric and natural gas utility infrastructure, with a major portion directed to our transmission and to comply with existing environmental regulations.distribution systems. We estimate that we will incurinvest up to $9.3$11.4 billion (Ameren Missouri – up to $3.9$4.5 billion; Ameren Illinois – up to $4.0$6.6 billion; ATXI – up to $1.4$0.3 billion) of capital expenditures during the period from 20152018 through 2019.
Existing and future environmental regulations, including those related to greenhouse gas emissions, or other actions taken by2022. These estimates do not reflect the EPA, could resultpotential additional investments identified in significant increases in capital expenditures and operating costs. These expenses could be prohibitive at some of Ameren Missouri's coal-fired energy centers. Ameren Missouri's capital expenditures are subject to MoPSC prudence reviews, which could result in cost disallowances as well as regulatory lag. Ameren's and Ameren Missouri's earnings could benefit from increased investment to comply with environmental regulations if those investments are reflected and recovered timely in rates.
Ameren Missouri continues to evaluate its longer-term needs for new baseload and peaking electric generation capacity. Ameren Missouri files a non-binding integrated
resource plan with the MoPSC every three years. Ameren Missouri’s integrated resource plan filed with the MoPSC in October 2014 is a 20-year plan that supports a more fuel-diverse energy portfolio in Missouri, including coal, solar, wind, natural gas discussed above, which could represent incremental investments of approximately $1 billion through 2020 and nuclear power. The plan includes expanding renewable generation, retiring coal-fired generation as energy centers reach the end of their useful lives, and adding natural-gas-fired combined cycle generation. Ameren Missouri continuesare subject to study future alternatives, includingregulatory approval. They also do not reflect potential additional customer energy efficiency programs, that could help defer new energy center construction. Ameren Missouri’s integrated resource plan is projected to achieve the carbon emissions reductions proposed in the EPA’s Clean Power Plan by 2035, rather than the EPA’s final target date of 2030 or its interim target dates beginning in 2020.
Ameren Missouri continues to evaluate its potential compliance plans for the proposed Clean Power Plan. Preliminary studies suggest that if the proposed Clean Power Plan were to be finalized in its current form, Ameren Missouri may need to incur new or accelerated capital expenditures and increased fuel costs in order to achieve compliance. As proposed, the Clean Power Plan would require the states, including Missouri and Illinois, to submit compliance plans as early as 2016. The states’ compliance plans might require Ameren Missouri to construct natural-gas-fired combined cycle generation and renewable generation, currently estimated to cost approximately $2 billion by 2020,investments that Ameren Missouri believes would otherwise not be necessary to meet the energy needs ofcould make if improvements in its customers. Additionally, Missouri’s implementation of the proposed rules, if adopted, could result in the closure or alteration of the operation of some of Ameren Missouri’s coal and natural gas-fired energy centers, which could result in increased operating costs or impairment of assets.
To fund investment requirements of our businesses, we seek to maintain access to the capital markets at commercially attractive rates. We seek to enhance regulatory frameworks and returns in order to improve liquidity, credit metrics, and related access to capital.were made.
Environmental regulations, including those related to CO2 emissions, or other actions taken by the EPA could result in significant increases in capital expenditures and operating costs. Certain of these regulations are being challenged through litigation or are being reviewed by the EPA, so their ultimate implementation, as well as the timing of any such implementation, is uncertain. However, the individual or combined effects of existing environmental regulations could result in significant capital expenditures, increased operating costs, or the closure or alteration of some of Ameren Missouri’s coal-fired energy centers. Ameren Missouri’s capital expenditures are subject to MoPSC prudence reviews, which could result in cost disallowances as well as regulatory lag. The cost of Ameren Illinois’ purchased power and natural gas purchased for resale could increase. However, Ameren Illinois expects that these costs would be recovered from customers with no material adverse effect on its results of operations, financial position, or liquidity. Ameren’s and Ameren Missouri’s earnings could benefit from increased investment to comply with environmental regulations if those investments are reflected and recovered on a timely basis in customer rates.
In December 2014, the
The Ameren Companies amended and restated theirhave multiyear credit agreements tothat cumulatively provide $2.1 billion of credit through December 11, 2019,2021, subject to a 364-day repayment term in the case of Ameren Missouri and Ameren Illinois. See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for additional information regarding the 2012 Credit Agreements.By the end of 2019, $951 million and $457 million of senior secured notes are scheduled to mature at Ameren Missouri and Ameren Illinois, respectively. Ameren Missouri and Ameren Illinois expect to refinance these senior secured notes. In addition, the Ameren Companies may refinance a portion of their short-term debt with long-term debt in 2018 and 2019. Ameren, Ameren Missouri, and Ameren Illinois believe that their liquidity is adequate given their expected operating cash from operating activities,flows, capital expenditures, and related financing plans. However, there can be no assurance that significant changes in economic conditions, disruptions in the capital and credit markets, or other unforeseen events will not materially affect their ability to execute their expected operating, capital, or financing plans.
Federal income tax legislation enacted under the TCJA will have significant impacts on our results of operations, financial position, liquidity, and financial metrics. The TCJA will benefit customers through lower rates for our services but is not expected to materially affect our earnings. However, our cash flows and rate base are expected to be materially affected in the near term. Our rate-regulated businesses recover income taxes in customer rates based on the federal and state statutory corporate income tax rates in effect when the revenue requirements used to determine those rates were established. However, there is a timing difference between when we collect funds from our customers for income taxes and when we pay such taxes. The TCJA eliminated 50% accelerated tax depreciation on nearly all capital investments, which has the effect of increasing Ameren’s near-term projected income tax liabilities. Ameren expects to largely offset its income tax obligations through about 2020 with existing net operating loss and tax credit carryforwards. Since we have been using existing net operating loss and tax credit carryforwards to largely offset income tax obligations, the effect of the reduced federal statutory corporate income tax rate is expected to be a decrease in operating cash flows. The decrease in operating cash flows results from reduced customer rates, reflecting the tax rate decrease, without a corresponding reduction in income tax payments until about 2021. Additionally, operating cash flows will be further reduced by lower customer rates, reflecting the return of excess deferred taxes previously collected from customers over periods of time determined by our regulators. The decrease in operating cash flows as a result of the TCJA is expected to be partially offset over time by increased customer rates due to higher rate base amounts, once approved by our regulators. We expect rate base amounts to be higher as a result of lower accumulated deferred income tax liabilities, due to the elimination of 50% accelerated tax depreciation, the reduced statutory income tax rate, and the return of excess deferred taxes to customers.Ameren expects a decrease in operating cash flows of approximately $1 billion from 2018 through 2022 (Ameren Missouri – $0.3 billion; Ameren Illinois – $0.4 billion) as a result of the TCJA, and expects an increase in rate base of approximately $1 billion over the same time period (Ameren Missouri – $0.3 billion; Ameren Illinois – $0.5 billion).
As of December 31, 2014,2017, Ameren had $531$235 million in tax benefits from federal and state net operating loss carryforwards (Ameren Missouri – $86 million and Ameren Illinois – $137 million) and $131$120 million in federal and state


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income tax credit carryforwards. These carryforwards (Ameren Missouri – $21 million andare expected to partially offset income tax obligations until 2021, at which time Ameren Illinois – $2 million). Theseexpects to begin making material income tax benefits are still subject to audits and examinations by taxing authorities.payments. Consistent with the tax allocation agreement between Ameren (parent) and its subsidiaries, these carryforwards are expected to partially offset income tax liabilities for Ameren Missouri and Ameren Illinois during 2015 and 2016, while Ameren does not expect to makebegin making material federal income tax payments until 2017. In addition, Ameren has $55 million of expected income tax refunds and state overpayments that will offset income tax liabilities into 2017. These tax benefits, primarily at theto Ameren (parent) level, when realized, will be available to fund electric transmission investments, specifically ATXI's Illinois Rivers project.beginning in 2018.
Ameren expects its cash used for currently planned capital expenditures and dividends to exceed cash provided by operating activities over the next several years. Ameren does not expect the need for public equity issuancesAs part of its plan to fund suchthese cash shortfalls, but may consider issuing stock throughrequirements, beginning in the first quarter of 2018, Ameren will use newly issued shares, rather than market-purchased shares, to satisfy requirements under its DRPlus and its 401(k) plans.employee benefit plans and expects to do so over the next five years. Additionally, Ameren may be required to issue incremental debt and/or equity, with the long-
The use of cash from operating activities
term intent to maintain strong financial metrics and short-term borrowingsan equity ratio around 50%, as calculated in accordance with ratemaking frameworks. Ameren Missouri and Ameren Illinois expect to fund cash flows needs through debt issuances, adjustments of dividends to Ameren (parent), and/or capital expenditurescontributions from Ameren (parent), with the intent to maintain strong financial metrics and other long-term investments may periodically resultan equity ratio around 50%, as calculated in a working capital deficit, as defined by current liabilities exceeding current assets, as was the case at December 31, 2014. The working capital deficit as of December 31, 2014, was primarily the result of our reliance on commercial paper issuances, as opposed to long-term debt issuances. Ameren is currently evaluating options for refinancing the short-term debt including the issuance of long-term notes. Ameren had $714 million of commercial paper issuances outstanding as of December 31, 2014. With the 2012 Credit Agreements, Ameren has access to $2.1 billion of credit capacity, of which $1.4 billion was available at December 31, 2014.accordance with ratemaking frameworks.
The above items could have a material impact on our results of operations, financial position, orand liquidity. Additionally, in the ordinary course of business, we evaluate strategies to enhance our results of operations, financial position, orand liquidity. These strategies may include acquisitions, divestitures, and opportunities to reduce costs or increase revenues, and other strategic initiatives to increase Ameren's stockholderAmeren’s shareholder value. We are unable to predict which, if any, of these initiatives will be executed. The execution of these initiatives may have a material impact on our future results of operations, financial position, or liquidity.
REGULATORY MATTERS
See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report.



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ACCOUNTING MATTERS
Critical Accounting Estimates
Preparation of the financial statements and related disclosures in compliance with GAAP requires the application of appropriate technical accounting rules and guidance, as well as the use of estimates. These estimates involve judgments regarding many factors that in and of themselves could materially affect the financial statements and disclosures. We have outlined below the critical accounting estimates that we believe are the most difficult, subjective, or complex. Any change in the assumptions or judgments applied in determining the following matters, among others, could have a material impact on future financial results.
Accounting Estimate Uncertainties Affecting Application
Regulatory Mechanisms and Cost Recovery
We defer costs in accordance with authoritative accounting guidance and make investmentsrecognize revenues that we assume will be collectedintend to collect in future rates.




















 
Regulatory environment and external regulatory decisions and requirements
Anticipated future regulatory decisions and our assessment of their impact
ImpactThe impact of deregulation, rate freezes, prudence reviews, complaint cases, and opposition during the ratemaking process that may limit our ability to timely recover costs and earn a fair return on our investments
Ameren Illinois’ assessment of and ability to estimate the current year’s electric delivery service costs to be reflected in revenues and recovered from customers in a subsequent year under the IEIMA performance-based formula ratemaking processframework
Ameren Illinois’ and ATXI'sATXI’s assessment of and ability to estimate the current year’s electric transmission service costs to be reflected in revenues and recovered from customers in a subsequent year under the FERC ratemaking processframeworks
Ameren Missouri'sMissouri’s estimate of revenue recovery under the MEEIA plans
Any adjustments related to the TCJA

Basis for Judgment
We determine whichThe application of accounting guidance for rate-regulated businesses results in recording regulatory assets and liabilities. Regulatory assets represent the deferral of incurred costs that are probable of future recovery in customer rates. Regulatory assets are amortized as the incurred costs are recoverablerecovered through customer rates. In some cases, we record regulatory assets before approval for recovery has been received from the applicable regulatory commission. We must use judgment to conclude that costs deferred as regulatory assets are probable of future recovery. We base our conclusion on certain factors including, but not limited to, orders issued by reviewing previous rulings byour regulatory authorities in jurisdictions where we operate and any other factorscommissions, legislation, or historical experience, as well as discussions with legal counsel. Regulatory liabilities represent revenues received from customers to fund expected costs that may indicate whether cost recovery is probable.have not yet been incurred or probable future refunds to customers. If facts and circumstances lead us to conclude that a recorded regulatory asset is no longer probable of recovery or that plant assets are probable of disallowance, we record a charge to earnings, which could be material. We also recognize revenues for alternative revenue programs authorized by our regulators that allow for an automatic rate adjustment, are probable of recovery, and are collected within 24 months following the end of the annual period in which they are recognized. Ameren Illinois estimates its annual revenue requirement pursuant to the IEIMA for interim periods by using internal forecasted information, such as projected operations and maintenance expenses, depreciation expense, taxes other than income taxes, and rate base, as well asand published forecasted data regarding that year'syear’s monthly average yields of the 30-year United States Treasury bonds. Ameren Illinois estimates its annual revenue requirement as of December 31 of each year using that year'syear’s actual operating results and assesses the probability of recovery from or refund to customers that the ICC will order at the end of the following year. Variations in costs incurred, investments made or orders by the ICC or courts can result in a subsequent change in Ameren Illinois'Illinois’ estimate. Ameren Illinois and ATXI follow a similar process for their FERC rate-regulated electric transmission businesses. Ameren Missouri estimates lost revenues resulting from theits MEEIA customer energy efficiency programs implemented by the MEEIA.energy-efficiency programs. Ameren Missouri uses a MEEIA rider to collect from or refund to customers any annual difference in the actual amounts incurred and the amounts collected from customers. The Ameren Companies made provisional estimates to deferred tax balances as a result of the TCJA. The revaluation of certain deferred taxes was deferred as a regulatory asset or liability on the balance sheet and will be collected from or refunded to customers as determined by our regulators. These estimates are subject to change, as discussed in the Accounting for Income Taxes section below. See Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for quantification of these assets or liabilities

for each of the Ameren Companies. See Note 1 - Summary of Significant Accounting Policies under Part II, Item 8, of this report for a listing of regulatory mechanisms used by Ameren Missouri and Ameren Illinois.

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Benefit Plan Accounting
Based on actuarial calculations, we accrue costs of providing future employee benefits in accordance with authoritative accounting guidance regardingfor the benefit plans.plans we offer our employees. See Note 1110 – Retirement Benefits under Part II, Item 8, of this report.










 
Future rate of return on pension and other plan assets
Valuation inputs and assumptions used in the fair value measurements of plan assets, excluding those inputs that are readily observable
Interest rates used in valuing benefit obligationsDiscount rate
Future compensation increase assumption
Health care cost trend rates
Timing of employee retirements and mortality assumptions
Ability to recover certain benefit plan costs from our ratepayerscustomers
Changing market conditions that may affect investment and interest rate environments
Impacts of the federal health care reform legislation enacted in 2010

Basis for Judgment
Ameren has defined benefit pension and postretirement benefit plans covering substantially all of its union employees. Ameren has defined benefit pension plans covering substantially all of its non-union employees and postretirement benefit plans covering non-union employees hired before October 2015. Our ultimate selection of the discount rate, health care trend rate, and expected rate of return on pension and other postretirement benefit plan assets is based on our consistent application of assumption-setting methodologies and our review of available historical, current, and projected rates, as applicable. We also make mortality assumptions for estimating our pension and other postretirement benefit obligations. During 2014, Ameren adopted the Society of Actuaries 2014 Mortality Tables Report and Mortality Improvement Scale. The updated mortality tables assume increasing life expectancies for our employees and retirees, which has resulted in an increase to estimate our pension and other postretirement benefit obligations. See Note 1110 – Retirement Benefits under Part II, Item 8, of this report for these assumptions and the sensitivity of Ameren’s benefit plans to potential changes in these assumptions.
Accounting for Contingencies
We make judgments and estimates in the recording and the disclosing of liabilities for claims, litigation, environmental remediation, the actions of various regulatory agencies, or other matters that occur in the normal course of business. We record a loss contingency when it is probable that a liability has been incurred and that the amount of the loss can be reasonably estimated.
 
Estimating financial impact of events
Estimating likelihood of various potential outcomes
Regulatory and political environments and requirements
Outcome of legal proceedings, settlements, or other factors
Changes in regulation, expected scope of work, technology or timing of environmental remediation


Basis for Judgment
The determination of a loss contingency requires significant judgment as to the expected outcome of eachthe contingency in future periods. In making the determination as to the amount of potential loss and the probability of loss, we consider all available evidence, includingthe nature of the litigation, the claim or assessment, opinions or views of legal counsel, and the expected outcome of potential litigation.litigation, among other things. If no estimate is better than another within our range of estimates, we record as our best estimate of a loss the minimum value of our estimated range of outcomes. As additional information becomes available, we reassess the potential liability related to the contingency and revise our estimates. The amount recorded for any contingency may differ from actual costs incurred when the contingency is resolved. Contingencies are normally resolved over long periods of time. In our evaluation of legal matters, management consults with legal counsel and relies on analysis of relevant case law and legal precedents. See Note 2 – Rate and Regulatory Matters, Note 109 – Callaway Energy Center and Note 1514 – Commitments and Contingencies and Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of this report for information on the Ameren Companies’ contingencies.
Accounting for Income Taxes
Based on authoritative accounting guidance, weWe record thea provision for income taxes, deferred tax assets and liabilities, and a valuation allowance against net deferred tax assets, if any. See Note 1312 – Income Taxes under Part II, Item 8, of this report.






 
Changes in business, industry, laws, technology, or economic and market conditions affecting forecasted financial condition and/or results of operations
Estimates of the amount and character of future taxable income
Enacted tax rates applicable to taxable income in years in which temporary differences are recovered or settled
Effectiveness of implementing tax planning strategies
Changes in income tax laws, including amounts subject to income tax, and the regulatory treatment of any tax reform changes
Results of audits and examinations by taxing authorities


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Basis for Judgment
The reporting of tax-related assets and liabilities requires the use of estimates and significant management judgment. Deferred tax assets and liabilities are recorded to represent future effects on income taxes for temporary differences between the basis of assets for financial reporting and tax purposes. Although management believes that current estimates for deferred tax assets and liabilities are reasonable, actual results could differ from these estimates for a variety of reasons, including a change in forecasted financial condition and/or results of operations, change in income tax laws, or enacted tax rates or amounts subject to income tax, the form, structure, and timing of asset or stock sales or dispositions, change in the regulatory treatment of any tax reform benefits, and results of audits and examinations by taxing authorities. Valuation allowances against deferred tax assets are recorded when management concludes it is more likely than not such asset will not be realized in future periods. Accounting for income taxes also requires that only tax benefits for positions taken or expected to be taken on tax returns that meet the more-likely-than-not recognition threshold can be recognized or continue to be recognized. Management evaluates each position solely on the technical merits and facts and circumstances of the position, assuming that the position will be examined by a taxing authority that has full knowledge of all relevant information. Significant judgment is required to determine recognition thresholds and the related amount of tax benefits to be recognized. At each period-end,period end, and as new developments occur, management reevaluates its tax positions. Additional interpretations, regulations, amendments, or technical corrections related to the federal income tax code as a result of the TCJA, as well as the associated treatment by our regulators, may impact the estimates for income taxes discussed above. See Note 1312 – Income Taxes under Part II, Item 8, of this report for the amount of deferred tax assets and uncertain tax positionsincome taxes recorded at December 31, 20142017.
Unbilled Revenue
At the end of each period, Ameren, Ameren Missouri, and Ameren Illinois estimate the usage that has been provided to customers but not yet billed. This usage amount, along with a per unit price, is used to estimate an unbilled balance.

For its electric distribution business, Ameren Illinois then considers and reflects the effect of the decoupling provisions of the FEJA.
 
Estimating customer energy usage
Estimating impacts of weather and other usage-affecting factors for the unbilled period
Estimating loss of energy during transmission and delivery



Basis for Judgment
We base our estimate of unbilled revenue each period on the volume of energy delivered, as valued by a model of billing cycles and historical usage rates and by growth or contraction by customer class for our service area. This figure is then adjusted for the modeled impact of seasonal and weather variations based on historical results. As a result of its regulatory framework, Ameren Illinois adjusts unbilled electric distribution revenues to reflect the decoupling provisions of the FEJA, with an offset to a regulatory asset or liability. See the balance sheet for each of the Ameren Companies under Part II, Item 8, of this report for unbilled revenue amounts.
Impact of FutureNew Accounting Pronouncements
See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report.
EFFECTS OF INFLATION AND CHANGING PRICES
Ameren’s rates for retail electric and natural gas utility service are regulated by the MoPSC and the ICC. Nonretail electric rates are regulated by the FERC. Rate regulation is generally based on the recovery of historical or projected costs. As a result, revenue increases could lag behind changing prices. Ameren Illinois’ and ATXI’s electric transmission rates are determined pursuant to formula ratemaking. Additionally, Ameren Illinois participates in the performance-based formula ratemaking processframeworks established pursuant to the IEIMA and the FEJA for its electric delivery service business.distribution business and its electric energy-efficiency investments. Ameren Illinois is required to purchase all of its power through procurement processes administered by the IPA. The cost of procured power can be affected by inflation. Within the IEIMA and the FEJA formula ratemaking frameworks, the monthly average yields of 30-year United States Treasury bonds are the basis for Ameren Illinois’ return on equity. Therefore, there is a direct correlation between the yield of United States Treasury bonds, which are affected by inflation, and the earnings ofannual return on equity applicable to Ameren Illinois’ electric distribution business. Inflation affects our operations, earnings, stockholders’ equity,business and financial performance.electric energy-efficiency investments. Ameren Illinois and ATXI use a company-specific, forward-looking formula ratemaking framework in setting their transmission rates. These forward-looking rates are updated each January with forecasted information. A reconciliation during the year, which adjusts for the actual revenue requirement and for actual sales volumes, is used to adjust billing rates in a subsequent year.
The current replacement cost of our utility plant substantially exceeds our recorded historical cost. Under existing regulatory practice, only the historical cost of plant is recoverable from customers. As a result, customer rates designed to provide recovery of historical costs through depreciation might not be adequate to replace plant in future years.
Ameren Missouri recovers the cost of fuel for electric generation and the cost of purchased power by adjusting rates as
allowed through the FAC. The March 2017 MoPSC electric rate order approved Ameren Missouri’s request for continued use of the FAC; however, the FAC

excludes substantially all transmission revenues and charges. Ameren Missouri is therefore exposed to transmission charges to the extent that they exceed transmission revenues. Ameren Illinois recovers power supply costs from electric customers by adjusting rates through a rider mechanism to accommodate changes in power prices.
Changes in the cost of electric transmission services affect Ameren Missouri, Ameren Illinois, and ATXI. The FERC regulates the rates charged and the terms and conditions for electric wholesale and unbundled retail transmission services. Because they are members of MISO, Ameren Missouri's, Ameren Illinois', and ATXI's transmission rates are calculated in accordance with the rate formulas contained in MISO's FERC-approved tariff. Under the MISO OATT, a portion of the revenue requirement related to certain projects eligible for cost sharing is allocated to multiple MISO pricing zones. The remaining revenue requirement is assigned to the pricing zone where the transmission assets are located. Ameren Missouri uses a rate formula that is updated in June of each year, which is based on the prior year's cost data. The Ameren Missouri zonal rate is charged to wholesale customers in the AMMO pricing zone. This zonal rate is not directly charged to Missouri retail customers, because the MoPSC includes transmission-related costs in setting bundled retail rates in Missouri. Ameren Illinois and ATXI have received FERC approval to use company-specific, forward-looking rate formula templates in setting their transmission rates. These forward-looking rates are updated each January with forecasted information. A reconciliation during the year, which adjusts for the actual revenue requirement and actual sales volumes, is used to adjust billing rates in a subsequent year. In Illinois, the AMIL


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pricing zone transmission rate is charged directly to wholesale customers and alternative retail electric suppliers that serve unbundled retail load. For Ameren Illinois retail customers who have not chosen an alternative retail electric supplier, the AMIL pricing zone transmission rate and other MISO-related costs are collected through a rider mechanism in Ameren Illinois' retail distribution tariffs.
In our Missouri and Illinois retail natural gas utility jurisdictions, changes in natural gas costs are generally reflected in billings to natural gas customers through PGA clauses.
See Part I, Item 1, and Note 2 – Rate and Regulatory Matters under Part II, Item 8, of this report for additional information on our cost recovery mechanisms.
ITEM 7A.QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
Market risk is the risk of changes in value of a physical asset or a financial instrument, derivative or nonderivative, caused by fluctuations in market variables such as interest rates, commodity prices, and equity security prices. A derivative is a contract whose value is dependent on, or derived from, the value of some underlying asset or index. The following discussion of our risk management activities includes forward-looking statements that involve risks and uncertainties. Actual results could differ materially from those projected in the forward-looking statements. We handle market risks in accordance with established policies, which may include entering into various derivative transactions. In the normal course of business, we also face risks that are either nonfinancial or nonquantifiable. Such risks, principally business, legal, and operational risks, are not part of the following discussion.
Our risk management objectives are to optimize our physical generating assets and to pursue market opportunities within prudent risk parameters. Our risk management policies are set by a risk management steering committee, which is composed of senior-level Ameren officers, with Ameren board of directorsdirectors’ oversight.
Interest Rate Risk
We are exposed to market risk through changes in interest rates associated with:
long-term and short-term variable-rate debt;
fixed-rate debt;
30-year United States Treasury bonds; and
the discount rate applicable to defined pension and postretirement benefit plans.plans, asset retirement obligations, and goodwill.
We manage our interest rate exposure by controlling the amount of debt instruments within our total capitalization portfolio and by monitoring the effects of market changes on interest rates. For defined pension and postretirement benefit plans, we control the duration and the portfolio mix of our plan assets. See Note 1 – Summary of Significant Accounting Policies and Note 10 – Retirement Benefits under Part II, Item 8, of this report for additional information related to asset retirement obligations, goodwill, and the defined pension and postretirement benefit plans.
The following table presents the estimated increase in our annual interest expense and decrease in net income if interest
rates were to increase by 1%100 basis points on variable-rate debt outstanding at December 31, 2014:2017:
 Interest Expense 
Net  Income(a)
 Interest Expense 
Net Income(a)
Ameren$9
$(5)$7
$(5)
Ameren Missouri 3
 (2) 2
 (2)
Ameren Illinois (b)
 (b)
 1
 (1)
(a)Calculations are based on an estimatedthe 2018 statutory tax raterates of 39%27%, 37%25%, and 41%28% for Ameren, Ameren Missouri, and Ameren Illinois, respectively.
(b)Less than $1 million.
Ameren Illinois’ annualThe return on equity component under the formula ratemaking process for its electric distribution businessIEIMA and the FEJA is directly correlatedequal to the calendar year average of the monthly yields of 30-year United States Treasury bonds plus 580 basis pointspoints. Therefore, Ameren Illinois’ annual return on equity under the formula ratemaking frameworks for a particular or calendar year. Theboth its electric distribution service and its electric energy-efficiency investments is directly correlated to the yields on such bonds, which are outside of Ameren Illinois’ control. A 50 basis point change in the average monthly yields of the 30-year United States Treasury bonds would result in an estimated $6$8 million change in Ameren'sAmeren’s and Ameren Illinois' 2015Illinois’ net income.income, based on its 2018 projected rate base.
Credit Risk
Credit risk represents the loss that would be recognized if counterparties should fail to perform as contracted. Exchange-traded contracts are supported by the financial and credit quality of the clearing members of the respective exchanges and carry only a nominal credit risk. In all other transactions, we are exposed to credit risk in the event of nonperformance by the counterparties to the transaction. See

Note 7 – Derivative Financial Instruments under Part II, Item 8, of this report for information on the potential loss on counterparty exposure as of December 31, 2014.2017.
Our revenues are primarily derived from sales or delivery of electricity and natural gas to customers in Missouri and Illinois. Our physical and financial instruments are subject to credit risk consisting of trade accounts receivables and executory contracts with market risk exposures. The risk associated with trade receivables is mitigated by the large number of customers in a broad range of industry groups who make up our customer base. At December 31, 2014,2017, no nonaffiliated customer represented more than 10%, in the aggregate, of our accounts receivable. Additionally, Ameren Illinois faces risks associated with the purchase of receivables. The Illinois Public Utilities Act requires Ameren Illinois to establish electric utility consolidated billing and purchase of receivables services. At the option of an alternative retail electric supplier, Ameren Illinois may be required to purchase the supplier'ssupplier’s receivables relating to Ameren Illinois' delivery serviceIllinois’ distribution customers who elected to receive power supply from the alternative retail electric supplier. When that option is selected, Ameren Illinois produces consolidated bills for the applicable retail customers reflectingto reflect charges for electric delivery servicedistribution and purchased receivables. As of December 31, 2014,2017, Ameren Illinois'Illinois’ balance of purchased accounts receivable associated with the utility consolidated billing and purchase of receivables services was $28$31 million. The risk associated with Ameren Illinois'Illinois’ electric and natural gas trade receivables is also mitigated by a rate adjustment mechanism that allows Ameren


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Illinois to recover the difference between its actual net bad debt write-offs under GAAP and the amount of net bad debt write-offs included in its base rates. Ameren Missouri and Ameren Illinois continue to monitor the impact of increasing rates on customer collections. Ameren Missouri and Ameren Illinois make adjustments to their respective allowance for doubtful accounts as deemed necessary to ensure that such allowances are adequate to cover estimated uncollectible customer account balances.
In December 2013, Ameren completed the divestiture of New AER to IPH. The transaction agreement between Ameren and IPH requires that Ameren, through December 2, 2015, maintains its financial obligations in existence as of December 2, 2013 under all credit support arrangements or obligations with respect to New AER and its subsidiaries. Ameren must also provide any additional credit support that may be contractually required pursuant to anyInvestment Price Risk
Plan assets of the pension and postretirement trusts, the nuclear decommissioning trust fund, and company-owned life insurance contracts of New AER,include equity and its subsidiaries as of the closing. IPH, New AER and its subsidiaries and Dynegy have agreeddebt securities. The equity securities are exposed to indemnify Ameren for certain losses relatingprice fluctuations in equity markets. The debt securities are exposed to this credit support. IPH’s indemnification obligations are secured by certain AERG and Genco assets. However, these indemnification obligations and security interests might not cover all losses that could be incurred by Amerenchanges in connection with this credit support. Dynegy emerged from its Chapter 11 bankruptcy case in October 2012. As of December 31, 2014, Dynegy’s credit ratings were sub-investment-grade. Neither IPH nor New AER and its subsidiaries have investment grade credit ratings. Dynegy, IPH, New AER, or their subsidiaries might be unable to pay their indemnity and other obligations under the transaction agreement, Marketing Company’s note to Ameren, or Dynegy’s limited guarantee to Ameren, which could have a material adverse impact on Ameren’s results of operations, financial position, and liquidity. As of December 31, 2014, the balance of the Marketing Company note to Ameren was $12 million. As of December 31, 2014, Ameren provided $114 million in guarantees and $9 million in letters of credit relating to its credit support of New AER.
Equity Price Riskinterest rates.
Our costs for providing defined benefit retirement and postretirement benefit plans are dependent upon a number of factors, including the rate of return on plan assets. Ameren manages plan assets in accordance with the “prudent investor” guidelines contained in ERISA. Ameren’s goal is to ensure that sufficient funds are available to provide benefits at the time they are payable, while also maximizing total return on plan assets and minimizing expense volatility consistent with its tolerance for risk. Ameren delegates investment management to specialists. Where appropriate, Ameren provides the investment manager with guidelines that specify allowable and prohibited investment types. Ameren regularly monitors manager performance and compliance with investment guidelines.
The expected return on plan assets assumption is based on historical and projected rates of return for current and planned asset classes in the investment portfolio. Projected rates of return for each asset class are estimated after an analysis of historical
experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we adjust the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns, and for the effect of expenses paid from plan assets.
In future years, the costs of such plans will be reflected in net income or regulatory assets. Contributions to the plans and future costs could increase materially if we do not achieve pension and postretirement asset portfolio investment returns equal to or in excess of our 20152018 assumed return on plan assets of 7.25% and 7.00%, respectively..
Ameren Missouri also maintains a trust fund, as required by the NRC and Missouri law, to fund certain costs of nuclear plant decommissioning. As of December 31, 2014,2017, this fund was invested in domestic equity securities (67%(66%) and debt securities (33%). As of December 31, 2014, the trust fund totaled $549 million (2013$494 million). By maintaining a portfolio that includes long-term equity investments, Ameren Missouri seeks to maximize the returns to be used to fund nuclear decommissioning costs within acceptable parameters of risk. However, the equity securities included in the portfolio are exposed to price fluctuations in equity markets. The debt securities are exposed to changes in interest rates. Ameren Missouri actively monitors the portfolio by benchmarking the performance of its investments against certain indices and by maintaining and periodically reviewing established target allocation percentages of the trust assets to various investment options. Ameren Missouri’s exposure to equity price market risk is in large part mitigated because Ameren Missouri is currently allowed to recover its decommissioning costs, which would include unfavorable investment results, through electric rates.
Additionally, Ameren hasand Ameren Illinois have company-owned life insurance contracts that are used to support Ameren’s deferred compensation plans. These life insurance contracts include equitywith net asset values of $136 million and debt investments that are exposed to price fluctuations in equity markets and to changes in interest rates.$9 million, respectively, as of December 31, 2017.
Commodity Price Risk
With regard to Ameren Missouri’s and Ameren Illinois’ electric and natural gas distribution businesses exposure to changing market prices is in large part mitigated by the fact that there are cost recovery mechanisms in place. These cost recovery mechanisms allow Ameren Missouri and Ameren Illinois to pass on to retail customers prudently incurred costs for fuel, purchased power, and natural gas supply.

Ameren Missouri’s and Ameren Illinois’ strategy is designed to reduce the effect of market fluctuations for their regulated customers. The effects of price volatility cannot be eliminated. However, procurement and sales strategies involve risk management techniques and instruments, as well as the management of physical assets.
Ameren Missouri has a FAC that allows it to recover or refund, through customer rates, 95% of changesthe variance in fuel and purchased


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powernet energy costs including transportation charges and revenues, net of off-system sales, greater or less thanfrom the amount set in base rates without a traditional rate proceeding, subject to MoPSC prudence review.reviews. Ameren Missouri remains exposed to the remaining 5% of such changes.
Ameren Illinois has a cost recovery mechanism for power purchased on behalf of its customers. Ameren Illinois is required to serve as the provider of last resort for electric customers withinin its service territory who have not chosen an alternative retail electric supplier. Ameren Illinois does not generate earnings based on the resale of power but rather on the delivery of energy. Ameren Illinois purchases power primarily through MISO, with additional procurement events administered by the IPA. The IPA has proposed and the ICC has approved multiple procurement events covering portions of years through 2018.2020. In 2014, approximately 741,000 retail customers, representing 74%2017, acting in its role as the provider of last resort, Ameren Illinois' annual retailIllinois supplied power for 23% of its kilowatthour sales had elected to purchase their electricity from an alternative retailits electric supplier.customers. Ameren Illinois expects full recovery of its purchased power costs.
Ameren Missouri and Ameren Illinois have PGA clauses that permit costs incurred for natural gas to be recovered directly from utility customers without a traditional rate proceeding, subject to prudence review.
With regardOur exposure to our exposure for commodity price risk for construction and maintenance activities Ameren is exposedrelated to changes in market prices for metal commodities and to labor availability.
See Transmission and Supply of Electric Power under Part I, Item 1, of this report for the percentages of our historical needs
satisfied by coal, nuclear, natural gas, oil, and renewables. Also see Note 1514 – Commitments and Contingencies under Part II, Item 8, of this report for additional information.
Commodity Supplier Risk
The use of ultra-low-sulfur coal is part of Ameren Missouri'sMissouri’s environmental compliance strategy. Ameren Missouri has a multiyear agreementagreements with multiple suppliers to purchase ultra-low-sulfur coal through 20172021 to comply with environmental regulations. The coal contract is with a single supplier. Disruptions ofto the deliveries of that ultra-low-sulfur coal from thea supplier could compromise Ameren Missouri'sMissouri’s ability to operate in compliance with emission standards. Other sourcesThe suppliers of ultra-low-sulfur coal are limited, and the construction of pollution control equipment requires significant lead time iftime. If Ameren Missouri were to experience a temporary disruption of ultra-low-sulfur coal deliveries that caused it to exhaust its existing inventory, and if other sources of ultra-low-sulfur coal were not available, Ameren Missouri would have to use its existing emission allowances, or purchase emission allowances to achieve compliance with environmental regulations.regulations, or purchase power necessary to meet demand.
Currently, theThe Callaway energy center uses nuclear fuel assemblies of a design fabricated by only a single supplier. That supplierWestinghouse, which is currently the only NRC-licensed supplier ableauthorized to provide fuel assemblies to the Callaway energy center. IfDuring the first quarter of 2017, Westinghouse filed voluntary petitions for a court-supervised restructuring process under Chapter 11 of the United States Bankruptcy Code. At this time, Ameren and Ameren Missouri should decidebelieve the restructuring proceeding will not affect Westinghouse’s performance under the terms of its existing contracts with Ameren Missouri, and therefore do not expect any material impact to Ameren Missouri’s operations. However, Ameren and Ameren Missouri could incur material unexpected costs as a result of the Westinghouse bankruptcy, such as the loss of fuel inventory that is stored at Westinghouse’s facility and the cost of replacement power if nuclear fuel assemblies were not available for a future scheduled refueling and maintenance outage. A change of fuel suppliers or toa change in the type of fuel assembly design that is currently licensed for use at the Callaway energy center up to 3could take an estimated three years of analysis and NRC licensing effort would be requiredefforts to fully implement such a change.implement. See Note 9 – Callaway Energy Center under Part II, Item 8, of this report for additional information.


Fair Value of Contracts
We use derivatives principally to manage the risk of changes in market prices for natural gas, power, and uranium, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. The following table presents the favorable (unfavorable) changes in the fair value of all derivative contracts marked-to-market during the year ended December 31, 2014.2017. We use various methods to determine the fair value of our contracts. In accordance with authoritative accounting guidance for fair value hierarchy levels, the sources we used to determine the fair value of these contracts were active quotes (Level 1), inputs corroborated by market data (Level 2), and other modeling and valuation methods that are not corroborated by market data (Level 3). See Note 8 – Fair Value Measurements under Part II, Item 8, of this report for additional information regarding the methods used to determine the fair value of these contracts.
Ameren
Missouri
 
Ameren
Illinois
 Ameren
Ameren
Missouri
 
Ameren
Illinois
 Ameren
Fair value of contracts at beginning of year, net$9
 $(153) $(144)$(4) $(180) $(184)
Contracts realized or otherwise settled during the period(15) 36
 21
(3) 4
 1
Changes in fair values attributable to changes in valuation technique and assumptions
 
 
Fair value of new contracts entered into during the period(5) (16) (21)11
 (7) 4
Other changes in fair value(17) (52) (69)4
 (34) (30)
Fair value of contracts outstanding at end of year, net$(28) $(185) $(213)$8
 $(217) $(209)

66


The following table presents maturities of derivative contracts as of December 31, 2014,2017, based on the hierarchy levels used to determine the fair value of the contracts:
Sources of Fair Value
Maturity
Less Than
1 Year
 
Maturity
1 - 3 Years
 
Maturity
3 - 5 Years
 
Maturity in
Excess of
5 Years
 
Total
Fair Value
Maturity
Less Than
1 Year
 
Maturity
1 – 3 Years
 Maturity
3 – 5 Years
 
Maturity in
Excess of
5 Years
 
Total
Fair Value
Ameren Missouri:
 
 
 
 

 
 
 
 
Level 1$(16) $(6) $
 $
 $(22)$3
 $1
 $
 $
 $4
Level 2(a)
(1) (3) (2) 
 (6)(3) (3) 
 
 (6)
Level 3(b)
2
 (2) 
 
 
8
 2
 
 
 10
Total$(15) $(11) $(2) $
 $(28)$8
 $
 $
 $
 $8
Ameren Illinois:
 
 
 
 


 

 

 

 

Level 1$
 $
 $
 $
 $
$(1) $
 $
 $
 $(1)
Level 2(a)
(31) (12) 
 
 (43)(10) (7) (1) 
 (18)
Level 3(b)
(10) (20) (18) (94) (142)(14) (30) (29) (125) (198)
Total$(41) $(32) $(18) $(94) $(185)$(25) $(37) $(30) $(125) $(217)
Ameren:                  
Level 1$(16) $(6) $
 $
 $(22)$2
 $1
 $
 $
 $3
Level 2(a)
(32) (15) (2) 
 (49)(13) (10) (1) 
 (24)
Level 3(b)
(8) (22) (18) (94) (142)(6) (28) (29) (125) (188)
Total$(56) $(43) $(20) $(94) $(213)$(17) $(37) $(30) $(125) $(209)
(a)
Principally fixed-price vs. floating over-the-counterOTC power swaps, power forwards, and fixed-price vs. floating over-the-counterOTC natural gas swaps.
(b)Principally power forward contract values based on information from external sources, historical results, and our estimates. Level 3 also includes option contract values based on a Black-Scholesan option valuation model.

67


ITEM 8.FINANCIAL STATEMENTS AND SUPPLEMENTARY DATA
Report of Independent Registered Public Accounting Firm
To the Board of Directors and Shareholders
of Ameren Corporation:
Opinions on the Financial Statements and Internal Control over Financial Reporting

We have audited the accompanying consolidated balance sheets of Ameren Corporation and its subsidiaries as of December 31, 2017 and 2016, and the related consolidated statements of income, comprehensive income, changes in shareholders’ equity and cash flows for each of the three years in the period ended December 31, 2017, including the related notes and financial statement schedules listed in the index appearing under Item 15(a)(2) (collectively referred to as the “consolidated financial statements”). We also have audited the Company’s internal control over financial reporting as of December 31, 2017, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).
In our opinion, the consolidated financial statements listed in the index appearing under Item 15(a)(1)referred to above present fairly, in all material respects, the financial position of Ameren Corporation and its subsidiaries atthe Company as of December 31, 20142017 and 2013,2016, and the results of their operations and their cash flows for each of the three years in the period ended December 31, 2014,2017, in conformity with accounting principles generally accepted in the United States of America. In addition, in our opinion, the financial statement schedules listed in the index appearing under Item 15(a)(2) present fairly, in all material respects, the information set forth therein when read in conjunction with the related consolidated financial statements. Also in our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2014,2017, based on criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). COSO.
Basis for Opinions
The Company’s management is responsible for these consolidated financial statements, and financial statement schedules, for maintaining effective internal control over financial reporting, and for its assessment of the effectiveness of internal control over financial reporting, included in Management’s Report on Internal Control over Financial Reporting appearing under Item 9A. Our responsibility is to express opinions on thesethe Company’s consolidated financial statements on the financial statement schedules, and on the Company’s internal control over financial reporting based on our integrated audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States).PCAOB. Those standards require that we plan and perform the audits to obtain reasonable assurance about whether the consolidated financial statements are free of material misstatement, whether due to error or fraud, and whether effective internal control over financial reporting was maintained in all material respects.
Our audits of the consolidated financial statements included performing procedures to assess the risks of material misstatement of the consolidated financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence supportingregarding the amounts and disclosures in the consolidated financial statements, assessingstatements. Our audits also included evaluating the accounting principles used and significant estimates made by management, andas well as evaluating the overall presentation of the consolidated financial statement presentation.statements. Our audit of internal control over financial reporting included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, and testing and evaluating the design and operating effectiveness of internal control based on the assessed risk. Our audits also included performing such other procedures as we considered necessary in the circumstances. We believe that our audits provide a reasonable basis for our opinions.
Definition and Limitations of Internal Control over Financial Reporting
A company’s internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (i) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (ii) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (iii) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.
Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness to future periods are subject to the risk that controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

/s/PricewaterhouseCoopers LLP
PricewaterhouseCoopers LLP
St. Louis, Missouri
March 2, 2015February 28, 2018
We have served as the Company’s auditor since at least 1932. We have not determined the specific year we began serving as auditor of the Company.


Report of Independent Registered Public Accounting Firm
To the Board of Directors and Shareholders
of Union Electric Company:
In our opinion,Opinion on the Financial Statements
We have audited the accompanying balance sheets of Union Electric Company as of December 31, 2017 and 2016, and the related statements of income and comprehensive income, of changes in shareholders’ equity and of cash flows for each of the three years in the period ended December 31, 2017, including the related notes and financial statementsstatement schedule listed in the index appearing under Item 15(a)(1)(2) (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of Union Electricthe Company atas of December 31, 20142017 and 2013,2016, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2014,2017, in conformity with accounting principles generally accepted in the United States of America. In addition, in our opinion, the financial statement schedule listed in the index appearing under Item 15(a)(2) presents fairly, in all material respects, the information set forth therein when read in conjunction with the related financial statements.
Basis for Opinion
Thesefinancial statements and financial statement schedule are the responsibility of the Company’s management. Our responsibility is to express an opinion on these the Company’sfinancial statements and financial statement schedule based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audits of these financial statements in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the

68


audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements, assessing the accounting principles used and significant estimates made by management, and evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.
/s/PricewaterhouseCoopers LLP
PricewaterhouseCoopers LLP
St. Louis, Missouri
March 2, 2015
Report of Independent Registered Public Accounting Firm
To the Board of Directors and Shareholders
of Ameren Illinois Company:
In our opinion, the financial statements listed in the index appearing under Item 15(a)(1) present fairly, in all material respects, the financial position of Ameren Illinois Company at December 31, 2014 and 2013, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2014, in conformity with accounting principles generally accepted in the United States of America. In addition, in our opinion, the financial statement schedule listed in the index appearing under Item 15(a)(2) presents fairly, in all material respects, the information set forth therein when read in conjunction with the related financial statements. These financial statements and financial statement schedule are the responsibility of the Company’s management. Our responsibility is to express an opinion on these financial statements and financial statement schedule based on our audits. We conducted our audits of these statements in accordance with the standards of the Public Company Accounting Oversight Board (United States).PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. Anmisstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit includesof its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.
Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence supportingregarding the amounts and disclosures in the financial statements, assessingstatements. Our audits also included evaluating the accounting principles used and significant estimates made by management, andas well as evaluating the overall presentation of the financial statement presentation.statements. We believe that our audits provide a reasonable basis for our opinion.
/s/PricewaterhouseCoopers LLP
PricewaterhouseCoopers LLP
St. Louis, Missouri
March 2, 2015February 28, 2018
We have served as the Company’s auditor since at least 1932. We have not determined the specific year we began serving as auditor of the Company.


69

TableReport of ContentsIndependent Registered Public Accounting Firm
To the Board of Directors and Shareholders

of Ameren Illinois Company:
Opinion on the Financial Statements
We have audited the accompanying balance sheets of Ameren Illinois Company as of December 31, 2017 and 2016, and the related statements of income and comprehensive income, of changes in shareholders’ equity and of cash flows for each of the three years in the period ended December 31, 2017, including the related notes and financial statement schedule listed in the index appearing under Item 15(a)(2) (collectively referred to as the “financial statements”). In our opinion, the financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2017 and 2016, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2017, in conformity with accounting principles generally accepted in the United States of America.
Basis for Opinion
Thesefinancial statements are the responsibility of the Company’s management. Our responsibility is to express an opinion on the Company’sfinancial statements based on our audits. We are a public accounting firm registered with the Public Company Accounting Oversight Board (United States) (“PCAOB”) and are required to be independent with respect to the Company in accordance with the U.S. federal securities laws and the applicable rules and regulations of the Securities and Exchange Commission and the PCAOB.
We conducted our audits of these financial statements in accordance with the standards of the PCAOB. Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement, whether due to error or fraud. The Company is not required to have, nor were we engaged to perform, an audit of its internal control over financial reporting. As part of our audits we are required to obtain an understanding of internal control over financial reporting but not for the purpose of expressing an opinion on the effectiveness of the Company’s internal control over financial reporting. Accordingly, we express no such opinion.
Our audits included performing procedures to assess the risks of material misstatement of the financial statements, whether due to error or fraud, and performing procedures that respond to those risks. Such procedures included examining, on a test basis, evidence regarding the amounts and disclosures in the financial statements. Our audits also included evaluating the accounting principles used and significant estimates made by management, as well as evaluating the overall presentation of the financial statements. We believe that our audits provide a reasonable basis for our opinion.
/s/ PricewaterhouseCoopers LLP
PricewaterhouseCoopers LLP
St. Louis, Missouri
February 28, 2018
We have served as the Company’s auditor since 1998.

AMEREN CORPORATION
CONSOLIDATED STATEMENT OF INCOME (LOSS)
(In millions, except per share amounts)
AMEREN CORPORATION
CONSOLIDATED STATEMENT OF INCOME
(In millions, except per share amounts)
AMEREN CORPORATION
CONSOLIDATED STATEMENT OF INCOME
(In millions, except per share amounts)
Year Ended December 31,Year Ended December 31,
2014 2013 20122017 2016 2015
Operating Revenues:
 
  
 
  
Electric$4,913
 $4,832
 $4,857
$5,310
 $5,196
 $5,180
Gas1,140
 1,006
 924
Natural gas867
 880
 918
Total operating revenues6,053
 5,838
 5,781
6,177
 6,076
 6,098
Operating Expenses:
 
  
 
  
Fuel826
 845
 714
737
 745
 878
Purchased power454
 502
 780
638
 621
 514
Gas purchased for resale615
 526
 472
Natural gas purchased for resale311
 341
 415
Other operations and maintenance1,691
 1,617
 1,511
1,660
 1,676
 1,694
Provision for Callaway construction and operating license
 
 69
Depreciation and amortization745
 706
 673
896
 845
 796
Taxes other than income taxes468
 458
 443
477
 467
 473
Total operating expenses4,799
 4,654
 4,593
4,719
 4,695
 4,839
Operating Income1,254
 1,184
 1,188
1,458
 1,381
 1,259
Other Income and Expenses:          
Miscellaneous income79
 69
 70
59
 74
 74
Miscellaneous expense22
 26
 37
21
 32
 30
Total other income57
 43
 33
38
 42
 44
Interest Charges341
 398
 392
391
 382
 355
Income Before Income Taxes970
 829
 829
1,105
 1,041
 948
Income Taxes377
 311
 307
576
 382
 363
Income from Continuing Operations593
 518
 522
529
 659
 585
Loss from Discontinued Operations, Net of Taxes (Note 16)(1) (223) (1,496)
Net Income (Loss)592
 295
 (974)
Less: Net Income (Loss) Attributable to Noncontrolling Interests:     
Income from Discontinued Operations, Net of Taxes
 
 51
Net Income529
 659
 636
Less: Net Income from Continuing Operations Attributable to
Noncontrolling Interests
6
 6
 6
Net Income Attributable to Ameren Common Shareholders:     
Continuing Operations6
 6
 6
523
 653
 579
Discontinued Operations
 
 (6)
 
 51
Net Income (Loss) Attributable to Ameren Corporation:     
Net Income Attributable to Ameren Common Shareholders$523
 $653
 $630
     
Earnings per Common Share – Basic:     
Continuing Operations587
 512
 516
$2.16
 $2.69
 $2.39
Discontinued Operations(1) (223) (1,490)
 
 0.21
Net Income (Loss) Attributable to Ameren Corporation$586
 $289
 $(974)
Earnings per Common Share – Basic$2.16
 $2.69
 $2.60
          
Earnings (Loss) per Common Share – Basic:     
Earnings per Common Share – Diluted:     
Continuing Operations$2.42
 $2.11
 $2.13
$2.14
 $2.68
 $2.38
Discontinued Operations
 (0.92) (6.14)
 
 0.21
Earnings (Loss) per Common Share – Basic$2.42
 $1.19
 $(4.01)
     
Earnings (Loss) per Common Share – Diluted:     
Continuing Operations$2.40
 $2.10
 $2.13
Discontinued Operations
 (0.92) (6.14)
Earnings (Loss) per Common Share – Diluted$2.40
 $1.18
 $(4.01)
Earnings per Common Share – Diluted$2.14
 $2.68
 $2.59
          
Dividends per Common Share$1.61
 $1.60
 $1.60
$1.778
 $1.715
 $1.655
Average Common Shares Outstanding – Basic242.6
 242.6
 242.6
242.6
 242.6
 242.6
Average Common Shares Outstanding – Diluted244.4
 244.5
 243.0
244.2
 243.4
 243.6

The accompanying notes are an integral part of these consolidated financial statements.

70



AMEREN CORPORATION
CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (LOSS)
(In millions)
 Year Ended December 31,
 2014 2013 2012
      
Income from Continuing Operations$593
 $518
 $522
Other Comprehensive Income (Loss), Net of Taxes:     
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $(7), $16, and $(6), respectively(12) 30
 (8)
Comprehensive Income from Continuing Operations581
 548
 514
Less: Comprehensive Income from Continuing Operations Attributable to Noncontrolling Interests6
 6
 6
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation575
 542
 508
      
Loss from Discontinued Operations, Net of Taxes(1) (223) (1,496)
Other Comprehensive Income (Loss) from Discontinued Operations, Net of Income Taxes (Benefit) of $-, $(10), and $40, respectively
 (18) 58
Comprehensive Loss from Discontinued Operations(1) (241) (1,438)
Less: Comprehensive Income from Discontinued Operations Attributable to Noncontrolling Interest
 1
 2
Comprehensive Loss from Discontinued Operations Attributable to Ameren Corporation(1) (242) (1,440)
Comprehensive Income (Loss) Attributable to Ameren Corporation$574
 $300
 $(932)
AMEREN CORPORATION
CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME
(In millions)
 Year Ended December 31,
 2017 2016 2015
      
Income from Continuing Operations$529
 $659
 $585
Other Comprehensive Income (Loss) from Continuing Operations, Net of Taxes     
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $3, $(7), and $3, respectively5
 (20) 6
Comprehensive Income from Continuing Operations534
 639
 591
Less: Comprehensive Income from Continuing Operations Attributable to Noncontrolling Interests6
 6
 6
Comprehensive Income from Continuing Operations Attributable to Ameren Common Shareholders528
 633
 585
Comprehensive Income from Discontinued Operations Attributable to Ameren Common Shareholders
 
 51
Comprehensive Income Attributable to Ameren Common Shareholders$528
 $633
 $636

The accompanying notes are an integral part of these consolidated financial statements.

71


AMEREN CORPORATION
CONSOLIDATED BALANCE SHEET
(In millions, except per share amounts)
AMEREN CORPORATION
CONSOLIDATED BALANCE SHEET
(In millions, except per share amounts)
AMEREN CORPORATION
CONSOLIDATED BALANCE SHEET
(In millions, except per share amounts)
December 31,December 31,
2014 20132017 2016
ASSETS      
Current Assets:      
Cash and cash equivalents$5
 $30
$10
 $9
Accounts receivable – trade (less allowance for doubtful accounts of $21 and $18, respectively)423
 404
Accounts receivable – trade (less allowance for doubtful accounts of $19 and $19, respectively)445
 437
Unbilled revenue265
 304
323
 295
Miscellaneous accounts and notes receivable81
 196
70
 63
Materials and supplies524
 526
Inventories522
 527
Current regulatory assets295
 156
144
 149
Current accumulated deferred income taxes, net352
 106
Other current assets86
 85
98
 113
Assets of discontinued operations (Note 16)15
 165
Total current assets2,046
 1,972
1,612
 1,593
Property and Plant, Net17,424
 16,205
Property, Plant, and Equipment, Net21,466
 20,113
Investments and Other Assets:      
Nuclear decommissioning trust fund549
 494
704
 607
Goodwill411
 411
411
 411
Regulatory assets1,582
 1,240
1,230
 1,437
Other assets664
 720
522
 538
Total investments and other assets3,206
 2,865
2,867
 2,993
TOTAL ASSETS$22,676
 $21,042
$25,945
 $24,699
LIABILITIES AND EQUITY      
Current Liabilities:      
Current maturities of long-term debt$120
 $534
$841
 $681
Short-term debt714
 368
484
 558
Accounts and wages payable711
 806
902
 805
Taxes accrued46
 55
52
 46
Interest accrued85
 86
99
 93
Customer deposits108
 107
Current regulatory liabilities106
 216
128
 110
Other current liabilities434
 351
326
 274
Liabilities of discontinued operations (Note 16)33
 45
Total current liabilities2,249
 2,461
2,940
 2,674
Long-term Debt, Net6,120
 5,504
7,094
 6,595
Deferred Credits and Other Liabilities:      
Accumulated deferred income taxes, net3,923
 3,250
2,506
 4,264
Accumulated deferred investment tax credits64
 63
49
 55
Regulatory liabilities1,850
 1,705
4,387
 1,985
Asset retirement obligations396
 369
638
 635
Pension and other postretirement benefits705
 466
545
 769
Other deferred credits and liabilities514
 538
460
 477
Total deferred credits and other liabilities7,452
 6,391
8,585
 8,185
Commitments and Contingencies (Notes 2, 10, 15 and 16)

 

Ameren Corporation Stockholders’ Equity:   
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 242.62
 2
Commitments and Contingencies (Notes 2, 9, and 14)

 

Ameren Corporation Shareholders’ Equity:   
Common stock, $.01 par value, 400.0 shares authorized – 242.6 shares outstanding2
 2
Other paid-in capital, principally premium on common stock5,617
 5,632
5,540
 5,556
Retained earnings1,103
 907
1,660
 1,568
Accumulated other comprehensive income (loss)(9) 3
Total Ameren Corporation stockholders’ equity6,713
 6,544
Accumulated other comprehensive loss(18) (23)
Total Ameren Corporation shareholders’ equity7,184
 7,103
Noncontrolling Interests142
 142
142
 142
Total equity6,855
 6,686
7,326
 7,245
TOTAL LIABILITIES AND EQUITY$22,676
 $21,042
$25,945
 $24,699

The accompanying notes are an integral part of these consolidated financial statements.

72


AMEREN CORPORATION
CONSOLIDATED STATEMENT OF CASH FLOWS
(In millions)
AMEREN CORPORATION
CONSOLIDATED STATEMENT OF CASH FLOWS
(In millions)
AMEREN CORPORATION
CONSOLIDATED STATEMENT OF CASH FLOWS
(In millions)
Year Ended December 31,Year Ended December 31,
2014 2013 20122017 2016 2015
Cash Flows From Operating Activities:          
Net income (loss)$592
 $295
 $(974)
Loss from discontinued operations, net of tax1
 223
 1,496
Adjustments to reconcile net income (loss) to net cash provided by operating activities:     
Net income$529
 $659
 $636
Income from discontinued operations, net of tax
 
 (51)
Adjustments to reconcile net income to net cash provided by operating activities:     
Provision for Callaway construction and operating license
 
 69
Depreciation and amortization710
 666
 633
876
 835
 777
Amortization of nuclear fuel81
 71
 83
76
 88
 97
Amortization of debt issuance costs and premium/discounts22
 24
 20
22
 22
 22
Deferred income taxes and investment tax credits, net451
 410
 257
539
 386
 369
Allowance for equity funds used during construction(34) (37) (36)(24) (27) (30)
Stock-based compensation costs25
 27
 29
Share-based compensation costs17
 17
 24
Other(24) 23
 (7)(10) 4
 (10)
Changes in assets and liabilities:          
Receivables31
 (60) 30
(53) (71) 83
Materials and supplies3
 60
 (28)
Inventories17
 11
 (14)
Accounts and wages payable10
 81
 (34)32
 19
 (2)
Taxes accrued(44) (195) (4)55
 13
 (22)
Regulatory assets and liabilities(281) 29
 14
36
 215
 94
Assets, other30
 20
 40
20
 (22) 46
Liabilities, other(28) (14) 5
(7) (9) (44)
Pension and other postretirement benefits(10) (28) (23)(21) (16) (9)
Counterparty collateral, net22
 41
 41
Premiums paid on long-term debt repurchases
 
 (138)
Net cash provided by operating activities – continuing operations1,557
 1,636
 1,404
2,104
 2,124
 2,035
Net cash provided (used in) by operating activities – discontinued operations(6) 57
 286
Net cash used in operating activities – discontinued operations
 (1) (4)
Net cash provided by operating activities1,551
 1,693
 1,690
2,104
 2,123
 2,031
Cash Flows From Investing Activities:          
Capital expenditures(1,785) (1,379) (1,063)(2,132) (2,076) (1,917)
Nuclear fuel expenditures(74) (45) (91)(63) (55) (52)
Purchases of securities – nuclear decommissioning trust fund(405) (214) (403)(413) (392) (363)
Sales and maturities of securities – nuclear decommissioning trust fund391
 196
 384
396
 377
 349
Proceeds from note receivable – Marketing Company95
 6
 
Contributions to note receivable – Marketing Company(89) (5) 
Other11
 1
 20
7
 5
 32
Net cash used in investing activities – continuing operations(1,856) (1,440) (1,153)(2,205) (2,141) (1,951)
Net cash provided by (used in) investing activities – discontinued operations139
 (283) (157)
Net cash used in investing activities – discontinued operations
 
 (25)
Net cash used in investing activities(1,717) (1,723) (1,310)(2,205) (2,141) (1,976)
Cash Flows From Financing Activities:          
Dividends on common stock(390) (388) (382)(431) (416) (402)
Dividends paid to noncontrolling interest holders(6) (6) (6)(6) (6) (6)
Short-term debt, net346
 368
 (148)(74) 257
 (413)
Maturities, redemptions and repurchases of long-term debt(697) (399) (760)
Redemptions, repurchases, and maturities of long-term debt(681) (395) (120)
Issuances of long-term debt898
 278
 882
1,345
 389
 1,197
Capital issuance costs(11) (2) (16)
Debt issuance costs(11) (9) (12)
Share-based payments(39) (83) (12)
Other1
 
 4
(1) (2) 
Net cash provided by (used in) financing activities – continuing operations141
 (149) (426)102
 (265) 232
Net change in cash and cash equivalents(25) (179) (46)1
 (283) 287
Cash and cash equivalents at beginning of year30
 209
 255
9
 292
 5
Cash and cash equivalents at end of year5
 30
 209
$10
 $9
 $292
Less: cash and cash equivalents at end of year – discontinued operations
 
 25
Cash and cash equivalents at end of year – continuing operations$5
 $30
 $184
          
Noncash financing activity – dividends on common stock$
 $
 $(7)
Cash Paid (Refunded) During the Year:          
Interest (net of $18, $37, and $30 capitalized, respectively)$333
 $393
 $433
Interest (net of $14, $15, and $17 capitalized, respectively)$370
 $358
 $335
Income taxes, net(27) 8
 1
(19) (12) (15)

The accompanying notes are an integral part of these consolidated financial statements.

73


AMEREN CORPORATION
CONSOLIDATED STATEMENT OF STOCKHOLDERS’ EQUITY
(In millions)
AMEREN CORPORATION
CONSOLIDATED STATEMENT OF SHAREHOLDERS’ EQUITY
(In millions)
AMEREN CORPORATION
CONSOLIDATED STATEMENT OF SHAREHOLDERS’ EQUITY
(In millions)
December 31,December 31,
2014 2013 20122017 2016 2015
Common Stock:     
Beginning of year$2
 $2
 $2
Shares issued
 
 
Common stock, end of year2
 2
 2
Common Stock$2
 $2
 $2
     
Other Paid-in Capital:          
Beginning of year5,632
 5,616
 5,598
5,556
 5,616
 5,617
Stock-based compensation activity(15) 16
 18
Share-based compensation activity(16) (60) (1)
Other paid-in capital, end of year5,617
 5,632
 5,616
5,540
 5,556
 5,616
Retained Earnings:          
Beginning of year907
 1,006
 2,369
1,568
 1,331
 1,103
Net income (loss) attributable to Ameren Corporation586
 289
 (974)
Net income attributable to Ameren common shareholders523
 653
 630
Dividends(390) (388) (389)(431) (416) (402)
Retained earnings, end of year1,103
 907
 1,006
1,660
 1,568
 1,331
Accumulated Other Comprehensive Income (Loss):          
Derivative financial instruments, beginning of year
 25
 7
Change in derivative financial instruments
 (21) 18
Divestiture of derivative financial instruments (Note 16)
 (4) 
Derivative financial instruments, end of year
 
 25
Deferred retirement benefit costs, beginning of year3
 (33) (57)(23) (3) (9)
Change in deferred retirement benefit costs(12) 29
 24
5
 (20) 6
Divestiture of deferred retirement benefit costs (Note 16)
 7
 
Deferred retirement benefit costs, end of year(9) 3
 (33)(18) (23) (3)
Total accumulated other comprehensive income (loss), end of year(9) 3
 (8)
Total Ameren Corporation Stockholders’ Equity$6,713
 $6,544
 $6,616
Total accumulated other comprehensive loss, end of year(18) (23) (3)
Total Ameren Corporation Shareholders’ Equity$7,184
 $7,103
 $6,946
          
Noncontrolling Interests:          
Beginning of year142
 151
 149
142
 142
 142
Net income attributable to noncontrolling interest holders6
 6
 
6
 6
 6
Dividends paid to noncontrolling interest holders(6) (6) (6)(6) (6) (6)
Divestiture of noncontrolling interest (Note 16)
 (9) 
Other
 
 8
Noncontrolling interests, end of year142
 142
 151
142
 142
 142
Total Equity$6,855
 $6,686
 $6,767
$7,326
 $7,245
 $7,088
          
     
Common stock shares at end of year242.6
 242.6
 242.6
242.6
 242.6
 242.6

The accompanying notes are an integral part of these consolidated financial statements.

74


UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF INCOME AND COMPREHENSIVE INCOME
(In millions)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF INCOME AND COMPREHENSIVE INCOME
(In millions)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF INCOME AND COMPREHENSIVE INCOME
(In millions)
Year Ended December 31,Year Ended December 31,
2014
2013 20122017
2016 2015
Operating Revenues:


  


  
Electric$3,388

$3,379
 $3,132
$3,413

$3,394
 $3,470
Gas164

161
 139
Natural gas126

128
 137
Other1

1
 1


1
 2
Total operating revenues3,553

3,541
 3,272
3,539

3,523
 3,609
Operating Expenses:


  


  
Fuel826

845
 714
737

745
 878
Purchased power119

127
 78
245

252
 111
Gas purchased for resale82
 78
 64
Natural gas purchased for resale47
 49
 57
Other operations and maintenance946
 915
 827
902
 893
 925
Provision for Callaway construction and operating license
 
 69
Depreciation and amortization473
 454
 440
533
 514
 492
Taxes other than income taxes322
 319
 304
328
 325
 335
Total operating expenses2,768
 2,738
 2,427
2,792
 2,778
 2,867
Operating Income785
 803
 845
747
 745
 742
Other Income and Expenses:          
Miscellaneous income60
 58
 63
48
 52
 52
Miscellaneous expense12
 11
 14
8
 10
 11
Total other income48
 47
 49
40
 42
 41
Interest Charges211
 210
 223
207
 211
 219
Income Before Income Taxes622
 640
 671
580
 576
 564
Income Taxes229
 242
 252
254
 216
 209
Net Income393
 398
 419
326
 360
 355
Other Comprehensive Income
 
 

 
 
Comprehensive Income$393
 $398
 $419
$326
 $360
 $355
          
          
Net Income$393
 $398
 $419
$326
 $360
 $355
Preferred Stock Dividends3
 3
 3
3
 3
 3
Net Income Available to Common Stockholder$390
 $395
 $416
Net Income Available to Common Shareholder$323
 $357
 $352

The accompanying notes as they relate to Ameren Missouri are an integral part of these financial statements.

75


UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
BALANCE SHEET
(In millions, except per share amounts)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
BALANCE SHEET
(In millions, except per share amounts)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
BALANCE SHEET
(In millions, except per share amounts)
December 31,December 31,
2014 20132017 2016
ASSETS      
Current Assets:      
Cash and cash equivalents$1
 $1
$
 $
Accounts receivable – trade (less allowance for doubtful accounts of $8 and $5, respectively)190
 191
Advances to money pool
 161
Accounts receivable – trade (less allowance for doubtful accounts of $7 and $7, respectively)200
 187
Accounts receivable – affiliates65
 1
11
 12
Unbilled revenue146
 168
165
 154
Miscellaneous accounts and notes receivable35
 57
35
 14
Materials and supplies347
 352
Inventories388
 392
Current regulatory assets163
 118
56
 35
Other current assets92
 71
50
 49
Total current assets1,039
 959
905
 1,004
Property and Plant, Net10,867
 10,452
Property, Plant, and Equipment, Net11,751
 11,478
Investments and Other Assets:      
Nuclear decommissioning trust fund549
 494
704
 607
Regulatory assets695
 534
395
 619
Other assets391
 465
288
 327
Total investments and other assets1,635
 1,493
1,387
 1,553
TOTAL ASSETS$13,541
 $12,904
$14,043
 $14,035
LIABILITIES AND STOCKHOLDERS’ EQUITY   
LIABILITIES AND SHAREHOLDERS’ EQUITY   
Current Liabilities:      
Current maturities of long-term debt$120
 $109
$384
 $431
Borrowings from money pool
 105
Short-term debt97
 
39
 
Accounts and wages payable405
 387
475
 444
Accounts payable – affiliates56
 30
60
 68
Taxes accrued32
 220
30
 30
Interest accrued58
 57
54
 54
Current regulatory liabilities18
 57
19
 12
Other current liabilities117
 82
103
 123
Total current liabilities903
 1,047
1,164
 1,162
Long-term Debt, Net3,879
 3,648
3,577
 3,563
Deferred Credits and Other Liabilities:      
Accumulated deferred income taxes, net2,806
 2,524
1,650
 3,013
Accumulated deferred investment tax credits61
 59
48
 53
Regulatory liabilities1,147
 1,041
2,664
 1,215
Asset retirement obligations389
 366
634
 629
Pension and other postretirement benefits274
 189
213
 291
Other deferred credits and liabilities30
 37
12
 19
Total deferred credits and other liabilities4,707
 4,216
5,221
 5,220
Commitments and Contingencies (Notes 2, 10, 14 and 15)
 
Stockholders’ Equity:   
Commitments and Contingencies (Notes 2, 9, 13, and 14)
 
Shareholders’ Equity:   
Common stock, $5 par value, 150.0 shares authorized – 102.1 shares outstanding511
 511
511
 511
Other paid-in capital, principally premium on common stock1,569
 1,560
1,858
 1,828
Preferred stock80
 80
80
 80
Retained earnings1,892
 1,842
1,632
 1,671
Total stockholders’ equity4,052
 3,993
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY$13,541
 $12,904
Total shareholders’ equity4,081
 4,090
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY$14,043
 $14,035
The accompanying notes as they relate to Ameren Missouri are an integral part of these financial statements.

76


UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF CASH FLOWS
(In millions)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF CASH FLOWS
(In millions)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF CASH FLOWS
(In millions)
Year Ended December 31,Year Ended December 31,
2014 2013 20122017 2016 2015
Cash Flows From Operating Activities:          
Net income$393
 $398
 $419
$326
 $360
 $355
Adjustments to reconcile net income to net cash provided by operating activities:          
Provision for Callaway construction and operating license
 
 69
Depreciation and amortization442
 419
 407
514
 506
 476
Amortization of nuclear fuel81
 71
 83
76
 88
 97
FAC prudence review charges
 26
 
Amortization of debt issuance costs and premium/discounts7
 7
 6
6
 6
 6
Deferred income taxes and investment tax credits, net245
 65
 287
82
 179
 82
Allowance for equity funds used during construction(32) (31) (31)(21) (23) (22)
Other3
 1
 8
4
 5
 2
Changes in assets and liabilities:          
Receivables(10) (59) 27
(46) 5
 72
Materials and supplies8
 45
 (48)
Inventories18
 (4) (39)
Accounts and wages payable25
 42
 (27)27
 (18) 3
Taxes accrued(197) 100
 (46)(1) 11
 1
Regulatory assets and liabilities(68) 68
 (50)26
 84
 117
Assets, other52
 18
 15
30
 (25) 26
Liabilities, other
 (29) 14
(23) (1) 4
Pension and other postretirement benefits1
 2
 2
(2) (4) (2)
Premiums paid on long-term debt repurchases
 
 (62)
Net cash provided by operating activities950
 1,143
 1,004
1,016
 1,169
 1,247
Cash Flows From Investing Activities:          
Capital expenditures(747) (648) (595)(773) (738) (622)
Nuclear fuel expenditures(74) (45) (91)(63) (55) (52)
Purchases of securities – nuclear decommissioning trust fund(405) (214) (403)(413) (392) (363)
Sales and maturities of securities – nuclear decommissioning trust fund391
 196
 384
396
 377
 349
Money pool advances, net
 24
 (24)161
 (125) (36)
Tax grants received related to renewable energy properties
 
 18
Other(2) 
 8
7
 (1) 
Net cash used in investing activities(837) (687) (703)(685) (934) (724)
Cash Flows From Financing Activities:          
Dividends on common stock(340) (460) (400)(362) (355) (575)
Return of capital to parent(215) 
 
Dividends on preferred stock(3) (3) (3)(3) (3) (3)
Short-term debt, net97
 
 
39
 
 (97)
Money pool borrowings, net(105) 105
 
Redemptions, repurchases, and maturities of long-term debt(109) (249) (427)(431) (266) (120)
Issuances of long-term debt350
 
 482
399
 149
 249
Capital issuance costs(3) 
 (7)(3) (3) (3)
Capital contribution from parent215
 4
 1
30
 44
 224
Net cash used in financing activities(113) (603) (354)(331) (434) (325)
Net change in cash and cash equivalents
 (147) (53)
 (199) 198
Cash and cash equivalents at beginning of year1
 148
 201

 199
 1
Cash and cash equivalents at end of year$1
 $1
 $148
$
 $
 $199
          
Noncash financing activity capital contribution from parent
$9
 $
 $
$
 $
 $38
          
Cash Paid (Refunded) During the Year:     
Interest (net of $16, $16, and $15 capitalized, respectively)$203
 $212
 $220
Cash Paid During the Year:     
Interest (net of $10, $12, and $12 capitalized, respectively)$202
 $209
 $212
Income taxes, net215
 86
 (3)178
 27
 72
The accompanying notes as they relate to Ameren Missouri are an integral part of these financial statements.

77


UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF STOCKHOLDERS’ EQUITY
(In millions)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF SHAREHOLDERS’ EQUITY
(In millions)
UNION ELECTRIC COMPANY (d/b/a AMEREN MISSOURI)
STATEMENT OF SHAREHOLDERS’ EQUITY
(In millions)
December 31,December 31,
2014 2013 20122017 2016 2015
Common Stock$511
 $511
 $511
$511
 $511
 $511
          
Other Paid-in Capital:          
Beginning of year1,560
 1,556
 1,555
1,828
 1,822
 1,569
Capital contribution from parent (Note 1)224
 4
 1
Return of capital to parent (Note 1)(215) 
 
Capital contribution from parent30
 6
 253
Other paid-in capital, end of year1,569
 1,560
 1,556
1,858
 1,828
 1,822
          
Preferred Stock80
 80
 80
80
 80
 80
          
Retained Earnings:          
Beginning of year1,842
 1,907
 1,891
1,671
 1,669
 1,892
Net income393
 398
 419
326
 360
 355
Common stock dividends(340) (460) (400)(362) (355) (575)
Preferred stock dividends(3) (3) (3)(3) (3) (3)
Retained earnings, end of year1,892
 1,842
 1,907
1,632
 1,671
 1,669
          
Total Stockholders’ Equity$4,052
 $3,993
 $4,054
Total Shareholders’ Equity$4,081
 $4,090
 $4,082

The accompanying notes as they relate to Ameren Missouri are an integral part of these financial statements.

78


AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
STATEMENT OF INCOME AND COMPREHENSIVE INCOME
(In millions)
Year Ended December 31,Year Ended December 31,
2014 2013 20122017 2016 2015
Operating Revenues:          
Electric$1,522
 $1,461
 $1,739
$1,784
 $1,736
 $1,683
Gas976
 847
 786
Natural gas743
 754
 783
Other
 3
 
1
 
 
Total operating revenues2,498
 2,311
 2,525
2,528
 2,490
 2,466
Operating Expenses:          
Purchased power343
 380
 705
417
 399
 420
Gas purchased for resale533
 448
 408
Natural gas purchased for resale264
 292
 358
Other operations and maintenance771
 693
 684
789
 804
 797
Depreciation and amortization263
 243
 221
341
 319
 295
Taxes other than income taxes138
 132
 130
137
 132
 130
Total operating expenses2,048
 1,896
 2,148
1,948
 1,946
 2,000
Operating Income450
 415
 377
580
 544
 466
Other Income and Expenses:          
Miscellaneous income17
 10
 7
11
 21
 21
Miscellaneous expense8
 9
 17
10
 12
 12
Total other income (expense)9
 1
 (10)
Total other income1
 9
 9
Interest Charges112
 143
 129
144
 140
 131
Income Before Income Taxes347
 273
 238
437
 413
 344
Income Taxes143
 110
 94
166
 158
 127
Net Income204
 163
 144
271
 255
 217
Other Comprehensive Loss, Net of Taxes:          
Pension and other postretirement benefit plan activity, net of income tax benefit of $(2), $(2) and $(2), respectively(3) (3) (3)
Pension and other postretirement benefit plan activity, net of income tax benefit of $-, $(1), and $(2), respectively
 (5) (3)
Comprehensive Income$201
 $160
 $141
$271
 $250
 $214
          
          
Net Income$204
 $163
 $144
$271
 $255
 $217
Preferred Stock Dividends3
 3
 3
3
 3
 3
Net Income Available to Common Stockholder$201
 $160
 $141
Net Income Available to Common Shareholder$268
 $252
 $214
 
The accompanying notes as they relate to Ameren Illinois are an integral part of these financial statements.

79


AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
BALANCE SHEET
(In millions)
AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
BALANCE SHEET
(In millions)
AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
BALANCE SHEET
(In millions)
December 31,December 31,
2014 20132017 2016
ASSETS      
Current Assets:      
Cash and cash equivalents$1
 $1
$
 $
Accounts receivable – trade (less allowance for doubtful accounts of $13 and $13, respectively)212
 201
Accounts receivable – trade (less allowance for doubtful accounts of $12 and $12, respectively)234
 242
Accounts receivable – affiliates22
 
9
 10
Unbilled revenue119
 135
158
 141
Miscellaneous accounts receivable9
 13
35
 22
Materials and supplies177
 174
Inventories134
 135
Current regulatory assets129
 38
87
 108
Current accumulated deferred income taxes, net160
 45
Other current assets15
 26
15
 25
Total current assets844
 633
672
 683
Property and Plant, Net6,165
 5,589
Property, Plant, and Equipment, Net8,293
 7,469
Investments and Other Assets:      
Goodwill411
 411
411
 411
Regulatory assets883
 701
822
 816
Other assets78
 120
147
 95
Total investments and other assets1,372
 1,232
1,380
 1,322
TOTAL ASSETS$8,381
 $7,454
$10,345
 $9,474
LIABILITIES AND STOCKHOLDERS’ EQUITY   
LIABILITIES AND SHAREHOLDERS’ EQUITY   
Current Liabilities:      
Current maturities of long-term debt$457
 $250
Short-term debt$32
 $
62
 51
Borrowings from money pool15
 56
Accounts and wages payable207
 243
337
 264
Accounts payable – affiliates50
 18
70
 63
Taxes accrued17
 23
19
 16
Interest accrued33
 33
Customer deposits77
 79
69
 69
Mark-to-market derivative liabilities42
 36
Current environmental remediation52
 43
42
 38
Current regulatory liabilities84
 159
92
 78
Other current liabilities124
 114
177
 109
Total current liabilities700
 771
1,358
 971
Long-term Debt, Net2,241
 1,856
2,373
 2,338
Deferred Credits and Other Liabilities:      
Accumulated deferred income taxes, net1,408
 1,116
1,021
 1,631
Accumulated deferred investment tax credits3
 4
1
 2
Regulatory liabilities703
 664
1,629
 768
Pension and other postretirement benefits277
 197
285
 346
Environmental remediation199
 232
134
 162
Other deferred credits and liabilities189
 166
234
 222
Total deferred credits and other liabilities2,779
 2,379
3,304
 3,131
Commitments and Contingencies (Notes 2, 14 and 15)

 

Stockholders’ Equity:   
Commitments and Contingencies (Notes 2, 13, and 14)

 

Shareholders’ Equity:   
Common stock, no par value, 45.0 shares authorized – 25.5 shares outstanding
 

 
Other paid-in capital1,980
 1,965
2,013
 2,005
Preferred stock62
 62
62
 62
Retained earnings611
 410
1,235
 967
Accumulated other comprehensive income8
 11
Total stockholders’ equity2,661
 2,448
TOTAL LIABILITIES AND STOCKHOLDERS’ EQUITY$8,381
 $7,454
Total shareholders’ equity3,310
 3,034
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY$10,345
 $9,474

The accompanying notes as they relate to Ameren Illinois are an integral part of these financial statements.

80


AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
STATEMENT OF CASH FLOWS
(In millions)
AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
STATEMENT OF CASH FLOWS
(In millions)
AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
STATEMENT OF CASH FLOWS
(In millions)
Year Ended December 31,Year Ended December 31,
2014 2013 20122017 2016 2015
Cash Flows From Operating Activities:          
Net income$204
 $163
 $144
$271
 $255
 $217
Adjustments to reconcile net income to net cash provided by operating activities:          
Depreciation and amortization259
 238
 214
341
 318
 292
Amortization of debt issuance costs and premium/discounts13
 15
 11
13
 14
 14
Deferred income taxes and investment tax credits, net196
 104
 104
171
 154
 221
Other(19) 4
 (11)
 (1) (14)
Changes in assets and liabilities:          
Receivables(13) 50
 23
(7) (72) 16
Materials and supplies(4) 15
 20
Inventories(1) 15
 25
Accounts and wages payable7
 19
 (21)19
 12
 37
Taxes accrued(7) 28
 3
18
 1
 (2)
Regulatory assets and liabilities(215) (35) 64
16
 120
 (26)
Assets, other15
 5
 19
(15) (3) 17
Liabilities, other1
 10
 11
3
 (5) (27)
Pension and other postretirement benefits(6) (8) (26)(14) (8) (4)
Counterparty collateral, net14
 43
 40

 3
 (3)
Premiums paid on long-term debt repurchases
 
 (76)
Net cash provided by operating activities445
 651
 519
815
 803
 763
Cash Flows From Investing Activities:          
Capital expenditures(835) (701) (442)(1,076) (924) (918)
Other7
 6
 5
6
 6
 5
Net cash used in investing activities(828) (695) (437)(1,070) (918) (913)
Cash Flows From Financing Activities:          
Dividends on common stock
 (110) (189)
 (110) 
Dividends on preferred stock(3) (3) (3)(3) (3) (3)
Short-term debt, net32
 
 
11
 51
 (32)
Money pool borrowings, net(41) 32
 24

 
 (15)
Redemptions, repurchases, and maturities of long-term debt(163) (150) (333)(250) (129) 
Issuances of long-term debt548
 278
 400
496
 240
 248
Capital issuance costs(6) (2) (6)(6) (4) (3)
Capital contribution from parent15
 
 
8
 
 25
Other1
 
 4
(1) (1) 
Net cash provided by (used in) financing activities383
 45
 (103)
Net cash provided by financing activities255
 44
 220
Net change in cash and cash equivalents
 1
 (21)
 (71) 70
Cash and cash equivalents at beginning of year1
 
 21

 71
 1
Cash and cash equivalents at end of year$1
 $1
 $
$
 $
 $71
          
Cash Paid (Refunded) During the Year:          
Interest (net of $2, $4, and $2 capitalized, respectively)$110
 $112
 $125
Interest (net of $4, $3, and $5 capitalized, respectively)$139
 $127
 $120
Income taxes, net(44) (23) (22)(22) 8
 (113)

The accompanying notes as they relate to Ameren Illinois are an integral part of these financial statements.

81


AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
STATEMENT OF STOCKHOLDERS’ EQUITY
(In millions)
AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
STATEMENT OF SHAREHOLDERS’ EQUITY
(In millions)
AMEREN ILLINOIS COMPANY (d/b/a AMEREN ILLINOIS)
STATEMENT OF SHAREHOLDERS’ EQUITY
(In millions)
December 31,December 31,
2014 2013 20122017 2016 2015
Common Stock$
 $
 $
$
 $
 $
          
Other Paid-in Capital
 
 

 
 
Beginning of year1,965
 1,965
 1,965
2,005
 2,005
 1,980
Capital contribution from parent (Note 1)15
 
 
Capital contribution from parent8
 
 25
Other paid-in capital, end of year1,980
 1,965
 1,965
2,013
 2,005
 2,005
          
Preferred Stock62
 62
 62
62
 62
 62
          
Retained Earnings:          
Beginning of year410
 360
 408
967
 825
 611
Net income204
 163
 144
271
 255
 217
Common stock dividends
 (110) (189)
 (110) 
Preferred stock dividends(3) (3) (3)(3) (3) (3)
Retained earnings, end of year611
 410
 360
1,235
 967
 825
          
Accumulated Other Comprehensive Income:          
Deferred retirement benefit costs, beginning of year11
 14
 17

 5
 8
Change in deferred retirement benefit costs(3) (3) (3)
 (5) (3)
Deferred retirement benefit costs, end of year8
 11
 14

 
 5
Total accumulated other comprehensive income, end of year8
 11
 14

 
 5
          
Total Stockholders’ Equity$2,661
 $2,448
 $2,401
Total Shareholders’ Equity$3,310
 $3,034
 $2,897
 
The accompanying notes as they relate to Ameren Illinois are an integral part of these financial statements.

82


AMEREN CORPORATION (Consolidated)
UNION ELECTRIC COMPANY (d/b/a Ameren Missouri)
AMEREN ILLINOIS COMPANY (d/b/a Ameren Illinois)
COMBINED NOTES TO FINANCIAL STATEMENTS DecemberDECEMBER 31, 20142017
NOTE 1 SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
General
Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005, administered by the FERC. Ameren’swhose primary assets are its equity interests in its subsidiaries, including Ameren Missouri and Ameren Illinois. subsidiaries.Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of other expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below.below, including Ameren Missouri, Ameren Illinois, and ATXI. Ameren also has other subsidiaries that conduct other activities, such as the provision of shared services. Ameren evaluates competitive electric transmission investment opportunities as they arise.
Union Electric Company, doing business as Ameren Missouri, operates a rate-regulated electric generation, transmission, and distribution business and a rate-regulated natural gas transmission and distribution business in Missouri. Ameren Missouri was incorporated in Missouri in 1922 and is successor to a number of companies, the oldest of which was organized in 1881. It is the largest electric utility in the state of Missouri. It supplies electric and natural gas service to a 24,000-square-mile24,000-square-mile area in central and eastern Missouri. This area has an estimated population of 2.8 million andMissouri, which includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.2 million customers and natural gas service to 127,0000.1 million customers.
Ameren Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric transmission, electric distribution, and natural gas transmission and distribution businesses in Illinois. Ameren Illinois was created by the merger of CILCO and IP with and into CIPS in 2010. CIPS was incorporated in Illinois in 1923 and wasis the successor to a number of companies, the oldest of which was organized in 1902. Ameren Illinois supplies electric and natural gas utility service to portions ofa 40,000 square mile area in central and southern Illinois having an estimated population of 3.1 million in an area of 40,000 square miles.Illinois. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 813,0000.8 million customers.
Ameren has various other subsidiaries responsible for activities such as the provision of shared services. Ameren also has a subsidiary, ATXI that operates a FERC rate-regulated electric transmission business. ATXI is developing MISO-approved electric transmission projects, including the Illinois Rivers Spoon River, and Mark Twain projects.projects, and placed the Spoon River project in service in February 2018.
Ameren’s financial statements are prepared on a consolidated basis and therefore include the accounts of its majority-owned subsidiaries. All intercompany transactions have been eliminated. Ameren is also pursuing reliability projects within Ameren Missouri'sMissouri and Ameren Illinois' service territories as well as competitive electric transmission investment opportunities outside of these territories, including investments outside of MISO.
In December 2013, Ameren completed the divestiture of
New AER to IPH. In January 2014, Medina Valley completed its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital. In addition,Illinois have no subsidiaries. All tabular dollar amounts are in 2013, Ameren abandoned the Meredosia and Hutsonville energy centers upon the completion of the divestiture of New AER to IPH. Ameren has begun to demolish the Hutsonville energy center and expects to demolish the Meredosia energy center thereafter. As a result of these events, Ameren segregated New AER’s and the Elgin, Gibson City, Grand Tower, Meredosia, and Hutsonville energy centers’ operating results, assets, and liabilities and presented them separately as discontinued operations for all periods presented in this report.millions, unless otherwise indicated. Unless otherwise stated, these notes to the financial statements exclude discontinued operations for all periods presented. See Note 16 – Divestiture Transactions
As of December 31, 2017 and Discontinued Operations for additional information regardingDecember 31, 2016, Ameren had unconsolidated variable interests as a limited partner in various equity method investments totaling $17 million and $9 million, respectively, included in “Other assets” on Ameren’s consolidated balance sheet. Ameren is not the primary beneficiary of these transactions.
The financial statementsinvestments because it does not have the power to direct matters that most significantly impact the activities of Ameren are prepared on a consolidated basis, and therefore includethese variable interest entities. As of December 31, 2017, the accountsmaximum exposure to loss related to these variable interests is limited to the investment in these partnerships of its majority-owned subsidiaries. Ameren Missouri and Ameren Illinois have no subsidiaries and therefore their financial statements are not prepared on a consolidated basis. All intercompany transactions have been eliminated. All tabular dollar amounts are in millions, unless otherwise indicated.$17 million plus associated outstanding funding commitments of $20 million.
Our accounting policies conform to GAAP. Our financial statements reflect all adjustments (which include normal, recurring adjustments) that are necessary, in our opinion, for a fair presentation of our results. The preparation of financial statements in conformity with GAAP requires management to make certain estimates and assumptions. Such estimates and assumptions affect reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at the dates of financial statements, and the reported amounts of revenues and expenses during the reported periods. Actual results could differ from those estimates.
Regulation
We are regulated by the MoPSC, the ICC, and the FERC. We defer certain costs as assets pursuant to actions of rate regulators or because of expectations that we will be able to recover such costs in future rates charged to customers. We also defer certain amounts as liabilities pursuant to actions of rate regulators or based on the expectation that such amounts will be returned to customers in future rates. Regulatory assets and liabilities are amortized consistent with the period of expected regulatory treatment. Ameren Missouri and Ameren Illinois have various rate-adjustment mechanisms in place that provide for the recovery of purchased natural gas and electric fuel and purchased power costs without a traditional regulatory rate review.
In Ameren Missouri’s and Ameren Illinois’ natural gas businesses, changes in natural gas costs are reflected in billings to their respective customers through PGA clauses. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either billed or refunded to customers in a subsequent period.

Ameren Missouri has a FAC that allows an adjustment of electric rates three times per year, without a traditional rate proceeding, for a pass-through to customers of 95% of the variance in net energy costs from the amount set in base rates, subject to MoPSC prudence review. The difference between the actual amounts incurred for these items and the amounts recovered from Ameren Missouri customers’ base rates is deferred as a regulatory asset or liability. The deferred amounts are either billed or refunded to electric customers in a subsequent period.
In Ameren Illinois’ electric distribution business, changes in purchased power and transmission service costs are reflected in billings to its customers through pass-through rate-adjustment clauses. The difference between actual purchased power and transmission service costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either billed or refunded to customers in a subsequent period.
In addition to the cost recoveryrate-adjustment mechanisms discussed in the Purchased Gas, Power, and Fuel Rate-adjustment Mechanisms section below,above, Ameren Missouri and Ameren Illinois have approvals from rate regulators to use other cost recovery mechanisms. Ameren Missouri has a vegetation management and infrastructure inspection cost tracker, a pension and postretirement benefit cost tracker, an uncertain tax positions tracker, a renewable energy standards cost tracker, a solar rebate program tracker, a storm restoration cost tracker, and the MEEIA energy efficiencyenergy-efficiency rider. Ameren Illinois'Illinois’ and ATXI'sATXI’s electric transmission rates are subjectdetermined pursuant to formula ratemaking. Additionally, Ameren Illinois' electric distribution business


83


Illinois participates in the performance-based formula ratemaking processframeworks established pursuant to the IEIMA.IEIMA and the FEJA for its electric distribution business and its electric energy-efficiency investments. Ameren Illinois also has an environmental cost rider,riders, an asbestos-related litigation rider, an energy efficiencynatural gas energy-efficiency rider, a QIP rider, a VBA rider, and a bad debt rider. See Note 2 – Rate and Regulatory Matters for additional information on the regulatory assets and liabilities.liabilities recorded at December 31, 2017 and 2016.
The Ameren Illinois asbestos-related litigation rider includes a trust fund. At December 31, 2017 and 2016, the trust fund balance of $23 million and $22 million, respectively, was reflected in “Other assets” on Ameren’s and Ameren Illinois’ balance sheets. This balance is restricted only for the use of funding certain asbestos-related claims. The rider is subject to the following terms: 90% of the cash expenditures in excess of the amount included in base electric rates is to be recovered from the trust fund. If cash expenditures are less than the amount in base rates, Ameren Illinois will contribute 90% of the difference to the trust fund.
Cash and Cash Equivalents
Cash and cash equivalents include cash on hand and temporary investments purchased with an original maturity of three months or less.
Allowance for Doubtful Accounts Receivable
The allowance for doubtful accounts represents our estimate of existing accounts receivable that will ultimately be uncollectible. The allowance is calculated by applying estimated loss factors to various classes of outstanding receivables, including unbilled revenue. The loss factors used to estimate uncollectible accounts are based upon both historical collections experience and management’s estimate of future collections success given the existing and anticipated future collections environment. Ameren Illinois has a rate mechanismbad debt rider that adjusts rates for net write-offs of customer accounts receivable above or below those being collected in rates.

Materials and SuppliesInventories
Materials and suppliesInventories are recorded at the lower of weighted-average cost or market. Cost is determined by the average-cost method. Materials and suppliesnet realizable value. Inventories are capitalized as inventory when purchased and then expensed as consumed or capitalized as property, plant, assetsand equipment when installed, as appropriate. The following table presents a breakdown of materials and suppliesinventories for each of the Ameren Companies at December 31, 20142017 and 20132016:
  Ameren Missouri Ameren Illinois Ameren
2014      
Fuel(a)
 $134
 $
 $134
Gas stored underground 16
 111
 127
Other materials and supplies 197
 66
 263
  $347
 $177
 $524
2013      
Fuel(a)
 $144
 $
 $144
Gas stored underground 17
 110
 127
Other materials and supplies 191
 64
 255
  $352
 $174
 $526
  Ameren Missouri Ameren Illinois Ameren
2017      
Fuel(a)
 $154
 $
 $154
Natural gas stored underground 8
 74
 82
Materials, supplies, and other 226
 60
 286
Total inventories $388
 $134
 $522
2016      
Fuel(a)
 $172
 $
 $172
Natural gas stored underground 9
 73
 82
Materials, supplies, and other 211
 62
 273
Total inventories $392
 $135
 $527
(a)Consists of coal, oil, and propane.

Property, Plant, and Plant,Equipment, Net
We capitalize the cost of additions to, and betterments of, units of property, plant, and plant.equipment. The cost includes labor, material, applicable taxes, and overhead. An allowance for funds used during construction, as discussed below, is also capitalized as a cost of our rate-regulated assets. Maintenance expenditures, including nuclear refueling and maintenance outages, are expensed as incurred. When units of depreciable property are retired, the original costs, less salvage values, are charged to accumulated depreciation. If environmental expenditures are related to assets currently in use, as in the case of the installation of pollution control equipment, the cost is capitalized and depreciated over the expected life of the asset. See Asset Retirement Obligations section below and Note 3 – Property, Plant, and Plant,Equipment, Net for additional information.
Depreciation
Depreciation is provided over the estimated lives of the various classes of depreciable property by applying composite rates on a straight-line basis to the cost basis of such property. The provision for depreciation for the Ameren Companies in 2014, 2013,2017, 2016, and 20122015 ranged from 3% to 4% of the average depreciable cost.
Allowance for Funds Used During Construction
We capitalize allowance for funds used during construction, or the cost of borrowed funds and the cost of equity funds (preferred and common stockholders’shareholders’ equity) applicable to rate-regulated construction expenditures, in accordance with the utility industry'sindustry’s accounting practice. Allowance for funds used during construction does not represent a current source of cash funds. This accounting practice offsets the effect on earnings of the cost of financing during construction, and it treats such financing costs in the same manner as construction charges for labor and materials.
Under accepted ratemaking practice, cash recovery of allowance for funds used during construction and other construction costs occurs when completed projects are placed in service and reflected in customer rates. The following table presents the annual allowance for funds used during construction debt and equity blended rates that were used during 2014, 2013,applied to construction projects in 2017, 2016, and 2012:2015:
 2014 2013 2012
Ameren Missouri7% 8% 8%
Ameren Illinois2% 8% 9%
 2017 2016 2015
Ameren Missouri7% 7% 7%
Ameren Illinois4% 5% 6%


84


Goodwill
Goodwill represents the excess of the purchase price of an acquisition over the fair value of the net assets acquired. Ameren and Ameren Illinois had goodwill of $411 million at December 31, 2014,2017 and 2013.
All of Ameren's2016. Ameren has four reporting units: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois'Transmission. Ameren Illinois has three reporting units: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission had goodwill of $238 million, $80 million, and $93 million, respectively, at December 31, 20142017 and 2013, was assigned to2016. The Ameren Transmission reporting unit had the same $93 million of goodwill as the Ameren Illinois Transmission reporting unit which is also theat December 31, 2017 and 2016.
Ameren and Ameren Illinois reportable segment.
We evaluate goodwill for impairment in each of their reporting units as of October 31 of each year, or more frequently if events and circumstances indicatechange that would more likely than not reduce the asset might be impaired.fair value of their reporting units below their carrying amounts. To determine whether the fair value of a reporting unit is more likely than not greater than its carrying amount, Ameren and Ameren Illinois appliedelect to perform either a qualitative goodwill evaluation modelassessment or to bypass the qualitative assessment and perform a quantitative test, on an annual basis. On December 31, 2016, due to a change in reporting units, Ameren and Ameren Illinois performed a quantitative test and determined that the estimated fair value of each reporting unit significantly exceeded its respective carrying value as of that date. Based on these results, Ameren and Ameren Illinois elected to perform a qualitative assessment for their annual goodwill impairment test conducted as of October 31, 2014. Based on the2017.
The results of Ameren’s and Ameren Illinois’ qualitative assessment Ameren and Ameren Illinois believeindicated that it was more likely than not that the fair value of the Ameren Illinoiseach reporting unit significantly exceeded its carrying value as of October 31, 2014, indicating2017, resulting in no impairment of Ameren’s or Ameren Illinois’ goodwill. The following factors, among others, were considered by Ameren and Ameren Illinois when assessingthey assessed whether it was more likely than not that the fair value of the Ameren Illinoiseach of their reporting unitunits exceeded its carrying value for theas of October 31, 2014, test:2017:
macroeconomic conditions, including those conditions within Ameren Illinois’ service territory;
pending regulatory rate casereview outcomes and projections of future regulatory rate casereview outcomes;
changes in laws and potential law changes;
observable industry market multiples;
achievement of IEIMA and FEJA performance metrics and the yield of 30-year United States Treasury bonds;
a potential
an unexpected further reduction in the FERC-allowed return on equity relatedwith respect to transmission services; and
actual and forecasted financial performance.
The goodwill assigned to the Ameren Illinois reporting unit on the December 31, 2014 balance sheets of Ameren and Ameren Illinois had no accumulated goodwill impairment losses. Ameren and Ameren Illinois will continue to monitor the actual and forecastedprojected operating results and cash flows, market
capitalization, and observable industry market multiples of the Ameren Illinois reporting unit for signs of possible declines in estimated fair value and potential goodwill impairment.flows.
Impairment of Long-lived Assets
We evaluate long-lived assets classified as held and used for impairment when events or changes in circumstances indicate that the carrying value of such assets may not be recoverable. Whether an impairment has occurred is determined by comparing the estimated undiscounted cash flows attributable to the assets to the carrying value of the assets. If the carrying value exceeds the undiscounted cash flows, we recognize an impairment charge equal to the amount by which the carrying value exceeds the estimated fair value of the assets. In the period in which we determine an asset meets held for sale criteria, we record an impairment charge to the extent the book value exceeds its estimated fair value less cost to sell.
Investments
Ameren We did not identify any events or changes in circumstances that indicated that the carrying value of long-lived assets may not be recoverable in 2017 and Ameren Missouri record investments held in Ameren Missouri's nuclear decommissioning trust fund at fair value. Losses on assets in the trust fund could result in higher funding requirements for decommissioning costs, which Ameren Missouri believes would be recovered in electric rates paid by its customers. Accordingly, Ameren and Ameren Missouri recognize a regulatory asset on their balance sheets for losses on investments held in the nuclear decommissioning trust fund. In addition, Ameren and Ameren Missouri recognize a regulatory liability on their balance sheets for gains on investments held in the nuclear decommissioning trust fund. As of December 31, 2014, the nuclear decommissioning trust fund had cumulative gains. See Note 9 – Nuclear Decommissioning Trust Fund Investments for additional information.2016.
Environmental Costs
Liabilities for environmental costs are recorded on an undiscounted basis when it is probable that a liability has been incurred and the amount of the liability can be reasonably estimated. Costs are expensed or deferred as a regulatory asset when it is expected that the costs will be recovered from customers in future rates.

Asset Retirement Obligations
We are required to record the estimated fair value of legal obligations associated with the retirement of tangible long-lived assets in the period in which the liabilities are incurred and to capitalize a corresponding amount as part of the book value of the related long-lived asset. In subsequent periods, we are required to make adjustments toadjust AROs based on changes in the estimated fair values of the obligations. Corresponding increasesobligations with a corresponding increase or decrease in the asset book value. Asset book values, reflected within “Property, Plant, and Equipment, Net” on the balance sheet, are depreciated over the remaining useful life of the related asset. Due to regulatory recovery, that depreciation is deferred as a regulatory balance. The depreciation of the asset book values at Ameren Missouri was $26 million, $31 million, and $13 million for the years ended December 31, 2017, 2016, and 2015, respectively, which was deferred as a reduction to the net regulatory liability. The depreciation deferred to the regulatory asset at Ameren Illinois was immaterial in each respective period. Ameren and Ameren Missouri have a nuclear decommissioning trust fund for the decommissioning of the Callaway energy center. Net realized and unrealized gains and losses within the nuclear decommissioning trust fund are deferred as a regulatory liability. Uncertainties as to the probability, timing, or amount of cash expenditures associated with AROs affect our estimates of fair value. Ameren and Ameren Missouri have recorded AROs for retirement costs associated with Ameren Missouri’s Callaway energy center decommissioning, costs, asbestos removal, CCR facilities, and river structures. Also, Ameren, Ameren Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal. In addition, Ameren, Ameren Missouri,removal and Ameren Illinois have recorded AROs for the disposal of certain transformers. Ameren and Ameren Missouri are evaluating the potential effect of the EPA's new rule regarding the management and disposal of CCR on their AROs associated with ash ponds. See Note 15 Commitments and Contingencies.
Asset removal costs accrued by our rate-regulated operations that do not constitute legal obligations are classified as regulatory liabilities. See Note 2 – Rate and Regulatory Matters.

85


The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the years ended December 31, 20142017 and 2013:2016:
 
Ameren
Missouri
 
Ameren
Illinois
 Ameren 
Balance at December 31, 2012$346
 $3
 $349
 
Liabilities settled(1) (a)
 (1) 
Accretion in 2013(b)
19
 (a)
 19
 
Change in estimates(c)
2
 (a)
 2
 
Balance at December 31, 2013$366
 $3
(d) 
$369
 
Liabilities incurred2
 
 2
 
Liabilities settled(2) (a)
 (2) 
Accretion in 2014(b)
21
 (a)
 21
 
Change in estimates(c)(e)
2
 4
 6
 
Balance at December 31, 2014$389
 $7
(d) 
$396
 
 
Ameren
Missouri
 
Ameren
Illinois
 Ameren 
Balance at December 31, 2015$617
 $6
 $623
 
Liabilities incurred3
 
 3
 
Liabilities settled(2) (a)
 (2) 
Accretion in 2016(b)
25
 (a)
 25
 
Change in estimates1
 
 1
 
Balance at December 31, 2016$644
(c) 
$6
(d) 
$650
(c) 
Liabilities incurred
 
 
 
Liabilities settled(12) (1) (13) 
Accretion in 2017(b)
26
 (a)
 26
 
Change in estimates(e)
(18) (1) (19) 
Balance at December 31, 2017$640
(c) 
$4
(d) 
$644
(c) 
(a)Less than $1 million.
(b)AccretionAmeren Missouri’s accretion expense was recordeddeferred as an increasea decrease to regulatory assets at Ameren Missouri and Ameren Illinois.liabilities.
(c)Ameren Missouri changed its fair value estimates for asbestos removal
Balance included $6 million and $15 million in 2013“Other current liabilities” on the balance sheet as of December 31, 2017 and 2014 and for certain CCR facilities in 2013.2016, respectively.
(d)Included in “Other deferred credits and liabilities” on the balance sheet.
(e)Ameren IllinoisMissouri changed its fair value estimate for asbestos removalprimarily because of an extension of the remediation period of certain CCR storage facilities, an update to the decommissioning of the Callaway energy center to reflect the cost study and funding analysis filed with the MoPSC in 2014.2017, and an increase in the assumed discount rate.
Ameren and Ameren Missouri have nuclear decommissioning trust fund assets of $549 million and $494 million as of December 31, 2014 and 2013, respectively, which are for decommissioning of the Callaway energy center.
See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the AROs related to the abandoned Meredosia and Hutsonville energy centers, which are presented as discontinued operations and therefore not included in the table above.
Noncontrolling Interests
As of December 31, 20142017 and 2013,2016, Ameren’s noncontrolling interests included the preferred stock of Ameren Missouri and Ameren Illinois.
Operating Revenue
The Ameren Companies record operating revenue for electric or natural gas service when it is delivered to customers. We accrue an estimate of electric and natural gas revenues for service rendered but unbilled at the end of each accounting period.
Ameren Illinois participates in the performance-based formula ratemaking framework pursuant to the IEIMA.IEIMA and the FEJA. In addition, Ameren Illinois’ and ATXI’s electric transmission service operating revenues are regulated by the FERC. The provisions of the IEIMA providesand the FERC’s electric transmission formula rate framework provide for an annual reconciliation of Ameren Illinois' electric delivery service revenue requirement. As of each balance sheet date, Ameren Illinois records its estimatereconciliations of the electric deliverydistribution and electric transmission service revenue effect resulting from the reconciliation of the revenue requirementrequirements necessary to reflect the actual recoverable costs incurred for thatin a given year with the revenue requirement that was reflectedrequirements in customer rates for that year. Ifyear, including an allowed return on equity. In each of those electric jurisdictions, if the current year'syear’s revenue requirement varies from the amount collected from customers, an adjustment is greater than the revenue requirement reflected in that year's customer rates, an increasemade to electric operating revenues with an offset to a regulatory asset is recordedor liability to reflect the expected recovery of those additional coststhat year’s actual revenue requirement. The regulatory balance is then collected from, customers within the next two years. If the current year's revenue requirement is less than the revenue requirement reflected in that year's customer rates, a reduction to electric operating revenues with an offset to a regulatory liability is recorded to reflect the expected refundor refunded to, customers within the next two years. See Note 2 – Rate and Regulatory Matters for information regarding Ameren Illinois'Illinois’ revenue requirement
reconciliation pursuant to the IEIMA.
Similar to the IEIMA process described above, Ameren Illinois and ATXI record the impact of a revenue requirement reconciliation for each company's electric transmission jurisdiction, pursuant to FERC-approved rate treatment.
Accounting for MISO Transactions
MISO-related purchase and sale transactions are recorded by Ameren, Ameren Missouri, and Ameren Illinois using settlement information provided by MISO. Ameren Missouri records these purchase and sale transactions on a net hourly position. Ameren Missouri records net purchases in a single hour in “Operating Expenses – Purchased power” and net sales in a single hour in “Operating Revenues – Electric” in its statement of income. Ameren Illinois records net purchases in “Operating Expenses – Purchased power” in its statement of income to reflect all of its MISO transactions relating to the procurement of power for its customers. On occasion, Ameren Missouri'sMissouri’s and Ameren Illinois'Illinois’ prior-period transactions will be resettled outside the routine settlement process because of a change in MISO’s tariff or a material interpretation thereof. In these cases, Ameren Missouri and Ameren Illinois recognize expenses associated with resettlements once the resettlement is probable and the resettlement amount can be estimated and recognize revenuesestimated. Revenues are recognized once the resettlement amount is received. There were no material MISO resettlements in 2017, 2016, or 2015.
Nuclear Fuel
Ameren Missouri’s cost of nuclear fuel is capitalized and then amortized to fuel expense on a unit-of-production basis. The cost is charged to "Operating“Operating Expenses – Fuel"Fuel” in the statement of income.


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Purchased Gas, Power and Fuel Rate-adjustment Mechanisms
Ameren Missouri and Ameren Illinois have various rate-adjustment mechanisms in place that provide for the recovery of purchased natural gas and electric fuel and purchased power costs without a traditional rate case proceeding. See Note 2 – Rate and Regulatory Matters for the regulatory assets and liabilities recorded at December 31, 2014 and 2013, related to the rate-adjustment mechanisms discussed below.
In Ameren Missouri’s and Ameren Illinois’ natural gas utility jurisdictions, changes in natural gas costs are reflected in billings to their natural gas utility customers through PGA clauses. The difference between actual natural gas costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either billed or refunded to natural gas utility customers in a subsequent period.
In Ameren Illinois’ retail electric utility jurisdiction, changes in purchased power and transmission service costs are reflected in billings to its electric utility customers through pass-through rate-adjustment clauses. The difference between actual purchased power and transmission service costs and costs billed to customers in a given period is deferred as a regulatory asset or liability. The deferred amount is either billed or refunded to electric utility customers in a subsequent period.
Ameren Missouri has a FAC that allows an adjustment of electric rates three times per year for a pass-through to customers of 95% of changes in fuel and purchased power costs, including transportation charges and revenues, net of off-system sales, greater or less than the amount set in base rates, subject to MoPSC prudence review. The difference between the actual amounts incurred for these items and the amounts recovered from Ameren Missouri customers' base rates is deferred as a regulatory asset or liability. The deferred amounts are either billed or refunded to electric utility customers in a subsequent period.
Stock-based Compensation
Stock-based compensation cost is measured at the grant date based on the fair value of the award, net of an assumed forfeiture rate. Ameren recognizes as compensation expense the estimated fair value of stock-based compensation on a straight-line basis over the requisite servicevesting period. See Note 1211 – Stock-based Compensation for additional information.
Excise Taxes
Ameren Missouri and Ameren Illinois collect from their customers certain excise taxes from customers that are levied on the sale or distribution of natural gas and electricity. Excise taxes are levied on Ameren Missouri'sMissouri’s electric and natural gas businesses and on Ameren Illinois'Illinois’ natural gas business andbusiness. They are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – Gas,Natural gas,” and “Operating Expenses – Taxes other than income taxes” on the statement of income or the statement of income and comprehensive income. Excise taxes for electric service in Illinois
are levied on the customercustomers and are therefore not included in Ameren Illinois'Illinois’ revenues and expenses. They are instead included in “Taxes accrued” on the balance sheet. The following table presents the excise taxes recorded in “Operating Revenues – Electric,” “Operating Revenues – Gas,Natural gas,” and “Operating Expenses – Taxes other than income taxes” for the years ended December 31, 2014, 2013,2017, 2016, and 2012:2015:
2014 2013 20122017 2016 2015
Ameren Missouri$151
 $152
 $139
$153
 $151
 $156
Ameren Illinois64
 61
 54
57
 57
 57
Ameren$215
 $213
 $193
$210
 $208
 $213

Unamortized Debt Discounts, Premiums, and Issuance Costs
Long-term debt discounts, premiums, and issuance costs are amortized over the lives of the related issuances. Credit facilityagreement fees are amortized over the credit facility term.term of the agreement.
Income Taxes
Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes, in accordance with authoritative accounting guidance.taxes. Deferred tax assets and liabilities are recognized for transactions that are treated differently for financial reporting and income tax return purposes. These deferred tax assets and liabilities are based on statutory tax rates.
We recognizeexpect that regulators will probably reduce future revenues for deferred tax liabilities that were initially recorded at rates in excess of the current statutory rate. Therefore, reductions in certain deferred tax liabilities that were recorded because of decreases in the statutory rate have been credited to a regulatory liability. A regulatory asset has been established to recognize the probable recovery through future customer rates of tax benefits related to the equity component of allowance for funds used during construction, as well as the effects of tax rate changes.
Investmentincreases. To the extent deferred tax credits used on tax returns for prior years have beenbalances are included in rate base, the revaluation of deferred taxes is recorded as a non-current liability. The credits are being amortized over the useful lives of the related investment. Deferred income taxes were recordedregulatory asset or liability on the temporary difference represented bybalance sheet and will be collected from or refunded to customers. For deferred tax balances not included in rate base, the revaluation of deferred investmenttaxes is recorded as an adjustment to income tax credits and a corresponding regulatory liability. This recognizesexpense on the expected reduction in rates for future lower income taxes associated with the amortization of the investment tax credits.statement. See Note 1312 – Income Taxes.Taxes for further information regarding both the revaluation of deferred taxes related to the TCJA.
Ameren Missouri, Ameren Illinois, and all the other Ameren subsidiary companies are parties to a tax allocation agreement with Ameren (parent) that provides for the allocation of consolidated tax liabilities. The tax allocation agreement specifies that each party be allocated an amount of tax using a stand-alone calculation, which is similar to that which would be owed or refunded had the party been separately subject to tax.tax considering the impact of consolidation. Any net benefit attributable to the parentAmeren (parent) is reallocated to the other parties. This reallocation is treated as a capital contribution to the party receiving the benefit. See Note 13 – Related-party Transactions for information regarding capital contributions under the tax allocation agreement.


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Earnings per Share
Basic earnings per share is computed by dividing net income attributable“Net Income Attributable to Ameren Corporation common stockholdersCommon Shareholders” by the weighted-average number of common shares outstanding during the period. Diluted earningsEarnings per diluted share is computed by dividing net income attributable“Net Income Attributable to common stockholdersAmeren Common Shareholders” by the diluted weighted-average number of diluted common shares outstanding during the period. Diluted earningsEarnings per diluted share reflects the potential dilution that would occur if certain stock-based performance share units were settled.
The following table presents Ameren’s basic and diluted earnings per share calculations and reconciles the weighted-average number of common shares outstandingperformance share units assumed to the diluted weighted-average number of common shares outstandingbe settled was 1.6 million, 0.8 million, and 1.0 million for the years ended December 31, 2014, 2013,2017, 2016, and 2012:
 2014 2013 2012
Net income (loss) attributable to Ameren Corporation:     
Continuing operations$587
 $512
 $516
Discontinued operations(1) (223) (1,490)
Net income (loss) attributable to Ameren Corporation$586
 $289
 $(974)
      
Average common shares outstanding – basic242.6
 242.6
 242.6
Assumed settlement of performance share units1.8
 1.9
 0.4
Average common shares outstanding – diluted244.4
 244.5
 243.0
      
Earnings (loss) per common share – basic:     
Continuing operations$2.42
 $2.11
 $2.13
Discontinued operations
 (0.92) (6.14)
Earnings (loss) per common share – basic$2.42
 $1.19
 $(4.01)
      
Earnings (loss) per common share – diluted:     
Continuing operations$2.40
 $2.10
 $2.13
Discontinued operations
 (0.92) (6.14)
Earnings (loss) per common share – diluted$2.40
 $1.18
 $(4.01)
2015, respectively. There were no potentially dilutive securities excluded from the diluted earnings per share calculations for the years ended December 31, 2014, 2013,2017, 2016, and 2012.2015.
Capital ContributionsDivestiture Transactions and Return of CapitalDiscontinued Operations
In December 2013 and January 2014, Ameren Missouricompleted the divestiture of New AER and Ameren Illinois received cash capital contributions of $215 million and $15 million, respectively, from Ameren (parent) as a result of the tax allocation agreement. Additionally, as of December 31, 2014, Ameren Missouri accrued a $9 million capital contributioncertain other assets. All matters related to the same agreement. In 2014,final tax basis of New AER and the related tax benefit resulting from its divestiture were resolved with the completion of the IRS audit of 2013. During 2015, based on the completion of the IRS audit of 2013, Ameren Missouri returned capitalremoved a reserve for unrecognized tax benefits of $215$53 million torecorded in 2013 and recognized a tax benefit from discontinued operations. Ameren (parent).
Supplemental Cash Flow Information
The following table presents additional information regarding Ameren's consolidated statement of cash flows for the years ended December 31, 2014, 2013,also paid $25 million and 2012:concluded its obligations with New AER.
 2014 2013 2012
Cash paid (refunded) during the year:
Interest     
Continuing operations(a)
$333
 $362
 $384
Discontinued operations(b)

 31
 49
 $333
 $393
 $433
      
Income taxes, net     
Continuing Operations$(41) $116
 $10
Discontinued Operations14
 (108) (9)
 $(27) $8
 $1
(a)Net of $18 million, $20 million, and $17 million capitalized, respectively.
(b)Net of $- million, $17 million, and $13 million capitalized, respectively.
See Note 3 – Property and Plant, Net, for information on accrued capital expenditures.


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Accounting Changes and Other Matters
The following is a summary of recently adopted authoritative accounting guidance, as well as guidance issued but not yet adopted, that could affect the Ameren Companies.
Presentation of an Unrecognized Tax BenefitRevenue from Contracts with Customers
In 2013, FASB issued additional authoritative accounting guidance, which became effective inMay 2014, to provide clarity for the financial statement presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss, or a tax credit carryforward exists. The objective of this guidance is to eliminate diversity in practice related to the presentation of certain unrecognized tax benefits. It requires entities to present an unrecognized tax benefit as a reduction to a deferred tax asset for a net operating loss carryforward, a similar tax loss, or a tax credit carryforward. Previously, unrecognized tax benefits were recorded in “Other deferred credits and liabilities” on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets. Beginning in 2014, unrecognized tax benefits are recorded as a reduction to the deferred tax assets for net operating losses and tax credit carryforwards within "Accumulated deferred income taxes, net" on our balance sheets. Unrecognized tax benefits that exceed these carryforwards are recorded in “Other deferred credits and liabilities” on the respective balance sheets. At December 31, 2014, unrecognized tax benefits of $52 million, $- million, and $- million were recorded in "Accumulated deferred income taxes, net" on Ameren's, Ameren Missouri's, and Ameren Illinois' balance sheets, respectively. At December 31, 2013, unrecognized tax benefits of $84 million, $15 million, and $- million previously recorded in "Other deferred credits and liabilities" on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets were reclassified to "Accumulated deferred income taxes, net" for comparative purposes. The implementation of the additional authoritative accounting guidance did not affect the Ameren Companies' results of operations or liquidity, as this guidance is presentation-related only.
Reporting Discontinued Operations and Disclosures of Components of an Entity
In 2014, FASB issued authoritative accounting guidance that changes the criteria for reporting and qualifying for discontinued operations. Underrecognizing revenue from a contract with a customer. The underlying principle of the new guidance a component ofis that an entity or a group of components of an entity, that either meets the criteria to be classified as held for sale or is disposed of by sale or otherwise is required to be reported in discontinued operations if the disposal represents a strategic shift that had, or will have, a major effect on an entity's operations and financial results. The guidance includes expanded disclosure requirements for discontinued operations and additional disclosures about a disposal of an individually significant component of an entity that does not qualify for discontinued operations presentation. The guidance is effective for the Ameren Companies in the first quarter of 2015 for components that are classified as held for sale or disposed of on or after January 1, 2015. Early adoption is permitted, but only for disposals or
classifications as held for sale that have not been reported in financial statements previously issued. Therefore, Ameren's existing discontinued operations are not subject to the new disclosure requirements. The guidance will not affect the Ameren Companies' results of operations, financial position, or liquidity, as this guidance is presentation-related only.
Revenue from Contracts with Customers
In 2014, FASB issued authoritative accounting guidance to clarify the principles for recognizing revenue and to develop a common revenue standard for GAAP. The guidance requires an entity to recognize an amount of revenue for the transfer of promised goods or services to customers at an amount that reflects the consideration which the entity expects to be entitled to receive in exchange for those goods or services. The guidance also requires additional disclosures to enable users of financial statements to understand the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers.customers, as well as separate presentation of alternative revenue programs on the income statement. Entities can apply the guidance to each reporting period presented (the full retrospective method), or they can record a cumulative effect adjustment to retained earnings in the period of initial adoption (the modified retrospective method).

We have completed the evaluation of our contracts. Adoption of this guidance will not result in material changes to the amount or timing of revenue recognition. We will apply the guidance using the full retrospective method. We will include disaggregated revenue disclosures by segment and customer class in the combined notes to the financial statements. This guidance will be effective for the Ameren Companies for the first quarter of 2018.
Improving the Presentation of Net Periodic Pension Cost and Net Periodic Postretirement Benefit Cost
In March 2017, the FASB issued authoritative guidance that requires an entity to report, including on a retrospective basis, the non-service cost or income components of net benefit cost separately from the service cost component and outside of operating income. Our adoption of this guidance will result in the reclassification of 2017 net benefit income of $44 million, $22 million, and $10 million, currently presented as a reduction of "Other operations and maintenance expense," on Ameren's, Ameren Missouri's, and Ameren Illinois' respective statements of income. These amounts will be presented outside of operating income. Similarly, 2016 net benefit income of $55 million, $18 million, and $24 million, currently presented as a reduction of "Other operations and maintenance expense" on Ameren's, Ameren Missouri's, and Ameren Illinois' respective statements of income, will also be reclassified and presented outside of operating income.
The guidance also permits an entity to capitalize only the service cost component as part of an asset, such as inventory or property, plant, and equipment, on a prospective basis. Previously, all of the net benefit cost components were eligible for capitalization. This change in the capitalization of net benefit costs is not expected to affect our ability to recover total net benefit cost through customer rates. This guidance will be effective for the Ameren Companies in the first quarter of 2018. See Note 10 – Retirement Benefits for the components of net benefit cost.
Restricted Cash
In November 2016, the FASB issued authoritative guidance that requires restricted cash and restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period total amounts shown on the statement of cash flows. We are currently assessing the impacts of this guidance on our statements of cash flows and disclosures. The guidance will be effective for the Ameren Companies in the first quarter of 2017. The guidance allows entities2018, and requires changes to choose one of two transition methods, either by applying the guidancebe applied retrospectively to each reporting period presentedpresented.
Classification of Certain Cash Receipts and Cash Payments
In August 2016, the FASB issued authoritative guidance that specifies the classification and presentation of certain cash flow items to reduce diversity in practice. This guidance will be effective for the Ameren Companies in the first quarter of 2018, and requires changes to be applied retrospectively. For Ameren and Ameren Illinois, the adoption of this guidance will result in the retrospective reclassification from operating activities to financing activities of $7 million of bond premiums received in 2016.
Financial Instruments – Recognition and Measurement, and Credit Losses
In January 2016, the FASB issued authoritative guidance that addressed certain aspects of recognition, measurement, presentation and disclosure of financial instruments. This guidance requires an entity to measure equity investments, other than those accounted for under the equity method of accounting, at fair value and to recognize changes in fair value in net income. The adoption of this guidance will not have a material impact on our results of operations or by recordingfinancial position. The recognition, measurement, and disclosure guidance will be effective for the Ameren Companies in the first quarter of 2018. The guidance requires changes to be applied retrospectively with a cumulative effect adjustment to retained earnings inas of the periodadoption date.
In June 2016, the FASB issued authoritative guidance that requires an entity to recognize an allowance for financial instruments that reflects its current estimate of initial adoption.credit losses expected to be incurred over the life of the financial instruments. The Ameren Companiesguidance requires an entity to measure expected credit losses using relevant information about past events, current conditions, and reasonable and supportable forecasts that affect the collectibility of the reported amount. We are currently assessing the impacts of this guidance on theirour results of operations, financial position, and liquidity,disclosures. The credit loss guidance will be effective for the Ameren Companies in the first quarter of 2020. It requires changes to be applied retrospectively with a cumulative effect adjustment to retained earnings as wellof the adoption date.
Leases
In February 2016, the FASB issued authoritative guidance that requires an entity to recognize assets and liabilities arising from all leases with a term greater than one year. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease will depend on its classification as a finance lease or operating lease. The guidance also requires additional disclosures to enable users of financial statements to understand the transition methodamount, timing, and uncertainty of cash flows arising from leases. This guidance will affect the Ameren Companies’ financial position by increasing the assets and liabilities recorded relating to their operating leases, which will be recognized and measured at the beginning of the earliest period presented. Other arrangements not previously accounted for as leases may be required to be accounted for as leases; these arrangements would similarly result in increases to assets and liabilities recorded. We are currently assessing our arrangements to determine those that theyare within the scope of this guidance. We are also

assessing the impacts of this guidance for effects on our results of operations, cash flows, and disclosures. This guidance will usebe effective for the Ameren Companies in the first quarter of 2019. See Note 14 – Commitments and Contingencies for additional information on our leases.
Reclassification of Certain Tax Effects from Accumulated OCI
In February 2018, the FASB issued authoritative guidance allowing a reclassification from accumulated OCI to adoptretained earnings for stranded tax effects resulting from the guidance.TCJA. This optional reclassification can be applied retrospectively to December 31, 2017, or in the period of adoption. We are currently assessing whether we will elect to perform such a reclassification and the potential impact.
NOTE 2 RATE AND REGULATORY MATTERS
Below is a summary of significant regulatory proceedings and related lawsuits. 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 effect on our results of operations, financial position, or liquidity.
Missouri
2014March 2017 Electric Rate CaseOrder
In March 2017, the MoPSC issued an order approving a unanimous stipulation and agreement in Ameren Missouri’s July 2014,2016 regulatory rate review. The order resulted in a $3.4 billion revenue requirement, which was a $92 million increase in Ameren Missouri filed a requestMissouri’s annual revenue requirement for electric service, compared with the MoPSC seeking approval to increase its annual revenues for electric service. The request, as amendedprior revenue requirement established in Februarythe MoPSC’s April 2015 seeks an annual revenue increase of approximately $190 million. The amended 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, electric infrastructure investments. Approximately $100 million of the amended request relates to an increase in net energy costs above the levels included in base rates authorized by the MoPSC in its December 2012 electric rate order. Absent initiationThe new rates, base level of this general rate proceeding, 95% of those costs would have been reflected in rate adjustments implemented under Ameren Missouri’s existing FAC. expenses, and amortizations became effective on April 1, 2017.
The amended electric rate increase request is based on a 10.4% return on common equity, a capital structure composed of 51.8% common equity, an electric rate base of $7 billion, and a test year ended March 31, 2014, with certain pro forma adjustments through true-up dates of


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December 31, 2014 and January 1, 2015.
Ameren Missouri's rate request also seeksorder authorized the continued use of the FAC and the regulatory tracking mechanisms for storm costs, vegetation management and infrastructure inspection costs, pension and postretirement benefits, and uncertain income tax positions, and renewable energy standards that the MoPSC authorized in earlier electric rate orders.
In October 2014, as part These regulatory tracking mechanisms provide for a base level of this rate case proceeding, the MoOPC, the MIEC, and other parties filed a rate shift request that seeksexpense to reduce Noranda’sbe reflected in Ameren Missouri’s base electric rates with an offsetting increasedifferences between the base amount and the actual expenses incurred deferred as a regulatory asset or liability. Excluding cost reductions associated with reduced sales volumes, the base level of net energy costs decreased by $54 million from the base level established in the MoPSC’s April 2015 electric ratesrate order. Changes in amortizations and the base level of expenses for Ameren Missouri’sthe other customers. Ameren Missouri supplies electricity to Noranda’s aluminum smelterregulatory tracking mechanisms, including extending the amortization period of certain regulatory assets, reduced expenses by $26 million from the base levels established in southeast Missouri under a 15-year agreement, that is subject to termination as early as 2020 upon at least five years notice by either party. Termination of the agreement by Ameren Missouri would require MoPSC approval.MoPSC’s April 2015 electric rate order.
MEEIA
In February 2015,November 2016, the MoPSC approved a $28 million MEEIA 2013 performance incentive based on a stipulation and agreement among Ameren Missouri, the MoPSC staff, recommended an increase to Ameren Missouri's annual revenues of $89 million based on a return on equity of 9.25%. In addition,and the MoPSC staff opposed the continued use of the regulatory tracking mechanisms for storm costs and vegetation management and infrastructure inspection costs. The MoPSC staff also opposed the recovery of $36 million in fixed costs not previously recovered associated with the accounting authority order discussed below.
The MoPSC proceedings relating to the proposed electric service rate increase are ongoing and a decision by the MoPSC is expected by May 2015, with new rates effective by June 2015.MoOPC. Ameren Missouri cannot predictwill collect the level of any electric service rate change the MoPSC may approve or whether any rate increaseperformance incentive over a two-year period that may eventually be approved will be sufficient for Ameren Missouri to recover its costs and to earn a reasonable return on its investments when the rate changes go into effect.
FAC Prudence Review and Accounting Authority Orderbegan in February 2017.
In July 2013,November 2015, the MoPSC issued an order with respectregarding the determination of a certain input used to its review of Ameren Missouri’s FAC calculation forcalculate the period from October 1, 2009, to May 31, 2011. In this order, the MoPSC ruled that Ameren Missouri should have included in the FAC calculation all revenues and costs associated with certain long-term partial requirements sales that were made by Ameren Missouri because of the loss of Noranda's load caused by a severe ice storm in 2009. As a result of the order, in 2013 Ameren Missouri recorded a pretax charge to earnings of $26 million, including $1 million for interest, for its estimated obligation to refund to its electric customers the earnings associated with these sales previously recognized for the period from October 1, 2009, to May 31, 2011. Ameren Missouri recorded the charge to “Operating Revenues – Electric” and the related interest to “Interest Charges” with a corresponding offset to “Current regulatory liabilities.” No similar revenues were excluded from FAC calculations after May 2011.
Separately, in July 2011,performance incentive. 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
during the time period of March 1, 2009, to May 31, 2011, not previously recovered from Noranda as a resultappeal 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. The MIEC and the MoOPC filed appeals of the MoPSC’s November 2013 accounting authority order with the Missouri Court of Appeals, Western District. In January 2015,December 2016, the Missouri Court of Appeals, Western District, upheld the MoPSC'sNovember 2015 MoPSC order. Ameren Missouri has not recorded any potential revenue associated with this accounting authority order.
MEEIA Filing
In December 2014,then appealed that decision to the Missouri Supreme Court. If the decision is overturned, Ameren Missouri filedwould recognize an energy efficiency plan with the MoPSC under the MEEIA. This filing proposed a three-year plan that includes a portfolio of customer energy efficiency programs alongadditional $9 million MEEIA 2013 performance incentive.
The MEEIA 2016 program provided Ameren Missouri with a cost recovery mechanism. If the plan is approved, beginning in January 2016, Ameren Missouri intends to invest $135 million over three years in the proposed customer energy efficiency programs. Ameren Missouri requested continued use of a MEEIA rider that allows it to collect from or refund to customers any difference in the actual amounts incurred and the amounts collected from customers for the MEEIA program costs and its lost revenues. In addition, Ameren Missouri requested incentivesperformance incentive to earn additional revenues by achieving certain energy efficiencycustomer energy-efficiency goals, including $25$27 million if 100% of its energy efficiencythe goals arewere achieved during the three-year period.period, with the potential to earn more if Ameren Missouri’s energy savings exceeded those goals. In September 2017, Ameren Missouri must achieve at least 70%received an order from the MoPSC approving Ameren Missouri’s energy savings results for the first year of the MEEIA 2016 programs. As a result of this order and in accordance with revenue recognition guidance, Ameren Missouri will recognize $5 million of additional revenues in the first quarter of 2018 relating to the MEEIA 2016 performance incentive.
MoPSC Federal Income Tax Proceeding
In February 2018, the MoPSC initiated proceedings to investigate how the effect of the reduction in the federal statutory corporate income tax rate enacted under the TCJA should be reflected in rates paid by customers of Missouri’s regulated utilities, including rates paid by electric and natural gas customers of Ameren Missouri. At this time, Ameren Missouri is unable to predict the timing or the magnitude of any impact on its energy efficiency goals before it earns any incentive award.electric and natural gas rates that may result from the ultimate resolution of this matter.

ATXI’s Mark Twain Project
The Mark Twain project is a MISO-approved transmission line to be located in northeast Missouri with an expected investment of $250 million. In the third quarter of 2017, ATXI finalized an alternative project route and reached agreements with Ameren Missouri and an electric cooperative in northeast Missouri to locate almost all of the Mark Twain project on existing line corridors. It also received assents for road crossings from the five affected counties in northeast Missouri. In January 2018, the MoPSC granted ATXI a certificate of convenience and necessity for the Mark Twain project. ATXI plans to begin construction in the second quarter of 2018 and to complete the project by the end of 2019.
Illinois
IEIMA & FEJA
Under the provisions of the IEIMA,a formula ratemaking framework effective through 2022, Ameren Illinois’ electric deliverydistribution service rates are subject to an annual revenue requirement reconciliation to its actual costs. Throughout eachrecoverable costs and allowed return on equity. The formula ratemaking framework qualifies as an alternative revenue program under GAAP. 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 reflected in customer rates 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.ICC. As of December 31, 2014,2017, Ameren Illinois had recorded regulatory assets of $101$54 million and $65$24 million, including interest, to reflect its expected 20142017 and 2013its approved 2016 revenue requirement reconciliation adjustments, respectively, with interest.respectively. As of December 31, 2013,2016, Ameren Illinois had recorded a $65$68 million regulatory liabilityasset to reflect its 2012approved 2015 revenue requirement reconciliation adjustment, which was refunded,collected, with interest, tofrom customers during 2014.2017.
In December 2014,2017, the ICC issued an order in Ameren Illinois’ annual update filing approvingthat approved a $204$17 million increasedecrease in Ameren


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Illinois’ electric delivery service revenue requirement beginning in January 2015.2018. This update reflectsreflected an increase to the annual formula rate based on 20132016 actual costs and expected net plant additions for 2014,2017, as well as an increase to include the 20132016 revenue requirement reconciliation adjustment. The increases in the update filing were more than offset by a decrease for the conclusion of the 2015 revenue requirement reconciliation adjustment, which was recordedfully collected from customers in 2017, consistent with the ICC’s December 2016 annual update filing order.
The FEJA revised certain portions of the IEIMA, including extending the IEIMA formula ratemaking framework through 2022, and clarifying that a common equity ratio up to and including 50% is prudent. Beginning in 2017, the FEJA permitted Ameren Illinois to recover, within the following two years, its electric distribution revenue requirement for a given year, independent of actual sales volumes. Prior to the FEJA, Ameren Illinois’ interim period revenue recognition was volume-based, as revenues were affected by the timing of sales volumes due to seasonal rates and changes in volumes resulting from, among other things, weather and energy efficiency. This previous revenue recognition method resulted in more revenue during the third quarter and less revenue during the other quarters of each year. Beginning in 2017, in connection with the decoupling provisions of the FEJA, Ameren Illinois changed the method it uses to recognize interim-period revenue. Ameren Illinois now recognizes revenue consistent with the timing of actual incurred electric distribution recoverable costs, and it recognizes revenue associated with the expected return on its rate base ratably over the year. The decoupling provisions of the FEJA do not expire at the end of 2022.
The FEJA allows Ameren Illinois to earn a return on its electric energy-efficiency program investments. Ameren Illinois’ electric energy-efficiency investments are deferred as a regulatory asset and earn a return at December 31, 2014, and an increase resulting from the conclusioncompany’s weighted-average cost of capital, with the equity return based on the monthly average yield of the 2014 refund30-year United States Treasury bonds plus 580 basis points. The equity portion of Ameren Illinois’ return on electric energy-efficiency investments can be increased or decreased by up to 200 basis points, depending on the achievement of annual energy savings goals. The FEJA increased the level of electric energy-efficiency saving targets through 2030. In June 2017, pursuant to the FEJA, Ameren Illinois filed with the ICC an energy-efficiency plan for 2018 through 2021. In September 2017, the ICC issued an order approving Ameren Illinois’ implementation of the FEJA electric energy-efficiency savings targets and investments. Ameren Illinois plans to invest up to $99 million per year in electric energy-efficiency programs from 2018 through 2021. Ameren Illinois plans to make similar yearly investments in electric energy-efficiency programs from 2022 through 2030. The ICC has the ability to reduce electric energy-efficiency savings goals if there are insufficient cost-effective programs available or if the savings goals would require investment levels that exceed amounts allowed by legislation. The electric energy-efficiency program investments and the return on those investments will be collected from customers forthrough a rider; they will not be included in the 2012 revenue requirement reconciliation adjustment.IEIMA formula ratemaking framework.
Income Tax Regulatory Mechanisms
In February 2014,2018, the ICC granted Ameren Illinois’ request, filed in January 2018, to establish a rider to pass through to Ameren Illinois’ electric distribution customers the reduction in the federal statutory corporate income tax rate enacted under the TCJA and the return of excess deferred taxes, net of the increase in state income taxes enacted in July 2017. Ameren Illinois' electric distribution customers will receive up to an estimated $50 million per year through the rider beginning in the first quarter of 2018 and continuing through 2019. Absent

this rider, Ameren Illinois' electric distribution customers would not benefit from Ameren Illinois' reduced income tax liability until 2020, at which time the net reduction in income taxes would have been reflected in customer rates through the revenue reconciliation process.
In January 2018, the ICC initiated a proceeding to require that Ameren Illinois record a regulatory liability, beginning January 25, 2018, for the net amount of the difference between revenues billed under natural gas rates in effect, pursuant to Ameren Illinois’ most recent natural gas rate order, and the revenues that would have been billed had the state and federal tax rate changes been in effect. In February 2018, Ameren Illinois filed an appeal of the ICC's December 2013 annual formula rate ordera response to the Appellate CourtICC seeking approval of a rider that calculates such differences, specifically by evaluating the Fourth Districtreturn of Illinois regarding the rate treatment of accumulatedexcess deferred taxes and income taxes relatedincluded in the revenue requirement prior to the transfer of formerreduction in the federal statutory corporate income tax rate enacted under the TCJA and the increase in state income taxes enacted in July 2017. Ameren Missouri electric assets located in IllinoisIllinois’ natural gas customers may receive up to Ameren Illinois. Ameren Illinois withdrew this appeal in February 2015.
Inan estimated $16 million through the December 2013 order,proposed rider, or through some other tariff approved by the ICC, disallowed,over a one-year period beginning in part, the recovery from customers of the debt premium costs paid by Ameren Illinois for a tender offer in August 2012 to repurchase outstanding senior secured notes. As a result of the ICC order, in 2013, Ameren and Ameren Illinois each recorded a pretax charge to earnings of $15 million relating to the partial disallowance of the debt premium costs. In the December 2014 order discussed above, the ICC allowed partial recovery from customers of certain previously disallowed debt premium costs. Accordingly, in 2014, Ameren and Ameren Illinois each recorded a pretax increase to earnings of $11 million to reflect the partial recovery of the debt premium costs. Ameren and Ameren Illinois recorded the effects of both orders to “Interest charges” with a corresponding offset to “Regulatory assets.”May 2018.
20152018 Natural Gas Delivery Service Regulatory Rate CaseReview
In January 2015,2018, Ameren Illinois filed a request with the ICC seeking approval to increase its annual revenues for natural gas delivery service by $53 million. $49 million, which included an estimated $42 million of annual revenues that would otherwise be recovered under a QIP rider. The request was based on a 10.25%10.3% return on common equity, a capital structure composed of 50% common equity, and a rate base of $1.2$1.6 billion. The request reflects the reduction in the federal corporate income tax rate as a result of the TCJA, as well as the increase in the Illinois corporate income tax rate that became effective in July 2017. In an attempt to reduce regulatory lag, Ameren Illinois used a 20162019 future test year in this proceeding. Included in the request was a proposal to implement a decoupling rider mechanism for residential and small nonresidential customers. The decoupling rider would ensure that changes in natural gas sales volumes do not affect Ameren Illinois' annual natural gas revenues for these rate classes.
A decision by the ICC in this proceeding is required by December 2015,2018, with new rates expected to be effective in January 2016.2019. Ameren Illinois cannot predict the level of any delivery service rate changes the ICC may approve, or whether the ICC will approve the decoupling rider, ornor whether any rate changes that may eventually be approved will be sufficient to enable Ameren Illinois to recover its costs and to earn a reasonable return on investments when the rate changes go into effect.
2013 Natural Gas Delivery Service Rate OrderATXI’s Illinois Rivers Project
In August 2017, the Illinois Circuit Court for Edgar County dismissed several of ATXI’s condemnation cases related to one line segment in the Illinois Rivers project. The estimated line segment capital expenditure investment is approximately $85 million, of which $36 million was invested as of December 2013,31, 2017. These cases had been filed to obtain easements and rights of way necessary to complete the line segment. The court found that required notice was not given to the relevant landowners during the underlying ICC issued a rate order that approved an increase in revenues for Ameren Illinois' natural gas delivery serviceproceeding. In November 2017, ATXI appealed this decision to the Illinois Supreme Court. ATXI plans to complete the project by the end 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 filed2019; however, delays associated with the Appellate Courtcondemnation proceedings or an appeal arising from the order dismissing the Edgar County cases could delay the completion date. The other eight line segments of the Fourth District of Illinois 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. Ameren Illinois sought a 10.4% return on common equity in this rate case. In February 2015, Ameren Illinois withdrew its appeal solely as it related to the rate treatment of the accumulated deferred income taxes.
ATXI Transmission Project
ATXI's Spoon RiverRivers project in northwest Illinois is a MISO-approved transmission line project with an expected cost of $150 million. 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 acquisitions.are not affected by these proceedings.
Federal
2011 Wholesale Distribution Rate Case
In January 2011, Ameren Illinois filed a request with the FERC to increase its annual revenues for electric delivery service to 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 effect on net income. In March 2011, the FERC issued an order authorizing the proposed rates to take effect, subject to refund when the final rates are determined. In September 2014, the FERC issued an order that finalized rates and resulted in refunds due to the wholesale customers. 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, the 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


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and concluded that no refund was warranted. Several wholesale customers filed a protest with the FERC regarding that conclusion. In June 2013, the 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, the FERC issued an order that denied Ameren Illinois’ rehearing requests of the July 2012 order and the June 2013 order. Separately, in June 2014, the FERC issued an order establishing settlement procedures and, if necessary, hearing procedures regarding Ameren Illinois’ July 2013 refund report. In July 2014, Ameren Illinois filed an appeal of the FERC order 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 filed a request for rehearing with the FERC of its June 2014 order regarding the July 2013 refund report. In November 2014, the United States Court of Appeals for the District of Columbia issued an order suspending the appeal until the related FERC proceedings have been completed.
Ameren Illinois estimates the maximum pretax charge to earnings for this possible refund obligation through December 31, 2014, is $22 million. Ameren and Ameren Illinois recorded a current liability representing their estimate of the probable refund due to electric transmission customers based on the June 2014 order. If Ameren Illinois was 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 was made.
FERC Complaint Cases
In November 2013, a customer group filed a complaint case with the FERC seeking a reduction in the allowed base return on common equity for the FERC-regulated MISO transmission rate base under the MISO tariff from 12.38% to 9.15%. Currently,In September 2016, the FERC-allowedFERC issued a final order in the November 2013 complaint case, which lowered the allowed base return on common equity for MISO transmission owners is 12.38%. In October 2014, the FERC issued an order establishing settlement procedures and, if necessary, hearing procedures regarding the15-month period of November 2013 to February 2015 to 10.32%, or a 10.82% total allowed base return on common equity. In January 2015,equity with the settlement judge terminated settlement proceedings and the FERC scheduled the caseinclusion of a 50 basis point incentive adder for hearing proceedings, requiringparticipation in an initial decisionRTO. The order required customer refunds, with interest, to be issued no later thanfor that 15-month period. In 2017, Ameren and Ameren Illinois refunded $21 million and $17 million, respectively, related to the November 30, 2015. As2013 complaint case. The 10.82% total allowed return on common equity has been reflected in rates since September 2016. The 10.82% allowed return on common equity may be replaced prospectively after the original 15-monthFERC issues a final order in the February 2015 complaint case, discussed below.
Since the maximum FERC-allowed refund period for the November 2013 complaint case ended in February 2015, another customer complaint case was filed in February 2015. MISO transmission owners subsequently filed a motion to dismiss the February 2015 complaint, as discussed below. The February 2015 complaint case seeks a further reduction in the allowed base return on common equity for the FERC-regulated MISO transmission rate base under the MISO tariff to 8.67%.
tariff. In October 2014,June 2016, an administrative law judge issued an initial decision in the February 2015 complaint case. If approved by the FERC, issued an order in a proceeding, in which the Ameren Companies were not involved, reducingit would lower the allowed base return on common equity for New England transmission ownersthe 15-month period of February 2015 to May 2016 to 9.70%, or a 10.20% total allowed return on equity with the inclusion of a 50 basis point incentive adder for participation in an RTO. It would also require customer refunds, with interest, for that 15-month period. A final FERC order would also establish the allowed return on common equity that will apply prospectively from 11.14% to 10.57%, with rate incentives
the effective date of such order, replacing the current 10.82% total return on common equity.allowed up to 11.74%. The FERCtiming of the issuance of the final order in the New EnglandFebruary 2015 complaint case is uncertain for two reasons. First, while the FERC reestablished a quorum of commissioners in August 2017 after six months without a quorum, the FERC is under no deadline to issue a final order. Second, in the second quarter of 2017, the United States Court of Appeals for the District of

Columbia Circuit vacated and remanded to the FERC an order in a separate case in which the FERC established the allowed base return on common equity methodology used in the two MISO complaint cases described above. Ameren is unable to predict the impact of the outcome of the United States Court of Appeals for the District of Columbia Circuit’s remand on the MISO FERC complaint cases at this time.
In September 2017, MISO transmission owners’owners, including Ameren Missouri, Ameren Illinois, and ATXI, filed a motion to dismiss the February 2015 complaint case applied observable market data from October 2012 to March 2013 to determinewith the FERC. The MISO transmission owners maintain that the February 2015 complaint was predicated on the premise that the now superseded 12.38% allowed base return on common equity was an unjust and unreasonable return and is therefore inapplicable given the current 10.32% allowed base return on common equity. The FERC expectsMISO transmission owners further maintain that the evidence and the calculation used in the New England transmission owners’ case to guide its decision in the MISO complaint case discussed above. The FERC calculation will establish thecurrent 10.32% allowed base return on common equity which specifies a unique time period for each complaint case,has not been proven to be unjust and will require multiple inputsunreasonable based on observable market data specific toinformation provided, including the utility industry and broader macroeconomic data. In January 2015, the settlement judge for the MISO complaint case ordered that July 13, 2015, should be the cut-off date for the observable market data to be used in the calculation of the allowed base return on common equity.Basedequity methodology ranges set forth in the February 2015 complaint case and in the initial decision issued by an administrative law judge in June 2016. Additionally, the MISO transmission owners maintain that the February 2015 complaint should be dismissed because the approach utilized in the case to assert that a return on common equity was unjust and unreasonable was insufficient. That same approach was rejected by the information in these orders,United States Court of Appeals for the District of Columbia Circuit, as discussed above. FERC is under no deadline to issue an order on this motion.
As of December 31, 2017, Ameren and Ameren Illinois recorded current regulatory liabilities representing their estimate of $42 million and $25 million, respectively, to reflect the requiredexpected refunds, fromincluding interest, associated with the refund effective date of November 12, 2013, through December 31, 2014.reduced allowed returns on common equity in the initial decision in the February 2015 complaint case. Ameren Missouri did not record a liability as of December 31, 2014, and does 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.
MISO Federal Income Tax Proceeding
In November 2014, weFebruary 2018, MISO transmission owners with forward-looking rate formulas, including Ameren Illinois and ATXI, filed a request with the FERC to include an incentive adder of upallow revisions to 50 basis points ontheir 2018 electric transmission rates to reflect the allowed base return on common equity for participation in an RTO, and we sought authorization to defer collection of it until after the issuanceimpact of the final order addressing the initial MISO complaint case discussed above. FERC approved the request to implement the incentive adder prospectively from January 6, 2015, and to defer collection of it until the issuance of the final order addressing the initial MISO complaint case.
Ameren Missouri Power Purchase Agreement with Entergy
Beginningreduction in 2005, the 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 that expired August 31, 2009. In May 2012, the FERC issued an order stating that Entergy should not have included additional charges to Ameren Missourifederal income taxes enacted under the power purchase agreement. Pursuant toTCJA. If approved, Ameren Illinois and ATXI’s 2018 electric transmission rates would be reduced by $27 million and $23 million, respectively. Absent this revision, the order,reduction in June 2012, Entergy paidfederal income taxes enacted under the TCJA would not be reflected in Ameren Missouri $31 million, with $24 million recorded as a reduction to “Operating Expenses – Purchased power” expenseIllinois' and $5 million for interest recorded as “Miscellaneous income” inATXI's electric transmission rates until 2020 through the statement of income. The remaining $2 million was recorded as an offset to the FAC under-recovered regulatory asset for the amount refundable to customers. The amount of the Entergy refund recorded to the FAC regulatory asset related to the period when the FAC was effective; therefore, such costs were previously included in customer rates. In November 2013, Entergy filed an appeal of the 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.


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The Louisiana Public Service Commission appealed the 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. That court ordered further FERC proceedings regarding Louisiana Public Service Commission’s complaint. Ameren Missouri estimates that it could incur an additional expense of up to $8 million if the FERC's May 2012 order is overturned on appeal. Ameren Missouri believes that the likelihood of incurring any expense is not probable, and therefore no liability has been recorded as of December 31, 2014.revenue reconciliation process.
Combined Construction and Operating License
In 2008, Ameren Missouri filed an application with the NRC for a COL for a newsecond nuclear unit at Ameren Missouri'sMissouri’s existing Callaway County, Missouri, energy center site. In 2009, Ameren Missouri suspended its efforts to build a newsecond nuclear unit at theits existing Callaway site, and the NRC suspended review of the COL application. The suspended status of the COL application currently extends through the end of 2015.
Ameren Missouri estimates the total costPrior to obtain a COL
for the Callaway site to be approximately $100 million. As of December 31, 2014,suspending its efforts, Ameren Missouri had capitalized investments of $69 million related to the project. Primarily because of changes in vendor support for licensing efforts at the developmentNRC, Ameren Missouri’s assessment of a new nuclear energy center.long-term capacity needs, declining costs of alternative generation technologies, and the regulatory framework in Missouri, Ameren 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 ofMissouri discontinued its investment. If efforts to license additionaland build a second nuclear generation are abandoned,unit at its existing Callaway site. As a result of this decision, in 2015, Ameren and Ameren Missouri recognized a $69 million noncash pretax provision for all of the NRC does not extend thepreviously capitalized COL costs. Ameren Missouri has withdrawn its COL application suspended status, or if management concludes it is probable thatwith the costs incurred will be disallowed in rates, a charge to earnings would be recognized in the period in which that determination is made.NRC.

Regulatory Assets and Liabilities
In accordance with authoritative accounting guidance regarding accounting for the effects of certain types of regulation, we defer certain costs as regulatory assets pursuant to actions of regulators or based on the expected abilitybecause we expect to recover such costs in rates charged to customers. We may also defer certain amounts as regulatory liabilities because of actions of regulators or because of the expectationwe expect that such amounts will be returned to customers in future rates. The following table presents our regulatory assets and regulatory liabilities at December 31, 20142017 and 2013:

2016:
93

  2017 2016
  
Ameren
Missouri
 
Ameren
Illinois
 Ameren  
Ameren
Missouri
 
Ameren
Illinois
 Ameren
Current regulatory assets:             
Under-recovered FAC(a)(b)
 $47
 $
 $47
  $21
 $
 $21
Under-recovered Illinois electric power costs(c)
 
 
 
  
 3
 3
Under-recovered PGA(c)
 1
 13
 14
  
 4
 4
MTM derivative losses(d)
 8

25
 33
  9
 15
 24
Energy-efficiency riders(e)
 
 
 
  5
 
 5
IEIMA revenue requirement reconciliation adjustment(a)(f)
 
 24
 24
  
 68
 68
FERC revenue requirement reconciliation adjustment(a)(g)
 
 9
 10
  
 7
 13
VBA rider(a)(h)
 
 15
 15
  
 11
 11
Table of Contents

  2014 2013
  
Ameren
Missouri
 
Ameren
Illinois
 Ameren  
Ameren
Missouri
 
Ameren
Illinois
 Ameren
Current regulatory assets:             
Under-recovered FAC(a)(b)
 $128
 $
 $128
  $104
 $
 $104
Under-recovered Illinois electric power costs(c)
 
 2
 2
  
 1
 1
Under-recovered PGA(c)
 
 20
 20
  
 1
 1
MTM derivative losses(d)
 32

42
 74
  14
 36
 50
Energy efficiency riders(e)

 3
 
 3
  
 
 
IEIMA revenue requirement reconciliation(a)(f)
 
 65
 65
  
 
 
FERC revenue requirement reconciliation(a)(g)

 
 
 3
  
 
 
Total current regulatory assets $163
 $129
 $295
  $118
 $38
 $156
Noncurrent regulatory assets:             
Pension and postretirement benefit costs(h)
 $148
 $275
 $423
  $44
 $140
 $184
Income taxes(i)
 253
 3
 256
  230
 7
 237
Asset retirement obligations(j)
 
 5
 5
  
 5
 5
Callaway costs(a)(k)
 36
 
 36
  40
 
 40
Unamortized loss on reacquired debt(a)(l)
 72
 80
 152
  77
 74
 151
Contaminated facilities costs(m)
 
 251
 251
  
 271
 271
MTM derivative losses(d)
 14

144
 158


8
 118
 126
Storm costs(n)
 
 3
 3
  5
 3
 8
Demand-side costs before the MEEIA implementation(a)(o)
 44
 
 44
  58
 
 58
Workers’ compensation claims(p)
 7
 7
 14
  6
 6
 12
Credit facilities fees(q)
 5
 
 5
  5
 
 5
Common stock issuance costs(r)
 2
 
 2
  4
 
 4
Construction accounting for pollution control equipment(a)(s)
 21
 
 21
  22
 
 22
Solar rebate program(a)(t)
 88
 
 88
  27
 
 27
IEIMA revenue requirement reconciliation(a)(f)
 
 101
 101
  
 65
 65
FERC revenue requirement reconciliation(a)(g)
 
 8
 12
  
 
 5
Other(u)
 5
 6
 11
  8
 12
 20
Total noncurrent regulatory assets $695
 $883
 $1,582
  $534
 $701
 $1,240
Current regulatory liabilities:             
Over-recovered FAC(b)
 $
 $
 $
  $26
 $
 $26
Over-recovered Illinois electric power costs(c)
 
 26
 26
  
 51
 51
Over-recovered PGA(c)
 2
 25
 27
  5
 29
 34
MTM derivative gains(d)
 16
 1
 17

 26
 1
 27
Wholesale distribution refund(v)
 
 
 
  
 13
 13
IEIMA revenue requirement reconciliation(f)
 
 
 
  
 65
 65
FERC revenue requirement reconciliation(g)
 
 11
 11
  
 
 
Refund reserves for FERC orders and audit findings(w)
 
 21
 25
  
 
 
Total current regulatory liabilities $18
 $84
 $106
  $57
 $159
 $216
Noncurrent regulatory liabilities:             
Income taxes(x)
 $41
 $14
 $55
  $37
 $3
 $40
Uncertain tax positions tracker(y)
 7
 
 7
  1
 
 1
Removal costs(z)
 886
 643
 1,529
  828
 610
 1,438
Asset retirement obligation(j)
 182
 
 182
  146
 
 146
Bad debt riders(aa)
 
 7
 7
  
 8
 8
Pension and postretirement benefit costs tracker(ab)
 24
 
 24
  15
 
 15
Energy efficiency riders(e)
 
 39
 39
  3
 33
 36
FERC revenue requirement reconciliation(g)
 
 
 
  
 10
 10
Other(ac)
 7
 
 7
  11
 
 11
Total noncurrent regulatory liabilities $1,147
 $703
 $1,850
  $1,041
 $664
 $1,705
  2017 2016
  
Ameren
Missouri
 
Ameren
Illinois
 Ameren  
Ameren
Missouri
 
Ameren
Illinois
 Ameren
Other 
 1
 1
  
 
 
Total current regulatory assets $56
 $87
 $144
  $35
 $108
 $149
Noncurrent regulatory assets:             
Pension and postretirement benefit costs(i)
 $84
 $215
 $299
  $175
 $319
 $494
Income taxes(j)
 139
 56
 197
  229
 1
 230
Uncertain tax positions tracker(a)(k)
 5
 
 5
  7
 
 7
ARO(l)
 
 1
 1
  
 3
 3
Callaway costs(a)(m)
 25
 
 25
  29
 
 29
Unamortized loss on reacquired debt(a)(n)
 61
 49
 110
  65
 59
 124
Environmental cost riders(o)
 
 173
 173
  
 196
 196
MTM derivative losses(d)
 4

192
 196


9
 178
 187
Storm costs(a)(p)
 
 10
 10
  
 15
 15
Demand-side costs before the MEEIA implementation(a)(q)
 11
 
 11
  18
 
 18
Workers’ compensation claims(r)
 5
 7
 12
  6
 7
 13
Credit facilities fees(s)
 3
 
 3
  4
 
 4
Construction accounting for pollution control equipment(a)(t)
 18
 
 18
  19
 
 19
Solar rebate program(a)(u)
 31
 
 31
  49
 
 49
IEIMA revenue requirement reconciliation adjustment(a)(f)
 
 54
 54
  
 23
 23
FERC revenue requirement reconciliation adjustment(a)(g)
 
 16
 27
  
 8
 10
FEJA energy-efficiency riders(a)(v)
 
 41
 41
  
 
 
Other 9
 8
 17
  9
 7
 16
Total noncurrent regulatory assets $395
 $822
 $1,230
  $619
 $816
 $1,437
Current regulatory liabilities:             
Over-recovered FAC(b)
 $4
 $
 $4
  $
 $
 $
Over-recovered Illinois electric power costs(c)
 
 16
 16
  
 25
 25
Over-recovered PGA(c)
 
 1
 1
  
 
 
MTM derivative gains(d)
 13
 
 13

 12
 11
 23
Energy-efficiency riders(e)
 2
 40
 42
  
 
 
Estimated refund for FERC complaint case(w)
 
 25
 42
  
 42
 62
Other 
 10
 10
  
 
 
Total current regulatory liabilities $19
 $92
 $128
  $12
 $78
 $110
Noncurrent regulatory liabilities:             
Income taxes(j)
 $1,392
 $842
 $2,323
  $33
 $4
 $37
Uncertain tax positions tracker(k)
 2
 
 2
  3
 
 3
Asset removal costs(x)
 995
 725
 1,725
  970
 697
 1,669
ARO(l)
 223
 
 223
  162
 
 162
Bad debt rider(y)
 
 2
 2
  
 3
 3
Pension and postretirement benefit costs tracker(z)
 35
 
 35
  35
 
 35
Energy-efficiency riders(e)
 
 
 
  
 45
 45
Renewable energy credits and zero-emission credits(aa)
 
 58
 58
  
 15
 15
Storm tracker(ab)
 6
 
 6
  7
 
 7
Other 11
 2
 13
  5
 4
 9
Total noncurrent regulatory liabilities $2,664
 $1,629
 $4,387
  $1,215
 $768
 $1,985
(a)These assets earn a return.
(b)Under-recovered or over-recovered fuel costs to be recovered or refunded through the FAC. Specific accumulation periods aggregate the under-recovered or over-recovered costs over four months, any related adjustments that occur over the following four months, and the recovery from or refund to customers that occurs over the next eight months.

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over four months, any related adjustments that occur over the following four months, and the recovery from customers that occurs over the next eight months.
(c)Costs under-Under-recovered or over-recovered costs from utility customers. Amounts will be recovered from, or refunded to, customers within one year of the deferral.
(d)Deferral of commodity-related derivative MTM losses or gains. See Note 7 – Derivative Financial Instruments for additional information.
(e)The Ameren Missouri balance relates to the MEEIA. Beginning in January 2014, aThe MEEIA rider allowedallows Ameren Missouri to collect from, or refund to, customers any annual difference in the actual amounts incurred and the amounts collected from customers for the MEEIA program costs, net shared benefits, and its lost revenues.the throughput disincentive. Under the MEEIA rider, collections from or refunds to customers occur one year after the program costs, net shared benefits, and lost revenuesthe throughput disincentive are incurred. The Ameren Illinois balance relates to a regulatory tracking mechanism to recover its electric and natural gas costs associated with developing, implementing, and evaluating customer energy efficiency and demand response programs. Any under-recovery or over-recovery will be collected from or refunded to customers over the 12 months following the plan year.

energy efficiency and demand response programs. Any under-recovery or over-recovery will be collected from or refunded to customers over the year following the plan year.
(f)The difference between Ameren Illinois'Illinois’ electric distribution service annual revenue requirement calculated under the IEIMA's performance-based formula ratemaking framework and the revenue requirement included in customer rates for that year. Subject to ICC approval, these amountsAny under-recovery or over-recovery will be collectedrecovered from or refunded to customers with interest within two years.
(g)Ameren Illinois'Illinois’ and ATXI'sATXI’s annual revenue requirement reconciliation adjustments calculated pursuant to the FERC'sFERC’s electric transmission formula ratemaking framework. TheAny under-recovery or over-recovery will be recovered from or refunded to customers within two years.
(h)Under-recovered natural gas sales volumes, including deviations from normal weather conditions. Each year’s amount will be recovered from, or refunded to, customers from April through December of the following year.
(i)These costs are being amortized in proportion to the recognition of prior service costs (credits) and actuarial losses (gains) attributable to Ameren’s pension plan and postretirement benefit plans. See Note 1110 – Retirement Benefits for additional information.
(i)(j)OffsetThe regulatory assets represent deferred income taxes that will be recovered from customers related to certainthe equity component of allowance for funds used during construction and the effects of tax rate changes from the TCJA and the increased income tax rate in Illinois. The regulatory liabilities represent deferred income taxes that will be refunded to customers related to depreciation differences, other tax liabilities, and the unamortized portion of investment tax credits recorded at rates in excess of current statutory rates. Amounts associated with the equity component of allowance for expected recoveryfunds used during construction, depreciation differences, and the unamortized portion of future income taxes when paid. Thisinvestment tax credits will be recoveredamortized over the expected life of the related assets. The amortization period for the effects of tax rate changes from the TCJA and the increased income tax rate in Illinois and the other tax liabilities will be determined in future rate orders by the applicable regulators. See Note 12 – Income Taxes for amounts related to the revaluation of deferred income taxes under the TCJA.
(j)(k)The tracker is amortized over three years, beginning from the date the amounts are included in rates. See Note 12 – Income Taxes for additional information.
(l)Recoverable or refundable removal costs for AROs, including net realized and unrealized gains and losses related to the nuclear decommissioning trust fund investments. See Note 1 – Summary of Significant Accounting Policies – Asset Retirement Obligations.
(k)(m)Ameren Missouri’s Callaway energy center operations and maintenance expenses, property taxes, and carrying costs incurred between the plant in-service date and the date the plant was reflected in rates. These costs are being amortized over the remaining life of the energy center's currentcenter’s original operating license which expires inthrough 2024.
(l)(n)Losses related to reacquired debt. These amounts are being amortized over the lives of the related new debt issuances or the original lives of the old debt issuances if no new debt was issued.
(m)(o)The recoverable portion of accrued environmental site liabilities that will be collected from electric and natural gas customers through ICC-approved cost recovery riders. The period of recovery will depend on the timing of remediation expenditures. See Note 1514 – Commitments and Contingencies for additional information.
(n)(p)Ameren Missouri's actual stormStorm costs that exceed the normalized storm costs for rate purposes. As approved by the December 2012 MoPSC electric rate order, the 2006, 2007,from 2013, 2015, and 2008 storm costs were amortized through December 2014. The Ameren Illinois balance includes 2013 storm costs2016 deferred in accordance with the IEIMA. These costs are being amortized over a five-year periodperiods beginning in 2013.the year the storm occurred.
(o)(q)Demand-side costs incurred prior to implementation of the MEEIA in 2013, including the costs of developing, implementing, and evaluating customer energy efficiencyenergy-efficiency and demand response programs. The MoPSC March 2017 electric rate order modified certain amortization periods for these costs. Costs incurred from May 2008 through September 2008, and from January 2010 through July 2012, are being amortized over a 10-yeartwo-year period that began in March 2009.April 2017. Costs incurred from October 2008 through December 2009 are no longer being amortized overas of April 2017, and a six-yearnew amortization period that beganfor these costs will be determined in July 2010.a future regulatory rate review. Costs incurred from January 2010August 2012 through February 2011 are being amortized over a six-year period that began in August 2011. Costs incurred from March 2011 through JulyDecember 2012 are being amortized over a six-year period that began in January 2013.The amortization period for costs incurred from August 2012 through December 2012 will be determined in the July 2014 electric rate case.June 2015.
(p)(r)The period of recovery will depend on the timing of actual expenditures.
(q)(s)Ameren Missouri’s costs incurred to enter into and maintain the 2012 Missouri Credit Agreement. Additional costs were incurred in December 2014 to amend and restate the 2012 Missouri Credit Agreement. These costs are being amortized over the life of the credit facility ending in December 2019, to construction work in progress, which will be depreciated when assets are placed intoin service. Additional costs were incurred in December 2016 to amend and restate the Missouri Credit Agreement.
(r)The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to recover its portion of Ameren’s September 2009 common stock issuance costs. These costs are being amortized over five years, beginning in July 2010.
(s)(t)The MoPSC’s May 2010 electric rate order allowed Ameren Missouri to record an allowance for funds used during construction for pollution control equipment at its Sioux energy center until the cost of that equipment was included in customer rates.rates beginning in 2011. These costs will beare being amortized over the expected life of the Sioux energy center, which is currently through 2033.
(t)(u)Costs associated with Ameren Missouri'sMissouri’s solar rebate program beginning in August 2012 to fulfill its renewable energy portfolio requirement. The amortization period for these costs will be three years, commencing with the effectiveness of Ameren Missouri's current JulyCosts incurred from 2010 to 2014 electric rate case.
(u)The Ameren Illinois balance includes Ameren Illinois Merger integration and optimization costs, which are being amortized over four years, beginning in January 2012. The Ameren Illinois total also includes costs related to the 2013 natural gas delivery service rate case costs, which are being amortized over a two-year period that began in January 2014. At Ameren Missouri,April 2017 as modified per the balance primarily includes the cost of renewable energy credits to fulfill its renewable energy portfolio requirement.MoPSC March 2017 electric rate order. Costs incurred from January 2010 through July 20122015 to 2016 are being amortized over three years, beginninga three-year period that began in January 2013.April 2017.
(v)Estimated refund to wholesale electric customers asElectric energy-efficiency program investments deferred under the FEJA. These investments will earn a return at Ameren Illinois’ weighted-average cost of December 31, 2013. See 2011 Wholesale Distribution Rate Case above.capital with the equity return based on the monthly average yield of the 30-year United States Treasury bonds plus 580 basis points. The investments are being amortized over their weighted-average useful lives beginning in the period in which they were made.
(w)Estimated refunds to transmission customers related to FERC orders and audit findings. In regards to the FERC orders, see Ameren Illinois Electric Transmission Rate Refund andFebruary 2015 FERC Complaint CasesCase discussed above.
(x)Unamortized portion of investment tax credits and federal excess deferred taxes. The unamortized portion of investment tax credits and the federal excess deferred taxes are being amortized over the expected life of the underlying assets.
(y)The tracker is amortized over three years, beginning from the date the amounts are included in rates. See Note 13 - Income Taxes for additional information.
(z)Estimated funds collected for the eventual dismantling and removal of plant retired from service, net of salvage value, upon retirement related to our rate-regulated operations.value.
(aa)(y)A regulatory tracking mechanism for the difference between the level of bad debt incurred by Ameren Illinois under GAAP and the level of such costs included in electric and natural gas rates. The over-recovery relating to 20122015 was refunded to customers from June 20132016 through May 2014.2017. The over-recovery relating to 20132016 is being refunded to customers from June 20142017 through May 2015.2018. The over-recovery relating to 20142017 will be refunded to customers from June 20152018 through May 2016.2019.
(ab)(z)A regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren Missouri under GAAP and the level of such costs built intoincluded in customer rates. For periodscosts incurred prior to August 2012, the MoPSC'samounts are being amortized over a two-year period that began in April 2017 as modified per the MoPSC’s March 2017 electric rate order. For costs incurred between August 2012 and December 20122014, the MoPSC’s May 2015 electric rate order directed the amortization period to occur over five years, beginninga five-year period that began in June 2015. For costs incurred between January 2013.2012 and December 2016, the MoPSC’s March 2017 electric rate order directed the amortization period to occur over a five-year period that began in April 2017. For periodscosts incurred after August 2012,December 2016, the amortization period will be determined in the July 2014a future electric regulatory rate case.review.
(ac)(aa)Balance includesFunds collected from customers and alternative retail electric suppliers for the costspurchase of renewable energy credits to fulfill Ameren Missouri's renewable energy portfolio requirement from August 2012and zero-emission credits through December 2013, which were less than the amount included in rates.IPA procurements. The balance also includes awill be amortized as the credits are purchased.
(ab)A regulatory tracking mechanism at Ameren Missouri for the difference between the level of storm costs incurred in a particular year and the level of such costs built intoincluded in rates. The amortizationFor periods for these over-recoveries will be determined inprior to December 2014, the July 2014MoPSC’s April 2015 electric rate case.order directed the amortization to occur over a five-year period that began in June 2015. For periods after December 2014, the MoPSC’s March 2017 electric rate order directed the amortization to occur over a five-year period that began in April 2017. The April 2015 MoPSC order did not approve the continued use of the storm cost regulatory tracking mechanism.
Ameren, Ameren Missouri, and Ameren Illinois continually assess the recoverability of their regulatory assets. Under current accounting standards, regulatoryRegulatory assets are charged to earnings when it is no longer probable that such amounts will be recovered through future revenues. To the extent that payments of regulatory liabilities are no longer probable, the amounts are credited to earnings.



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NOTE 3 PROPERTY, PLANT, AND PLANT,EQUIPMENT, NET
The following table presents property, plant, and plant,equipment, net, for each of the Ameren Companies at December 31, 20142017 and 20132016:
 
Ameren
Missouri(a)
 
Ameren
Illinois
 Other 
Ameren(a)
 
Ameren
Missouri(a)
 
Ameren
Illinois
 Other 
Ameren(a)
2014        
Property and plant, at original cost:        
Electric $17,052
 $6,517
 $344
 $23,913
2017        
Property, plant, and equipment at original cost:(b)
        
Electric generation $11,132
 $
 $
 $11,132
Electric distribution 5,766
 5,649
 
 11,415
Electric transmission 1,201
 2,298
 1,167
 4,666
Natural gas 431
 1,854
 
 2,285
 474
 2,419
 
 2,893
Other(c)
 922
 757
 242
 1,921
 17,483
 8,371
 344
 26,198
 19,495
 11,123
 1,409
 32,027
Less: Accumulated depreciation and amortization 7,086
 2,422
 251
 9,759
 8,305
 3,082
 246
 11,633
 10,397
 5,949
 93
 16,439
 11,190
 8,041
 1,163
 20,394
Construction work in progress:                
Nuclear fuel in process 209
 
 
 209
 148
 
 
 148
Other 261
 216
 299
 776
 413
 252
 259
 924
Property and plant, net $10,867
 $6,165
 $392
 $17,424
2013        
Property and plant, at original cost:        
Electric $15,964
 $5,426
 $336
 $21,726
Property, plant, and equipment, net $11,751
 $8,293
 $1,422
 $21,466
2016        
Property, plant, and equipment at original cost:(b)
        
Electric generation $10,911
 $
 $
 $10,911
Electric distribution 5,563
 5,287
 
 10,850
Electric transmission 1,151
 2,016
 712
 3,879
Natural gas 413
 1,562
 
 1,975
 455
 2,186
 
 2,641
Other(c)
 879
 719
 239
 1,837
 16,377
 6,988
 336
 23,701
 18,959
 10,208
 951
 30,118
Less: Accumulated depreciation and amortization 6,766
 1,627
 251
 8,644
 7,880
 2,850
 231
 10,961
 9,611
 5,361
 85
 15,057
 11,079
 7,358
 720
 19,157
Construction work in progress:                
Nuclear fuel in process 246
 
 
 246
 206
 
 
 206
Other 595
 228
 79
 902
 193
 111
 446
 750
Property and plant, net $10,452
 $5,589
 $164
 $16,205
Property, plant, and equipment, net $11,478
 $7,469
 $1,166
 $20,113
(a)
Amounts in Ameren and Ameren Missouri include two CTs under separate capital lease agreements. The gross cumulative asset value of those agreements was $233$233 million and $228$232 millionat December 31, 20142017 and 2013,2016, respectively. The total accumulated depreciation associated with the two CTs was $66$83 million and $56$77 million at December 31, 20142017 and 2013,2016, respectively. In addition,See Note 5 – Long-term Debt and Equity Financings for additional information on these capital lease agreements.
(b)The estimated lives for each asset group are as follows: 5 to 72 years for electric generation, excluding Ameren Missouri has investments in debt securities,Missouri’s hydro generating assets which were classified as held-to-maturity, relatedhave useful lives of up to the two CTs from the city of Bowling Green150 years, 20 to 80 years for electric distribution, 50 to 75 years for electric transmission, 20 to 80 years for natural gas, and Audrain County. 5 to 55 years for other.
(c)Other property, plant, and equipment includes assets used to support electric and natural gas services.
Capitalized software costs are classified within “Property, Plant, and Equipment, Net” on the balance sheet and are amortized on a straight-line basis over the expected period of benefit, ranging from 5 to 10 years. The following table presents the gross carrying value of capitalized software, the related accumulated amortization, and the amortization expense of capitalized software by year:
  
Amortization Expense(a)
 Gross Carrying Value Accumulated Amortization
  201720162015 20172016 20172016
Ameren $58
$52
$47
 $655
$622
 $(466)$(408)
Ameren Missouri 20
17
16
 191
178
 (107)(87)
Ameren Illinois 36
33
27
 241
225
 (146)(110)
(a)As of December 31, 2014 and 2013,2017, the carrying valueestimated amortization expense of these debt securities was $294 million and $299 million, respectively.capitalized software for each of the five succeeding years is not expected to differ materially from the current year expense.

The following table provides accrued capital and nuclear fuel expenditures at December 31, 20142017, 20132016, and 20122015, which represent noncash investing activity excluded from the accompanying statements of cash flows:
 
Ameren(a)
 
Ameren
Missouri
 
Ameren
Illinois
Accrued capital expenditures:     
2014$181
 $72
 $59
2013175
 74
 86
2012107
 63
 37
Accrued nuclear fuel expenditures:     
201413
 13
 (b)
20138
 8
 (b)
20128
 8
 (b)
 
Ameren(a)
 
Ameren
Missouri
 
Ameren
Illinois
Accrued capital expenditures:     
2017$361
 $159
 $175
2016251
 116
 87
2015235
 85
 92
Accrued nuclear fuel expenditures:     
201710
 10
 (b)
201620
 20
 (b)
201516
 16
 (b)
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)Not applicable.
NOTE 4 SHORT-TERM DEBT AND LIQUIDITY
The liquidity needs of the Ameren Companies are typically supported through the use of available cash, short-term intercompany borrowings, drawings under committed bank credit agreements, or commercial paper issuances.issuances, or in the case of Ameren Missouri and Ameren Illinois, short-term affiliate borrowings.
2012 Credit Agreements
On December 11, 2014, each of the 2012The Credit Agreements was amended and restated. The amended and
restated agreements extended the maturity dates of the 2012 Credit Agreements from November 14, 2017, to December 11, 2019, resulting inprovide $2.1 billion of credit cumulatively through maturity in December 2021. The maturity date may be extended for two additional one-year periods upon mutual consent of the borrowers and lenders. Credit available under the agreements is provided through the extended maturity date. The facilities continue to include 24by a group of 22 international, national, and regional lenders, with no single lender providing more than $115$118 million of credit in aggregate.

The obligations of each borrower under the respective 2012 Credit Agreements to which it is a party are several and not joint, and, exceptjoint. Except under limited circumstances relating to expenses and indemnities, the obligations of Ameren Missouri and Ameren


96


Illinois under the respective 2012 Credit Agreements are not guaranteed by Ameren (parent) or any other subsidiary of Ameren. The following table presents the maximum aggregate amount available to each borrower under each facility is shown in the following table (the amount being each borrower's "Borrowing Sublimit"):facility:
  2012 Missouri Credit Agreement
2012 Illinois
Credit Agreement
Ameren $700
$500
Ameren Missouri 800
(a)
Ameren Illinois   (a)
800
  
Missouri
Credit Agreement
Illinois
Credit Agreement
Ameren (parent) $700
$500
Ameren Missouri 800
(a)
Ameren Illinois (a)
800
(a)Not applicable.
Ameren hasThe borrowers have the option to seek additional commitments from existing or new lenders to increase the total facility size of the 2012 Credit Agreements up to a maximum amount of $1.2$1.2 billion for the 2012 Missouri Credit Agreement and $1.3$1.3 billion for the 2012 Illinois Credit Agreement. The 2012 Credit Agreements, as well as the Borrowing Sublimits of Ameren Ameren Missouri, and Ameren Illinois, will mature and expire on December 11, 2019. The principal amount of each revolving loan owed by a borrower under any of the 2012 Credit Agreements to which it is a party will be(parent) borrowings are due and payable no later than the maturity date of such 2012the Credit Agreement. The principal amount of each revolving loan owed byAgreements. Ameren Missouri orand Ameren Illinois borrowings under the applicable 2012 Credit Agreement will beare due and payable no later than the earlier of the maturity date or 364 days after the originating date of such loan.the borrowing.
The obligations of allthe borrowers under the 2012 Credit Agreements are unsecured. Loans are available on a revolving basis under each of the 2012 Credit Agreements. Funds borrowed may be repaid and, subject to satisfaction of the conditions to borrowing, reborrowed from time to time. At the election of each borrower, the interest rates on such loans will be the alternate base rate plus the margin applicable to the
particular borrower and/or the eurodollar rate plus the margin applicable to the particular borrower. The applicable margins will be determined by the borrower'sborrower’s long-term unsecured credit ratings or, if no such ratings are then in effect, the borrower'sborrower’s corporate/issuer ratings then in effect. The 2012 Credit Agreements provide for the issuance of letters of credit for the account of the borrowers up to a maximum of 25% of the aggregate initial commitment under the applicable 2012 Credit Agreement. The borrowers have received commitments from the lenders to issue letters of credit up to $100 million under each of the 2012 Credit Agreements. In addition, the issuance of letters of credit is subject to the $2.1$2.1 billion overall combined facility borrowing limitations of the 2012 Credit Agreements.
The borrowers will use the proceeds from any borrowings under the 2012 Credit Agreements for general corporate purposes, including working capital, commercial paper liquidity support, issuance of letters of credit, loan funding under the Ameren money pool arrangements, and other short-term intercompanyaffiliate loan arrangements, or for paying fees and expenses incurred in connection with the 2012 Credit Agreements. Both of the 2012 Credit Agreements are available to Ameren to support issuances under Ameren's commercial paper program, subject to borrowing sublimits.arrangements. The 2012 Missouri Credit Agreement and the 2012 Illinois Credit Agreement are available to support issuances under Ameren Missouri's(parent)’s, Ameren Missouri’s and Ameren Illinois'Illinois’ commercial paper programs, respectively.respectively, subject to borrowing

sublimits. As of December 31, 2014,2017, based on commercial paper outstanding and letters of credit issued under the 2012 Credit Agreements, the aggregate amount of credit capacity available to Ameren (parent), Ameren Missouri, and Ameren Illinois, collectively, at December 31, 2014, was $1.4 billion.$1.6 billion.
Ameren, Ameren Missouri, and Ameren Illinois did not borrow under the 2012 Credit Agreements for the years ended December 31, 20142017 and 2013.2016.

Commercial Paper
The following table summarizes the borrowing activity and relevant interest rates under Ameren Missouri's(parent)’s, Ameren Missouri’s and Ameren Illinois'Illinois’ commercial paper program,programs for the years ended December 31, 20142017 and 20132016:
 Ameren (parent)Ameren MissouriAmeren IllinoisAmeren Consolidated Ameren (parent)Ameren MissouriAmeren IllinoisAmeren Consolidated
2014    
2017    
Average daily commercial paper outstanding $423
 $110
$165
$639
 $573
 $5
$90
$668
Outstanding borrowings at period-end 585
 97
32
714
 383
 39
62
484
Weighted-average interest rate 0.36% 0.38%0.32%0.36% 1.30% 1.24%1.35%1.31%
Peak commercial paper during period(a)
 $625
 $495
$300
$910
Peak outstanding commercial paper during period(a)
 $841
 $64
$469
$948
Peak interest rate 0.75% 0.70%0.60%0.75% 1.90% 1.78%2.00%2.00%
2013    
2016    
Average daily commercial paper outstanding $54
 $
$
$54
 $440
 $60
$52
$552
Outstanding borrowings at period-end 368
 

368
 507
 
51
558
Weighted-average interest rate 0.56% %%0.56% 0.82% 0.74%0.69%0.80%
Peak commercial paper during period(a)
 $368
 $
$
$368
Peak outstanding commercial paper during period(a)
 $574
 $208
$195
$839
Peak interest rate 0.85% %%0.85% 1.05% 0.85%0.90%1.05%



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(a)The timing of peak outstanding commercial paper issuances varies by company. Therefore, the sum of the peak amounts presented by the companies may not equal the Ameren consolidated peak amount for the period.
Indebtedness Provisions and Other Covenants
The information below presentsis a summary of the Ameren Companies’ compliance with indebtedness provisions and other covenants.
The 2012 Credit Agreements contain conditions for borrowings and issuances of letters of credit. These conditions include the absence of default or unmatured default, material accuracy of representations and warranties (excluding any representation after the closing date as to the absence of material adverse change and material litigation, and the absence of any notice of violation, liability, or requirement under any environmental laws that could have a material adverse effect), and obtainment ofobtaining required regulatory authorizations. In addition, it is a condition for any Ameren Illinois borrowing that, at the time of and after giving effect to such borrowing, Ameren Illinois not be in violation of any limitation on its ability to incur unsecured indebtedness contained in its articles of incorporation.
The 2012 Credit Agreements also contain nonfinancial covenants, including restrictions on the ability to incur certain liens, to transact with affiliates, to dispose of assets, to make investments in or transfer assets to its affiliates, and to merge with other entities. The 2012 Credit Agreements require each of Ameren, Ameren Missouri, and Ameren Illinois to maintain consolidated indebtedness of not more than 65% of its consolidated total capitalization pursuant to a defined calculation set forth in the agreements. As of December 31, 2014,2017, the ratios of consolidated indebtedness to total consolidated capitalization, calculated in accordance with the provisions of the 2012 Credit Agreements, were 50%53%, 49%48%, and 47%, for Ameren, Ameren Missouri, and Ameren Illinois, respectively. In addition, under the 2012 Illinois Credit Agreement and, by virtue of the cross-default provisions of the 2012 Missouri Credit Agreement, under the 2012 Missouri Credit Agreement, Ameren is required to maintain a ratio of consolidated funds from operations plus interest expense to consolidated interest expense of2.0 to 1.0. However, the interest coverage requirement will only apply at such times as Ameren does not have a senior long-term unsecured credit rating of at least Baa3 from Moody's or BBB- from S&P. As of December 31, 2014, Ameren exceeded the rating requirements and the interest coverage requirement was not applicable. Failure of a borrower to satisfy a financial covenant constitutes an immediate default under the applicable 2012 Credit Agreement.
The 2012 Credit Agreements contain default provisions that apply separately to each borrower; provided, however, thatborrower. However, a default of Ameren Missouri or Ameren Illinois under the applicable 2012 Credit Agreement willcredit agreement is also be deemed to constitute a default of Ameren (parent) under such agreement. Defaults include a cross-default toresulting from a default of such borrower under any other agreement covering outstanding indebtedness of such
borrower and certain subsidiaries (other than project finance subsidiaries and nonmaterial subsidiaries) in excess of $75$100 million in the aggregate (including under the other 2012 Credit Agreement)credit agreement). However, under the default provisions of the 2012 Credit Agreements, any default of Ameren (parent) under any 2012 Credit Agreementeither credit agreement that results solely from a default of Ameren Missouri or Ameren Illinois thereunder does not result in a cross-default of Ameren (parent) under the other 2012 Credit Agreement.credit agreement. Further, the 2012 Credit AgreementAgreements default provisions provide that an Ameren (parent) default under anyeither of the 2012 Credit Agreements does not constitute a default by Ameren Missouri or Ameren Illinois.
None of the Ameren Companies'Companies’ credit agreements or financing agreements contain credit rating triggers that would cause a default or acceleration of repayment of outstanding balances. Management believes that theThe Ameren Companies were in compliance with the provisions and covenants of their credit agreements at December 31, 20142017.

Money Pools
Ameren has money pool agreements with and among its subsidiaries to coordinate and provide for certain short-term cash and working capital requirements.
Ameren Missouri, Ameren Illinois, and Ameren ServicesATXI may participate in the utility money pool as both lenders and borrowers. Ameren (parent) and Ameren Services may participate in the utility money pool only as a lender. Internallenders. Surplus internal funds are surplus funds contributed to the money pool from participants. The primary sources of external funds for the utility money pool are the 2012 Credit Agreements and the commercial paper programs. The total amount available to the pool participants from the utility money pool at any given time is reduced by the amount of borrowings made by participants, but it is increased to the extent that the pool participants advance surplus funds to the utility money pool or remit funds from other external sources. The availability of funds is also determined by funding requirement limits established by regulatory authorizations. Participants receiving a loan under the money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the utility money pool. The average interest rate for borrowing under the money pool for the year ended December 31, 2014,2017, was 0.19% (2013 - 0.14%1.19% (2016 – 0.52%).
See Note 1413 – Related PartyRelated-party Transactions for the amount of interest income and expense from the money pool arrangements recorded by the Ameren Companies for the years ended December 31, 2014, 2013,2017, 2016, and 2012.2015.



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NOTE 5 LONG-TERM DEBT AND EQUITY FINANCINGS
The following table presents long-term debt outstanding, including maturities due within one year, for the Ameren Companies as of December 31, 20142017 and 20132016:
 2014 2013
Ameren (Parent):   
8.875% Senior unsecured notes due 2014$
 $425
Less: Maturities due within one year
 (425)
Long-term debt, net$
 $
Ameren Missouri:   
Senior secured notes:(a)
   
5.50% Senior secured notes due 2014
 104
4.75% Senior secured notes due 2015114
 114
5.40% Senior secured notes due 2016260
 260
6.40% Senior secured notes due 2017425
 425
6.00% Senior secured notes due 2018(b)
179
 179
5.10% Senior secured notes due 2018199
 199
6.70% Senior secured notes due 2019(b)
329
 329
5.10% Senior secured notes due 2019244
 244
5.00% Senior secured notes due 202085
 85
3.50% Senior secured notes due 2024350
 
5.50% Senior secured notes due 2034184
 184
5.30% Senior secured notes due 2037300
 300
8.45% Senior secured notes due 2039(b)
350
 350
3.90% Senior secured notes due 2042(b)
485
 485
Environmental improvement and pollution control revenue bonds:   
1992 Series due 2022(c)(d)
47
 47
1993 5.45% Series due 2028(e)
(e)
 (e)
1998 Series A due 2033(c)(d)
60
 60
1998 Series B due 2033(c)(d)
50
 50
1998 Series C due 2033(c)(d)
50
 50
Capital lease obligations:   
City of Bowling Green capital lease (Peno Creek CT) due 202254
 59
Audrain County capital lease (Audrain County CT) due 2023240
 240
Total long-term debt, gross4,005
 3,764
Less: Unamortized discount and premium(6) (7)
Less: Maturities due within one year(120) (109)
Long-term debt, net$3,879
 $3,648
 2017 2016
Ameren (Parent):   
2.70% Senior unsecured notes due 2020$350
 $350
3.65% Senior unsecured notes due 2026350
 350
Total long-term debt, gross700
 700
Less: Unamortized debt issuance costs(4) (6)
Long-term debt, net$696
 $694
Ameren Missouri:   
Bonds and notes:   
6.40% Senior secured notes due 2017(a)
$
 $425
6.00% Senior secured notes due 2018(a)(b)
179
 179
5.10% Senior secured notes due 2018(a)
199
 199
6.70% Senior secured notes due 2019(a)(b)
329
 329
5.10% Senior secured notes due 2019(a)
244
 244
5.00% Senior secured notes due 2020(a)
85
 85
1992 Series bonds due 2022(c)(d)
47
 47
3.50% Senior secured notes due 2024(a)
350
 350
2.95% Senior secured notes due 2027(a)
400
 
5.45% First mortgage bonds due 2028(e)
(e)
 (e)
1998 Series A bonds due 2033(c)(d)
60
 60
1998 Series B bonds due 2033(c)(d)
50
 50
1998 Series C bonds due 2033(c)(d)
50
 50
5.50% Senior secured notes due 2034(a)
184
 184
5.30% Senior secured notes due 2037(a)
300
 300
8.45% Senior secured notes due 2039(a)(b)
350
 350
3.90% Senior secured notes due 2042(a)(b)
485
 485
3.65% Senior secured notes due 2045(a)
400
 400
Capital lease obligations:   
City of Bowling Green capital lease (Peno Creek CT) due 2022(f)
36
 42
Audrain County capital lease (Audrain County CT) due 2023(f)
240
 240
Total long-term debt, gross3,988
 4,019
Less: Unamortized discount and premium(7) (6)
Less: Unamortized debt issuance costs(20) (19)
Less: Maturities due within one year(384) (431)
Long-term debt, net$3,577
 $3,563

99


2014 20132017 2016
Ameren Illinois:      
Senior secured notes:   
6.20% Senior secured notes due 2016(f)
$54
 $54
6.25% Senior secured notes due 2016(g)
75
 75
Bonds and notes:   
6.125% Senior secured notes due 2017(g)(h)
250
 250
$
 $250
6.25% Senior secured notes due 2018(g)(h)
144
 144
144
 144
9.75% Senior secured notes due 2018(g)(h)
313
 313
313
 313
2.70% Senior secured notes due 2022(g)(h)
400
 400
400
 400
5.90% First mortgage bonds due 2023(i)
(i)
 (i)
5.70% First mortgage bonds due 2024(j)
(j)
 (j)
3.25% Senior secured notes due 2025(g)
300
 
300
 300
6.125% Senior secured notes due 2028(g)
60
 60
60
 60
6.70% Senior secured notes due 2036(g)
61
 61
1993 Series B-1 Senior unsecured notes due 2028(d)(k)
17
 17
6.70% Senior secured notes due 2036(f)(g)
42
 42
61
 61
6.70% Senior secured notes due 2036(l)
42
 42
4.80% Senior secured notes due 2043(g)
280
 280
280
 280
4.30% Senior secured notes due 2044(g)
250
 
250
 250
Environmental improvement and pollution control revenue bonds:   
5.90% Series 1993 due 2023(i)
(i)
 32
5.70% 1994A Series due 2024(j)
(j)
 36
5.95% 1993 Series C-1 due 2026(k)

 35
5.70% 1993 Series C-2 due 2026(k)

 8
1993 Series B-1 due 2028(d)(k)
17
 17
5.40% 1998A Series due 2028(j)

 19
5.40% 1998B Series due 2028(j)

 33
Fair-market value adjustments
 4
4.15% Senior secured notes due 2046(g)
490
 490
3.70% First mortgage bonds due 2047(m)
500
 
Total long-term debt, gross2,246
 1,863
2,857
 2,607
Less: Unamortized discount and premium(5) (7)(3) 
Less: Unamortized debt issuance costs(24) (19)
Less: Maturities due within one year
 
(457) (250)
Long-term debt, net$2,241
 $1,856
$2,373
 $2,338
ATXI:   
3.43% Senior notes due 2050(n)
$450
 $
Total long-term debt, gross450
 
Less: Unamortized debt issuance costs(2) 
Long-term debt, net$448
 $
Ameren consolidated long-term debt, net$6,120
 $5,504
$7,094
 $6,595
(a)These notes are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture. The notes have a fall-away lien provision and will remain secured only as long as any first mortgage bonds issued under the Ameren Missouri mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Missouri senior secured notes currently outstanding, we do not expect the first mortgage bond lien protection associated with these notes to fall away untilbefore 2042.
(b)
Ameren Missouri has agreed during the life of these notes, not to optionally redeem, purchase or otherwise retire in full its first mortgage bonds. Ameren Missouri has also agreed to prevent a first mortgage bond release date from occurring asthat so long as any of the 8.45% senior secured notes due 2039 and any of the 3.90% senior secured notes due 2042 remain outstanding.
are outstanding, Ameren Missouri will not permit a release date to occur, and so long as any of the 6.00% senior secured notes due 2018, 6.70% senior secured notes due 2019, and 8.45% senior secured notes due 2039 are outstanding, Ameren Missouri will not optionally redeem, purchase, or otherwise retire in full the outstanding first mortgage bonds not subject to release provisions.
(c)These bonds are collaterally secured by first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage indenture and have a fall-away lien provision similar to that of Ameren Missouri'sMissouri’s senior secured notes. The bonds are also backed by an insurance guarantee policy.
(d)
The interest rates and the periods during which such rates apply vary depending on our selection of defined rate modes. Maximum interest rates could reach 18%, depending on the series of bonds. The bonds are callable at 100% of par value. The average interest rates for 20142017 and 20132016 were as follows:
    
2014 20132017 2016
Ameren Missouri 1992 Series due 20220.10% 0.17%1.43% 0.66%
Ameren Missouri 1998 Series A due 20330.26% 0.34%1.77% 0.91%
Ameren Missouri 1998 Series B due 20330.27% 0.33%1.75% 0.92%
Ameren Missouri 1998 Series C due 20330.26% 0.34%1.73% 0.97%
Ameren Illinois 1993 Series B-1 due 20280.21% 0.14%1.08% 0.70%
(e)
These bonds are first mortgage bonds issued by Ameren Missouri under the Ameren Missouri mortgage bond indenture and are secured by substantially all Ameren Missouri property and franchises. The bonds are callable at 100% of par value. Less than $1 million principal amount of the bonds remain outstanding.
(f)Payments due to the lessor under these capital lease obligations are paid to a trustee, which is authorized to utilize the cash only to pay equal amounts due to Ameren Missouri under related bonds issued by the lessor and held by Ameren Missouri. The timing and amounts of payments due from Ameren Missouri under the capital lease agreements are equal to the timing and amount of bond service payments due to Ameren Missouri, resulting in no net cash flow. The balance of both the capital lease obligations and the related investments in debt securities, recorded in "Other Assets," was $276 million and $282 million, respectively, as of December 31, 2017 and 2016.
(g)These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under the CILCOits 1992 mortgage indenture. The notes have a fall-away lien provision, and Ameren Illinois could cause these notes to become unsecured at any time by redeeming the pollution control bonds 5.90% Series 1993 due 2023 (of which less than $1 million remains outstanding). Ameren Illinois may resecure these notes if it chooses.
(g)These notesThey are collaterally secured by mortgage bonds issued by Ameren Illinois undersubstantially all property of the Ameren Illinois mortgage indenture.former IP and CIPS. The notes have a fall-away lien provision and will remain secured only as long as any series of first mortgage bonds issued under the Ameren Illinoisits 1992 mortgage indenture remain outstanding. Redemption, purchase, or maturity of all first mortgage bonds, including first mortgage bonds currently outstanding and any that may be issued in the future, would result in a release of the first mortgage bonds currently securing these notes, at which time these notes would become unsecured obligations. Considering the Ameren Illinoismaturity date of these senior secured notes currently outstanding,and the 3.70% first mortgage bonds due 2047, we do not expect the mortgage bond lien protection associated with these notes to fall away until 2024.away.
(h)Ameren Illinois has agreed duringthat so long as any of the life2.70% senior secured notes due 2022 are outstanding, Ameren Illinois will not permit a release date to occur, and so long as any of thesethe 9.75% senior secured notes due 2018 and 6.25% senior secured notes due 2018 are outstanding, Ameren Illinois will not to optionally redeem, purchase or otherwise retire in full its Ameren Illinois mortgage bonds; therefore, an Ameren Illinoisthe outstanding first mortgage bondbonds not subject to release provisions; therefore, a release date will not occur asso long as any of these notes are outstanding.

remain outstanding.
(i)These bonds are first mortgage bonds issued by Ameren Illinois under the CILCOits 1933 mortgage indenture andindenture. They are secured by substantially all property of the former CILCO. The bonds are callable at 100% of par value. Less than $1 million principal amount of the bonds remain outstanding.
(j)These bonds are first mortgage bonds issued by Ameren Illinois under the Ameren Illinoisits 1992 mortgage indenture andindenture. They are secured by substantially all property of the former IP and CIPS. The bonds are callable at 100% of par value. The bonds are also backed by an insurance guarantee policy. Less than $1 million principal amount of the bonds remains outstanding.

100


and CIPS. The bonds are callable at 100% of par value. The bonds are also backed by an insurance guarantee policy. Less than $1 million principal amount of the bonds remain outstanding.
(k)
The bonds are callable at 100% of par value.
(l)These notes are collaterally secured by first mortgage bonds issued by Ameren Illinois under its 1933 mortgage indenture. They are secured by substantially all property of the former CILCO. The notes have a fall-away lien provision, and Ameren Illinois could cause these notes to become unsecured at any time by redeeming the 5.90% first mortgage bonds due 2023 (of which less than $1 million principal amount remains outstanding).
(m)These bonds are first mortgage bonds issued by Ameren Illinois under its 1992 mortgage indenture. They are secured by substantially all property of the former IP and CIPS.
(n)The following table presents the principal maturities schedule for the 3.43% senior notes due 2050:
Payment Date Principal Payment
August 2022$49.5
August 2024 49.5
August 2027 49.5
August 2030 49.5
August 2032 49.5
August 2038 49.5
August 2043 76.5
August 2050 76.5
Total$450.0
The following table presents the aggregate maturities of long-term debt, including current maturities, for the Ameren Companies at December 31, 20142017:
 
 Ameren
Missouri(a)
 
 Ameren
Illinois(a)
 
Ameren
Consolidated
Ameren
(parent)(a)
 
 Ameren
Missouri(a)
 
 Ameren
Illinois(a)
 
 ATXI(a)
 
Ameren
Consolidated
2015 $120
 $
 $120
2016 266
 129
 395
2017 431
 250
 681
2018 383
 457
 840
$
 $384
 $457
 $
 $841
2019 581
 
 581

 581
 
 
 581
2020350
 92
 
 
 442
2021
 8
 
 
 8
2022
 56
 400
 50
 506
Thereafter 2,224
 1,410
 3,634
350
 2,867
 2,000
 400
 5,617
Total $4,005
 $2,246
 $6,251
$700
 $3,988
 $2,857
 $450
 $7,995
(a)
Excludes unamortized discount, unamortized premium, and premiumdebt issuance costs of $4 million, $627 million, $27 million and $52 million at Ameren (parent), Ameren Missouri, and Ameren Illinois and ATXI, respectively.

All classes of Ameren Missouri’s and Ameren Illinois’ preferred stock are entitled to cumulative dividends, have voting rights, and are not subject to mandatory redemption. The preferred stock of Ameren'sAmeren’s subsidiaries wasis included in "Noncontrolling Interests"“Noncontrolling Interests” on Ameren'sAmeren’s consolidated balance sheet. The following table presents the outstanding preferred stock of Ameren Missouri and Ameren Illinois, which is redeemable, at the option of the issuer, at the prices shown below as of December 31, 20142017 and 20132016:
 Redemption Price(per share) 2014 2013 Redemption Price (per share) 2017 2016
Ameren Missouri:            
Without par value and stated value of $100 per share, 25 million shares authorizedWithout par value and stated value of $100 per share, 25 million shares authorized      Without par value and stated value of $100 per share, 25 million shares authorized      
$3.50 Series130,000 shares $110.00
 $13
 $13
130,000 shares $110.00
 $13
 $13
$3.70 Series40,000 shares 104.75
 4
 4
40,000 shares 104.75
 4
 4
$4.00 Series150,000 shares 105.625
 15
 15
150,000 shares 105.625
 15
 15
$4.30 Series40,000 shares 105.00
 4
 4
40,000 shares 105.00
 4
 4
$4.50 Series213,595 shares 110.00
(a) 
21
 21
213,595 shares 110.00
(a) 
21
 21
$4.56 Series200,000 shares 102.47
 20
 20
200,000 shares 102.47
 20
 20
$4.75 Series20,000 shares 102.176
 2
 2
20,000 shares 102.176
 2
 2
$5.50 Series A14,000 shares 110.00
 1
 1
14,000 shares 110.00
 1
 1
TotalTotal   $80
 $80
Total   $80
 $80
Ameren Illinois:            
With par value of $100 per share, 2 million shares authorizedWith par value of $100 per share, 2 million shares authorized      With par value of $100 per share, 2 million shares authorized      
4.00% Series144,275 shares $101.00
 $14
 $14
144,275 shares $101.00
 $14
 $14
4.08% Series45,224 shares 103.00
 5
 5
45,224 shares 103.00
 5
 5
4.20% Series23,655 shares 104.00
 2
 2
23,655 shares 104.00
 2
 2
4.25% Series50,000 shares 102.00
 5
 5
50,000 shares 102.00
 5
 5
4.26% Series16,621 shares 103.00
 2
 2
16,621 shares 103.00
 2
 2
4.42% Series16,190 shares 103.00
 2
 2
16,190 shares 103.00
 2
 2
4.70% Series18,429 shares 103.00
 2
 2
18,429 shares 103.00
 2
 2
4.90% Series73,825 shares 102.00
 7
 7
73,825 shares 102.00
 7
 7
4.92% Series49,289 shares 103.50
 5
 5
49,289 shares 103.50
 5
 5
5.16% Series50,000 shares 102.00
 5
 5
50,000 shares 102.00
 5
 5
6.625% Series124,274 shares 100.00
 12
 12
124,274 shares 100.00
 12
 12
7.75% Series4,542 shares 100.00
 1
 1
4,542 shares 100.00
 1
 1
TotalTotal   $62
 $62
Total   $62
 $62
Total AmerenTotal Ameren   $142
 $142
Total Ameren   $142
 $142
(a)
In the event of voluntary liquidation, $105.50.


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Ameren has 100 million shares of $0.01 par value preferred stock authorized, with no such shares outstanding. Ameren Missouri has 7.5 million shares of $1 par value preference stock authorized, with no such preference stockshares outstanding. Ameren Illinois has 2.6 million shares of no par value preferred stock authorized, with no such shares outstanding.
Ameren
In May 2014,December 2017, Ameren, (parent) repaid at maturity $425 millionAmeren Missouri, and Ameren Illinois filed a Form S-3 shelf registration statement with the SEC, registering the issuance of its 8.875% senior unsecured notes, plus accrued interest.an indeterminate amount of certain types of securities. The notes were repaid with proceeds from commercial paper issuances.registration statement became effective immediately upon filing and expires in December 2020.
Ameren filed a Form S-3 registration statement with the SEC in May 2014,2017, authorizing the offering of 8.66 million additional shares of its common stock under DRPlus, which expires in May 2017.2020. Shares of common stock sold under DRPlus are, at Ameren’s option, newly issued shares, treasury shares, or shares
purchased in the open market or in privately negotiated transactions. As of December 31, 2017 and 2016, DRPlus participant funds of $8 million were reflected on Ameren’s consolidated balance sheets in “Other current assets.”
In October 2013, Ameren filed a Form S-8 registration statement with the SEC, authorizing the offering of 4 million additional shares of its common stock under its 401(k) plan. Shares of common stock sold under the 401(k) plan are, at Ameren’s option, newly issued shares, treasury shares, or shares purchased in the open market or in privately negotiated transactions.
In June 2012, Ameren, Ameren Missouri, and Ameren Illinois filed a Form S-3 shelf registration statement registering the issuance of an indeterminate amount of certain types of securities, which expires in June 2015.
From 20122015 through 2014,2017, Ameren shares for its DRPlus and its 401(k) plans were purchased in the open market.


Ameren Missouri
In April 2014,June 2017, Ameren Missouri issued $350$400 million of 3.50%2.95% senior secured notes due April 15, 2024,June 2027, with interest payable semiannually on AprilJune 15 and OctoberDecember 15 of each year, beginning OctoberDecember 15, 2014.2017. Ameren Missouri received proceeds of $348$396 million, which were used, in conjunction with other available funds, to repay at maturity $425 million of Ameren Missouri’s 6.40% senior secured notes in June 2017.
In February 2016, $260 million principal amount of Ameren Missouri’s 5.40% senior secured notes matured and were repaid with cash on hand and commercial paper borrowings.
In June 2016, Ameren Missouri issued $150 million of 3.65% senior secured notes due in April 2045, with interest payable semiannually in April and October of each year, beginning in October 2016. Ameren Missouri received proceeds of $148 million from the June 2016 issuance, which was used to repay outstanding short-term debt, including short-term debt that Ameren Missouri incurred in connection with the repayment of $114 million of its 4.75% senior secured notes that matured in April 2015.
For information on Ameren Missouri’s capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions.
Ameren Illinois
In November 2017, Ameren Illinois issued $500 million of 3.70% first mortgage bonds due December 2047, with interest payable semiannually on June 1 and December 1 of each year, beginning June 1, 2018. Ameren Illinois received proceeds of $492 million, which were used to repay at maturity $104outstanding short-term debt, including short-term debt that Ameren Illinois incurred in connection with the repayment of $250 million of its 5.50%6.125% senior secured notes due May 15, 2014 and to repay a portion of its short-term debt.that matured in November 2017.
In October 2013, $44June 2016, Ameren Illinois’ $54 million principal amount of Ameren Missouri’s 1993 5.45% Series tax-exempt first mortgage bonds were redeemed at par value plus accrued interest,6.20% senior secured notes and $200$75 million principal amount of Ameren Missouri’s 4.65%6.25% senior secured notes matured and were retired.repaid with commercial paper borrowings.
Ameren Illinois
In January 2014, Ameren Illinois redeemed the following environmental improvement and pollution control revenue bonds at par value plus accrued interest:
Senior Secured NotesPrincipal Amount
5.90% Series 1993 due 2023(a)
$32
5.70% 1994A Series due 2024(a)
36
1993 Series C-1 5.95% due 202635
1993 Series C-2 5.70% due 20268
5.40% 1998A Series due 202819
5.40% 1998B Series due 202833
Total amount redeemed$163
(a)Less than $1 million principal amount of the bonds remain outstanding after redemption.
In June 2014,December 2016, Ameren Illinois issued $250$240 million of 4.30%4.15% senior secured notes due July 1, 2044,in March 2046, with interest payable semiannually on January 1in March and July 1,September, beginning January 1, 2015.in March 2017. Ameren Illinois received proceeds of $246$245 million from the issuance, which werewas used to repay a portion of its short-term debt.
For information on Ameren Illinois’ capital contributions, refer to Capital Contributions in Note 13 – Related-party Transactions.
ATXI
In December 2014, Ameren Illinois issued $300June 2017, pursuant to a note purchase agreement, ATXI agreed to issue $450 million principal amount of 3.25%3.43% senior securedunsecured notes, due March 1, 2025,2050, with interest payable semiannually on March 1the last day of February and September 1,August of each year, beginning March 1, 2015. Ameren Illinois received proceedsFebruary 28, 2018, through a private placement offering exempt from registration under the Securities Act of $298 million, which were used to repay a portion of its short-term debt.
In December 2013, Ameren Illinois1933, as amended. ATXI issued $280$150 million principal amount of 4.80% senior securedthe notes due December 15, 2043, with interest payable semiannually onin June 152017 and December 15, beginning June 15, 2014. Ameren Illinoisthe remaining $300 million principal amount of the notes in August 2017. ATXI received net proceeds of $276 million. The proceeds$449 million from the notes, which were used by ATXI to repay existing short-term and long-term affiliate debt.
ATXI may prepay at any time not less than 5% of the principal amount of notes then outstanding at 100% of the principal amount plus a make-whole premium. In the event of a change of control, as defined in the agreement, each holder of notes may require ATXI to prepay the entire unpaid principal amount of the notes held by such holder at a price equal to 100% of the principal amount of such notes together with other available cash, to repay at maturity $150 million of its 8.875% senior secured notes due December 15, 2013,accrued and to repay its short-term debt.unpaid interest thereon.

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Indenture Provisions and Other Covenants
Ameren Missouri’s and Ameren Illinois’ indentures and articles of incorporation include covenants and provisions related to issuances of first mortgage bonds and preferred stock. Ameren Missouri and Ameren Illinois are required to meet certain ratios to issue additional first mortgage bonds and preferred stock. A failure to achieve these ratios would not result in a default under these covenants and provisions but would restrict the companies’ ability to issue bonds or preferred stock. The following table summarizes the required and actual interest coverage ratios for interest charges, dividend coverage ratios, and bonds and preferred stock issuable as of December 31, 20142017, at an assumed interest rate of 5% and dividend rate of 6%.
Required Interest
Coverage Ratio(a)
Actual Interest
Coverage Ratio
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
Actual Dividend
Coverage Ratio
Preferred Stock
Issuable
Required Interest
Coverage Ratio(a)
Actual Interest
Coverage Ratio
Bonds Issuable(b)
 
Required Dividend
Coverage Ratio(c)
Actual Dividend
Coverage Ratio
Preferred Stock
Issuable
 
Ameren Missouri
>2.0
4.3
$3,605
  
>2.5
115.1
$2,568
>2.0
4.8
$4,222
 
>2.5
95.4
$2,118
 
Ameren Illinois
>2.0
6.4
3,358
(d) 
>1.5
2.7
208
>2.0
7.1
4,119
(d) 
>1.5
2.9
203
(e) 
(a)Coverage required on the annual interest charges on first mortgage bonds outstanding and to be issued. Coverage is not required in certain cases when additional first mortgage bonds are issued on the basis of retired bonds.

(b)
Amount of bonds issuable based either on required coverage ratios or unfunded property additions, whichever is more restrictive. The amounts shown also include bonds issuable based on retired bond capacity of $8321,629 million and $204$529 million at Ameren Missouri and Ameren Illinois, respectively.
(c)Coverage required on the annual dividend on preferred stock outstanding and to be issued, as required in the respective company’s articles of incorporation.
(d)Amount of bonds issuable by Ameren Illinois based on unfunded property additions and retired bonds solely under the former IPits 1992 mortgage indenture.
(e)Preferred stock issuable is restricted by the amount of preferred stock that is currently authorized by Ameren Illinois’ articles of incorporation.
Ameren’s indenture does not require Ameren to comply with any quantitative financial covenants. The indenture does, however, include certain cross-default provisions. Specifically, either (1) the failure by Ameren to pay when due and upon expiration of any applicable grace period any portion of any Ameren indebtedness in excess of $25 million, or (2) the acceleration upon default of the maturity of any Ameren indebtedness in excess of $25 million under any indebtedness agreement, including borrowings under the Credit Agreements or the Ameren commercial paper program, constitutes a default under the indenture, unless such past due or accelerated debt is discharged or the acceleration is rescinded or annulled within a specified period.
Ameren Missouri and Ameren Illinois and certain other nonregistrant Ameren subsidiaries are subject to Section 305(a) of the Federal Power Act, which makes it unlawful for any officer or director of a public utility, as defined in the Federal Power Act, to participate in the making or paying of any dividend from any funds “properly included in capital account.” The FERC has consistently interpreted the provision to allow dividends to be paid as long as (1) the source of the dividends is clearly disclosed, (2) the dividends are not excessive, and (3) there is no self-dealing on the part of corporate officials. At a minimum, Ameren believes that dividends can be paid by its subsidiaries that are public utilities from net income and retained earnings. In addition, under Illinois law, Ameren Illinois may not pay any dividend on its stock unless, among other things, its earnings and earned surplus are sufficient to declare and pay a dividend after provision is made for reasonable and proper reserves, or unless Ameren Illinois has specific authorization from the ICC.
Ameren Illinois’ articles of incorporation require dividend payments on its common stock to be based on ratios of common stock to total capitalization and other provisions related to certain operating expenses and accumulations of earned surplus. Ameren Illinois committedhas made a commitment to the FERC to maintain a minimum 30% ratio of common stock equity to total capitalization. As of December 31, 20142017, using the FERC-agreed upon calculation method, Ameren Illinois’ ratio of common stock equity to total capitalization was 53%51%.
ATXI’s note purchase agreement includes financial covenants that require ATXI not to permit at any time (1) debt to exceed 70% of total capitalization or (2) secured debt to exceed 10% of total assets. The note purchase agreement also contains restrictive covenants that, among other things, restrict the ability of ATXI to (1) enter into certain transactions with affiliates; (2) consolidate, merge, transfer or lease all or substantially all of its assets; and (3) create liens.
At December 31, 2017, the Ameren Companies were in compliance with the provisions and covenants contained in their indentures and articles of incorporation, as applicable, and ATXI was in compliance with the provisions and covenants contained in its note purchase agreement. In order for the Ameren Companies to issue securities in the future, they will have to comply with all applicable requirements in effect at the time of any such issuances.
Off-Balance-Sheet Arrangements
At December 31, 20142017, none of the Ameren Companies had any significant off-balance-sheet financing arrangements, other than operating leases entered into in the ordinary course of business. None of the Ameren Companies expect to engage in any significant off-balance-sheet financing arrangements in the near future. See Note 16 – Divestiture Transactions and Discontinued Operations for Ameren (parent) guarantees andbusiness, letters of credit, issued to support New AER basedand Ameren (parent) guarantee arrangements on the transaction agreement with IPH.behalf of its subsidiaries.



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NOTE 6 OTHER INCOME AND EXPENSES
The following table presents the components of "Other“Other Income and Expenses"Expenses” in the Ameren Companies’ statements of income (loss) for the years ended December 31, 20142017, 20132016, and 20122015:
2014 2013 2012 2017 2016 2015 
Ameren:(a)
            
Miscellaneous income:            
Allowance for equity funds used during construction$34
 $37
 $36
 $24
 $27
 $30
 
Interest income on industrial development revenue bonds27
 27
 28
 26
 27
 27
 
Interest income10
(b) 
3
 4
(d) 
Interest income(b)
8
  
13
  
14
 
Other8
(c) 
2
 2
 1
 7
 3
 
Total miscellaneous income$79
 $69
 $70
 $59
 $74
 $74
 
Miscellaneous expense:            
Donations$10
 $12
 $24
(e) 
$8
 $16
 $15
 
Other12
 14
 13
 13
 16
 15
 
Total miscellaneous expense$22
 $26
 $37
 $21
 $32
 $30
 
Ameren Missouri:            
Miscellaneous income:            
Allowance for equity funds used during construction$32
 $31
 $31
 $21
 $23
 $22
 
Interest income on industrial development revenue bonds27
 27
 28
 26
 27
 27
 
Interest income1
 
 4
(d) 
1
 1
 1
 
Other
 1
 2
 
Total miscellaneous income$60
 $58
 $63
 $48
 $52
 $52
 
Miscellaneous expense:            
Donations$6
 $4
 $9
 $2
 $4
 $5
 
Other6
 7
 5
 6
 6
 6
 
Total miscellaneous expense$12
 $11
 $14
 $8
 $10
 $11
 
Ameren Illinois:            
Miscellaneous income:            
Allowance for equity funds used during construction$2
 $6
 $5
 $3
 $4
 $8
 
Interest income7
(b) 
2
 
 
Interest income(b)
7
  
12
  
12
 
Other8
(c) 
2
 2
 1
 5
 1
 
Total miscellaneous income$17
 $10
 $7
 $11
 $21
 $21
 
Miscellaneous expense:            
Donations$4
 $4
 $11
(e) 
$5
 $6
 $5
 
Other4
 5
 6
 5
 6
 7
 
Total miscellaneous expense$8
 $9
 $17
 $10
 $12
 $12
 
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)Includes Ameren Illinois'Illinois’ interest income received in 2014 relating toon the 2013 and 2014 IEIMA revenue requirement reconciliation adjustment regulatory assets.
(c)Includes Ameren Illinois' income earned in 2014 from customer-requested construction.
(d)Includes Ameren Missouri's interest income relating to a refund of charges included in an expired power purchase agreement with Entergy. See Note 2 – Rate and Regulatory Matters for additional information.
(e)
Includes Ameren Illinois' one-time $7.5 million contribution to the Illinois Science and Energy Innovation Trust pursuant to the IEIMA as a result of Ameren Illinois' participation in the electric delivery formula ratemaking process.
NOTE 7 DERIVATIVE FINANCIAL INSTRUMENTS
We use derivatives to manage the risk of changes in market prices for natural gas, power, and uranium, as well as the risk of changes in rail transportation surcharges through fuel oil hedges. Such price fluctuations may cause the following:
an unrealized appreciation or depreciation of our contracted commitments to purchase or sell when purchase or sale prices under the commitments are compared with current commodity prices;
market values of natural gas and uranium inventories that differ from the cost of those commodities in inventory; and
actual cash outlays for the purchase of these commodities
that differ from anticipated cash outlays.
The derivatives that we use to hedge these risks are governed by our risk management policies for forward contracts, futures, options, and swaps. Our net positions are continually assessed within our structured hedging programs to determine whether new or offsetting transactions are required. The goal of the hedging program is generally to mitigate financial risks while ensuring that sufficient volumes are available to meet our requirements. Contracts we enter into as part of our risk management program may be settled financially, settled by physical delivery, or net settled with the counterparty.



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The following table presents open gross commodity contract volumes by commodity type for derivative assets and liabilities as of December 31, 20142017 and 2013.2016. As of December 31, 2014,2017, these contracts ranextended through October 2017, October 2019, March 2023, May 2032, and October 2016September 2021 for fuel oils, natural gas, power, and uranium, respectively.
Quantity (in millions, except as indicated)Quantity (in millions, except as indicated)
2014201320172016
CommodityAmeren MissouriAmeren IllinoisAmerenAmeren MissouriAmeren IllinoisAmerenAmeren MissouriAmeren IllinoisAmerenAmeren MissouriAmeren IllinoisAmeren
Fuel oils (in gallons)(a)
50(b)5066(b)6628
(b)
28
30
(b)
30
Natural gas (in mmbtu)281081362810813624
139
163
25
129
154
Power (in megawatthours)11112311143
9
12
1
9
10
Uranium (pounds in thousands)332(b)332796(b)796370
(b)
370
345
(b)
345
(a)Fuel oils consistConsists of heating oil, ultra-low-sulfur diesel and crude oil.products.
(b)Not applicable.
Authoritative accounting guidance regarding derivative instruments requires that allAll contracts considered to be derivative instruments are required to be recorded on the balance sheet at their fair values, unless the NPNS exception applies. See Note 8 – Fair Value Measurements for discussion of our methods of assessing the fair value of derivative instruments. Many of our physical contracts, such as our purchased power contracts, qualify for the NPNS exception to derivative accounting rules. The revenue or expense on NPNS contracts is recognized at the contract price upon physical delivery.
If we determine that a contract meets the definition of a derivative and is not eligible for the NPNS exception, we review the contract to determine if it qualifies for hedge accounting. We also consider whether the resulting gains or losses resulting from such derivatives qualify for regulatory deferral. Derivative contracts that qualify for regulatory deferral are recorded at fair value, with changes in fair value recorded as regulatory assets or regulatory
liabilities in the period in which the change occurs. We believe derivative losses and gains deferred as regulatory assets and regulatory liabilities are probable of recovery, or refund, through future rates charged to customers. Regulatory assets and regulatory liabilities are amortized to operating income as related losses and gains are reflected in rates charged to customers. Therefore, gains and losses on these derivatives have no effect on operating income. As of December 31, 20142017 and 2013,2016, all contracts that qualifymet the definition of a derivative and were not eligible for hedge accounting receivethe NPNS exception received regulatory deferral.
Authoritative accounting guidance permits companies to offset fair value amounts recognized for the right to reclaim cash collateral (a receivable) or the obligation to return cash collateral (a liability) against fair value amounts recognized for derivative instruments that are executed with the same counterparty under a master netting arrangement. The Ameren Companies did not elect to adopt this guidance for any eligible commodity contracts.


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The following table presents the carrying value and balance sheet location of all derivative commodity contracts, none of which were designated as hedging instruments, as of December 31, 20142017 and 20132016:
Balance Sheet Location 
Ameren
Missouri
 
Ameren
Illinois
 AmerenBalance Sheet Location 
Ameren
Missouri
 
Ameren
Illinois
 Ameren 
2014      
Fuel oilsOther current assets$2
$
$2
Natural gasOther current assets 1
 1
 2
PowerOther current assets 15
 
 15
Total assets$18
$1
$19
Fuel oilsOther current liabilities$22
$
$22
Other deferred credits and liabilities 7
 
 7
Natural gasMTM derivative liabilities (a)
 31
 (a)
Other current liabilities 6
 
 37
Other deferred credits and liabilities 6
 13
 19
PowerMTM derivative liabilities (a)
 11
 (a)
Other current liabilities 3
 
 14
Other deferred credits and liabilities 
 131
 131
UraniumOther current liabilities 2
 
 2
Total liabilities$46
$186
$232
2013      
2017       
Fuel oilsOther current assets$6
$
$6
Other current assets$5
$
$5
 
Other assets 3
 
 3
Other assets 2
 
 2
 
Natural gasOther current assets 1
 1
 2
Other assets 1
 
 1
 
PowerOther current assets 23
 
 23
Other current assets 9
 
 9
 
Total assets$33
$1
$34
Total assets (a)
$17
$
$17
 
Natural gasOther current liabilities 5
 12
 17
 
Other deferred credits and liabilities 3
 10
 13
 
PowerOther current liabilities 1
 13
 14
 
Other deferred credits and liabilities 
 182
 182
 
UraniumOther deferred credits and liabilities 
(b) 

 
(b) 
Total liabilities (c)
$9
$217
$226
 
2016       
Fuel oilsOther current liabilities$2
$
$2
Other current assets$2
$
$2
 
Other deferred credits and liabilities 1
 
 1
Other assets 1
 
 1
 
Natural gasMTM derivative liabilities (a)
 27
 (a)
Other current assets 1
 11
 12
 
Other current liabilities 5
 
 32
Other assets 1
 2
 3
 
PowerOther current assets 9
 
 9
 
Total assets (a)
$14
$13
$27
 
Fuel oilsOther current liabilities$5
$
$5
 
Natural gasOther current liabilities 1
 3
 4
 
Other deferred credits and liabilities 6
 19
 25
Other deferred credits and liabilities 5
 5
 10
 
PowerMTM derivative liabilities (a)
 9
 (a)
Other current liabilities 3
 12
 15
 
Other current liabilities 4
 
 13
Other deferred credits and liabilities 
 173
 173
 
Other deferred credits and liabilities 
 99
 99
UraniumOther current liabilities 5
 
 5
Other deferred credits and liabilities 4
 
 4
 
Other deferred credits and liabilities 1
 
 1
Total liabilities (c)
$18
$193
$211
 
Total liabilities$24
$154
$178
(a)Balance sheet line item not applicable to registrant.
The following table presents the cumulative amount of pretax net gains (losses) on all derivative instruments deferred in regulatory assets or regulatory liabilities as of December 31, 2014 and 2013:
  
Ameren
Missouri
 
Ameren
Illinois
 Ameren
2014      
Fuel oils derivative contracts(a)
$(29)$
$(29)
Natural gas derivative contracts(b)
 (11) (43) (54)
Power derivative contracts(c)
 12
 (142) (130)
Uranium derivative contracts(d)
 (2) 
 (2)
2013      
Fuel oils derivative contracts$2
$
$2
Natural gas derivative contracts (10) (45) (55)
Power derivative contracts 19
 (108) (89)
Uranium derivative contracts (6) 
 (6)
(a)
Represents net losses associated with fuel oilsgains on all derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri’s rail transportation surcharges for coal through December 2017. Current lossesinstruments is deferred as a regulatory assets include $21 million and $21 million at Ameren and Ameren Missouri,
liability.

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respectively.
(b)
Represents net losses associated with natural gasBeginning in 2017, as a result of rulebook amendments at the Chicago Mercantile Exchange, the fair value of uranium derivative contracts. These contractsliabilities are a partial hedge of natural gas requirements through October 2019 at Amerenoffset by certain settlement payments made to the exchange previously characterized as collateral and included within “Other assets” on Ameren’s and Ameren Missouri and through October 2018 at Ameren Illinois. Current gains deferred as regulatory liabilities include $2 million, $1 million, and $1 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively. Current losses deferred as regulatory assets include $37 million, $6 million, and $31 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively.
Missouri’s balance sheet.
(c)
RepresentsThe cumulative amount of pretax net gains (losses) associated with powerlosses on all derivative contracts. These contracts are a partial hedge of power price requirements through May 2032 at Ameren and Ameren Illinois and through December 2015 at Ameren Missouri. Current gainsinstruments is deferred as a regulatory liabilities include $15 million and $15 million at Ameren and Ameren Missouri, respectively. Current losses deferred as regulatory assets include $14 million, $3 million, and $11 million at Ameren, Ameren Missouri, and Ameren Illinois, respectively.
(d)
Represents net losses associated with uranium derivative contracts at Ameren Missouri. These contracts are a partial hedge of Ameren Missouri's uranium requirements through December 2016. Current losses deferred as regulatory assets include $2 million and $2 million at Ameren and Ameren Missouri, respectively.
asset.
Derivative instruments are subject to various credit-related losses in the event of nonperformance by counterparties to the transaction. Exchange-traded contracts are supported by the financial and credit quality of the clearing members of the respective exchanges andexchanges; these contracts have nominal credit risk. In all other transactions, we are exposed to credit risk. Our credit risk management program involves establishing credit limits and collateral requirements for counterparties, using master netting arrangements or similar agreements, and reporting daily exposure to senior management.
We believe that entering into master netting arrangements or similar agreements mitigates the level of financial loss that could result from default by allowing net settlement of derivative assets and liabilities. We generally enter into the following master netting arrangements: (1) the International Swaps and Derivatives Association Agreement, a standardized financial natural gas and electric contract; (2) the Master Power Purchase and Sale Agreement, created by the Edison Electric Institute and the National Energy Marketers Association, a standardized contract for the purchase and sale of wholesale power; and (3) the North American Energy Standards Board Inc. Agreement, a standardized contract for the purchase and sale of natural gas. These master netting arrangements allow the counterparties to net settle sale and purchase transactions. Further, collateral requirements are calculated at the master netting arrangement or similar agreement level by counterparty.
The following table providesAmeren Companies elect to present the recognized gross derivative balances and the netfair value amounts of those derivativesderivative assets and derivative liabilities subject to an enforceable master netting arrangement or similar agreement as ofgross on the balance sheet. However, if the gross amounts recognized on the balance sheet were netted with derivative instruments and cash collateral received or posted, the net amounts would not be materially different from the gross amounts at December 31, 20142017 and 2013:2016.
    Gross Amounts Not Offset on the Balance Sheet  
Commodity Contracts Eligible to be Offset Gross Amounts Recognized on the Balance Sheet Derivative Instruments 
Cash Collateral Received/Posted(a)
 
Net
Amount
2014        
Assets:        
Ameren Missouri$18
$5
$
$13
Ameren Illinois 1
 
 
 1
Ameren$19
$5
$
$14
Liabilities:        
Ameren Missouri$46
$5
$5
$36
Ameren Illinois 186
 
 
 186
Ameren$232
$5
$5
$222
2013        
Assets:        
Ameren Missouri$33
$9
$
$24
Ameren Illinois 1
 1
 
 
Ameren$34
$10
$
$24
Liabilities:        
Ameren Missouri$24
$9
$9
$6
Ameren Illinois 154
 1
 15
 138
Ameren$178
$10
$24
$144
(a)
Cash collateral received reduces gross asset balances and is included in “Other current liabilities” and “Other deferred credits and liabilities” on the balance sheet. Cash collateral posted reduces gross liability balances and is included in “Other current assets” and “Other assets” on the balance sheet.
Concentrations of Credit Risk
In determining our concentrations of credit risk related to derivative instruments, we review our individual counterparties and categorize each counterparty into groupings according to the primary business in which each engages. We calculate maximum exposures based on the gross fair value of financial instruments, including NPNS and other accrual contracts. These exposures are calculated on a gross basis, which include affiliate exposure not eliminated at the consolidated Ameren level. As of December 31, 2014,2017, if counterparty groups were to fail completely to perform on contracts, the Ameren Ameren Missouri, and Ameren Illinois'Companies’ maximum exposure was $5 million, $5 million, and $- million, respectively. The potential loss on counterparty exposures is reduced by the application of master netting arrangements and

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collateral held, to the extent of reducing the exposure to zero. As of December 31, 2014, the potential loss afterwould have been immaterial with or without consideration of the application of master netting arrangements or similar agreements and collateral held for Ameren, Ameren Missouri, and Ameren Illinois was $5 million, $5 million, and $- million, respectively.held.

Derivative Instruments with Credit Risk-Related Contingent Features
Our commodity contracts contain collateral provisions tied to the Ameren Companies’ credit ratings. If we were to experience an adverse change in our credit ratings were downgraded, or if a counterparty with reasonable grounds for uncertainty regarding performance ofour ability to satisfy an obligation requested adequate assurance of performance, additional collateral postings might be required. The following table presents, as of December 31, 2014,2017, the aggregate fair value of all derivative instruments with credit risk-related contingent features in a gross liability position, the cash collateral posted, and the aggregate amount of additional collateral that counterparties could be required to be posted with counterparties.require. The additional collateral required is the net liability position allowed under the master netting arrangements or similar agreements, assuming (1) the credit risk-related contingent features underlying these arrangements were triggered on December 31, 2014,2017, and (2) those counterparties with rights to do so requested collateral.
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional Collateral Required(b)
Aggregate Fair Value of
Derivative Liabilities(a)
 
Cash
Collateral Posted
 
Potential Aggregate Amount of
Additional Collateral Required(b)
2017     
Ameren Missouri$96
 $4
 $88
$55
 $3
 $44
Ameren Illinois74
 
 71
43
 
 38
Ameren$170
 $4
 $159
$98
 $3
 $82
(a)Prior toBefore consideration of master netting arrangements or similar agreements and including NPNS and other accrual contract exposures.
(b)As collateral requirements with certain counterparties are based on master netting arrangements or similar agreements, the aggregate amount of additional collateral required to be posted is determined after consideration of the effects of such arrangements.
NOTE 8 FAIR VALUE MEASUREMENTS
Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. We use various methods to determine fair value, including market, income, and cost approaches. With these approaches, we adopt certain assumptions that market participants would use in pricing the asset or liability, including assumptions about market risk or the risks inherent in the inputs to the valuation. Inputs to valuation can be readily observable, market-corroborated, or unobservable. We use valuation techniques that maximize the use of observable inputs and minimize the use of unobservable inputs. Authoritative accounting guidance established a fair value hierarchy that prioritizes the inputs used to measure fair value. All financial assets and liabilities carried at fair value are classified and disclosed in one of the following three hierarchy levels:
Level 11:: Inputs based on quoted prices in active markets for identical assets or liabilities. Level 1 assets and liabilities are primarily exchange-traded derivatives and assets, including cash and cash equivalents and listed equity securities, such as those held in Ameren Missouri’s nuclear decommissioning trust fund.
The market approach is used to measure the fair value of equity securities held in Ameren Missouri'sMissouri’s nuclear decommissioning trust fund. Equity securities in this fund are representative of the S&P 500 index, excluding securities of Ameren Corporation, owners and/or operators of nuclear power plants, and the trustee and investment managers. The S&P 500 index comprises stocks of large-capitalization companies.
Level 2: Market-based inputs corroborated by third-party brokers or exchanges based on transacted market data. Level 2 assets and liabilities include certain assets held in Ameren Missouri’s
nuclear decommissioning trust fund, including corporate bonds and other fixed-income securities, United States Treasury and agency securities, and certain over-the-counter derivative instruments, including natural gas and financial power transactions.
Fixed income securities are valued by using prices from independent industry recognizedindustry-recognized data vendors who provide values that are either exchange-based or matrix-based. The fair value measurements of fixed incomefixed-income securities classified as Level 2 are based on inputs other than quoted prices that are observable for the asset or liability. Examples are matrix pricing, market corroborated pricing, and inputs such as yield curves and indices. Level 2 fixed income securities in the nuclear decommissioning trust fund are primarily corporate bonds, asset-backed securities, and United States agency bonds.
Derivative instruments classified as Level 2 are valued by corroborated observable inputs, such as pricing services or prices from similar instruments that trade in liquid markets. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. To derive our forward view to price our derivative instruments at fair value, we average the midpoints ofbid/ask spreads to the bid/ask spreads.midpoints. To validate forward prices obtained from outside parties, we compare the pricing to recently settled market transactions. Additionally, a review of all sources is performed to identify any anomalies or potential errors. Further, we consider the volume of transactions on certain trading platforms in our reasonableness assessment of the averaged midpoint. Naturalmidpoints. The value of natural gas derivative contracts are valuedis based upon exchange closing prices without significant unobservable adjustments. PowerThe value of power derivatives contracts are valuedis based upon exchange closing prices or the use of multiple forward prices provided by third parties. The prices are averaged and shaped to a monthly profile when needed without significant unobservable adjustments.



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Level 33:: Unobservable inputs that are not corroborated by market data. Level 3 assets and liabilities are valued by internally developed models and assumptions or methodologies that use significant unobservable inputs. Level 3 assets and liabilities include derivative instruments that trade in less liquid markets, where pricing is largely unobservable. We value Level 3 instruments by using pricing models with inputs that are often unobservable in the market, as wellsuch as certain internal assumptions.assumptions, quotes or prices from outside sources not supported by a liquid market, or escalation rates. Our development and corroboration process entails obtaining multiple quotes or prices from outside sources. As a
part of our reasonableness review,reviews and an evaluation of all sources is performed to identify any anomalies or potential errors.
We perform an analysis each quarter to determine the appropriate hierarchy level of the assets and liabilities subject to fair value measurements. Financial assets and liabilities are classified in their entirety according to the lowest level of input that is significant to the fair value measurement. All assets and liabilities whose fair value measurement is based on significant unobservable inputs are classified as Level 3.

The following table describes the valuation techniques and unobservable inputs utilized by the Ameren Companies for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy for the periodperiods ended December 31, 2014:2017 and 2016:
  Fair Value    Weighted
  AssetsLiabilities Valuation Technique(s)Unobservable InputRangeAverage
Level 3 Derivative asset and liability – commodity contracts(a):
   
AmerenFuel oils$2
$(8) Option model
Volatilities(%)(b)
3 - 3932
     Discounted cash flow
Ameren Missouri credit risk(%)(b)(c)
0.43(d)
      
Escalation rate(%)(e)(f)
5(d)
 Natural Gas1
(2) Option model
Volatilities(%)(b)
31 - 14463
 


 
Nodal basis($/mmbtu)(e)
(0.40) - 0(0.20)
 


 Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.40) - 0.10(0.20)
 


 
Counterparty credit risk(%)(b)(c)
0.43 - 133
 


 
Ameren Missouri and Ameren Illinois credit risk(%)(b)(c)
0.43(d)
 
Power(g)
11
(144) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(h)
27 - 5032
      
Estimated auction price for FTRs($/MW)(e)
(1,833) - 2,743171
      
Nodal basis($/MWh)(e)
(6) - 0(2)
      
Counterparty credit risk(%)(b)(c)
0.26(d)
      
Ameren Missouri and Ameren Illinois credit risk(%)(b)(c)
0.43(d)
     Fundamental energy production model
Estimated future gas prices($/mmbtu)(e)
4 - 54
      
Escalation rate(%)(e)(i)
0 - 11
     Contract price allocation
Estimated renewable energy credit costs($/credit)(e)
5 - 76
 Uranium
(2) Discounted cash flow
Average forward uranium pricing($/pound)(e)
35 - 4036
Ameren MissouriFuel oils$2
$(8) Option model
Volatilities(%)(b)
3 - 3932
     Discounted cash flow
Ameren Missouri credit risk(%)(b)(c)
0.43(d)
      
Escalation rate(%)(e)(f)
5(d)
 Natural Gas
(1) Option model
Volatilities(%)(b)
31 - 14453
 


 
Nodal basis($/mmbtu)(e)
(0.40) - 0(0.30)
 


 Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.10)(d)
 


 
Counterparty credit risk(%)(b)(c)
0.57 - 135
 


 
Ameren Missouri credit risk(%)(b)(c)
0.43(d)
 
Power(g)
11
(2) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(b)
27 - 5032
      
Estimated auction price for FTRs($/MW)(e)
(1,833) - 2,743171
      
Counterparty credit risk(%)(b)(c)
0.26(d)
      
Ameren Missouri credit risk(%)(b)(c)
0.43(d)
 Uranium
(2) Discounted cash flow
Average forward uranium pricing($/pound)(e)
35 - 4036
Ameren IllinoisNatural Gas$1
$(1) Option model
Volatilities(%)(b)
50 - 14494
 


 
Nodal basis($/mmbtu)(e)
(0.10) - 0(0.10)
 


 Discounted cash flow
Nodal basis($/mmbtu)(e)
(0.40) - 0.10(0.20)
 


 
Counterparty credit risk(%)(b)(c)
0.43 - 20.83
 


 
Ameren Illinois credit risk(%)(b)(c)
0.43(d)
  Fair Value    Weighted
  AssetsLiabilities Valuation Technique(s)Unobservable InputRangeAverage
Level 3 Derivative asset and liability – commodity contracts(a):
   
2017        
 Fuel oils$3
$
 Option model
Volatilities(%)(b)
20  26
22
     Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.12  0.72
0.41
      
Ameren Missouri credit risk(%)(c)(d)
0.37(e)
 Natural Gas1
(4) Option model
Volatilities(%)(b)
26  46
37
 


 
Nodal basis($/mmbtu)(c)
(0.50)  (0.30)
(0.40)
 


 Discounted cash flow
Nodal basis($/mmbtu)(b)
(1.20)  0.10
(1)
 


 
Counterparty credit risk(%)(c)(d)
0.37  0.92
0.53
 


 
Ameren credit risk(%)(c)(d)
0.37(e)
 
Power(f)
8
(196) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(g)
24  46
28
      
Estimated auction price for FTRs($/MW)(b)
(65)  1,823
251
      
Nodal basis($/MWh)(g)
(10)  0
(2)
      
Counterparty credit risk(%)(c)(d)
0.28(e)
      
Ameren Illinois credit risk(%)(c)(d)
0.37(e)
     Fundamental energy production model
Estimated future natural gas prices($/mmbtu)(b)
3  4
3
      
Escalation rate(%)(b)(h)
5(e)
     Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5  7
6
2016        
 Fuel oils$1
$
 Option model
Volatilities(%)(b)
24 – 6628
     Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.13 – 0.220.15
      
Ameren Missouri credit risk(%)(c)(d)
0.38(e)
      
Escalation rate(%)(b)(i)
(2) – 20
 Natural Gas$1
$(1) Option model
Volatilities(%)(b)
31 – 6636
      
Nodal basis($/mmbtu)(b)
(0.40) – (0.10)(0.20)
     Discounted cash flow
Nodal basis($/mmbtu)(b)
(0.80) – 0(0.50)
      
Counterparty credit risk(%)(c)(d)
0.13 – 81
      
Ameren Illinois credit risk(%)(c)(d)
0.38(e)
 
Power(f)
9
(187) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(g)
26 – 4429
      
Estimated auction price for FTRs($/MW)(b)
(71) – 5,270125
      
Nodal basis($/MWh)(g)
(6) – 0(2)
      
Ameren Illinois credit risk(%)(c)(d)
0.38(e)
     Fundamental energy production model
Estimated future natural gas prices($/mmbtu)(b)
3 – 43
      
Escalation rate(%)(b)(h)
5(e)
     Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 – 76
 Uranium
(4) Option model
Volatilities(%)(b)
24(e)

109


  Fair Value    Weighted
  AssetsLiabilities Valuation Technique(s)Unobservable InputRangeAverage
 
Power(g)

(142) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(e)
27 - 3832
      
Nodal basis($/MWh)(e)
(6) - 0(2)
      
Ameren Illinois credit risk(%)(b)(c)
0.43(d)
     Fundamental energy production model
Estimated future gas prices($/mmbtu)(e)
4 - 54
      
Escalation rate(%)(e)(i)
0 - 11
     Contract price allocation
Estimated renewable energy credit costs($/credit)(e)
5 - 76
Fair ValueWeighted
AssetsLiabilitiesValuation Technique(s)Unobservable InputRangeAverage
Discounted cash flow
Average forward uranium pricing($/pound)(b)
22 – 2422
Ameren Missouri credit risk(%)(c)(d)
0.38(e)
(a)The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(c)Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(d)Not applicable.
(e)Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(f)Escalation rate applies to fuel oil prices 2017 and beyond.
(g)Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2018. Valuations beyond 2018 use fundamentally modeled pricing by month for peak and off-peak demand.
(h)The balance at Ameren is comprised of Ameren Missouri and Ameren Illinois power contracts, which respond differently to unobservable input changes due to their opposing positions. As such, refer to the power sensitivity analysis for each company above.
(i)Escalation rate applies to power prices 2026 and beyond.
The following table describes the valuation techniques and unobservable inputs for the fair value of financial assets and liabilities classified as Level 3 in the fair value hierarchy as of December 31, 2013:
  Fair Value    Weighted
  AssetsLiabilities Valuation TechniqueUnobservable InputRangeAverage
Level 3 Derivative asset and liability – commodity contracts(a):
   
AmerenFuel oils$8
$(3) Option model
Volatilities(%)(b)
10 - 3516
     Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.26 - 21
 
Power(e)
21
(110) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(c)
25 - 5132
      
Estimated auction price for FTRs($/MW)(b)
(1,594) - 945305
      
Nodal basis($/MWh)(c)
(3) - (1)(2)
      
Counterparty credit risk(%)(c)(d)
0.39 - 0.500.42
      
Ameren Missouri and Ameren Illinois credit risk(%)(c)(d)
2(f)
     Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 55
      
Escalation rate(%)(b)(g)
3 - 44
     Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 76
 Uranium
(6) Discounted cash flow
Average forward uranium pricing($/pound)(b)
34 - 4136
Ameren MissouriFuel oils$8
$(3) Option model
Volatilities(%)(b)
10 - 3516
     Discounted cash flow
Counterparty credit risk(%)(c)(d)
0.26 - 21
 
Power(e)
21
(2) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(c)
25 - 5140
      
Estimated auction price for FTRs($/MW)(b)
(1,594) - 945305
      
Nodal basis($/MWh)(c)
(3) - (1)(2)
      
Counterparty credit risk(%)(c)(d)
0.39 - 0.500.42
      
Ameren Missouri credit risk(%)(c)(d)
2(f)
 Uranium
(6) Discounted cash flow
Average forward uranium pricing($/pound)(b)
34 - 4136
Ameren Illinois
Power(e)
$
$(108) Discounted cash flow
Average forward peak and off-peak pricing – forwards/swaps($/MWh)(b)
27 - 3630
      
Nodal basis($/MWh)(b)
(4) - 0(2)
      
Ameren Illinois credit risk(%)(c)(d)
2(f)
     Fundamental energy production model
Estimated future gas prices($/mmbtu)(b)
4 - 55
      
Escalation rate(%)(b)(g)
3 - 44
     Contract price allocation
Estimated renewable energy credit costs($/credit)(b)
5 - 76

110


(a)
The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)Generally, significant increases (decreases) in this input in isolation would result in a significantly higher (lower) fair value measurement.
(c)Generally, significant increases (decreases) in this input in isolation would result in a significantly lower (higher) fair value measurement.
(d)Counterparty credit risk is applied only to counterparties with derivative asset balances. Ameren Missouri and Ameren Illinois credit risk is applied only to counterparties with derivative liability balances.
(e)Not applicable.
(f)Power valuations use visible third-party pricing evaluated by month for peak and off-peak demand through 2017.2021. Valuations beyond 20172021 use fundamentally modeled pricing by month for peak and off-peak demand.
(f)(g)Not applicable.Ameren Missouri and Ameren Illinois power contracts respond differently to unobservable input changes because of their opposing positions.
(g)(h)Escalation rate applies to power prices 2026in 2031 and beyond.
(i)Escalation rate applies to fuel oil prices in 2019 and beyond.
In accordance with applicable authoritative accounting guidance, weWe consider nonperformance risk in our valuation of derivative instruments by analyzing the credit standing of our counterparties and considering any counterparty credit enhancements (e.g., collateral). The guidance also requires that the fair value measurement of liabilities reflect the nonperformance risk of the reporting entity, as applicable. Therefore, we have factored the impact of our credit standing, as well as any potential credit enhancements, into the fair value measurement of both derivative assets and derivative liabilities. Included in our valuation, and based on current market conditions, is a valuation adjustment for counterparty default
derived from market data such as the price of credit default swaps, bond yields, and credit ratings. No gains or losses related to valuation adjustments for counterparty default risk were recorded at Ameren, Ameren Missouri, or Ameren Illinois in 2014, 20132017, 2016, or 2012.2015. At December 31, 20142017, and 2016, the counterparty default risk liability valuation adjustment related to derivative contracts totaled $1 million, less than $1 million, and $1 million,was immaterial for Ameren, Ameren Missouri, and Ameren Illinois, respectively. At December 31, 2013, the counterparty default risk liability valuation adjustment related to derivative contracts totaled $3 million, less than $1 million, and $3 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively.Illinois.

The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 20142017:
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total  
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total 
Assets:                  
Ameren
Derivative assets – commodity contracts(a):
         
Derivative assets – commodity contracts(a):
         
Fuel oils $
 $
 $2
 $2
 Fuel oils $4
 $
 $3
 $7
 
Natural gas 
 1
 1
 2
 Natural gas 
 
 1
 1
 
Power 
 4
 11
 15
 Power 
 1
 8
 9
 
Total derivative assets – commodity contracts $
 $5
 $14
 $19
 Total derivative assets – commodity contracts $4
 $1
 $12
 $17
 
Nuclear decommissioning trust fund:         Nuclear decommissioning trust fund:         
Cash and cash equivalents $1
 $
 $
 $1
 Cash and cash equivalents $2
 $
 $
 $2
 
Equity securities:         Equity securities:         
U.S. large capitalization 364
 
 
 364
 U.S. large capitalization 468
 
 
 468
 
Debt securities:         Debt securities:         
Corporate bonds 
 63
 
 63
 U.S. Treasury and agency securities 
 125
 
 125
 
Municipal bonds 
 2
 
 2
 Corporate bonds 
 82
 
 82
 
U.S. treasury and agency securities 
 102
 
 102
 Other 
 25
 
 25
 
Asset-backed securities 
 10
 
 10
 Total nuclear decommissioning trust fund $470
 $232
 $
 $702
(b) 
Other 
 5
 
 5
 Total Ameren $474
 $233
 $12
 $719
 
Total nuclear decommissioning trust fund $365
 $182
 $
 $547
(b) 
Total Ameren $365
 $187
 $14
 $566
 
Ameren Missouri
Derivative assets – commodity contracts(a):
         
Derivative assets – commodity contracts(a):
         
Fuel oils $
 $
 $2
 $2
 Fuel oils $4
 $
 $3
 $7
 
Natural gas 
 1
 
 1
 Natural gas 
 
 1
 1
 
Power 
 4
 11
 15
 Power 
 1
 8
 9
 
Total derivative assets – commodity contracts $
 $5
 $13
 $18
 Total derivative assets – commodity contracts $4
 $1
 $12
 $17
 

111


 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total  
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total 
Nuclear decommissioning trust fund:         Nuclear decommissioning trust fund:         
Cash and cash equivalents $1
 $
 $
 $1
 Cash and cash equivalents $2
 $
 $
 $2
 
Equity securities:         Equity securities:         
U.S. large capitalization 364
 
 
 364
 U.S. large capitalization 468
 
 
 468
 
Debt securities:         Debt securities:         
Corporate bonds 
 63
 
 63
 U.S. Treasury and agency securities 
 125
 
 125
 
Municipal bonds 
 2
 
 2
 Corporate bonds 
 82
 
 82
 
U.S. treasury and agency securities 
 102
 
 102
 Other 
 25
 
 25
 
Asset-backed securities 
 10
 
 10
 Total nuclear decommissioning trust fund $470
 $232
 $
 $702
(b) 
Other 
 5
 
 5
 Total Ameren Missouri $474
 $233
 $12
 $719
 
Total nuclear decommissioning trust fund $365
 $182
 $
 $547
(b) 
Total Ameren Missouri $365
 $187
 $13
 $565
 
Ameren Illinois
Derivative assets – commodity contracts(a):
         
Natural gas $
 $
 $1
 $1
 
Liabilities:                  
Ameren
Derivative liabilities – commodity contracts(a):
         
Derivative liabilities – commodity contracts(a):
         
Fuel oils $21
 $
 $8
 $29
 
Natural gas 1
 53
 2
 56
 
Power 
 1
 144
 145
 Natural gas 1
 25
 4
 30
 
Uranium 
 
 2
 2
 Power 
 
 196
 196
 
Total Ameren $22
 $54
 $156
 $232
 Total Ameren $1
 $25
 $200
 $226
 
Ameren Missouri
Derivative liabilities – commodity contracts(a):
         
Derivative liabilities – commodity contracts(a):
         
Fuel oils $21
 $
 $8
 $29
 Natural gas 
 7
 1
 8
 
Natural gas 1
 10
 1
 12
 Power 
 
 1
 1
 
Power 
 1
 2
 3
 Total Ameren Missouri $
 $7
 $2
 $9
 
Uranium 
 
 2
 2
 
Total Ameren Missouri $22
 $11
 $13
 $46
 
Ameren Illinois
Derivative liabilities – commodity contracts(a):
         
Derivative liabilities – commodity contracts(a):
         
Natural gas $
 $43
 $1
 $44
 Natural gas $1
 $18
 $3
 $22
 
Power 
 
 142
 142
 Power 
 
 195
 195
 
Total Ameren Illinois $
 $43
 $143
 $186
 Total Ameren Illinois $1
 $18
 $198
 $217
 
(a)The derivative asset and liability balances are presented net of counterparty credit considerations.
(b)Balance excludes $2 million of receivables, payables, and accrued income, net.
The following table sets forth, by level within the fair value hierarchy, our assets and liabilities measured at fair value on a recurring basis as of December 31, 20132016:
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant
Other
Unobservable
Inputs
(Level 3)
 Total 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total 
Assets:                 
Ameren
Derivative assets – commodity contracts(a):
        
Derivative assets – commodity contracts(a):
         
Fuel oils $1
 $
 $8
 $9
Fuel oils $2
 $
 $1
 $3
 
Natural gas 
 2
 
 2
Natural gas 2
 12
 1
 15
 
Power 
 2
 21
 23
Power 
 
 9
 9
 
Total derivative assets – commodity contracts $1
 $4
 $29
 $34
Total derivative assets – commodity contracts $4
 $12
 $11
 $27
 

112


 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant
Other
Unobservable
Inputs
(Level 3)
 Total
Nuclear decommissioning trust fund:        
Cash and cash equivalents $3
 $
 $
 $3
 
Quoted Prices in
Active Markets for
Identical Assets
or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total 
Equity securities:        Nuclear decommissioning trust fund:         
U.S. large capitalization 332
 
 
 332
Cash and cash equivalents $1
 $
 $
 $1
 
Debt securities:        Equity securities:         
Corporate bonds 
 52
 
 52
U.S. large capitalization 408
 
 
 408
 
Municipal bonds 
 2
 
 2
Debt securities:         
U.S. treasury and agency securities 
 94
 
 94
U.S. Treasury and agency securities 
 112
 
 112
 
Asset-backed securities 
 10
 
 10
Corporate bonds 
 67
 
 67
 
Other 
 1
 
 1
Other 
 17
 
 17
 
Total nuclear decommissioning trust fund $335
 $159
 $
 $494
Total nuclear decommissioning trust fund $409
 $196
 $
 $605
(b) 
Total Ameren $336
 $163
 $29
 $528
Total Ameren $413
 $208
 $11
 $632
 
Ameren Missouri
Derivative assets – commodity contracts(a):
        
Derivative assets – commodity contracts(a):
         
Fuel oils $1
 $
 $8
 $9
Natural gas 
 1
 
 1
Power 
 2
 21
 23
Fuel oils $2
 $
 $1
 $3
 
Total derivative assets – commodity contracts $1
 $3
 $29
 $33
Natural gas 
 1
 1
 2
 
Nuclear decommissioning trust fund:        Power 
 
 9
 9
 
Cash and cash equivalents $3
 $
 $
 $3
Total derivative assets – commodity contracts $2
 $1
 $11
 $14
 
Equity securities:        Nuclear decommissioning trust fund:         
U.S. large capitalization 332
 
 
 332
Cash and cash equivalents $1
 $
 $
 $1
 
Debt securities:        Equity securities:         
Corporate bonds 
 52
 
 52
U.S. large capitalization 408
 
 
 408
 
Municipal bonds 
 2
 
 2
Debt securities:         
U.S. treasury and agency securities 
 94
 
 94
U.S. Treasury and agency securities 
 112
 
 112
 
Asset-backed securities 
 10
 
 10
Corporate bonds 
 67
 
 67
 
Other 
 1
 
 1
Other 
 17
 
 17
 
Total nuclear decommissioning trust fund $335
 $159
 $
 $494
Total nuclear decommissioning trust fund $409
 $196
 $
 $605
(b) 
Total Ameren Missouri $336
 $162
 $29
 $527
Total Ameren Missouri $411
 $197
 $11
 $619
 
Ameren Illinois
Derivative assets – commodity contracts(a):
        
Derivative assets – commodity contracts(a):
         
Natural gas $
 $1
 $
 $1
Natural gas $2
 $11
 $
 $13
 
Liabilities:                 
Ameren
Derivative liabilities – commodity contracts(a):
        
Derivative liabilities – commodity contracts(a):
         
Fuel oils $
 $
 $3
 $3
Fuel oils $5
 $
 $
 $5
 
Natural gas 3
 54
 
 57
Natural gas 
 13
 1
 14
 
Power 
 2
 110
 112
Power 
 1
 187
 188
 
Uranium 
 
 6
 6
Uranium 
 
 4
 4
 
Total Ameren $3
 $56
 $119
 $178
Total Ameren $5
 $14
 $192
 $211
 
Ameren Missouri
Derivative liabilities – commodity contracts(a):
        
Derivative liabilities – commodity contracts(a):
         
Fuel oils $
 $
 $3
 $3
Fuel oils $5
 $
 $
 $5
 
Natural gas 3
 8
 
 11
Natural gas 
 6
 
 6
 
Power 
 2
 2
 4
Power 
 1
 2
 3
 
Uranium 
 
 6
 6
Uranium 
 
 4
 4
 
Total Ameren Missouri $3
 $10
 $11
 $24
Total Ameren Missouri $5
 $7
 $6
 $18
 
Ameren Illinois
Derivative liabilities – commodity contracts(a):
        
Derivative liabilities – commodity contracts(a):
         
Natural gas $
 $46
 $
 $46
Natural gas $
 $7
 $1
 $8
 
Power 
 
 108
 108
Power 
 
 185
 185
 
Total Ameren Illinois $
 $46
 $108
 $154
Total Ameren Illinois $
 $7
 $186
 $193
 
(a)The derivative asset and liability balances are presented net of counterparty credit considerations.

(b)Balance excludes $2 million of receivables, payables, and accrued income, net.
113


The following table summarizes the changes in the fair value ofAll costs related to financial assets and liabilities classified as Level 3 in the fair value hierarchy forare expected to be recoverable through customer rates; therefore, there is no impact to net income resulting from changes in the yearfair value of these instruments. For the years ended December 31, 2014:2017 and 2016, the balances and changes in the fair value of Level 3 financial assets and liabilities associated with fuel oils, natural gas, and uranium were immaterial.

   Net Derivative Commodity Contracts
   
Ameren
Missouri
 
Ameren
Illinois
 Ameren
Fuel oils:      
Beginning balance at January 1, 2014$5
$(a)
$5
Realized and unrealized gains (losses) included in regulatory assets/liabilities: (9) (a)
 (9)
Settlements (2) (a)
 (2)
Ending balance at December 31, 2014$(6)$(a)
$(6)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014$(6)$(a)
$(6)
Natural gas:      
Beginning balance at January 1, 2014$
$
$
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 
 1
 1
Purchases 
 (2) (2)
Sales (1) 
 (1)
Settlements 
 1
 1
Ending balance at December 31, 2014$(1)$
$(1)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014$
$2
$2
Power:      
Beginning balance at January 1, 2014$19
$(108)$(89)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 (14) (39) (53)
Purchases 34
 
 34
Sales (1) 
 (1)
Settlements (29) 5
 (24)
Ending balance at December 31, 2014$9
$(142)$(133)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014$
$(43)
 $
(43)
Uranium:      
Beginning balance at January 1, 2014$(6)$(a)
$(6)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 (1) (a)
 (1)
Settlements 5
 (a)
 5
Ending balance at December 31, 2014$(2)$(a)
$(2)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2014$(1)$(a)
$(1)
(a)Not applicable.

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The following table summarizes the changes in the fair value of power financial assets and liabilities classified as Level 3 in the fair value hierarchy for the year ended December 31, 2013:hierarchy:
   Net Derivative Commodity Contracts
   
Ameren
Missouri
 
Ameren
Illinois
 Ameren
Fuel oils:      
Beginning balance at January 1, 2013$5
$(a)
$5
Purchases 3
 (a)
 3
Sales (1) (a)
 (1)
Settlements (2) (a)
 (2)
Ending balance at December 31, 2013$5
$(a)
$5
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013$
$(a)
$
Natural gas:      
Beginning balance at January 1, 2013$
$
$
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 
 (1) (1)
Purchases 
 1
 1
Ending balance at December 31, 2013$
$
$
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013$
$
$
Power:      
Beginning balance at January 1, 2013$11
$(111)$(100)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 3
 (18) (15)
Purchases 40
 
 40
Settlements (36) 21
 (15)
Transfers into Level 3 (3) 
 (3)
Transfers out of Level 3 4
 
 4
Ending balance at December 31, 2013$19
$(108)$(89)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013$(1)$(24)$(25)
Uranium:      
Beginning balance at January 1, 2013$(2)$(a)
$(2)
Realized and unrealized gains (losses) included in regulatory assets/liabilities:

 (3) (a)
 (3)
Purchases (2) (a)
 (2)
Settlements 1
 (a)
 1
Ending balance at December 31, 2013$(6)$(a)
$(6)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2013$(2)$(a)
$(2)
  Net Derivative Commodity Contracts
  
Ameren
Missouri
 
Ameren
Illinois
 Ameren
For the year ended December 31, 2016      
Beginning balance at January 1, 2016$16
$(170)$(154)
Realized and unrealized gains (losses) included in regulatory assets/liabilities (1) (29) (30)
Purchases 13
 
 13
Settlements (21) 14
 (7)
Ending balance at December 31, 2016$7
$(185)$(178)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2016$
$(27)$(27)
For the year ended December 31, 2017      
Beginning balance at January 1, 2017$7
$(185)$(178)
Realized and unrealized gains (losses) included in regulatory assets/liabilities (4) (21) (25)
Purchases 14
 
 14
Sales 1
 
 1
Settlements (11) 11
 
Ending balance at December 31, 2017$7
$(195)$(188)
Change in unrealized gains (losses) related to assets/liabilities held at December 31, 2017$
$(22)$(22)
(a)Not applicable.
Transfers ininto or out of Level 3 represent either (1) existing assets and liabilities that were previously categorized as a higher level, but were recategorized to Level 3 because the inputs to the model became unobservable during the period, or (2) existing assets and liabilities that were previously classified as Level 3, but were recategorized to a higher level because the lowest significant input became observable during the period. Transfers between Level 2 and Level 3 for power derivatives were primarily caused by changes in availability of financial trades observable on electronic exchanges between the periods. Any reclassifications are reported as transfers out of Level 3 at the fair value measurement reported at the beginning of the period in which the changes occur. For the years ended December 31, 20142017 and 2013,2016, there were no material transfers between Level 1 and Level 2, related to derivative commodity contracts. For the year ended December 31, 2014, there were no transfers betweenLevel 1 and Level 3, or Level 2 and Level 3 related to derivative commodity contracts. For the year ended December 31, 2013, there were $(3) million of transfers out of Level 2 into Level 3 and $4 million of transfers into Level 2 out of Level 3 related to power contracts at Ameren and Ameren Missouri.
See Note 1110 – Retirement Benefits for the fair value hierarchy tables detailing Ameren’s pension and postretirement plan assets as of December 31, 20142017, as well as a table summarizing the changes in Level 3 plan assets during 20142017.
The Ameren Companies’ carrying amounts of cash and cash equivalents, accounts receivable, unbilled revenue, accounts payable, and other current financial instruments approximate fair value because of the short-term nature of these instruments. They are considered to be Level 1 in the fair value hierarchy. Ameren's and Ameren Missouri's carrying amounts of investments in debt securities related to the two CTs from the city of Bowling Green and Audrain County approximate fair value. These investments are classified as held-to-maturity. These investments are considered Level 2 in the fair value hierarchy, as they are valued based on similar market transactions. The Ameren Companies'Companies’ short-term borrowings also approximate fair value because of their short-term nature. Ameren and Ameren Illinois have company-owned life insurance that is recorded in “Other Assets” on the respective balance sheet and measured at net asset value. These investments do not consider the observability of inputs; therefore, they are not included within the fair value hierarchy. As of December 31, 2017 and 2016, the net asset value of Ameren (parent)’s company-owned life insurance was $136 million and $123 million, respectively. As of December 31, 2017 and 2016, the net asset value of Ameren Illinois’ company owned life insurance was $9 million and $8 million, respectively.
Short-term borrowings are considered to be Level 2 in the fair value hierarchy as they are valued based on market rates for similar market transactions. The estimated fair value of long-term debt and preferred stock is based on the quoted market prices for same or similar issuances for companies with similar credit profiles or on the current rates offered to the Ameren Companies for similar financial instruments,

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which fair value measurement is considered Level 2 in the fair value hierarchy.

The following table presents the carrying amounts and estimated fair values of our long-term debt, capital lease obligations, and preferred stock at December 31, 20142017 and 20132016:
2014 20132017 2016
Carrying Amount Fair Value Carrying Amount Fair ValueCarrying Amount Fair Value Carrying Amount Fair Value
Ameren:(a)
              
Long-term debt and capital lease obligations (including current portion)(a)$6,240
 $7,135
 $6,038
 $6,584
$7,935
 $8,531
 $7,276
 $7,772
Preferred stock142
 122
 142
 118
Preferred stock(b)
142
 131
 142
 131
Ameren Missouri:              
Long-term debt and capital lease obligations (including current portion)(a)$3,999
 $4,518
 $3,757
 $4,124
$3,961
 $4,348
 $3,994
 $4,304
Preferred stock80
 73
 80
 71
80
 80
 80
 79
Ameren Illinois:              
Long-term debt (including current portion)$2,241
 $2,517
 $1,856
 $2,028
$2,830
 $3,028
 $2,588
 $2,765
Preferred stock62
 49
 62
 47
62
 51
 62
 52
(a)Preferred stock isAmeren and Ameren Missouri have two CTs under separate capital lease agreements. The capital lease obligations as of December 31, 2017 and 2016, were $276 million and $282 million, respectively. In addition, Ameren and Ameren Missouri have investments in debt securities, classified as held-to-maturity and recorded in "Noncontrolling Interests" on“Other Assets” that are related to the consolidated balance sheet.
NOTE 9 NUCLEAR DECOMMISSIONING TRUST FUND INVESTMENTS
Ameren Missouri has investments in debt and equity securities that are held in a trust fund for the purpose of funding the decommissioning of its Callaway energy center. We have classified these investments as available for sale, and we have recorded all such investments at their fair market value at December 31, 2014, and 2013. See Note 10 – Callaway Energy Center for additional information.
Investments in the nuclear decommissioning trust fund have a target allocation of 60% to 70% in equity securities, with the balance invested in debt securities.
The following table presents proceeds from the sale and maturities of investments in Ameren Missouri’s nuclear decommissioning trust fund and the gross realized gains and losses resulting from those sales for the years ended
December 31, 2014, 2013, and 2012:
 2014 2013 2012
Proceeds from sales and maturities$391
 $196
 $384
Gross realized gains7
 7
 6
Gross realized losses2
 5
 2
Net realized and unrealized gains and losses are deferred and recorded as regulatory assets or regulatory liabilities on Ameren’s and Ameren Missouri’s balance sheets. This reporting is consistent with the method used to account for the decommissioning costs recovered in rates. Gains or losses associated with assets in the trust fund could result in lower or higher funding requirements for decommissioning costs, which are expected to be reflected in electric rates paid by Ameren Missouri’s customers. See Note 2 – Rate and Regulatory Matters.

The following table presents the costs and fair values of investments in debt and equity securities in Ameren Missouri’s nuclear decommissioning trust fund at December 31, 2014 and 2013:
Security TypeCost Gross Unrealized Gain Gross Unrealized Loss Fair Value
2014       
Debt securities$175
 $7
$(a)
 $182
Equity securities138
 230
 4
 364
Cash1
 
 
 1
Other(b)
2
 
 
 2
Total$316
 $237
$4
 $549
2013       
Debt securities$157
 $4
$2
 $159
Equity securities137
 199
 4
 332
Cash3
 
 
 3
Other(b)
(a)
 
 
 (a)
Total$297
 $203
$6
 $494
(a)Amount less than $1 million.capital lease obligation CTs from the city of Bowling Green and Audrain County. As of December 31, 2017 and 2016, the fair value of these investments approximate carrying value of $276 million and $282 million, respectively.
(b)Represents payables relating to pending security purchases, net of receivables related to pending security sales and interest receivables.Preferred stock is recorded in “Noncontrolling Interests” on the consolidated balance sheet.

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Table of Contents

The following table presents the costs and fair values of investments in debt securities in Ameren Missouri’s nuclear decommissioning trust fund according to their contractual maturities at December 31, 2014:
 Cost Fair Value
Less than 5 years$98
 $99
5 years to 10 years41
 42
Due after 10 years36
 41
Total$175
 $182
We have unrealized losses relating to certain available-for-sale investments included in our decommissioning trust fund, recorded as regulatory assets as discussed above. Decommissioning will not occur until the operating license for our nuclear energy center expires. Ameren Missouri submitted a license extension application to the NRC to extend the Callaway energy center’s operating license to 2044. The following table presents the fair value and the gross unrealized losses of the available-for-sale securities held in Ameren Missouri's nuclear decommissioning trust fund. They are aggregated by investment category and the length of time that individual securities have been in a continuous unrealized loss position at December 31, 2014:
  Less than 12 Months  12 Months or Greater Total
  Fair Value 
Gross
Unrealized
Losses
  Fair Value 
Gross
Unrealized
Losses
 Fair Value 
Gross
Unrealized
Losses
Debt securities$28
$(a)
  $8
$(a)
 $36
$(a)
Equity securities6
 1
  5
 3
 11
 4
Total$34
$1
  $13
$3
 $47
$4
(a)Amount less than $1 million.
NOTE 109 CALLAWAY ENERGY CENTER
Spent Nuclear Fuel
Under the NWPA, the DOE is responsible for disposing of spent nuclear fuel from the Callaway energy center and other commercial nuclear energy centers. UnderThe NWPA established the NWPA,fee paid by Ameren Missouri and other utilities that own and operate those energy centers are responsible for paying the disposal costs. The NWPA established the fee that these utilities payto the federal government for disposing of the spent nuclear fuel at one mill, or one-tenth(one-tenth of one cent,cent), for each kilowatthour generated and sold by those plants. The NWPA also requires the DOE annually to review the nuclear waste fee annually against the cost of the nuclear waste disposal program and to propose to the United States Congress any fee adjustment necessary to offset the costs of the program. As required by the NWPA, Ameren Missouri and other utilities have entered into standard contracts with the federal government. The government, represented by the DOE, is responsible for implementing these provisions of the NWPA.DOE. Consistent with the NWPA and its standard contract, which stated that the DOE would begin to dispose of spent nuclear fuel by 1998, Ameren Missouri had historically collected one mill from its electric customers for each kilowatthour of electricity that it generatesgenerated and sellssold from its Callaway energy center. However, as described below, Ameren Missouri has suspended collection of this fee.
Although both the NWPA and the standard contract stated that the federal government would begin to dispose of spent nuclear fuel by 1998,Because the federal government is not meeting its disposal obligation. Ameren Missouri has sufficient installed capacity atobligation, the Callaway energy center to store its spent nuclear fuel generated through 2020 and it has the capability for additional storage capacity for spent nuclear fuel generated through the endcollection of the energy center’s current licensed life.this fee was suspended in May 2014. The DOE'sDOE’s delay in carrying out its obligation to dispose of spent nuclear fuel from the Callaway energy center is not expected to adversely affect the continued operations of the energy center.
In January 2013, the DOE issued its plan for the management and disposal of spent nuclear fuel. The DOE's plan calls for a pilot interim storage facility to begin operation with an initial focus on accepting spent nuclear fuel from shutdown reactor sites by 2021. By 2025, a larger interim storage facility would be available, potentially co-located with the pilot facility on a geologic repository. The plan also proposes to begin operation of a permanent geological repository by 2048.
Because the federal government is not meeting its disposal obligation, the Nuclear Energy Institute, a number of individual utilities, and the National Association of Regulatory Utility Commissioners sued the DOE in the United States Court of Appeals for the District of Columbia Circuit, seeking the suspension of the one mill nuclear waste fee. In November 2013, the court ordered the DOE to submit a proposal to the United States Congress to reduce the fee to zero. In January 2014, the DOE submitted that proposal, and it became effective in May 2014. Since the nuclear waste fee was previously included in Ameren Missouri’s FAC, the cost reduction will be passed on to electric utility customers with no material effect on Ameren’s or Ameren Missouri’s net income.
As a result of the DOE'sDOE’s failure to begin to dispose of spent nuclear fuel from commercial nuclear energy centers and fulfill its contractual obligations, Ameren Missouri and other nuclear energy center owners have also sued the DOE to recover costs incurred for ongoing storage of their spent fuel. Ameren Missouri filed a breach of contract lawsuit to recover costs that it incurred through 2009. The lawsuit sought reimbursement for the cost of reracking the Callaway energy center’s spent fuel pool, for certain NRC fees, and for Missouri ad valorem taxes that Ameren Missouri would not have incurred had the DOE performed its


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contractual obligations. The parties entered intoresulted in a settlement agreement that provides for annual recoveryreimbursement of additional spent fuel storage and related costs incurred from 2010 through 2016, with the ability to extend the recovery period as mutually agreed upon by the parties. Included in these reimbursements are costs related to a dry spent fuel storage facility thatcosts. Ameren Missouri is constructing at its Callaway energy center. Ameren Missouri intends to begin transferring spent fuel assemblies to this facilityreceived reimbursements from the DOE of $3 million, $24 million, and $14 million in 2015.2017, 2016, and 2015, respectively. Ameren Missouri will continue to apply for reimbursement from the DOE for the cost to construct and operate the dry spent fuel storage facility along with related allowable costs.
In December 2011, Ameren Missouri submitted a license extension application to the NRC to extend its Callaway energy center's operating license from 2024 to 2044. There is no deadline by which the NRC must act on this application. Among the rules upon which the NRC has historically relied in approving license extensions are rules dealingcosts associated with the ongoing storage of spent fuel.
Supplier of Fuel Assemblies
The Callaway energy center uses nuclear fuel atassemblies fabricated by Westinghouse, which is the reactor site and withonly NRC-licensed supplier authorized to provide fuel assemblies to the NRC's confidence that permanent disposalCallaway energy center. During the first quarter of spent nuclear fuel will be available when needed. In2017, Westinghouse filed voluntary petitions for a June 2012 decision,court-supervised restructuring process under Chapter 11 of the United States CourtBankruptcy Code. Westinghouse could petition the bankruptcy court to reject Ameren Missouri’s contracts as part of Appeals for the District of Columbia Circuit vacated these rules and remandedrestructuring process. If the casebankruptcy court agrees, this could result in Ameren Missouri not having access to the NRC, holding that the NRC's obligations under the National Environmental Policy Act required a more thorough environmental analysis in support of the NRC's waste confidence decision. As a result, the NRC stated that it would not issue licenses dependent on the vacated rules until it appropriately addressed the court's remand. In October 2014, after it completed the required environmental analysis, the NRC lifted its suspension on final licensing decisions. In February 2015, the staff of the NRC issued its recommendation that the NRC approve Ameren Missouri's application for a 20-year renewal offuel assemblies necessary to refuel the Callaway energy center's operating license.center in future scheduled refueling and maintenance outages. At this time, Ameren and Ameren Missouri believe the restructuring proceeding will not affect Westinghouse’s performance under the terms of its existing contracts with Ameren Missouri, and therefore do not expect any material impact to Ameren Missouri’s operations. However, Ameren and Ameren Missouri could incur material unexpected costs as a result of the Westinghouse bankruptcy, such as the loss of fuel inventory that is stored at Westinghouse’s facility and the cost of replacement power if nuclear fuel assemblies were not available for a future scheduled refueling and maintenance outage. A change of fuel suppliers or a change in the type of fuel assembly design that is currently licensed for use at the Callaway energy center could take an estimated three years of analysis and NRC licensing efforts to implement.

Decommissioning
Electric utility rates currently charged to customers provide for the recovery of the Callaway energy center'scenter’s decommissioning costs, which include decontamination, dismantling, and site restoration costs, over an assumed 40-yearthe expected life of the nuclear center, ending with the expiration of the energy center's current operating license in 2024.center. Amounts collected from customers are deposited into the external nuclear decommissioning trust fund to provide for the Callaway energy center’s decommissioning. It is assumed that the Callaway energy center site will be eventually decommissioned through the immediate dismantlement method and removed from service. Ameren and Ameren Missouri have recorded an ARO for the Callaway energy center decommissioning costs at fair value, which represents the present value of estimated future cash outflows. Annual decommissioning costs of $7 million are included in the costs of service used to establish electric rates for Ameren Missouri'sMissouri’s customers. Every three years, the MoPSC requires Ameren Missouri to file an updated cost study and funding analysis for decommissioning its Callaway energy center. Electric rates may be adjusted at such times to reflect changed estimates. The lastAn updated cost study and funding analysis was filed with the MoPSC in September 2011. The2017 and reflected within the ARO. In January 2018, the MoPSC has authorized a delay of the 2014approved no change in electric rates for decommissioning costs based on Ameren Missouri’s updated cost study and funding analysis filing until 2015 pending the outcome of Ameren Missouri’s operating license extension
analysis.
application under review by the NRC. Following the NRC’s decision regarding Ameren Missouri’s operating license extension application, an updated cost study and a revised funding analysis will be filed. Rates charged to customers will be adjusted accordingly, as approved by the MoPSC, to reflect the operating license extension application decision, the updated cost study and the revised funding analysis. If the assumed return on trust assets is not earned, we believe that it is probable that any such earnings deficiency will be recovered in rates. The fair value of the trust fund for Ameren Missouri'sMissouri’s Callaway energy center is reported as "Nuclear“Nuclear decommissioning trust fund"fund” in Ameren'sAmeren’s and Ameren Missouri'sMissouri’s balance sheets. This amount is legally restricted and may be used only to fund the costs of nuclear decommissioning. Changes in the fair value of the trust fund are recorded as an increase or decrease to the nuclear decommissioning trust fund, with an offsetting adjustment to the related regulatory liability. If the assumed return on trust assets is not earned, Ameren Missouri believes that it is probable that any such earnings deficiency will be recovered in rates.
Ameren Missouri has investments in debt and equity securities that are held in a trust fund for the purpose of funding the decommissioning of its Callaway energy center. We have classified these investments as available for sale, and we have recorded all such investments at their fair market value at December 31, 2017 and 2016. Investments in the nuclear decommissioning trust fund have a target allocation of 60% to 70% in equity securities, with the balance invested in debt securities.
The following table presents proceeds from the sale and maturities of investments in Ameren Missouri’s nuclear decommissioning trust fund and the gross realized gains and losses resulting from those sales for the years ended December 31, 2017, 2016, and 2015:
 2017 2016 2015
Proceeds from sales and maturities$396
 $377
 $349
Gross realized gains13
 7
 8
Gross realized losses5
 4
 2
Net realized and unrealized gains and losses are deferred and are currently reflected in the regulatory liability related to AROs on Ameren’s and Ameren Missouri’s balance sheets. This reporting is consistent with the method used to account for the decommissioning costs recovered in rates. Gains or losses associated with assets in the trust fund could result in lower or higher funding requirements for decommissioning costs, which are expected to be reflected in electric rates paid by Ameren Missouri’s customers. See Note 2 – Rate and Regulatory MattersMatters.
The following table presents the costs and Note 9 – Nuclearfair values of investments in debt and equity securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund at December 31, 2017 and 2016:
Security TypeCost Gross Unrealized Gain Gross Unrealized Loss Fair Value
2017       
Debt securities$228
 $5
$1
 $232
Equity securities155
 318
 5
 468
Cash and cash equivalents2
 
 
 2
Other(a)
2
 
 
 2
Total$387
 $323
$6
 $704
2016       
Debt securities$197
 $3
$4
 $196
Equity securities161
 253
 6
 408
Cash and cash equivalents1
 
 
 1
Other(a)
2
 
 
 2
Total$361
 $256
$10
 $607
(a)Represents net receivables and payables relating to pending security sales, interest, and security purchases.

The following table presents the costs and fair values of investments in debt securities in Ameren’s and Ameren Missouri’s nuclear decommissioning trust fund according to their contractual maturities at December 31, 2017:
 Cost Fair Value
Less than 5 years$120
 $120
5 years to 10 years54
 55
Due after 10 years54
 57
Total$228
 $232
There are unrealized losses relating to certain available-for-sale investments included in the nuclear decommissioning trust fund, deferred within the regulatory liability as discussed above. Decommissioning Trust Fund Investmentswill not occur until Ameren Missouri’s nuclear energy center is retired. The Callaway energy center’s operating license expires in 2044.
Insurance
The following table presents insurance coverage at Ameren Missouri’s Callaway energy center at December 31, 2017. The property coverage and the nuclear liability coverage renewal dates are April 1 and January 1, respectively, of each year.
Type and Source of CoverageMaximum Coverages 
Maximum Assessments
for Single Incidents
 
Public liability and nuclear worker liability:    
American Nuclear Insurers$450
 $
 
Pool participation12,986
(a) 
127
(b) 
 $13,436
(c) 
$127
 
Property damage:    
NEIL and EMANI$3,200
(d) 
$30
(e) 
Replacement power:    
NEIL$490
(f) 
$7
(e) 
(a)Provided through mandatory participation in an industrywide retrospective premium assessment program.
(b)Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $450 million in the event of an incident at any licensed United States commercial reactor, payable at $19 million per year.
(c)Limit of liability for each incident under the Price-Anderson liability provisions of the Atomic Energy Act of 1954, as amended. This limit is subject to change to account for the effects of inflation and changes in the number of licensed reactors.
(d)NEIL provides $2.7 billion in property damage, stabilization, decontamination, and premature decommissioning insurance for radiation events and $2.3 billion in property damage insurance for nonradiation events. EMANI provides $490 million in property damage insurance for both radiation and nonradiation events.
(e)All NEIL insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.
(f)Provides replacement power cost insurance in the event of a prolonged accidental outage. Weekly indemnity up to $4.5 million for 52 weeks, which commences after the first 12 weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter, for a total not exceeding the policy limit of $490 million. Nonradiation events are limited to $328 million.
The Price-Anderson Act is a federal law that limits the liability for additional information relatedclaims from an incident involving any licensed United States commercial nuclear energy center. The limit is based on the number of licensed reactors. The limit of liability and the maximum potential annual payments are adjusted at least every five years for inflation to reflect changes in the Consumer Price Index. The most recent five-year inflationary adjustment became effective in September 2013. Owners of a nuclear reactor cover this exposure through a combination of private insurance and mandatory participation in a financial protection pool, as established by the Price-Anderson Act.
Losses resulting from terrorist attacks on nuclear facilities are subject to industrywide aggregates. Terrorist acts against one or more commercial nuclear power plants insured by NEIL or EMANI within a stated time period would be treated as a single event, and the owners of the nuclear power plants would share one full limit of liability. NEIL policies have an aggregate limit of $3.2 billion within a 12-month period for radiation events, or $1.8 billion for events not involving radiation contamination. The EMANI policies have an aggregate limit of €600 million for radiation and nonradiation events within a period of 72 hours.
If losses from a nuclear incident at the Callaway energy center.center exceed the insurance limits, or are not covered by insurance, or if coverage is unavailable, Ameren Missouri is at risk for any uninsured losses. If a serious nuclear incident were to occur, it could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, or liquidity.
NOTE 1110 RETIREMENT BENEFITS
The primary objective of the Ameren pension and postretirement benefit plans is to provide eligible employees with pension and postretirement health care and life insurance benefits. Ameren offershas defined benefit pension and postretirement benefit plans covering substantially all of its union employees. Ameren has defined benefit pension plans covering substantially all of its non-union employees and postretirement benefit plans covering non-union employees hired before October 2015. Ameren uses a measurement date of December 31

for its pension and postretirement benefit plans. Ameren Missouri and Ameren Illinois each participate in Ameren’s single-employer pension and other postretirement plans. Ameren’s qualified pension plan is the Ameren Retirement Plan. Ameren also has an unfunded nonqualified pension plan, the Ameren Supplemental Retirement Plan, which is available forto provide certain management employees and retirees to providewith a supplemental benefit when their qualified pension plan benefits are capped to complyin compliance with Internal Revenue Code limitations. Ameren’s other postretirement plans areplan is the Ameren Retiree Medical PlanWelfare Benefit Plan. Effective December 31, 2016, the applicable assets and liabilities of the Ameren Group Life Insurance Plan were merged with the Ameren Retiree Welfare Benefit Plan. Only Ameren subsidiaries participate in the plans listed above.
In December 2013, Ameren completed the divestiture of New AER to IPH. In accordance with the transaction agreement, Ameren retained the pension obligations as of December 2, 2013, associated with the current and former employees of New AER and its subsidiaries who were included in the Ameren Retirement Plan and the Ameren Supplemental Retirement Plan. Ameren also retained the postretirement benefit obligations associated with the employees of New AER and its subsidiaries who were eligible to retire at December 2, 2013, and who were included in the Ameren Retiree Medical Plan and the Ameren Group Life Insurance Plan.
Ameren’s unfunded obligation under its pension and other postretirement benefit plans was $710$551 million and $461$774 million as of December 31, 20142017, and December 31, 2013,2016, respectively. These net liabilities are recorded in "Other“Other current liabilities," "Pensionliabilities” and “Pension and other postretirement benefits," and "Other assets"


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benefits” on Ameren'sAmeren’s consolidated balance sheet. The primary factor contributing to the increasedecrease in the unfunded obligation during 20142017 was the result of a 75larger-than-expected increase in the return on plan assets of the pension and postretirement trusts, offset by a 50 basis point decrease in the pension and other postretirement benefit plan discount rates used to determine the present value of the obligation. The offset to the increasedecrease in the unfunded obligation was primarily an increasealso resulted in a decrease to "Regulatory assets"“Regulatory assets” on Ameren's,Ameren’s, Ameren Missouri's,Missouri’s, and Ameren Illinois' consolidatedIllinois’ balance sheet.sheets.
The following table presents the net benefit liability recorded on the balance sheets of each of the Ameren Companies as of December 31, 20142017 and 20132016:
2014
2013
2017
2016
Ameren(a)
$710
$461
$551
$774
Ameren Missouri277
191
215
293
Ameren Illinois(b)278
159
213
315
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)Other postretirement benefit liability is recorded in “Other assets” on the balance sheet.


Ameren recognizes the underfunded status of its pension and postretirement plans as a liability on its consolidated balance sheet, with offsetting entries to accumulated OCI and regulatory assets, in accordance with authoritative accounting guidance.assets. The following table presents the funded status of Ameren'sAmeren’s pension and postretirement benefit plans as of December 31, 20142017 and 20132016. It also provides the amounts included in regulatory assets and accumulated OCI at December 31, 20142017 and 20132016, that have not been recognized in net periodic benefit costs.
2014 20132017 2016
Pension Benefits(a)
 
Postretirement
Benefits(a)
 
Pension Benefits(a)
 
Postretirement
Benefits(a)
Pension Benefits(a)
 
Postretirement
Benefits(a)
 
Pension Benefits(a)
 
Postretirement
Benefits(a)
Accumulated benefit obligation at end of year$4,176
$(b)
 $3,698
$(b)
$4,577
$(b)
 $4,288
$(b)
Change in benefit obligation:              
Net benefit obligation at beginning of year$3,900
$1,096
 $4,051
$1,157
$4,518
$1,170
 $4,197
$1,094
Service cost79
 19
 91
 22
93
 21
 81
 19
Interest cost183
 50
 163
 46
179
 47
 185
 50
Participant contributions
 16
 
 16

 8
 
 8
Actuarial (gain) loss462
 84
 (207) (76)
Curtailment gain(c)

 
 
 (3)
Settlement(d)

 
 
 (5)
Actuarial loss255
 53
 265
 52
Benefits paid(214) (65) (198) (64)(218) (59) (210) (54)
Federal subsidy on benefits paid(b)
 3
 (b)
 3
(b)
 
 (b)
 1
Net benefit obligation at end of year4,410
 1,203
 3,900
 1,096
4,827
 1,240
 4,518
 1,170
Change in plan assets:              
Fair value of plan assets at beginning of year3,461
 1,074
 3,127
 938
3,813
 1,101
 3,653
 1,071
Actual return on plan assets448
 75
 376
 156
634
 171
 313
 73
Employer contributions99
 6
 156
 25
64
 2
 57
 2
Federal subsidy on benefits paid(b)
 3
 (b)
 3
(b)
 
 (b)
 1
Participant contributions
 16
 
 16

 8
 
 8
Benefits paid(214) (65) (198) (64)(218) (59) (210) (54)
Fair value of plan assets at end of year3,794
 1,109
 3,461
 1,074
4,293
 1,223
 3,813
 1,101
Funded status – deficiency616
 94
 439
 22
534
 17
 705
 69
Accrued benefit cost at December 31$616
$94
 $439
$22
$534
$17
 $705
$69
Amounts recognized in the balance sheet consist of:              
Noncurrent asset(e)
$
$
 $
$(9)
Current liability(f)
3
 2
 3
 1
Current liability(c)
3
 3
 3
 2
Noncurrent liability613
 92
 436
 30
531
 14
 702
 67
Net liability recognized$616
$94
 $439
$22
$534
$17
 $705
$69
Amounts recognized in regulatory assets consist of:              
Net actuarial (gain) loss$452
$(7) $282
$(71)$374
$(69) $535
$(29)
Prior service cost (credit)(6) (16) (7) (20)
Prior service credit(3) (3) (4) (8)
Amounts (pretax) recognized in accumulated OCI consist of:              
Net actuarial (gain) loss29
 (5) 17
 (12)
Prior service cost (credit)
 (1) 
 (1)
Net actuarial loss30
 2
 43
 
Prior service credit
 
 
 (1)
Total$475
$(29) $292
$(104)$401
$(70) $574
$(38)
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries.

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Table of Contents

(b)Not applicable.
(c)Effective with the divestiture of New AER on December 2, 2013, the liability for active management employees of New AER and its subsidiaries not eligible to retire were neither transferred to IPH nor retained by Ameren, which resulted in a curtailment gain. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the divestiture.
(d)Effective with the divestiture of New AER on December 2, 2013, the liability for active union employees of New AER and its subsidiaries not eligible to retire was transferred to IPH based on the assumption of the collective bargaining agreements in place, which resulted in a settlement. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the divestiture.
(e)Included in "Other assets"“Other current liabilities” on Ameren's consolidated balance sheet.
(f)Included in "Other current liabilities" on Ameren'sAmeren’s consolidated balance sheet.
The following table presents the assumptions used to determine our benefit obligations at December 31, 20142017 and 20132016:
Pension Benefits Postretirement BenefitsPension Benefits Postretirement Benefits
2014 2013 2014 20132017 2016 2017 2016
Discount rate at measurement date4.00% 4.75% 4.00% 4.75%3.50% 4.00% 3.50% 4.00%
Increase in future compensation3.50
 3.50
 3.50
 3.50
3.50
 3.50
 3.50
 3.50
Medical cost trend rate (initial)(a)(a)
 (a)
 5.00
 5.00
(b)
 (b)
 5.00
 5.00
Medical cost trend rate (ultimate)(a)(a)
 (a)
 5.00
 5.00
(b)
 (b)
 5.00
 5.00
Years to ultimate rate(a)
 (a)
 
 
(a)Not applicableInitial and ultimate medical cost trend rate for certain Medicare-eligible participants is 3.00%.
(b)Not applicable.
Ameren determines discount rate assumptions by identifying a theoretical settlement portfolio of high-quality corporate bonds sufficient to provide for a plan'splan’s projected benefit payments. The settlement portfolio of bonds is selected from a pool of more than 700600 high-quality corporate bonds. A single discount rate is then determined; that rate results in a discounted value of the plan'splan’s benefit payments that equates to the market value of the selected bonds. In addition, during 2014,2017, Ameren adopted the Society of Actuaries 2014 Mortality Tables Report and2017 Mortality Improvement Scale. The updated scale assumes a lower rate of mortality tables assume increasing life expectancies for our employees and retirees, which resultedimprovement as compared to the 2016 Mortality Improvement Scale that Ameren

used in an increase2016, resulting in a decrease to our pension and other postretirement benefit obligations.
Funding
Pension benefits are based on the employees’ years of service, age, and compensation. Ameren’s pension plans are funded in compliance with income tax regulations, and federal funding, or
and other regulatory requirements. As a result, Ameren expects to fund its pension plan at a level equal to the greater of the pension expensecost or the legally required minimum contribution. Considering its assumptions at December 31, 20142017, its investment performance in 2014,2017, and its pension funding policy, Ameren expects to make annual contributions of less than $251 million to $11560 million in each of the next five years, with aggregate estimated contributions of $290120 million. We expect Ameren Missouri’sMissouri and Ameren Illinois’Illinois expect their portion of the future funding requirements to be 41%35% and 40%55%, respectively. These amounts are estimates. They may change based on actual investment performance, changes in interest rates, changes in our assumptions, changes in government regulations, and any voluntary contributions. Our funding policy for postretirement benefits is primarily to fund the Voluntary Employee Beneficiary Association (VEBA) trusts to match the annual postretirement expense.

The following table presents the cash contributions made to our defined benefit retirement plan and to our postretirement plans during 20142017, 20132016, and 20122015:
Pension Benefits Postretirement BenefitsPension Benefits Postretirement Benefits
2014 2013 2012 2014 2013 20122017 2016 2015 2017 2016 2015
Ameren Missouri$41
 $60
 $52
 $3
 $10
 $9
$19
 $21
 $47
 $1
 $1
 $8
Ameren Illinois39
 50
 46
 2
 11
 35
37
 30
 45
 1
 1
 8
Other19
 46
 30
 1
 4
 1
8
 6
 19
 
 
 2
Ameren(a)
99
 156
 128
 6
 25
 45
64
 57
 111
 2
 2
 18
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Investment Strategy and Policies
Ameren manages plan assets in accordance with the “prudent investor” guidelines contained in ERISA. The investment committee, to the extent that authority is delegated to it by the finance committeewhich includes members of Ameren’s board of directors,senior management, approves and implements investment strategy and asset allocation guidelines for the plan assets. The investment committee includes members of senior management. The investment committee’s goals are twofold: first, to ensure that sufficient funds are available to provide the benefits at the time they are payable; and second, to maximize
total return on plan assets and to minimize expense volatility consistent with its tolerance for risk. Ameren delegates the task of investment management to specialists in each asset class. As appropriate, Ameren provides each investment manager with guidelines that specify allowable and prohibited investment types. The investment committee regularly monitors manager performance and compliance with investment guidelines.
The expected return on plan assets assumption is based on historical and projected rates of return for current and planned


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asset classes in the investment portfolio. Projected rates of return for each asset class were estimated after an analysis of historical experience, future expectations, and the volatility of the various asset classes. After considering the target asset allocation for each asset class, we adjusted the overall expected rate of return for the portfolio for historical and expected experience of active portfolio management results compared with benchmark returns
and for the effect of expenses paid from plan assets. Ameren will use an expected return on plan assets for its pension plan assets and postretirement plan assets of 7.25%7.00% and 7.00%, respectively, in 2015.2018. No plan assets are expected to be returned to Ameren during 2015.2018.


Ameren’s investment committee strives to assemble a portfolio of diversified assets that does not create a significant concentration of risks. The investment committee develops asset allocation guidelines between asset classes, and it creates diversification through investments in assets that differ by type (equity, debt, real estate, private equity), duration, market capitalization, country, style (growth or value), and industry, among other factors. The diversification of assets is displayed in the target allocation table below. The investment committee also routinely rebalances the plan assets to adhere to the diversification goals. The investment committee’s strategy reduces the concentration of investment risk; however, Ameren is still subject to overall market risk. The following table presents our target allocations for 20152018 and our pension and postretirement plans’ asset categories as of December 31, 20142017 and 20132016:
Asset
Category
Target Allocation
2015
 Percentage of Plan Assets at December  31,
Target Allocation
2018
 Percentage of Plan Assets at December 31,
2014 20132017 2016
Pension Plan:        
Cash and cash equivalents0% - 5% 2% 2%
0%  5%
 1% 1%
Equity securities:        
U.S. large-capitalization29% - 39% 34% 36%
29%  39%
 34% 34%
U.S. small- and mid-capitalization2% - 12% 7% 8%
3%  13%
 9% 9%
International and emerging markets9% - 19% 12% 14%
9%  19%
 14% 14%
Total equity50% - 60% 53% 58%
51%  61%
 57% 57%
Debt securities35% - 45% 41% 36%
35%  45%
 37% 37%
Real estate0% -   9%   4% 4%
0%   9%  
 5% 5%
Private equity0% -   4%   (a)
 (a)
0%   5%  
 (a)
 (a)
Total  100% 100%  100% 100%
Postretirement Plans:        
Cash and cash equivalents0% - 10% 4% 4%
0%  7%
 2% 3%
Equity securities:        
U.S. large-capitalization33% - 43% 40% 41%
34%  44%
 41% 40%
U.S. small- and mid-capitalization3% - 13% 7% 8%
2%  12%
 8% 7%
International10% - 20% 13% 14%
International and emerging markets
9%  19%
 14% 14%
Total equity55% - 65% 60% 63%
55%  65%
 63% 61%
Debt securities30% - 40% 36% 33%
33%  43%
 35% 36%
Total  100% 100%  100% 100%
(a)
Less than 1% of plan assets.
In general, the United States large-capitalization equity investments are passively managed or indexed, whereas the international, emerging markets, United States small-capitalization, and United States mid-capitalization equity investments are actively managed by investment managers. Debt securities include a broad range of fixed incomefixed-income vehicles. Debt security investments in high-yield securities, emerging market securities, and non-United States dollar-denominatednon-United-States-dollar-denominated securities are owned by the plans, but in limited quantities to reduce risk. Most of the debt security investments are under active management by investment managers. Real estate investments include private real estate vehicles; however, Ameren does not, by policy, hold direct investments in real estate property. Ameren’s investment in private equity funds is spread among nine different limited partnerships, with invested capital ranging from $0.1 million to $5 million in each, which invest primarily in a diversified number of small United States-based companies. No further commitments may be made to private equity investments without approval by the finance committee of the board of directors. Additionally, Ameren’s investment committee allows investment managers to use derivatives, such as index futures, exchange traded funds, foreign exchange futures, and options, in certain situations to increase or to reduce market exposure in an efficient and timely manner.
Fair Value Measurements of Plan Assets
Investments in the pension and postretirement benefit plans were stated at fair value as of December 31, 20142017. The fair value of an asset is the amount that would be received upon its sale in an orderly transaction between market participants at the measurement date. Cash and cash equivalents have initial maturities of three months or less and are recorded at cost plus accrued interest. The carrying amounts of cash and cash equivalents approximate fair value because of the short-term nature of these instruments. Investments traded in active markets on national or international securities exchanges are valued at closing prices on the measurement date or, if that is not a business day, on the last business day on or before the measurementthat date. Securities traded in over-the-counter markets are valued based onby quoted market prices, broker or dealer quotations, or alternative pricing sources with reasonable levels of price transparency. Investments measured under NAV as a practical expedient are based on the fair values of the underlying assets provided by the funds and their administrators. The fair value of real estate investments is based on NAV; it is determined by annual appraisal reports prepared by an independent real estate appraiser. Investments measured at NAV often provide for daily, monthly, or quarterly redemptions with 60 or less days of notice depending on the fund. For some funds, redemption may also require approval from the fund’s board of directors. Derivative contracts are valued at fair value, as determined by the

121


investment managers (or independent third parties on behalf of the investment managers), who use proprietary models and take into consideration exchange quotations on underlying instruments, dealer quotations, and other market information. The fair value of real estate is based on annual appraisal reports prepared by an independent real estate appraiser.

The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension planplans’ assets measured at fair value as of December 31, 20142017:
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Measured at NAV Total
Cash and cash equivalents$
 $38
 $
 $38
$
 $
 $
 $25
 $25
Equity securities:                
U.S. large-capitalization
 1,331
 
 1,331

 
 
 1,523
 1,523
U.S. small- and mid-capitalization270
 
 
 270
379
 
 
 
 379
International and emerging markets134
 360
 
 494
179
 
 
 450
 629
Debt securities:                
Corporate bonds
 1,026
 
 1,026

 726
 
 15
 741
Municipal bonds
 175
 
 175

 91
 
 
 91
U.S. treasury and agency securities6
 366
 
 372
U.S. Treasury and agency securities8
 816
 
 
 824
Other
 31
 
 31

 7
 
 
 7
Real estate
 
 147
 147

 
 
 196
 196
Private equity
 
 13
 13

 
 
 4
 4
Derivative assets1
 
 
 1
Total$411
 $3,327
 $160
 $3,898
$566
 $1,640
 $
 $2,213
 $4,419
Less: Medical benefit assets at December 31(a)
      (125)        (153)
Plus: Net receivables at December 31(b)
      21
        27
Fair value of pension plans assets at year end      $3,794
Fair value of pension plans’ assets at December 31        $4,293
(a)Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation.
(b)Receivables related to pending security sales, offset by payables related to pending security purchases.
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the pension planplans’ assets measured at fair value as of December 31, 20132016:
Quoted Prices in
Active Markets for
Identified Assets or Liabilities
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total
Quoted Prices in
Active Markets for
Identified Assets or Liabilities
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Measured at NAV Total
Cash and cash equivalents$5
 $39
 $
 $44
$
 $
 $
 $33
 $33
Equity securities:                
U.S. large-capitalization107
 1,162
 
 1,269

 
 
 1,352
 1,352
U.S. small- and mid-capitalization273
 
 
 273
361
 
 
 
 361
International and emerging markets143
 372
 
 515
133
 
 
 389
 522
Debt securities:                
Corporate bonds
 860
 
 860

 617
 
 13
 630
Municipal bonds
 149
 
 149

 95
 
 
 95
U.S. treasury and agency securities
 256
 
 256
U.S. Treasury and agency securities
 701
 
 
 701
Other
 27
 
 27

 21
 
 
 21
Real estate
 
 131
 131

 
 
 202
 202
Private equity
 
 15
 15

 
 
 6
 6
Derivative assets1
 
 
 1
Derivative liabilities(1) 
 
 (1)
Total$528
 $2,865
 $146
 $3,539
$494
 $1,434
 $
 $1,995
 $3,923
Less: Medical benefit assets at December 31(a)
      (112)        (132)
Plus: Net receivables at December 31(b)
      34
        22
Fair value of pension plans assets at year end      $3,461
Fair value of pension plans’ assets at December 31 ��      $3,813
(a)Medical benefit (health and welfare) component for accounts maintained in accordance with Section 401(h) of the Internal Revenue Code to fund a portion of the postretirement obligation.
(b)Receivables related to pending security sales, offset by payables related to pending security purchases.

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The following table summarizes the changes in the fair value of the pension plan assets classified as Level 3 in the fair value hierarchy for each of the years ended December 31, 2014 and 2013:
 
Beginning
Balance at
January 1,
 
Actual Return on
Plan Assets Related
to Assets Still Held
at the Reporting Date
 
Actual Return on
Plan Assets Related
to Assets Sold
During the Period
 
Purchases,
Sales, and
Settlements, Net
 
Net
Transfers
into (out of)
of Level 3
 
Ending Balance at
December 31,
2014:           
Real estate$131
 $11
 $
 $5
 $
 $147
Private equity15
 (9) 10
 (3) 
 13
2013:           
Real estate$118
 $9
 $
 $4
 $
 $131
Private equity19
 (9) 11
 (6) 
 15
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plansplans’ assets measured at fair value as of December 31, 20142017:
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Measured at NAV Total
Cash and cash equivalents$89
 $
 $
 $89
$44
 $
 $
 $
 $44
Equity securities:                
U.S. large-capitalization291
 101
 
 392
332
 
 
 110
 442
U.S. small- and mid-capitalization70
 
 
 70
80
 
 
 
 80
International37
 94
 
 131
International and emerging markets53
 
 
 101
 154
Other
 7
   7

 8
 
 
 8
Debt securities:                
Corporate bonds
 105
 
 105

 144
 
 
 144
Municipal bonds
 111
 
 111

 110
 
 
 110
U.S. treasury and agency securities
 89
 
 89
U.S. Treasury and agency securities
 76
 
 
 76
Other
 44
 
 44

 4
 
 34
 38
Total$487
 $551
 $
 $1,038
$509
 $342
 $
 $245
 $1,096
Plus: Medical benefit assets at December 31(a)
      125
        153
Less: Net payables at December 31(b)
      (54)        (26)
Fair value of postretirement benefit plans assets at year end      $1,109
Fair value of postretirement benefit plans’ assets at December 31        $1,223
(a)Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.
(b)Payables related to pending security purchases, offset by interest receivables and receivables related to pending security sales.
The following table sets forth, by level within the fair value hierarchy discussed in Note 8 – Fair Value Measurements, the postretirement benefit plansplans’ assets measured at fair value as of December 31, 20132016:
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Total
Quoted Prices in
Active Markets for
Identified Assets
(Level 1)
 
Significant Other
Observable
Inputs
(Level 2)
 
Significant Other
Unobservable
Inputs
(Level 3)
 Measured at NAV Total
Cash and cash equivalents$77
 $
 $
 $77
$53
 $
 $
 $
 $53
Equity securities:                
U.S. large-capitalization297
 101
 
 398
291
 
 
 101
 392
U.S. small- and mid-capitalization77
 
 
 77
72
 
 
 
 72
International39
 96
 
 135
International and emerging markets40
 
 
 92
 132
Other
 2
 
 2

 7
 
 
 7
Debt securities:                
Corporate bonds
 97
 
 97

 141
 
 
 141
Municipal bonds
 103
 
 103

 110
 
 
 110
U.S. treasury and agency securities
 72
 
 72
U.S. Treasury and agency securities
 68
 
 
 68
Other
 40
 
 40

 
 
 19
 19
Total$490
 $511
 $
 $1,001
$456
 $326
 $
 $212
 $994
Plus: Medical benefit assets at December 31(a)
      112
        132
Less: Net payables at December 31(b)
      (39)        (25)
Fair value of postretirement benefit plans assets at year end      $1,074
Fair value of postretirement benefit plans’ assets at December 31        $1,101
(a)Medical benefit (health and welfare) component for 401(h) accounts to fund a portion of the postretirement obligation. These 401(h) assets are included in the pension plan assets shown above.

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(b)Payables related to pending security purchases, offset by Medicare, interest receivables and receivables related to pending security sales.

Net Periodic Benefit Cost
The following table presents the components of the net periodic benefit cost of ourAmeren’s pension and postretirement benefit plans during 20142017, 20132016, and 20122015:
 
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
2014   
Service cost$79
 $19
Interest cost183
 50
Expected return on plan assets(229) (65)
Amortization of:   
Prior service credit(1) (5)
Actuarial (gain) loss49
 (7)
Net periodic benefit cost (benefit)$81
 $(8)
2013   
Service cost$91
 $22
Interest cost163
 46
Expected return on plan assets(218) (62)
Amortization of:   
Prior service credit(2) (6)
Actuarial loss87
 8
Curtailment gain(12) (7)
Net periodic benefit cost(b)
$109
 $1
2012   
Service cost$81
 $22
Interest cost166
 47
Expected return on plan assets(208) (56)
Amortization of:   
Transition obligation
 2
Prior service credit(3) (6)
Actuarial loss75
 5
Net periodic benefit cost(c)
$111
 $14
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries.
(b)The net periodic benefit cost includes a $6 million and a $7 million net gain for pension benefits and postretirement benefits, respectively, which was included in "Income (loss) from discontinued operations, net of taxes" on Ameren's consolidated statement of income (loss). This net gain includes the curtailment gain recognized in 2013 as a result of a significant reduction in employees as of the December 2, 2013 closing date of the New AER divestiture. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the divestiture.
(c)The net periodic benefit cost includes $9 million and $- million in total net costs for pension benefits and postretirement benefits, respectively, which were included in "Income (loss) from discontinued operations, net of taxes" on Ameren's consolidated statement of income (loss). See Note 16 – Divestiture Transactions and Discontinued Operations for additional information on the divestiture.
The current year expected return on plan assets is determined primarily by adjusting the prior year market-related asset value for current year contributions, disbursements, and expected return, plus 25% of the actual return in excess of (or less than) expected return for the four prior years.
 Pension Benefits Postretirement Benefits
2017   
Service cost$93
 $21
Interest cost179
 47
Expected return on plan assets(262) (75)
Amortization of:   
Prior service credit(1) (5)
Actuarial (gain) loss55
 (6)
Net periodic benefit cost (income)$64
 $(18)
2016   
Service cost$81
 $19
Interest cost185
 50
Expected return on plan assets(253) (72)
Amortization of:   
Prior service credit(1) (5)
Actuarial (gain) loss32
 (11)
Net periodic benefit cost (income)$44
 $(19)
2015   
Service cost$92
 $24
Interest cost174
 48
Expected return on plan assets(248) (68)
Amortization of:   
Prior service credit(1) (5)
Actuarial loss74
 5
Curtailment gain1
 
Net periodic benefit cost$92
 $4
The estimated amounts that will be amortized from regulatory assets and accumulated OCI into Ameren’s net periodic benefit cost in 20152018 are as follows:
Pension Benefits
Ameren(a)
 
Postretirement Benefits
Ameren(a)
Pension Benefits(a)
 
Postretirement Benefits(a)
Regulatory assets:      
Prior service credit$(1) $(4)$(1) $(2)
Net actuarial (gain) loss60
 (1)
Accumulated OCI:   
Net actuarial loss86
 15
5
 
Accumulated OCI:   
Net actuarial (gain) loss2
 (2)
Total$87
 $9
$64
 $(3)
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Prior service cost is amortized on a straight-line basis over the average future service of active participants benefiting under the plan amendment. The netNet actuarial (gain) lossgains or losses subject to amortization isare amortized on a straight-line basis over 10 years.
The Ameren Companies are responsible for their share of the pension and postretirement benefit costs. The following table presents the

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pension costs and the postretirement benefit costs incurred and included in continuing operations for the years ended December 31, 20142017, 20132016, and 20122015:
Pension Costs Postretirement CostsPension Costs Postretirement Costs
2014 2013 2012 2014 2013 20122017 2016 2015 2017 2016 2015
Ameren Missouri(a)$50
 $69
 $63
 $3
 $8
 $10
$24
 $26
 $54
 $(4) $(5) $8
Ameren Illinois30
 41
 37
 (9) 
 4
41
 22
 38
 (14) (13) (3)
Other1
 5
 2
 (2) 
 
(1) (4) 
 
 (1) (1)
Ameren(a)
81
 115
 102
 (8) 8
 14
64
 44
 92
 (18) (19) 4
(a)Includes amountsDoes not include the impact of the regulatory tracking mechanism for the difference between the level of pension and postretirement benefit costs incurred by Ameren registrantMissouri and nonregistrant subsidiaries.the level of such costs included in customer rates.

The expected pension and postretirement benefit payments from qualified trust and company funds, which reflect expected future service, as of December 31, 20142017, are as follows:
  Pension Benefits Postretirement Benefits
  
Paid from
Qualified
Trust
 
        Paid from
         Company
      Funds
 
        Paid from
         Qualified
      Trust
 
        Paid from
         Company
      Funds
2015$253
 $3
 $58
 $2
2016256
 3
 61
 2
2017257
 4
 64
 2
2018260
 3
 68
 2
2019260
 3
 70
 2
2020 - 20241,273
 11
 388
 11
  Pension Benefits Postretirement Benefits
  
Paid from
Qualified
Trust Funds
 
Paid from
Company
Funds
 
Paid from
Qualified
Trust Funds
 
Paid from
Company
Funds
2018$255
 $3
 $57
 $2
2019261
 3
 59
 2
2020266
 3
 62
 2
2021277
 3
 64
 2
2022280
 3
 65
 2
2023  2027
1,421
 13
 331
 12
The following table presents the assumptions used to determine net periodic benefit cost for our pension and postretirement benefit plans for the years ended December 31, 20142017, 20132016, and 20122015:
Pension Benefits Postretirement BenefitsPension Benefits Postretirement Benefits
2014 2013 2012 2014 2013 20122017 2016 2015 2017 2016 2015
Discount rate at measurement date4.75% 4.00% 4.50% 4.75% 4.00% 4.50%4.00% 4.50% 4.00% 4.00% 4.50% 4.00%
Expected return on plan assets7.25
 7.50
 7.75
 7.00
 7.25
 7.50
7.00
 7.00
 7.25
 7.00
 7.00
 7.00
Increase in future compensation3.50
 3.50
 3.50
 3.50
 3.50
 3.50
3.50
 3.50
 3.50
 3.50
 3.50
 3.50
Medical cost trend rate (initial)(a)(a)
 (a)
 (a)
 5.00
 5.00
 5.50
(b)
 (b)
 (b)
 5.00
 5.00
 5.00
Medical cost trend rate (ultimate)(a)(a)
 (a)
 (a)
 5.00
 5.00
 5.00
(b)
 (b)
 (b)
 5.00
 5.00
 5.00
Years to ultimate rate(a)
 (a)
 (a)
 
 
 1 year
(a)Initial and ultimate medical cost trend rate for certain Medicare-eligible participants is 3.00%.
(b)Not applicableapplicable.
The table below reflects the sensitivity of Ameren’s plans to potential changes in key assumptions:
Pension Benefits Postretirement BenefitsPension Benefits Postretirement Benefits
Service Cost
and Interest
Cost
 
    Projected
    Benefit
     Obligation
 
    Service Cost
    and Interest
    Cost
 
    Postretirement
      Benefit
       Obligation
Service Cost
and Interest
Cost
 
Projected
Benefit
Obligation
 
Service Cost
and Interest
Cost
 
Postretirement
Benefit
Obligation
0.25% decrease in discount rate$(1) $138
 $1
 $39
$(1) $157
 $
 $44
0.25% increase in salary scale2
 13
 
 
2
 15
 
 
1.00% increase in annual medical trend
 
 3
 36

 
 4
 71
1.00% decrease in annual medical trend
 
 (2) (33)
 
 (4) (71)
Other
Ameren sponsors a 401(k) plan for eligible employees. The Ameren 401(k) plan covered all eligible employees at December 31, 20142017. The plan allowedallows employees to contribute a portion of their compensation in accordance with specific guidelines. Ameren matchedmatches a percentage of the employee contributions up to certain limits. The following table presents the portion of the matching contribution to the Ameren 401(k) plan attributable to the continuing operations for each of the Ameren Companies for the years ended December 31, 20142017, 20132016, and 20122015:
2014 2013 20122017 2016 2015
Ameren Missouri$16
 $16
 $16
$16
 $16
 $16
Ameren Illinois11
 10
 9
13
 12
 12
Other1
 1
 1
1
 1
 1
Ameren(a)
28
 27
 26
30
 29
 29

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(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries.
NOTE 1211 STOCK-BASED COMPENSATION
The 2014 Incentive Plan is Ameren’s long-term incentivestock compensation plan available for eligible employees and directors, the 2006 Incentive Plan, was replaced prospectively for new grants by the 2014 Incentive Plan effective in April 2014.directors. The 2014 Incentive Plan provides for a maximum of 8 million common shares to be available for grant to eligible employees and directors. It retains many of the features of the 2006 Incentive Plan. To the extent that the issuance of a share that is subject to an outstanding award under the 2006 Incentive Plan would cause Ameren to exceed the maximum authorizedAt December 31, 2017, there were 4.9 million common shares under the 2006 Incentive Plan, the issuance of that share will take place under the 2014 Incentive Plan. This will reduce the maximum number of shares that may be grantedremaining for grant under the 2014 Incentive Plan. The 2014 Incentive Plan awards may be stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, performance share units, cash-based awards, and other stock-based awards.
Performance Share Units
A share unit vests and entitles an employee to receive shares of Ameren common stock (plus accumulated dividends) if, at the end of

the three-year performance period, certain specified performance or market conditions have been met and if the individual remains employed by Ameren through the required vesting period. The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the performance goals. The vesting period for share units awarded extends beyond the three-year performance period to the payout date.
A summary ofThe following table summarizes the nonvested shares at December 31, 2014, and changes duringperformance share unit activity for the year ended December 31, 20142017, under the 2006 Incentive Plan and the 2014 Incentive Plan are presented below::
  Performance Share Units
  
Share
Units
 
Weighted-average
Fair Value per Share Unit
Nonvested at January 1, 20141,218,544
 $33.23
Granted(a)
688,323
 38.90
April Grants(b)
38,559
 50.34
Unearned or forfeited(c)
(97,432) 34.42
Earned and vested(d)
(685,617) 36.12
Nonvested at December 31, 20141,162,377
 $35.35
  Performance Share Units
  
Share
Units
 
Weighted-average Grant Date
Fair Value per Share Unit
Nonvested at January 1, 2017(a)
780,545
 $47.54
Granted(b)
508,161
 59.16
Forfeitures(50,523) 52.50
Undistributed vested units(c)
(342,694) 51.65
Nonvested at December 31, 2017(a)
895,489
 $52.28
(a)Excludes 369,878 and 712,572 performance share units granted to retirement-eligible employees as of January 1, 2017 and December 31, 2017, respectively, as the undistributed performance share units are fully vested.
(b)Includes performance share units (share units) granted to certain executive and nonexecutive officers and other eligible employees in 20142017 under the 2006 Incentive Plan and the 2014 Incentive Plan.
(b)In April 2014, certain executive officers were granted additional share units under the 2006 Incentive Plan and the 2014 Incentive Plan. The significant assumptions used to calculate fair value included a prorated three-year risk-free rate ranging from 0.76% to 0.79%, volatility of 12% to 18% for the peer group, and Ameren’s attainment of a three-year average earnings per share threshold during the performance period.
(c)
Includes share units granted in 2012 that were not earned based on performance provisions of the award grants.
(d)
Includes share units granted in 2012 that vested as of December 31, 2014, that were earned pursuant to the provisions of the award grants. Also includes share units that vested due to attainment of retirement eligibility by certain employees. Actual shares issued for retirement-eligible employees will vary depending on actual performance over the three-year measurement period.
Ameren recordedThe following table presents the stock-based compensation expense of $19 million, $20 million, and $22 million for the years ended December 31, 2014, 2013,2017, 2016, and 2015:
 2017 2016 2015
Ameren Missouri$4
 $4
 $5
Ameren Illinois2
 2
 3
Other(a)
12
 11
 11
Ameren18
 17
 19
Less income tax benefit7
 6
 7
Stock-based compensation expense, net$11
 $11
 $12
(a)Represents compensation expense of employees of Ameren Services. These amounts are not included in the Ameren Missouri and Ameren Illinois amounts above.
2012, respectively, and a related tax benefit of $7 million, $8 million, and $8 million for the years ended December 31, 2014, 2013, and 2012, respectively. Ameren settled performance share units of $39 million, $83 million, and restricted shares of $33$27 million, $11 million, and $11 million for the years ended December 31, 2014, 2013,2017, 2016, and 20122015. There were no significant compensation costs capitalized related to the performance share units during the years ended December 31, 20142017, 20132016, and 20122015. As of December 31, 20142017, total compensation cost of $1829 million related to nonvested awards not yet recognized hasis expected to be recognized over a weighted-average period of 2022 months.
Performance Share Units
Performance share units have been granted under the 2006 Incentive Plan and the 2014 Incentive Plan. A share unit vests and entitles an employee to receive shares of Ameren common stock (plus accumulated dividends) if, at the end of the three-year performance period, certain specified performance or market conditions have been met and if the individual remains employed by Ameren. The exact number of shares issued pursuant to a share unit varies from 0% to 200% of the target award, depending on actual company performance relative to the performance goals.
The fair value of each share unit awarded in 2014, excluding
the grants issued in April for certain executive officers, under the 2006 Incentive Plan and the 2014 Incentive Plan was determined to be $38.90. That amount wasis based on Ameren'sAmeren’s closing common share price at December 31st of $36.16 at December 31, 2013,the year prior to the award year and lattice simulations. Lattice simulations are used to estimate expected share payout based on Ameren'sAmeren’s total shareholder return for a three-year3-year performance period relative to the designated peer group beginning January 1, 2014.1st of the award year. The simulations can produce a greater fair value for the share unit than the applicable closing common share price because they include the weighted payout scenarios in which an increase in the share price has occurred. The significant assumptions used to calculate fair value also includedinclude a three-year risk-free rate, of 0.78%, volatility of 12% to 18% for the peer group, and Ameren's attainment of a three-year average earnings per share threshold during the performance period.
The fair value of each share unit awarded in January 2013 under the 2006 Incentive Plan was determined to be $31.19. That amount was based on Ameren’s closing common share price of $30.72 at December 31, 2012, and lattice simulations. Lattice simulations are used to estimate expected share payout based on Ameren’s total shareholder return for a three-year performance period relative to the designated peer group beginning January 1, 2013. The simulations can produce a greater fair value for the share unit than the applicable closing common share price because they include the weighted payout scenarios in which an increase in the share price has occurred. The significant assumptions used to calculate fair value also


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included a three-year risk-free rate of 0.36%, volatility of 12% to 21% for the peer group, and Ameren’s attainment of a three-year average earnings per share threshold during the performance period. The following table presents the fair value of each share unit awarded under the 2014 Incentive Plan along with the significant assumptions used to calculate the fair value of each share unit for the years ended December 31, 2017, 2016, and 2015:
 201720162015
Fair value of share units awarded$59.16$44.13$52.88
Ameren’s closing common share price at December 31 of the prior year$52.46$43.23$46.13
Three-year risk free rate1.47%1.31%1.10%
Volatility range15% - 21%15% - 20%12% - 18%
period.

NOTE 1312 INCOME TAXES
Federal Tax Reform
The TCJA was enacted on December 22, 2017. Substantially all of the provisions of the TCJA affecting the Ameren Companies, other than certain transition depreciation rules, are effective for taxable years beginning after December 31, 2017. The TCJA includes significant changes to the Internal Revenue Code, including amendments that significantly change the taxation of business entities and specific provisions related to regulated public utilities. The most significant change that affects the Ameren Companies is the reduction in the federal

corporate statutory income tax rate from 35% to 21%. Specific provisions related to regulated public utilities generally allow for the continued deductibility of interest expense, the elimination of accelerated depreciation tax benefits from certain regulated utility capital investments acquired after September 27, 2017, and the continuation of certain rate normalization requirements related to the flow back of excess deferred taxes. Ameren (parent) will be subject to provisions of the TCJA that limit the deductibility of interest expense.
In accordance with GAAP, the tax effects of changes in tax laws must be recognized in the period in which the law is enacted. GAAP also requires deferred tax assets and liabilities to be measured at the tax rate that is expected to apply when temporary differences are realized or settled. Thus, in December 2017, the Ameren Companies’ deferred taxes were revalued using the new tax rate. To the extent deferred tax balances are included in rate base, the revaluation of deferred taxes was deferred as a regulatory asset or liability on the balance sheet and will be collected from or refunded to customers. For deferred tax balances not included in rate base, the revaluation of deferred taxes was recorded as income tax expense.
As a result of the complexity of the TCJA, the SEC staff issued guidance to clarify the accounting for income taxes if information is not yet available or complete. This guidance provides for up to a one year period in which to complete the required analysis and update provisional estimates. The guidance provides three scenarios associated with a company’s status of accounting for income tax reform: (1) a company has completed itsaccounting for certain effects of tax reform, (2) a company is able to make areasonable estimate for certain effects of tax reform and records that estimate as aprovisional amount, or (3) a company is not able to make a reasonable estimate andtherefore continues to apply income tax accounting that is based on the taxlaws in effect immediately prior to the enactment of the TCJA.
As of December 31, 2017, the Ameren Companies have made reasonable estimates for the measurement and accounting of certain effects of the TCJA, which have been reflected in their financial statements. We have recorded provisional estimates primarily related to depreciation transition rules and 2017 property, plant, and equipment, compensation, and pension-related deductions which would impact our revaluation of deferred taxes at December 31, 2017. These items may be resolved through additional analysis, which is incomplete due to the timing of the enactment of the TCJA and complexity associated with applying its provisions. Additionally, interpretations, regulations, amendments, and technical corrections of the TCJA by various regulators could also resolve provisional items. The TCJA had the following provisional effects for the year ended December 31, 2017:
 Ameren Missouri Ameren Illinois Other Ameren
Increase (Decrease)       
Accumulated deferred income taxes, net$(1,419) $(871) $37
 $(2,253)
Income tax expense (benefit)(a)
32
 (5) 127
 154
Noncurrent regulatory assets(89) (24) (1) (114)
Noncurrent regulatory liabilities1,362
 842
 89
 2,293
For our regulated operations, reductions in accumulated deferred income tax balances due to the reduction in the federal statutory corporate income tax rate to 21% will result in amounts previously collected from utility customers for these deferred taxes being refundable to those customers, generally through reductions in future rates. The TCJA includes provisions related to the IRS normalization rules that address the time period in which certain plant-related components of the excess deferred taxes are to be reflected in customer rates. This time period for the Ameren Companies is approximately 35 to 60 years. Other components of the excess deferred taxes will be reflected in customer rates as determined by our state and federal regulators, which could be a shorter time period than that applicable to certain plant-related components. See Note 2 – Rate and Regulatory Matters for information regarding the various proceedings for the TCJA impacts with our regulators.
Illinois Income Tax Rate
In July 2017, Illinois enacted a law that increased the state’s corporate income tax rate from 7.75% to 9.5% as of July 1, 2017. The law made the increase in the state’s corporate income taxrate permanent. That rate was previously scheduled to go to 7.3% in 2025. In July 2017, Ameren recorded an expense of $14 million at Ameren (parent) due to the revaluation of accumulated deferred taxes and the estimated state apportionment of such taxes. Beyond this expense, Ameren does not expect this tax increase to have a material impact on its consolidated net income prospectively. The tax increase is not expected to materially impact the earnings of the Ameren Illinois Electric Distribution, the Ameren Transmission, or the Ameren Illinois Transmission segments, since these businesses operate under formula ratemaking frameworks. The tax increase unfavorably affected the 2017 net income of the Ameren Illinois Natural Gas segment by less than $1 million. In addition, in the third quarter of 2017, Ameren’s and Ameren Illinois’ accumulated deferred tax balances were revalued using the state’s new corporate income tax rate, which resulted in a net increase to the liability balances of $97 million and $79 million, respectively. These increased liabilities were offset by a regulatory asset, as well as income tax expense, as discussed above.

The following table presents the principal reasons for the difference between the effective income tax rate and the federal statutory federalcorporate income tax rate for the years ended December 31, 20142017, 20132016, and 20122015:
Ameren Missouri Ameren Illinois AmerenAmeren Missouri Ameren Illinois Ameren
2014     
Statutory federal income tax rate:35 % 35 % 35 %
2017     
Federal statutory corporate income tax rate:35 % 35 % 35 %
Increases (decreases) from:          
Amortization of investment tax credit(1) 
 (1)
Depreciation differences1
 (1) 
Amortization of deferred investment tax credit(1) 
 (1)
State tax4
 6
 6
TCJA6
 (1) 14
Tax credits(1) 
 
Other permanent items
 (1) (2)
Effective income tax rate44 % 38 % 52 %
2016     
Federal statutory corporate income tax rate:35 % 35 % 35 %
Increases (decreases) from:     
Depreciation differences1
 
 
Amortization of deferred investment tax credit(1) 
 
State tax3
 5
 4
Stock-based compensation(a)

 
 (2)
Valuation allowance
 
 1
Other permanent items
 (2) (1)
Effective income tax rate38 % 38 % 37 %
2015     
Federal statutory corporate income tax rate:35 % 35 % 35 %
Increases (decreases) from:     
Depreciation differences
 (2) (1)
Amortization of deferred investment tax credit(1) 
 (1)
State tax3
 6
 4
3
 5
 5
Other permanent items
 
 1

 (1) 
Effective income tax rate37 % 41 % 39 %37 % 37 % 38 %
2013     
Statutory federal income tax rate:35 % 35 % 35 %
Increases (decreases) from:     
Depreciation differences
 (1) 
Amortization of investment tax credit(1) 
 (1)
State tax3
 6
 4
Other permanent items1
 
 
Effective income tax rate38 % 40 % 38 %
2012     
Statutory federal income tax rate:35 % 35 % 35 %
Increases (decreases) from:     
Depreciation differences(1) 
 (1)
Amortization of investment tax credit(1) (1) (1)
State tax3
 6
 5
Reserve for uncertain tax positions1
 
 
Other permanent items
 
 (1)
Effective income tax rate37 % 40 % 37 %
(a)Reflects the adoption of authoritative accounting guidance related to share-based compensation, which resulted in the recognition of a $21 million income tax benefit in 2016.


127


The following table presents the components of income tax expense (benefit) for the years ended December 31, 20142017, 20132016, and 20122015:
 Ameren Missouri Ameren Illinois Other Ameren
2014       
Current taxes:       
Federal$(13) $(51) $27
 $(37)
State(3) (2) (32) (37)
Deferred taxes:       
Federal222
 159
 (12) 369
State28
 38
 22
 88
Deferred investment tax credits, amortization(5) (1) 
 (6)
Total income tax expense$229
 $143
 $5
 $377
2013       
Current taxes:       
Federal$136
 $(15) $(239)
(a) 
$(118)
State41
 21
 (43)
(a) 
19
Deferred taxes:       
Federal64
 99
 205
(a) 
368
State6
 6
 36
(a) 
48
Deferred investment tax credits, amortization(5) (1) 
 (6)
Total income tax expense (benefit)$242
 $110
 $(41) $311
2012       
Current taxes:       
Federal$(25) $(7) $72
 $40
State(10) (3) 23
 10
Deferred taxes:       
Federal248
 76
 (120) 204
State44
 30
 (14) 60
Deferred investment tax credits, amortization(5) (2) 
 (7)
Total income tax expense (benefit)$252
 $94
 $(39) $307
(a)These amounts are substantially related to the reversal of unrecognized tax benefits as a result of IRS guidance related to the deductibility of expenditures to maintain, replace or improve steam or electric power generation property, along with casualty loss deductions for storm damage. The amounts also reflect the increase in deferred tax expense due to available net operating losses.
The Illinois corporate income tax rate was increased to 9.5% from January 2011 through December 2014. The tax rate decreased to 7.75% on January 1, 2015 and is scheduled to decrease to 7.3% on January 1, 2025.
 Ameren Missouri Ameren Illinois Other Ameren
2017       
Current taxes:       
Federal$149
 $(34) $(110) $5
State23
 29
 (20) 32
Deferred taxes:       
Federal76
 185
 250
 511
State11
 (13) 36
 34
Amortization of deferred investment tax credits(5) (1) 
 (6)
Total income tax expense$254
 $166
 $156
 $576
2016       
Current taxes:       
Federal$31
 $(8) $(24) $(1)
State6
 12
 (21) (3)
Deferred taxes:       
Federal161
 117
 21
 299
State23
 37
 32
 92
Amortization of deferred investment tax credits(5) 
 
 (5)
Total income tax expense$216
 $158
 $8
 $382
2015       
Current taxes:       
Federal$110
 $(83) $(29) $(2)
State17
 (11) (10) (4)
Deferred taxes:       
Federal71
 193
 35
 299
State16
 29
 31
 76
Amortization of deferred investment tax credits(5) (1) 
 (6)
Total income tax expense$209
 $127
 $27
 $363
The following table presents the accumulated deferred income tax assets and deferred tax liabilities recorded as a result of temporary differences at December 31, 20142017 and 20132016:
Ameren Missouri Ameren Illinois Other AmerenAmeren Missouri Ameren Illinois Other Ameren
2014       
2017       
Accumulated deferred income taxes, net liability (asset):              
Plant related$2,776
 $1,393
 $16
 $4,185
$2,064
 $1,264
 $146
 $3,474
Regulatory assets, net82
 (5) 1
 78
Regulatory assets and liabilities, net(317) (206) (24) (547)
Deferred employee benefit costs(80) (45) (95) (220)(53) (17) (61) (131)
Revenue requirement reconciliation adjustments


 66
 3
 69

 20
 
 20
Tax carryforwards(107) (139) (429) (675)(31) (43) (287) (361)
Other86
 (22) 70
 134
(13) 3
 61
 51
Total net accumulated deferred income tax liabilities (assets)(a)
$2,757
 $1,248
 $(434) $3,571
$1,650
 $1,021
 $(165) $2,506
2013       
2016       
Accumulated deferred income taxes, net liability (asset):              
Plant related$2,513
 $1,243
 $13
 $3,769
$3,103
 $1,769
 $147
 $5,019
Regulatory assets, net74
 2
 
 76
Regulatory assets and liabilities, net75
 (1) 
 74
Deferred employee benefit costs(74) (85) (114) (273)(76) (38) (97) (211)
Revenue requirement reconciliation adjustments

 (4) 2
 (2)
 34
 
 34
Tax carryforwards(76) (95) (370) (541)(66) (138) (472) (676)
Other67
 10
 38
 115
(23) 5
 42
 24
Total net accumulated deferred income tax liabilities (assets)(b)
$2,504
 $1,071
 $(431) $3,144
$3,013
 $1,631
 $(380) $4,264

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(a)Includes $49 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2014.
(b)Includes $20 million recorded in "Other current assets" on Ameren Missouri's balance sheet as of December 31, 2013.
The following table presents the components of accumulated deferred income tax assets relating to net operating loss carryforwards, tax credit carryforwards, and charitable contribution carryforwards at December 31, 20142017: and 2016:
Ameren Missouri Ameren Illinois Other AmerenAmeren Missouri Ameren Illinois Other Ameren
2017       
Net operating loss carryforwards:              
Federal(a)
$75
 $127
 $255
 $457
$
 $41
 $162
 $203
State(b)
11
 10
 53
 74
State(a)

 
 32
 32
Total net operating loss carryforwards$86
 $137
 $308
 $531
$
 $41
 $194
 $235
Tax credit carryforwards:              
Federal(c)
$21
 $1
 $77
 $99
State(d)
1
 2
 33
 36
State valuation allowance(e)
(1) (1) (2) (4)
Federal(b)
$31
 $2
 $80
 $113
State(c)

 
 7
 7
Total tax credit carryforwards$21
 $2
 $108
 $131
$31
 $2
 $87
 $120
Charitable contribution carryforwards(f)(d)
$
 $
 $19
 $19
$
 $
 $11
 $11
Valuation allowance(g)(e)

 
 (6) (6)
 
 (5) (5)
Total charitable contribution carryforwards$
 $
 $13
 $13
$
 $
 $6
 $6
2016       
Net operating loss carryforwards:       
Federal$33
 $137
 $324
 $494
State4
 
 41
 45
Total net operating loss carryforwards$37
 $137
 $365
 $539
Tax credit carryforwards:       
Federal$29
 $1
 $79
 $109
State
 
 21
 21
Total tax credit carryforwards$29
 $1
 $100
 $130
Charitable contribution carryforwards$
 $
 $18
 $18
Valuation allowance
 
 (11) (11)
Total charitable contribution carryforwards$
 $
 $7
 $7
(a)
Will begin to expire in 2028.
(b)
Will begin to expire in 2020.
(c)
Will begin to expire in 2029.
(d)
Began to expire in 2013.
(e)This balance increased by less than $1 million, $- million,between 2033 and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2014.
(f)These began to expire in 2013.
(g)This balance increased by $3 million, $- million and $- million for Ameren, Ameren Missouri and Ameren Illinois, respectively, during 2014.
The following table presents the components of deferred tax assets relating to net operating loss carryforwards, tax credit carryforwards, and charitable contribution carryforwards at December 31, 2013:
 Ameren Missouri Ameren Illinois Other Ameren
Net operating loss carryforwards:       
Federal(a)
$61
 $84
 $215
 $360
State(b)
3
 11
 34
 48
Total net operating loss carryforwards$64
 $95
 $249
 $408
Tax credit carryforwards:       
Federal(c)
$12
 $
 $76
 $88
State(d)
1
 1
 32
 34
State valuation allowance(e)
(1) (1) (2) (4)
Total tax credit carryforwards$12
 $
 $106
 $118
Charitable contribution carryforwards(f)
$
 $
 $18
 $18
Valuation allowance(g)

 
 (3) (3)
Total charitable contribution carryforwards$
 $
 $15
 $15
(a)
Will begin to expire in 2028
2036. Any net operating loss carryforward generated after January 1, 2018, will not have an expiration date as a result of the TCJA.
(b)Will begin to expire in 2019.between 2029 and 2037.
(c)Will begin to expire in 2029.between2019 and 2022.
(d)Began toWill expire in 2013.between 2018 and 2021.
(e)
Balance increased by $2 million, $- million, and $- millionSee Schedule II under Part IV, Item 15, in this report for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2013.
information on changes in the valuation allowance.
(f)These began to expire in 2013.
(g)This balance increased by $3 million, $- million, and $- million for Ameren, Ameren Missouri, and Ameren Illinois, respectively, during 2013.

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Uncertain Tax Positions
A reconciliationAs of the change in the unrecognized tax benefit balance during the years ended December 31, 2012, 2013,2017 and 2014, is as follows:
 Ameren Missouri Ameren Illinois Other Ameren
Unrecognized tax benefits – January 1, 2012$124
 $11
 $13
 $148
Increases based on tax positions prior to 20124
 
 1
 5
Decreases based on tax positions prior to 2012(7) (1) (5) (13)
Increases based on tax positions related to 201215
 3
 (1) 17
Changes related to settlements with taxing authorities
 
 
 
Decreases related to the lapse of statute of limitations
 
 (1) (1)
Unrecognized tax benefits – December 31, 2012$136
 $13
 $7
 $156
Increases based on tax positions prior to 2013
 2
 5
 7
Decreases based on tax positions prior to 2013(122) (16) (5) (143)
Increases (decreases) based on tax positions related to 201316
 
 53
(a) 
69
Changes related to settlements with taxing authorities
 
 
 
Decreases related to the lapse of statute of limitations1
 
 
 1
Unrecognized tax benefits – December 31, 2013$31
 $(1) $60
 $90
Increases based on tax positions prior to 20141
 1
 4
 6
Decreases based on tax positions prior to 2014(32) (1) (9) (42)
Increases based on tax positions related to 2014
 
 
 
Changes related to settlements with taxing authorities
 
 
 
Increases related to the lapse of statute of limitations
 
 
 
Unrecognized tax benefits (detriments) – December 31, 2014$
 $(1) $55
 $54
Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2012$3
 $(1) $(1) $1
Total unrecognized tax benefits (detriments) that, if recognized, would affect the effective tax rates as of December 31, 2013$3
 $
 $51
(a) 
$54
Total unrecognized tax benefits that, if recognized, would affect the effective tax rates as of December 31, 2014$
 $(1) $53
(a) 
$52
(a)Primarily due to tax positions relating to the New AER divestiture. The income statement impact of this unrecognized tax benefit was included in "Income (loss) from discontinued operations, net of taxes" on Ameren's consolidated statement of income (loss). See Note 16 – Divestiture Transactions and Discontinued Operations for additional information.
The Ameren Companies recognize interest charges (income) and penalties accrued on tax liabilities on a pretax basis as interest charges (income) or miscellaneous expense, respectively, in the statements of income.
A reconciliation of the change in the liability for interest on unrecognized tax benefits during the years ended December 31, 2012, 2013, and 2014, is as follows:
 Ameren Missouri Ameren Illinois Other Ameren
Liability for interest – January 1, 2012$6
 $1
 $(2) $5
Interest charges (income) for 20122
 
 (1) 1
Liability for interest – December 31, 2012$8
 $1
 $(3) $6
Interest charges (income) for 2013(8) (1) 4
 (5)
Liability for interest – December 31, 2013$
 $
 $1
 $1
Interest charges (income) for 2014
 
 (1) (1)
Liability for interest – December 31, 2014$
 $
 $
 $
As of December 31, 20122013, and 2014,2016, the Ameren Companies have accrued no amount for penalties with respect to unrecognizeddid not record any uncertain tax benefits.

positions.
In 2014,2015, final settlements for tax years 2007 through 20112012 and 2013 were reached with the IRS. These settlements, which resolved the uncertain tax positions associated with the timing of research tax deductions for these years, resulted in a decrease in Ameren’s and Ameren Missouri’s unrecognized tax benefits of $20 million, and $13 million, respectively. In addition, theThe 2015 settlement for tax years 2007 through 2011 provided certainty for the previously uncertain tax positions associated with the timing of research tax deductions for the remaining open tax years of 2012, 2013, and 2014. As a result, the certainty provided from the settlement resulted in an $18 million decrease in both Ameren’s and Ameren Missouri’s unrecognized tax benefits. The settlement also resulted in a $2 million increase to Ameren’s state unrecognized tax benefits. The net reduction in unrecognized tax benefits in 2014 did not materially affect income tax expense for the Ameren Companies.

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In 2013, unrecognized tax benefits related to the deductibility of expenditures to maintain, replace, or improve steam or electric power generation property, along with casualty loss deductions for storm damage, were reduced by $103 million, $95 million, and $5 million for Ameren, Ameren Missouri, and Ameren Illinois, respectively. This reduction in unrecognized tax benefits did not affect income tax expense for the Ameren Companies. However, the liability for interest related to these unrecognized tax benefits was released in 2013. In 2013, Ameren adopted an accounting method change as a result of guidance issued by the IRS, with respect to the amount and timing of the deductions to maintain, replace, or improve generation property.
It is reasonably possible that a settlement will be reached with the IRS in the next 12 months2013 tax year affected discontinued operations. See Note 1 – Summary of Significant Accounting Policies for the years 2012 and 2013. However, the Ameren Companies do not believe any settlements would have a material effect on its net income from continuing operations.additional information.
State income tax returns are generally subject to examination for a period of three years after filing. The state impact of any federal changes remains subject to examination by various states for a period of up to one year after formal notification to the states. The Ameren Companies currently do not have material state income tax issues under examination, administrative appeals, or litigation.
Ameren Missouri has an uncertain tax position tracker. Under Missouri'sMissouri’s regulatory framework, uncertain tax positions do not reduce Ameren Missouri'sMissouri’s electric rate base. When an uncertain income tax position liability is resolved, the MoPSC requires, through the uncertain tax position tracker, the creation of a regulatory asset or regulatory liability to reflect the time value, using the weighted-average cost of capital included in each of the electric rate orders in effect before the tax position was resolved, of the difference between the uncertain tax position liability that was excluded from rate base and the final tax liability. The resulting regulatory asset or liability will affect earnings in the year it is created andcreated. It will then will be amortized over three years, beginning on the effective date of new rates established in the next electric regulatory rate case.review.
NOTE 1413 RELATED PARTYRELATED-PARTY TRANSACTIONS
TheIn the normal course of business, Ameren CompaniesMissouri and Ameren Illinois have engaged in, and may in the future engage in, affiliate transactions in the normal course of business.transactions. These transactions primarily consist of natural gas and power purchases and sales, services received or rendered, and borrowings and lendings. Transactions between affiliatesAmeren’s subsidiaries are reported as intercompanyaffiliate transactions on their individual financial statements, but those transactions are eliminated in consolidation for Ameren’s consolidated financial statements. Below are the material related partyrelated-party agreements.

Electric Power Supply Agreements
Capacity Supply Agreements
Ameren Illinois must acquire capacity and energy sufficient to meet its obligations to customers. Ameren Illinois uses periodic RFP processes, that are administered by the IPA and approved by the ICC, to contract capacity and energy on behalf of its customers. Ameren Missouri participates in the RFP process and has been a winning supplier for certain periods.
Capacity Supply Agreements
In 2010,a procurement event in 2012, Ameren Missouri contracted to supply a portion of Ameren Illinois’ capacity requirements for less than $1$3 million for the period from June 1, 2010, through12 months ended May 31, 2013.2015. In 2012,a procurement event in 2015, Ameren Missouri contracted to supply a portion of Ameren Illinois'Illinois’ capacity requirements for $1 million and $3$15 million for the 12 months ending May 31, 2014, and 2015, respectively.2017.
Energy Swaps and Energy Products
Ameren Illinois must acquire energy sufficient to meet its obligations to customers.
In 2011, Ameren Illinois used an RFP process, administered byBased on the IPA, to procure energy products that settled physically from June 1, 2011, through May 31, 2014. Ameren Missouri was among the winning suppliers in the energy product RFP process. In 2011,outcome of IPA-administered procurement events, Ameren Missouri and Ameren Illinois entered into energy
product agreements by which Ameren Missouri agreed to sell and Ameren Illinois agreed to purchase approximately 16,800 megawatthours at approximately $37 per megawatthour during the 12 months ended May 31, 2012, approximately 40,800 megawatthours at approximately $29 per megawatthour during the 12 months ended May 31, 2013, and approximately 40,800 megawatthours at approximately $28 per megawatthour during the 12 months ended May 31, 2014. The energy product agreements between Ameren Missouri and Ameren Illinois for the periods ended May 31, 2012, and May 31, 2013, were for off-peak hours only.
In 2014, Ameren Illinois used an RFP process, administered by the IPA, to procure energy products that will settle physically from December 1, 2014, through May 31, 2017. Ameren Missouri was among the winning suppliers in the energy product RFP process. As a result, Ameren Missouri and Ameren Illinoishave entered into energy product agreements by which Ameren Missouri agreed to sell, and Ameren Illinois agreed to purchase, approximately 168,400a set amount of megawatthours at approximately $51 per megawatthour during thea predetermined price over a specified period of January 1, 2015,time. The following table presents the agreements the companies have entered into, as well as the specified performance period, price, and amount of megawatthours included in each agreement:
IPA Procurement EventPerformance PeriodMWh
 Average Price per MWh
May 2014
January 2015  February 2017
168,400
$51
April 2015
June 2015  June 2017
667,000
 36
September 2015
November 2015  May 2018
339,000
 38
April 2016
June 2017  September 2018
375,200
 35
September 2016
May 2017  September 2018
82,800
 34
April 2017
March 2019  May 2020
85,600
 34
Collateral Postings
Under the terms of the Illinois energy product agreements entered into through February 28, 2017.RFP processes administered by the IPA, suppliers must post collateral under certain market conditions to protect Ameren Illinois in the event of nonperformance. The collateral postings are unilateral, which means that only the suppliers can be required to post collateral. Therefore, Ameren Missouri, as a winning supplier in the RFP process, may be required to post collateral. As of December 31, 2017 and 2016, there were no collateral postings required of Ameren Missouri related to the Illinois energy product agreements.
Interconnection and Transmission Agreements
Ameren Missouri and Ameren Illinois are parties to an interconnection agreement for the use of their respective transmission lines and other facilities for the distribution of power. These agreements have no contractual expiration date, but may be terminated by either party with three years’ notice.
Joint Ownership Agreement
ATXI and Ameren Illinois have a joint ownership agreement to construct, own, operate, and maintain certain electric transmission assets in Illinois. Under the terms of this agreement, Ameren Illinois and ATXI are responsible for their applicable


131


share of all costs related to the construction, operation, and maintenance of electric transmission systems. Currently, there are no construction projects or joint ownership of existing assets under this agreement.
Support Services Agreements
Ameren Services provides support services to its affiliates. The costs of support services, including wages, employee benefits, professional services, and other expenses, are based on, or are an allocation of, actual costs incurred. A sharedThe support services support agreement can be terminated at any time by the mutual agreement of Ameren Services and that affiliate or by either party with 60 days'days’ notice before the end of a calendar year.
In addition, Ameren Missouri and Ameren Illinois provide affiliates, primarily Ameren Services, with access to their facilities for administrative purposes. The costcosts of the rent and facility services are based on, or are an allocation of, actual costs incurred.
Separately, Ameren Missouri and Ameren Illinois provide storm-related and miscellaneous support services to each other on an as-needed basis.
Transmission Services
Ameren Illinois takesreceives transmission serviceservices from MISOATXI for theits retail load it serves in the AMIL pricing zone. ATXI is one of the transmission owners in the AMIL pricing zone. Accordingly ATXI
receives transmission payments from Ameren Illinois through the MISO billing process.
Money Pool
See Note 4 – Short-term Debt and Liquidity and Note 5 – Long-term Debt and Equity Financings for a discussion of affiliate borrowing arrangements.
Collateral Postings
Under the terms of the Illinois power procurement agreements entered into through RFP processes administered by the IPA, suppliers must post collateral under certain market conditions to protect Ameren Illinois in the event of nonperformance. The collateral postings are unilateral, meaning that only the suppliers can be required to post collateral. Therefore, Ameren Missouri, as a winning supplier in the RFP process, may be required to post collateral. As of December 31, 2014 and 2013, there were no collateral postings required of Ameren Missouri related to the Illinois power procurement agreements.
Tax Allocation Agreement
See Note 1 – Summary of Significant Accounting Policies for a discussion of the tax allocation agreement. AtAs of December 31, 2014,2017 and 2016, Ameren Missouri had income taxes payable to Ameren (parent) of $11 million and $16 million, respectively, included in “Accounts payable - affiliates” on its balance sheet. As of December 31, 2017 and 2016, Ameren Illinois had an intercompany receivable balance withincome taxes payable to Ameren (parent) of $58$17 million and $15$3 million, respectively, included in “Accounts payable - affiliates” on its balance sheet. See below for capital contributions received related to the tax allocation agreement.
Capital Contributions


132

TableIn 2017, Ameren Missouri received cash capital contributions of Contents$30 million from Ameren (parent) as a result of the tax allocation agreement. In 2017, Ameren Illinois received cash capital contributions of $8 million from Ameren (parent).
In 2016, Ameren Missouri received cash capital contributions of $44 million from Ameren (parent) as a result of the tax allocation agreement, which included the accrued capital contribution from 2015.

In 2015, Ameren Missouri received cash capital contributions of $224 million from Ameren (parent) as a result of the tax allocation agreement, which included the accrued capital contribution from 2014. Additionally, as of December 31, 2015, Ameren Missouri accrued a $38 million capital contribution related to the same agreement. In 2015, Ameren Illinois received cash capital contributions of $25 million from Ameren (parent).
The following table presents the impact on Ameren Missouri and Ameren Illinois of related partyrelated-party transactions for the years ended December 31, 20142017, 20132016, and 20122015. It is based primarily on the agreements discussed above and the money pool arrangements discussed in Note 4 – Short-term Debt and Liquidity.
AgreementIncome Statement Line Item                        
Ameren
Missouri
 
Ameren
Illinois
Income Statement Line Item 
Ameren
Missouri
 
Ameren
Illinois
Ameren Missouri power supply agreementsOperating Revenues 2014$5
$(a)
Operating Revenues 2017$23
$(a)
with Ameren Illinois 2013 3
 (a)
 2016 28
 (a)
  2012 (b)
 (a)
  2015 15
 (a)
Ameren Missouri and Ameren IllinoisOperating Revenues 2014 21
 2
Operating Revenues 2017 26
 4
rent and facility services 2013 21
 1
 2016 25
 5
  2012 19
 1
  2015 25
 4
Ameren Missouri and Ameren IllinoisOperating Revenues 2014 1
 (b)
Operating Revenues 2017 (b)
 1
miscellaneous support services 2013 1
 3
 2016 1
 (b)
 2012 1
 (b)
 2015 2
 (b)
Total Operating Revenues 2014$27
$2
 2017$49
$5
 2013 25
 4
 2016 54
 5
  2012 20
 1
  2015 42
 4
Ameren Illinois power supplyPurchased Power 2014$(a)
$5
Purchased Power 2017$(a)
$23
agreements with Ameren Missouri 2013 (a)
 3
 2016 (a)
 28
  2012 (a)
 (b)
  2015 (a)
 15
Ameren Illinois transmissionPurchased Power 2014 (a)
 2
Purchased Power 2017 (a)
 2
services with ATXI 2013 (a)
 2
services from ATXI 2016 (a)
 2
 2012 (a)
 3
 2015 (a)
 2
Total Purchased Power 2014$(a)
$7
 2017$(a)
$25
 2013 (a)
 5
 2016 (a)
 30
 2012 (a)
 3
 2015 (a)
 17
Ameren Services support servicesOther Operations and 2014$124
$109
Other Operations and 2017$149
$139
agreementMaintenance 2013 116
 93
Maintenance 2016 129
 123
  2012 106
 88
  2015 131
 119
Insurance premiums(c)
Other Operations and 2014 (b)
 (a)
Maintenance 2013 (b)
 (a)
  2012 (b)
 (a)
Total Other Operations and 2014$124
$109
Maintenance Expenses 2013 116
 93
  2012 106
 88
Money pool borrowings (advances)Interest (Charges) 2014$(b)
$(b)
(Interest Charges) 2017$1
$(b)
Income 2013 (b)
 (b)
Miscellaneous Income 2016 (b)
 (b)
  2012 (b)
 (b)
  2015 (b)
 (b)
(a)Not applicable.
(b)Amount less than $1 million.
(c)Represents insurance premiums paid to Missouri Energy Risk Assurance Company LLC, an affiliate, for replacement power.

NOTE 1514 COMMITMENTS AND CONTINGENCIES
We are involved in legal, tax, and regulatory proceedings before various courts, regulatory commissions, authorities, and governmental agencies with respect to matters that arise in the ordinary course of business, some of which involve substantial amounts of money. We believe that the final disposition of these proceedings, except as otherwise disclosed in these notes to our financial statements, will not have a material adverse effect on our results of operations, financial position, or liquidity.
See also Note 1 – Summary of Significant Accounting Policies, Note 2 – Rate and Regulatory Matters, Note 109 – Callaway Energy Center, Note 14 – Related Party Transactions, and Note 1613 – DivestitureRelated-party Transactions and Discontinued Operations in this report.

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Callaway Energy Center
The following table presents insurance coverage at Ameren Missouri’s Callaway energy center at December 31, 2014. The property coverage and the nuclear liability coverage must be renewed on April 1 and January 1, respectively, of each year.
Type and Source of CoverageMaximum Coverages Maximum Assessments 
Public liability and nuclear worker liability:    
American Nuclear Insurers$375

$
 
Pool participation13,241
(a)  
128
(b)  
 $13,616
(c)  
$128
 
Property damage:    
Nuclear Electric Insurance Limited$2,250
(d)  
$23
(e)  
European Mutual Association for Nuclear Insurance500
(f)  

 
 $2,750
 $23
 
Replacement power:    
Nuclear Electric Insurance Limited$490
(g)  
$9
(e)  
Missouri Energy Risk Assurance Company LLC$64
(h)  
$
 
(a)Provided through mandatory participation in an industrywide retrospective premium assessment program.
(b)
Retrospective premium under the Price-Anderson Act. This is subject to retrospective assessment with respect to a covered loss in excess of $375 million in the event of an incident at any licensed United States commercial reactor, payable at $19 million per year.
(c)
Limit of liability for each incident under the Price-Anderson Act liability provisions of the Atomic Energy Act of 1954, as amended. A company could be assessed up to $128 million per incident for each licensed reactor it operates, with a maximum of $19 million per incident to be paid in a calendar year for each reactor. This limit is subject to change to account for the effects of inflation and changes in the number of licensed reactors.
(d)NEIL provides $2.25 billion in property damage, decontamination, and premature decommissioning insurance.
(e)All NEIL-insured plants could be subject to assessments should losses exceed the accumulated funds from NEIL.
(f)European Mutual Association for Nuclear Insurance provides $500 million in excess of the $2.25 billion property coverage provided by NEIL.
(g)
Provides replacement power cost insurance in the event of a prolonged accidental outage. Weekly indemnity is up to $4.5 million for 52 weeks, which commences after the first eight weeks of an outage, plus up to $3.6 million per week for a minimum of 71 weeks thereafter, for a total not exceeding the policy limit of $490 million. Nonradiation events are sub-limited to $328 million.
(h)
Provides replacement power cost insurance in the event of a prolonged accidental outage. The coverage commences after the first 52 weeks of insurance coverage from NEIL concludes; it is a weekly indemnity of up to $0.9 million for 71 weeks in excess of the $3.6 million per week set forth above. Missouri Energy Risk Assurance Company LLC is an affiliate; it has reinsured this coverage with third-party insurance companies. See Note 14 – Related Party Transactions for more information on this affiliate transaction.
The Price-Anderson Act is a federal law that limits the liability for claims from an incident involving any licensed United States commercial nuclear energy center. The limit is based on the number of licensed reactors. The limit of liability and the maximum potential annual payments are adjusted at least every five years for inflation to reflect changes in the Consumer Price Index. The most recent five-year inflationary adjustment became effective in September 2013. Owners of a nuclear reactor cover this exposure through a combination of private insurance and mandatory participation in a financial protection pool, as established by the Price-Anderson Act.
Losses resulting from terrorist attacks on nuclear facilities are covered under NEIL’s policies, subject to an industrywide aggregate policy coverage limit of $3.24 billion within a 12-month period, or $1.83 billion for events not involving radiation contamination.
If losses from a nuclear incident at the Callaway energy center exceed the limits of, or are not covered by, insurance or if coverage is unavailable, Ameren Missouri is at risk for any uninsured losses. If a serious nuclear incident were to occur, it could have a material adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, or liquidity.

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Leases
We lease various facilities, office equipment, plant equipment, and rail cars under capital and operating leases. The following table presents our lease obligations at December 31, 20142017:
2015 2016 2017 2018 2019 After 5 Years Total2018 2019 2020 2021 2022 After 5 Years Total
Ameren:(a)
                          
Minimum capital lease payments(b)
$33
 $33
 $33
 $32
 $32
 $360
 $523
Minimum capital lease payments(b)(c)
$32
 $32
 $32
 $33
 $32
 $264
 $425
Less amount representing interest27
 27
 27
 26
 25
 97
 229
26
 25
 25
 25
 24
 24
 149
Present value of minimum capital lease payments$6
 $6
 $6
 $6
 $7
 $263
 $294
$6
 $7
 $7
 $8
 $8
 $240
 $276
Operating leases(c)
13
 12
 12
 12
 11
 38
 98
Operating leases10
 9
 8
 6
 6
 14
 53
Total lease obligations$19
 $18
 $18
 $18
 $18
 $301
 $392
$16
 $16
 $15
 $14
 $14
 $254
 $329
Ameren Missouri:                          
Minimum capital lease payments(b)
$33
 $33
 $33
 $32
 $32
 $360
 $523
Minimum capital lease payments(b)(c)
$32
 $32
 $32
 $33
 $32
 $264
 $425
Less amount representing interest27
 27
 27
 26
 25
 97
 229
26
 25
 25
 25
 24
 24
 149
Present value of minimum capital lease payments$6
 $6
 $6
 $6
 $7
 $263
 $294
$6
 $7
 $7
 $8
 $8
 $240
 $276
Operating leases(c)
11
 11
 11
 10
 10
 37
 90
Operating leases8
 8
 7
 6
 6
 14
 49
Total lease obligations$17
 $17
 $17
 $16
 $17
 $300
 $384
$14
 $15
 $14
 $14
 $14
 $254
 $325
Ameren Illinois:                          
Operating leases(c)
$1
 $1
 $1
 $1
 $1
 $1
 $6
$1
 (d)
 (d)
 (d)
 (d)
 $1
 $2
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.
(b)See Properties under Part I, Item 2, and Note 3 – Property, Plant, and Plant,Equipment, Net of this report for additional information.
(c)Amounts related to certain land-related leases have indefinite payment periods. The annual obligations of $2 million, $1 million,See Note 5 – Long-term Debt and $1 millionEquity Financings for Ameren, Ameren Missouri,additional information on Ameren’s and Ameren Illinois for these items are included in the 2015 through 2019 columns, respectively.Missouri’s capital lease agreements.
(d)Less than $1 million.
The following table presents total rental expense,operating lease expenses included in operating expenses,“Operating Expenses” in the statement of income for the years ended December 31, 20142017, 20132016, and 20122015:
2014 2013 20122017 2016 2015
Ameren(a)
$37
 $32
 $33
$11
 $38
 $36
Ameren Missouri32
 29
 29
10
 34
 34
Ameren Illinois25
 21
 19
1
 30
 28
(a)Includes amounts for Ameren registrant and nonregistrant subsidiaries and intercompany eliminations.

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Other Obligations
To supply a portion of the fuel requirements of ourAmeren Missouri’s energy centers, we haveAmeren Missouri has entered into various long-term commitments for the procurement of coal, natural gas, nuclear fuel, and methane gas. WeAmeren Missouri and Ameren Illinois also have entered into various long-term commitments for purchased power and natural gas for distribution. The table below presents our estimated minimum fuel, purchased power, and other commitments for fuel at December 31, 20142017. Ameren’s and Ameren Missouri’s purchased power commitments include a 102-megawatt power purchase agreement with a wind farm operator, which expires in 2024. Ameren’s and Ameren Illinois’ purchased power commitments include the Ameren Illinois power purchase agreements entered into as part of the IPA-administered power procurement process. Included in the Other column are minimum purchase commitments under contracts for equipment, design and construction, and meter reading services, among other agreements, at December 31, 20142017. In addition, the Other column includes Ameren's and Ameren Missouri's obligations related to customer energy efficiency programs under the MEEIA as approved by the MoPSC's December 2012 electric rate order. Ameren Missouri expects to incur costs of $71 million in 2015 for these customer energy efficiency programs. See Note 2 – Rate and Regulatory Matters for additional information about the MEEIA.
Coal 
Natural
Gas(a)
 
Nuclear
Fuel
 
Purchased
Power(b)
 
Methane
Gas
 Other TotalCoal 
Natural
Gas(a)
 
Nuclear
Fuel
 
Purchased
Power(b)(c)
 
Methane
Gas
 Other Total
Ameren:(c)(d)
                          
2015$654
 $222
 $53
 $190
 $3
 $195
 $1,317
2016659
 125
 60
 104
 3
 78
 1,029
2017682
 85
 59
 66
 4
 53
 949
2018111
 53
 82
 55
 5
 51
 357
$463
 $205
 $67
 $170
 $3
 $73
 $981
2019114
 32
 42
 56
 5
 54
 303
383
 163
 26
 63
 4
 37
 676
202085
 110
 39
 14
 4
 36
 288
202127
 46
 45
 3
 5
 25
 151
2022
 11
 12
 2
 5
 25
 55
Thereafter
 71
 138
 596
 76
 350
 1,231

 38
 45
 18
 58
 95
 254
Total$2,220
 $588
 $434
 $1,067
 $96
 $781
 $5,186
$958
 $573
 $234
 $270
 $79
 $291
 $2,405
Ameren Missouri:                          
2015$654
 $39
 $53
 $21
 $3
 $128
 $898
2016659
 22
 60
 21
 3
 39
 804
2017682
 17
 59
 21
 4
 26
 809
2018111
 11
 82
 21
 5
 27
 257
$463
 $42
 $67
 $
 $3
 $53
 $628
2019114
 10
 42
 21
 5
 27
 219
383
 36
 26
 
 4
 24
 473
202085
 29
 39
 
 4
 24
 181
202127
 13
 45
 
 5
 25
 115
2022
 6
 12
 
 5
 25
 48
Thereafter
 22
 138
 106
 76
 183
 525

 16
 45
 
 58
 75
 194
Total$2,220
 $121
 $434
 $211
 $96
 $430
 $3,512
$958
 $142
 $234
 $
 $79
 $226
 $1,639
Ameren Illinois:                          
2015$
 $183
 $
 $169
 $
 $29
 $381
2016
 103
 
 83
 
 24
 210
2017
 68
 
 45
 
 24
 137
2018
 42
 
 34
 
 24
 100
$
 $163
 $
 $170
 $
 $19
 $352
2019
 22
 
 35
 
 27
 84

 127
 
 63
 
 13
 203
2020
 81
 
 14
 
 12
 107
2021
 33
 
 3
 
 
 36
2022
 5
 
 2
 
 
 7
Thereafter
 49
 
 490
 
 167
 706

 22
 
 18
 
 
 40
Total$
 $467
 $
 $856
 $
 $295
 $1,618
$
 $431
 $
 $270
 $
 $44
 $745
(a)Includes amounts for generation and for distribution.
(b)The purchased power amounts for Ameren and Ameren Illinois includeexclude agreements through 2032 for renewable energy credits through 2032 with various renewable energy suppliers. The agreements contain a provision that allows Ameren Illinoissuppliers due to reduce the quantity purchased incontingent nature of the event that Ameren Illinois would not be able to recover the costs associated with the renewable energy credits.payment amounts.
(c)The purchased power amounts for Ameren and Ameren Missouri exclude a 102-megawatt power purchase agreement with a wind farm operator, which expires in 2024, due to the contingent nature of the payment amounts.
(d)Includes amounts for Ameren registrant and nonregistrant subsidiaries.
Environmental Matters
We are subject to various environmental laws and regulations enforced by federal, state, and local authorities. From the beginning phases of sitingThe development and development to the operation of existing or new electric generation, transmission, and distribution facilities and natural gas storage, transmission, and distribution facilities our activities involvecan trigger compliance obligations with diverserespect to environmental laws and regulations. These laws and regulations address emissions, discharges to water, water usage, impacts to air, land, and water, and chemical and waste handling. Complex and lengthy processes are required to obtain and renew approvals, permits, orand licenses for new, existing or modified facilities. Additionally, the use and handling of various chemicals or hazardous materials require release prevention plans and
emergency response procedures.
The EPA is developing and implementinghas promulgated environmental regulations that will have a significant impact on the electric utility industry. Over time, compliance with these regulations could be costly for certain companies, including Ameren Missouri, that operatewhich operates coal-fired power plants. Significant new rules proposed or promulgatedAs of December 31, 2017, Ameren Missouri’s fossil fuel-fired energy centers represented 17% and 33% of Ameren’s and Ameren Missouri’s rate base, respectively. Regulations that apply to air emissions from the electric utility industry include the regulationNSPS, the CSAPR, the MATS, and the revised National Ambient Air Quality Standards, which are subject to periodic review for certain pollutants. Collectively, these regulations cover a variety of pollutants, such as SO2, particulate matter, NOx, mercury, toxic metals, and acid gases, and CO2 emissions from existing power plants through the proposed Clean Power Plan and from new power plants through the revised NSPS; revised national ambient air quality standards for ozone, fine particulates, SO2,plants. Water intake and NOx emissions; the CSAPR, which requires further reductions of SO2 emissions and NOx emissions from power plants; a regulation governing management of CCR and CCR


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impoundments; the MATS, which require reduction of emissions of mercury, toxic metals, and acid gases from power plants; revised NSPS for particulate matter, SO2, and NOx emissions from new sources; new effluent standards applicable to waste water discharges from power plants and new regulationsare regulated under the Clean Water Act thatAct. Such regulation could require significant capital expenditures, such as modifications to water intake structures or new cooling towersmore stringent limitations on wastewater discharges at Ameren Missouri’s energy centers, either of which could result in significant capital

expenditures. The management and disposal of coal ash is regulated under the CCR rule, which will require the closure of surface impoundments and the installations of dry ash handling systems at several of Ameren Missouri’s energy centers. Certain of these new and proposed regulations, if adopted, are likely to be challenged through litigation, so their ultimate implementation, as well as the timing of any such implementation, is uncertain. Although many details of the future regulations are unknown, theThe individual or combined effects of the new and proposedexisting environmental regulations could result in significant capital expenditures, and increased operating costs, for Ameren and Ameren Missouri. Compliance with these environmental laws and regulations could be prohibitively expensive, result inor the closure or alteration of the operation ofoperations at some of Ameren Missouri’s energy centers, or require capital investment.centers. Ameren and Ameren Missouri expect thesethat such compliance costs would be recoverable through rates, subject to MoPSC prudence review, but the nature and timing of costs as well as the applicableand their recovery could be subject to regulatory framework, could result in regulatory lag.
As of December 31, 2014,Ameren Missouri’s current plan for compliance with existing air emission regulations includes burning ultra-low-sulfur coal and installing new or optimizing existing pollution control equipment. Ameren and Ameren Missouri estimate that they will need to make capital expenditure investmentsexpenditures of $350$325 million to $400$425 million from 2018 through 20192022 in order to comply with existing environmental regulations. Considerable uncertainty remains in this estimate.Additional environmental controls beyond 2022 could be required. This estimate of capital expenditures includes expenditures required by the CCR regulations, by the Clean Water Act rule applicable to cooling water intake structures at existing power plants, and by effluent limitation guidelines applicable to steam electric generating units, all of which are discussed below. The actual amount of capital investmentsexpenditures required to comply with existing environmental regulations may vary substantially from the above estimate due tobecause of uncertainty as to whether the preciseEPA will substantially revise regulatory obligations, exactly which compliance strategies that will be used and their ultimate cost, among other things. This estimate does not include the impacts of the proposed Clean Power Plan’s reduction in emissions of CO2, which is discussed below.
Ameren Missouri's current plan for compliance with existing environmental regulations for air emissions includes burning ultra-low-sulfur coal and installing new or optimizing existing pollution control equipment. Ameren Missouri has two scrubbers at its Sioux energy center, which are used to reduce SO2 emissions and other pollutants. Ameren Missouri's compliance plan assumes the installation of additional controls including mercury control technology at multiple energy centers within its coal-fired fleet through 2019. However, Ameren Missouri continues to evaluate its operations and options to determine how to comply with the CSAPR, the MATS, and other recently finalized or proposed EPA regulations. Ameren Missouri may be required to install additional pollution controls within the next six to 10 years. As the Clean Power Plan is still subject to revision by the EPA and implementation by the states, Ameren Missouri has not finalized a compliance plan for the proposed rule.
The following sections describe the more significant new or proposed environmental laws and rules and environmental enforcement and remediation matters that affect or could affect our operations. The EPA has initiated an administrative review of several regulations and rulemaking activities, including the effluent limitation guidelines and the CCR rule, which could ultimately result in the revision of all or part of such rules.
Clean Air Act
Both federalFederal and state laws require significant reductions in SO2 and NOx through either emission source reductions or the use and retirement of emission allowances. In 2005,The first phase of the CSAPR emission reduction requirements became effective in 2015. The second phase of emission reduction requirements, which were revised by the EPA issued regulations with respect to SO2 and NOx emissions (the CAIR). The CSAPR replaced the CAIR andin 2016, became effective on January 1, 2015 for SO2 and annual NOx reductions, and on May 1, 2015, will become effective for ozone season NOx reductions. There will be further reductions in 2017 and2017; additional emission reduction requirements may apply in subsequent years. To achieve compliance with the CSAPR, Ameren Missouri expects to have sufficiently reduced emissions and have sufficient allowances for 2015 to avoid making external purchases to comply with CSAPR. Ameren Missouri has already taken actions to prepare for the implementation of the CSAPR, including the installation ofburns ultra-low-sulfur coal, operates two scrubbers at its Sioux energy center, and burning ultra-low sulfur coal.optimizes other existing pollution control equipment. Ameren Missouri doesdid not expect to make additional capital investments to comply with the CSAPR.2017 CSAPR requirements. However, Ameren Missouri willexpects to incur additional operations and maintenance costs to lower its emissions at one or more of its energy centers in complianceto comply with the CSAPR.CSAPR in future years. These higher operations and maintenance costs are expected to be collectedrecovered from customers through the FAC or higher base rates.
CO2 Emissions Standards
In December 2011,2015, the EPA issued the MATS under the Clean Air Act,Power Plan, which requires emission reductions for mercury and other hazardous air pollutants, such as acid gases, trace metals, and hydrogen chloride emissions. The MATS do not require a specific control technology to achieve the emission reductions. The MATS will apply to each unit at a coal-fired power plant. However, in certain cases, compliance can be achieved by averaging emissions from similar units at the same power plant. Compliance is required by April 2015 or, with a case-by-case extension, by April 2016. Ameren Missouri's Labadie and Meramec energy centers were granted extensions and expect to comply with the MATS by April 2016. Ameren Missouri expects to make additional capital investments to comply with the MATS. These capital expenditure investments are included in Ameren's and Ameren Missouri's estimate above. In addition, Ameren Missouri will incur additional operations and maintenance costs to lower its emissions at one or more of its energy centers in compliance with the MATS. These higher operations and maintenance costs are expected to be collected from customers through the FAC or higher base rates.
In December 2014, the EPA published its proposal to strengthen the 2008 national ambient air quality standard for ozone. A final standard is expected in October 2015, after which states that do not meet the standard must develop and implement plans to achieve compliance with the air quality standard. Ameren Missouri is currently evaluating the proposed standard and the possible effects on its operations.
Greenhouse Gas Regulation
Beginning in 2011, greenhouse gas emissions from stationary sources, such as power plants, became subject to regulation under the Clean Air Act. As a result of this action, Ameren Missouri is required to consider the emissions of


137


greenhouse gases in any air permit application.
Recognizing the difficulties presented by regulating at once virtually all emitters of greenhouse gases, the EPA issued the “Tailoring Rule,” whichwould have established new higher emission thresholds for regulating greenhouse gas emissions from stationary sources, such as power plants, through operating permits and the NSR programs. The rule requires any source that already has an operating permit to have provisions relating to greenhouse gas emissions added to its permit upon renewal. Currently, all Ameren Missouri energy centers have operating permits that have been modified to address greenhouse gas emissions. In June 2014, the United States Supreme Court ruled that the EPA may regulate greenhouse gas emissions through operating permits and NSR programs at stationary sources that are already subject to those programs, but may not apply operating permits and NSR programs to non-stationary sources solely as a result of their greenhouse gas emissions. Ameren Missouri does not expect the decision to have a significant effect on its operations.
In January 2014, the EPA published proposed regulations that would set revised CO2 emissions standards for new power plants. The proposed standards would establish separate emissions limits for new natural-gas-fired plants and new coal-fired plants. In June 2014, the EPA proposed the Clean Power Plan, which sets forth CO2 emissions standards that would be applicable to existing power plants. The proposed Clean Power Plan would require each state to develop plans to achieve CO2 emission standards thatUnited States Supreme Court stayed the rule in February 2016, pending various legal challenges. In October 2017, the EPA calculated for each state. The EPA believes thatannounced a proposal to repeal the Clean Power Plan would achieve a 30% reduction inPlan. In December 2017, the nation's existing power plantEPA issued an advanced notice of proposed rulemaking to solicit input from stakeholders as to how the EPA should regulate CO2 emissions from 2005 levels by 2030. The proposed rule also has interim goals of aggressively reducingexisting power plants under the Clean Air Act. Accordingly, we no longer expect the Clean Power Plan to take effect. However, the EPA may issue new requirements that would regulate CO2 emissions by 2020. The EPA expects the proposed rule will be finalized in 2015. If the proposed rule is finalized, states would have one to three years to develop compliance plans. States would be allowed to develop independent plans or to join with other states to develop joint plans. Ameren Missouri is evaluating the proposed Clean Power Plan and the potential impact to its operations, including those related to electric system reliability. Significant uncertainty exists regarding the standard forfrom existing power plants, asplants. We cannot predict the finalized rule could be different fromoutcome of the proposed rule and will be subject toEPA’s future rulemaking or the outcome of any legal challenges eitherrelating to such future rulemakings, any of which could result in the amount and timing of CO2 emission standards being revised.
Preliminary studies suggest that if the proposed Clean Power Plan were to be finalized in its current form, Ameren Missouri may need to incur new or accelerated capital expenditures and increased fuel costs in order to achieve compliance. As proposed, the Clean Power Plan would require the states, including Missouri and Illinois, to submit compliance plans as early as 2016. The states’ compliance plans might require Ameren Missouri to construct natural gas-fired combined cycle generation and renewable generation, at a currently estimated cost of approximately $2 billion by 2020, that Ameren Missouri believes would otherwise not be necessary to meet the energy needs of its customers. Additionally, Missouri’s implementation of the proposed rules, if adopted, could result in
the closure or alteration of the operation of some of Ameren Missouri’s coal and natural gas-fired energy centers, which could result in increased operating costs or impairment of assets. Ameren Missouri expects substantially all of these increased costs, which could begin in 2017, to be recoverable, subject to MoPSC prudence review, through substantially higher electric rates charged to its customers.
Future federal and state legislation or regulations that mandate limits on the emission of greenhouse gases may result in significant increases in capital expenditures and operating costs, which could lead to increased liquidity needs and higher financing costs. These compliance costs could be prohibitive at some of Ameren Missouri’s energy centers, which could result in the impairment of long-lived assets if costs are not recovered through rates. Mandatory limits on the emission of greenhouse gases could increase costs for its customers or have a materialan adverse effect on Ameren's and Ameren Missouri'sour results of operations, financial position, and liquidity if regulators delay or deny recovery in rates of these compliance costs. Ameren's and Ameren Missouri's earnings might benefit from increased investment to comply with greenhouse gas limitations to the extent that the investments are reflected and recovered timely in rates charged to customers.liquidity.
NSR and Clean Air Litigation
In January 2011, the Department of Justice, on behalf of the EPA, filed a complaint against Ameren Missouri in the United States District Court for the Eastern District of Missouri. The EPA's complaint, as amended in October 2013, allegesalleged that in performing projects at its Rush Island coal-fired energy center in 2007 and 2010, Ameren Missouri violated provisions of the Clean Air Act and Missouri law. The litigation has been divided into two phases: liability and remedy. In January 2012,2017, the district court granted, in part, Ameren Missouri's motion to dismiss various aspectsissued a liability ruling that the projects violated provisions of the EPA's penalty claims.Clean Air Act and Missouri law. The EPA'scase then proceeded to the second phase to determine the actions required to remedy the violations found in the liability phase. The EPA previously withdrew all claims for unspecified injunctive relief remain.penalties and fines. No date has been set by the district court for a trial on the remedy phase of the litigation. At the conclusion of both phases of the litigation, Ameren Missouri believes its defenses are meritorious and is defending itself vigorously. However, there can be no assurances that it will be successful in its efforts.intends to appeal the liability ruling to the United States Court of Appeals for the Eighth Circuit.
The ultimate resolution of this matter could have a material adverse effect on the future results of operations, financial position, and liquidity of Ameren and Ameren Missouri. AAmong other things and subject to economic and regulatory considerations, resolution of this matter could result in increased capital expenditures for the installation of pollution control equipment, as well as increased operations and maintenance expenses, and penalties.expenses. We are unable to predict the ultimate resolution of these mattersthis matter or the costs that might be incurred.

Clean Water Act
In August 2014, the EPA published theissued its final rule applicable to cooling water intake structures at existing power plants. The rule requires a case-by-case evaluation and plan for reducing the mortality of aquatic organisms impinged on the facility’s intake screens or entrained through the plant'splant’s cooling water system.Implementation All of this rule will be administered through each power plant’s water discharge permitting process. AllAmeren Missouri’s coal-fired and nuclear energy centers at Ameren Missouri are subject to


138


this the cooling water intake structures rule. The rule will be implemented during the permit renewal process of each energy center’s water discharge permit, between 2018 and 2023.
Additionally, in 2015, the EPA issued a rule to revise the effluent limitation guidelines applicable to steam electric generating units. These guidelines established national standards for water discharges that are based on the effectiveness of available control technology. The EPA’s 2015 rule prohibits effluent discharges of certain waste streams and imposes more stringent limitations on certain water discharges from power plants. In September 2017, the EPA published a rule that postponed the compliance dates by two years for the limitations applicable to two specific waste streams so that it could potentially revise those standards.
Both the intake and effluent rules, if implemented as enacted, could have an adverse effect on Ameren’s and Ameren Missouri’s results of operations, financial position, and liquidity if itsshould such implementation requires the installation of cooling towers orrequire extensive modifications to the cooling water systems and water discharge systems at ourAmeren Missouri’s energy centers, and if thosesuch investments are not recovered on a timely basis in electric rates charged to ourAmeren Missouri’s customers.
In April 2013, the EPA announced its proposal to revise the effluent limitation guidelines applicable to steam electric generating units under the Clean Water Act. Effluent limitation guidelines are national standards for wastewater discharges to surface water that are based on the effectiveness of available control technology. The EPA's proposed rule raised several compliance options that would prohibit effluent discharges of certain, but not all, waste streams and impose more stringent limitations on certain components in wastewater discharges from power plants. If the rule is enacted as proposed, Ameren Missouri would be subject to the revised limitations beginning as early as July 1, 2017, but no later than July 1, 2022. The EPA is expected to issue final guidelines in September 2015.
AshCCR Management
In December 2014,2015, the EPA issued regulations regarding the management and disposal of CCR which willfrom coal-fired energy centers. These regulations affect futureCCR disposal and handling costs at Ameren Missouri'sMissouri’s energy centers. The EPA regulations will be effective 180 days after publication in the Federal Register, which is anticipated in early 2015. The rule allows for the management of CCR as a solid waste, as well as for its continued beneficial uses, such as recycling, which could reduce the amount to be disposed. The rule established criteria regarding the structural integrity, location, and operation of CCR impoundments and landfills. It requires groundwater monitoring andThey require closure of impoundments if theperformance criteria relating to groundwater standards under the ruleimpacts and location restrictions are not achieved. In September 2017, the EPA granted petitions filed on behalf of coal-fired electricity generators in which the EPA agreed to reconsider certain provisions of the CCR rules. Ameren and Ameren Missouri is currently evaluating the rule to determine its impacthave AROs of $150 million recorded on current managementtheir respective balance sheets as of CCR and the potential costsDecember 31, 2017, associated with compliance. Ameren Missouri is also evaluatingCCR storage facilities that reflect the potential effect the new rule will have on its AROs associated with ash ponds. Ameren Missouri's capital expenditure plan includes the cost of constructing landfills as part of its environmental compliance plan. Ameren Missouri expects certain of its ash ponds could be closed within the next five years.
The EPA's regulations issued in December 2014 regarding the2015. Ameren plans to close these CCR storage facilities between 2018 and 2024. Ameren Missouri also estimates it will need to make capital expenditures of $300 million to $350 million from 2018 through 2022 to implement its CCR management and disposal of CCR do not apply to inactive ash ponds at plants no longer in operation, such as the Meredosia and Hutsonville energy centers.compliance plan.
Remediation
WeThe Ameren Companies are involved in a number of remediation actions to clean up sites affected by the use or disposal of materials containing hazardous substances, as required by federalsubstances. Federal and state law. Such laws can require that responsible parties to fund remediation actions regardless of their degree of fault, the legality of original disposal, or the ownership of a disposal site. Ameren Missouri and Ameren Illinois have each been identified by federal or state governments as a potentially responsible party at several contaminated sites.
As of December 31, 2014,2017, Ameren Illinois owned or was otherwise responsible for 44 former MGP sites in Illinois. These sitesIllinois, which are in various stages of investigation, evaluation, remediation, and closure. Ameren Illinois estimates it could substantially conclude remediation efforts at most of these sites by 2018.2023. The ICC allows Ameren Illinois to recover such remediation and related litigation costs associated with its former MGP sites from its electric and natural gas utility customers through environmental adjustment ratecost riders. To be recoverable, such costs must be prudently incurred. Costs are subject to annual prudence review by the ICC. As of December 31, 2014,2017, Ameren Illinois estimated the obligation related to these former MGP sites at $250$175 million to $314$249 million. Ameren and Ameren Illinois recorded a liability of $250$175 million to represent theirthe estimated minimum obligation for these sites, as no other amount within the range was a better estimate.
The scope and extent to whichof the remediation activities at these former MGP sites are remediated may increase as remediation efforts continue. Considerable uncertainty remains in these estimates asbecause many site-specific factors can influence the ultimate actual costs, including site specific unanticipated underground structures, the degree to which groundwater is encountered, regulatory changes, local ordinances, and site accessibility. The actual costs and timing of completion may vary substantially from these estimates.
Ameren Illinois formerly used an off-site landfill, which Ameren Illinois did not own, in connection with the operation of a previously-owned energy center. Ameren Illinois could be required to perform certain maintenance activities at that landfill. As of December 31, 2014, Ameren Illinois estimated the obligation related to this site at $0.5 million to $6 million. Ameren Illinois recorded a liability of $0.5 million to represent its estimated minimum obligation for this site, as no other amount within the range was a better estimate. Ameren Illinois is also responsible for the cleanup of some underground storage tanks and a water treatment plant in Illinois. As of December 31, 2014, Ameren Illinois recorded a liability of $0.7 million to represent its best estimate of the obligation for these sites.
In 2008, the EPA issued an administrative order to Ameren Missouri pertaining to a former coal tar distillery operated by Koppers Company or its predecessor and successor companies. While Ameren Missouri is the current owner of the site, which is located in St. Louis, Missouri, it did not conduct any of the manufacturing operations involving coal tar or its byproducts. Ameren Missouri, along with two other potentially responsible parties, are performing a site investigation. As of December 31, 2014, Ameren Missouri estimated its obligation at $2 million to $5 million. Ameren Missouri recorded a liability of $2 million to represent its estimated minimum obligation, as no other amount within the range was a better estimate.
Ameren Missouri also participated in the investigation of various sites known as Sauget Area 2 located in Sauget, Illinois. In 2000, the EPA notified Ameren Missouri and numerous other companies including Solutia, Inc., that former landfills and lagoons at those sites may contain soil and groundwater contamination. These sites are known as Sauget Area 2. From about 1926 until 1976, Ameren


139


Missouri operated an energy center adjacent to Sauget Area 2. Ameren Missouri currently owns a parcel of property at Sauget Area 2 that was once used as a landfill. Under the terms of an Administrative Order on Consent, Ameren Missouri joined with other potentially responsible parties to evaluate the extent of potential contamination with respect to Sauget Area 2.
In December 2013, the EPA issued its record of decision for Sauget Area 2 approving the investigation and the remediation alternativesactions recommended by the potentially responsible parties. Further negotiation among the potentially responsible parties will determine how to fund the implementation of the EPA-approved cleanup remedies. As of December 31, 2014,2017 and 2016, Ameren Missouri estimated its obligation related to Sauget Area 2 at $1$1 million to $2.5 million.$2.5 million. Ameren Missouri recorded a liability of $1$1 million to represent its estimated minimum obligation, as no other amount within the range was a better estimate.
In 2012, Ameren Missouri signed an administrative order with the EPA and agreed to investigate soil and groundwater conditions at an Ameren Missouri-owned substation in St. Charles, Missouri. As of December 31, 2014, Ameren Missouri estimated the obligation related to this cleanup at $1.6 million to $4.5 million. Ameren Missouri recorded a liability of $1.6 million to represent its estimated minimum obligation for this site, as no other amount within the range was a better estimate.
Our operations or those of our predecessor companies involve the use of, disposal of, and in appropriate circumstances, the cleanup of substances regulated under environmental laws. We are unable to determine whether such practices will result in future environmental commitments or will affect our results of operations, financial position, or liquidity.
Pumped-storage Hydroelectric Facility Breach
Ameren Missouri Municipal Taxes
The cities of Creve Coeur and Winchester, Missouri, on behalf of themselves and other municipalities in Ameren Missouri’s service area, filed a class action lawsuit in November 2011 against Ameren Missouri in the Circuit Court of St. Louis County, Missouri. The lawsuit alleges that Ameren Missouri failed to collect and pay gross receipts taxes or license fees on certain revenues, including revenues from wholesale power and interchange sales. In December 2005, there was2017, the court issued a breach of the upper reservoir at Ameren Missouri's Taum Sauk pumped-storage hydroelectric energy center. This resulted in significant flooding in the local area, which damagedfinal order approving a state park.settlement agreement between Ameren Missouri had liability insurance coverage forand the Taum Sauk incident, subject to certain limits and deductibles.
In 2010,municipalities. The settlement agreement requires Ameren Missouri sued an insurance company that was providingto make payments representing certain tax receipts to the municipalities during the first quarter of 2018, in addition to payment of certain future gross receipts taxes. The future gross receipts taxes are recoverable from customers. Ameren and Ameren Missouri with liability coveragerecorded immaterial current liabilities on the date of the Taum Sauk incident. In the litigation, Ameren Missouri claims that the insurance company breached its duty to indemnify Ameren Missouri for losses resulting from the incident. In September 2014, the United States District Court for the Eastern District of Missouri ordered the case to be transferred to the United States District Court for the Southern District of New York for trial. The transfer order has been stayed pending resolution of Ameren Missouri’s October 2014 appeal of that order to the United States Court of Appeals for the Eighth Circuit.
In June 2014, Ameren Missouri reached a settlement with another group of insurers who provided Ameren Missouri with liability coverage on the date of the Taum Sauk incident. In accordance with that settlement, Ameren Missouri received a payment of $27 million.
As of December 31, 2014, Ameren Missouri had an insurance receivable of $41 million. It ultimately expects to collect this receivable from the remaining insurance company in the pending litigation described above. This receivable is included in “Other assets” on Ameren’s and Ameren Missouri’stheir respective balance sheets as of December 31, 2017, to represent the payments made in February 2018 under the settlement agreement.
NOTE 15 SEGMENT INFORMATION
Ameren has four segments: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission. The Ameren Missouri segment includes all of the operations of Ameren Missouri. Ameren Illinois Electric Distribution consists of the electric distribution business of Ameren Illinois. Ameren Illinois Natural Gas consists of the natural gas business of Ameren Illinois. Ameren Transmission is primarily composed of the aggregated electric transmission businesses of Ameren Illinois and ATXI. The category called Other primarily includes Ameren parent company activities and Ameren Services.
Ameren Missouri has one segment. Ameren Illinois has three segments: Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Illinois Transmission. See Note 1 – Summary of Significant Accounting Policies for additional information regarding the operations of Ameren Missouri, Ameren Illinois, and ATXI.
Segment operating revenues and a majority of operating expenses are directly recognized and incurred by Ameren Illinois to each Ameren Illinois segment. Common operating expenses, miscellaneous income and expenses, interest charges, and income tax expense are allocated by Ameren Illinois to each Ameren Illinois segment based on certain factors, which primarily relate to the nature of the cost. Additionally, Ameren Illinois Transmission earns revenue from transmission service provided to Ameren Illinois Electric Distribution and wholesale customers. The transmission expense for Illinois customers who have elected to purchase their power from Ameren Illinois is recovered through a cost recovery mechanism with no net effect on Ameren Illinois Electric Distribution earnings, as costs are offset by corresponding revenues. Transmission revenues from these transactions are reflected in Ameren Transmission’s and Ameren Illinois Transmission’s operating revenues. An intersegment elimination at Ameren and Ameren Illinois occurs to eliminate these transmission revenues and expenses.

The following tables present revenues, net income attributable to common shareholders, and capital expenditures by segment at Ameren and Ameren Illinois for the years ended December 31, 20142017, 2016, and 2015. Ameren's and Ameren Missouri's results of operations, financial position, and liquidity could be adversely affected if Ameren Missouri's remaining liability insurance claim is not paid.
Asbestos-related Litigation
Ameren, Ameren Missouri, and Ameren Illinois have been named, along with numerous other parties, in a number of lawsuits filed by plaintiffs claiming varying degrees of injury from asbestos exposure at our presentmanagement review segment capital expenditure information rather than any individual or former energy centers. Most have been filed in the Circuit Court of Madison County, Illinois. The total number of defendants named in each case varies, with 78 as the average number of parties as of December 31, 2014. Each lawsuit seeks unspecified damages that, if awarded at trial, typically would be shared among the various defendants.asset amount.
The following table presents the pending asbestos-related lawsuits filed against the Ameren Companies as of December 31, 2014:
Ameren 
Ameren
Missouri
 
Ameren
Illinois
 
Total(a)
1 45 57 70
 Ameren Missouri Ameren Illinois Electric Distribution Ameren Illinois Natural Gas Ameren Transmission Other 
Intersegment
Eliminations
 Consolidated
2017             
External revenues$3,490
 $1,565
 $742
 $382
 $(2) $
 $6,177
Intersegment revenues49
 4
 1
 44
(a) 

 (98) 
Depreciation and amortization533
 239
 59
 60
 5
 
 896
Interest income27
 7
 
 
 11
 (11) 34
Interest charges207
 73
 36
 67
(b) 
19
 (11) 391
Income taxes254
 83
 36
 90
 113
 
 576
Net income (loss) attributable to Ameren common shareholders from continuing operations323
 131
 60
 140
 (131) 
 523
Capital expenditures773
 476
 245
 644
 1
 (7) 2,132
2016             
External revenues$3,469
 $1,545
 $753
 $309
 $
 $
 $6,076
Intersegment revenues54
 4
 1
 46
(a) 

 (105) 
Depreciation and amortization514
 226
 55
 43
 7
 
 845
Interest income28
 11
 
 1
 11
 (11) 40
Interest charges211
 72
 34
 58
(b) 
18
 (11) 382
Income taxes216
 78
 39
 74
 (25) 
 382
Net income (loss) attributable to Ameren common shareholders from continuing operations357
 126
 59
 117
 (6) 
 653
Capital expenditures738
 470
 181
 689
 4
 (6) 2,076
2015             
External revenues$3,566
 $1,529
 $782
 $219
 $2
 $
 $6,098
Intersegment revenues43
 3
 1
 40
(a) 

 (87) 
Depreciation and amortization492
 212
 52
 33
 7
 
 796
Interest income28
 12
 
 
 7
 (6) 41
Interest charges219
 71
 35
 35
(b) 
1
 (6) 355
Income taxes209
 71
 24
 51
 8
 
 363
Net income (loss) attributable to Ameren common shareholders from continuing operations352
 123
 37
 83
 (16) 
 579
Capital expenditures622
 491
 133
 669
 2
 
 1,917
(a)Total does not equal the sumAmeren Transmission earns revenue from transmission service provided to Ameren Illinois Electric Distribution. See discussion of the subsidiary unit lawsuits because some of the lawsuits name multiple Ameren entities as defendants.
At December 31, 2014, Ameren, Ameren Missouri, and Ameren Illinois had liabilities of $12 million, $5 million, and $7 million, respectively, recorded to represent their best estimates of their obligations related to asbestos claims.
Ameren Illinois has a tariff rider to recover the costs of IP asbestos-related litigation claims, subject to the following terms: 90% of the cash expenditures in excess of the amount included in base electric rates is to be recovered from a trust fund that was established when Ameren acquired IP. At December 31, 2014, the trust fund balance was $22 million, including accumulated interest. If cash expenditures are less than the amount in base rates, Ameren Illinois will contribute 90% of the difference to the trust fund. Once the trust fund is depleted, 90% of allowed cash expenditures in excess of base rates will be recovered through charges assessed to customers under the tariff rider. The rider will permit recovery from electric customers within IP’s historical service territory.
Ameren Illinois Municipal Taxes
Ameren Illinois previously received tax liability notices from eight municipalities, including the City of O'Fallon, alleging that Ameren Illinois failed to collect prior-period taxes from certain customers in each municipality. In November 2014, Ameren Illinois reached a settlement agreement with the City of O'Fallon and paid $1 million for the prior-period taxes. With respect to the seven other communities, Ameren Illinois believes its defenses to


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the allegations are meritorious and its potential loss is immaterial.
NOTE 16 DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
On December 2, 2013, Ameren completed the divestiture of New AER to IPH in accordance with the transaction agreement between Ameren and IPH dated March 14, 2013, as amended by a letter agreement dated December 2, 2013.
Ameren retained certain pension and postretirement benefit obligations associated with current and former employees of AER, with the exception of the pension and postretirement benefit obligations associated with current and former employees of EEI, which were assumed by IPH. Ameren retained the Meredosia and Hutsonville energy centers, including their AROs. These energy centers were abandoned and had an immaterial property and plant asset balance as of December 31, 2014. The EPA's regulations issued in December 2014 regarding the management and disposal of CCR, as discussed in Note 15 – Commitments and Contingencies, do not apply to inactive ash ponds at plants no longer in operation, such as the Meredosia and Hutsonville energy centers. All other AROs associated with AER were assumed by New AER or by Rockland Capital, the
third-party buyer of the Grand Tower energy center, as discussed below.
The transaction agreement with IPH, as amended, provides that if the Elgin, Gibson City, and Grand Tower gas-fired energy centers are subsequently sold by Medina Valley and if Medina Valley receives additional proceeds from such sale, Medina Valley will pay Genco any proceeds from such sale, net of taxes and other expenses, in excess of the $137.5 million previously paid to Genco. On January 31, 2014, Medina Valley completed the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital for a total purchase price of $168 million. The agreement with Rockland Capital requires $17 million of the purchase price to be held in escrow until January 31, 2016, to fund certain indemnity obligations, if any, of Medina Valley. The Rockland Capital escrow receivable balance and the corresponding payable due to Genco is reflected on Ameren's December 31, 2014, consolidated balance sheet in "Other assets" and in "Other deferred credits and liabilities," respectively. Medina Valley expects to pay Genco any remaining portion of the escrow balance on January 31, 2016. Ameren did not record a gain from its sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers.

Discontinued Operations Presentation
In March 2013, Ameren determined that New AER and the Elgin, Gibson City, and Grand Tower gas-fired energy centers qualified for discontinued operations presentation. In addition, in December 2013, coinciding with the completion of the divestiture of New AER to IPH, Ameren determined that the Meredosia and Hutsonville energy centers, which were both not operating, had been abandoned and also qualified for discontinued operations presentation. Ameren has begun to demolish the Hutsonville energy center and expects to demolish the Meredosia energy center thereafter. The disposal groups have been aggregated in the disclosures below. The following table presents the components of discontinued operations in Ameren's consolidated statement of income (loss) for the years ended December 31, 2014, 2013, and 2012:
 Year ended 
 2014 2013 2012 
Operating revenues$1
 $1,037
 $1,047
 
Operating expenses(2)
(1,207)
(a) 
(3,474)
(b) 
Operating income (loss)(1) (170) (2,427) 
Other income (loss)
 (1) 
 
Interest charges
 (39) (56) 
Income (loss) before income taxes(1) (210) (2,483) 
Income tax (expense) benefit
 (13) 987
 
Income (loss) from discontinued operations, net of taxes$(1) $(223) $(1,496) 
(a)Includes a $201 million pretax loss on disposal relating to the New AER divestiture.transactions above.
(b)Includes a noncash pretax asset impairment chargeAmeren Transmission interest charges include an allocation of $2.58 billion to reduce the carrying value of AER's energy centers to their estimated fair value under held and used accounting guidance.financing costs from Ameren (parent).
Ameren’s results of operations for the year ended December 31, 2014, include adjustments for the New AER net working capital amount owed to IPH and for certain contingent liabilities associated with the New AER divestiture. In 2014, Ameren paid $13 million to IPH for the final working capital adjustment and a portion of the previously-recorded contingent liabilities. Additionally, Ameren recognized the operating revenues and operating expenses associated with the Elgin, Gibson City, and Grand Tower gas-fired energy centers prior to the completion of their sale to Rockland Capital on January 31, 2014. The final tax
basis of the AER disposal group and the related tax benefit resulting from the transaction with IPH are dependent upon the resolution of tax matters under audit. It is reasonably possible in the next 12 months these tax audits will be completed. As a result, tax expense and benefits ultimately realized from the divestitures may differ materially from those recorded as of December 31, 2014, including the final resolution of Ameren's uncertain tax positions.
Ameren recorded a pretax charge to earnings related to the


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New AER divestiture of $201 million for the year ended December 31, 2013. The loss was recorded in “Operating expenses” within the components of the discontinued operations statement of income (loss). Ameren did not receive any cash proceeds from IPH for the divestiture of New AER. In 2013, Ameren adjusted the accumulated deferred income taxes on its consolidated balance sheet to reflect the excess of tax basis over financial reporting basis of its stock investment in AER. This change in basis resulted in a discontinued operations deferred tax expense of $99 million, which was partially offset by the expected tax benefits of $86 million related to the pretax loss from discontinued operations, including the loss on disposal, during the year ended December 31, 2013.Illinois
As discussed above, on January 31, 2014, Medina Valley completed the sale of the Elgin, Gibson City, and Grand Tower gas-fired energy centers to Rockland Capital for a total purchase price of $168 million. Ameren did not recognize a gain from the third-party sale to Rockland Capital for any value in excess of its $137.5 million carrying value for this disposal group because any excess amount that Medina Valley may receive, net of taxes and other expenses, over the carrying value, will ultimately be paid to Genco pursuant to the transaction agreement with IPH.
New AER and the Elgin, Gibson City, and Grand Tower energy centers were impaired under held and used accounting guidance in 2012. In early 2012, the observable market price for power for delivery in that year and in future years in the Midwest sharply declined below 2011 levels. As a result of this sharp decline in the market price of power and the related impact on electric margins, Ameren evaluated, during the first quarter of 2012, whether the carrying values of Merchant Generation coal-fired energy centers were recoverable. AERG's Duck Creek energy center's carrying value exceeded its estimated undiscounted future cash flows. As a result, Ameren recorded a noncash pretax asset impairment charge of $628 million to reduce the carrying value of that energy center to its estimated fair value during the first quarter of 2012. In December 2012, Ameren determined that the estimated undiscounted cash flows during the period in which it expected to continue to own its Merchant Generation energy centers would be insufficient to recover the carrying value of those energy centers. Accordingly, Ameren recorded a noncash pretax impairment charge of $1.95 billion in the fourth quarter of 2012.


The following table presents the carrying amounts of the components of assets and liabilities segregated on Ameren's consolidated balance sheets as discontinued operations at December 31, 2014 and 2013:
 December 31, 2014 December 31, 2013
Assets of discontinued operations   
Accounts receivable and unbilled revenue$
 $5
Materials and supplies
 5
Property and plant, net
 142
Accumulated deferred income taxes, net(a)
15
 13
Total assets of discontinued operations$15
 $165
Liabilities of discontinued operations   
Accounts payable and other current obligations$1
 $5
Asset retirement obligations(b)
32
 40
Total liabilities of discontinued operations$33
 $45
 Ameren Illinois Electric Distribution 
Ameren Illinois
Natural Gas
 Ameren Illinois Transmission 
Intersegment
Eliminations
 Consolidated 
2017          
External revenues$1,569
 $743
 $216
 $
 $2,528
 
Intersegment revenues
 
 42
(a) 
(42) 
 
Depreciation and amortization239
 59
 43
 
 341
 
Interest income7
 
 
 
 7
 
Interest charges73
 36
 35
 
 144
 
Income taxes83
 36
 47
 
 166
 
Net income available to common shareholder131
 60
 77
 
 268
 
Capital expenditures476
 245
 355
 
 1,076
 
2016          
External revenues$1,549
 $754
 $187
 $
 $2,490
 
Intersegment revenues
 
 45
(a) 
(45) 
 
Depreciation and amortization226
 55
 38
 
 319
 
Interest income11
 
 1
 
 12
 
Interest charges72
 34
 34
 
 140
 
Income taxes78
 39
 41
 
 158
 
Net income available to common shareholder126
 59
 67
 
 252
 
Capital expenditures470
 181
 273
 
 924
 
2015          
External revenues$1,532
 $783
 $151
 $
 $2,466
 
Intersegment revenues
 
 38
(a) 
(38) 
 
Depreciation and amortization212
 52
 31
 
 295
 
Interest income12
 
 
 
 12
 
Interest charges71
 35
 25
 
 131
 
Income taxes71
 24
 32
 
 127
 
Net income available to common shareholder123
 37
 54
 
 214
 
Capital expenditures491
 133
 294
 
 918
 
(a)Ameren Illinois Transmission earns revenue from transmission service provided to Ameren Illinois Electric Distribution. See discussion of transactions above.
SELECTED QUARTERLY INFORMATION (Unaudited) (In millions, except per share amounts)
Ameren2017  2016
Quarter endedMarch 31 June 30 September 30 December 31  March 31 June 30 September 30 December 31
Operating revenues$1,514
 $1,538
 $1,723
 $1,402
  $1,434
 $1,427
 $1,859
 $1,356
Operating income254
 398
 581
 225
  220
 325
 691
 145
Net income (loss)104
 194
 290
 (59)
(a) 
 107
 148
 371
 33
Net income (loss) attributable to Ameren common shareholders$102
 $193
 $288
 $(60)  $105
 $147
 $369
 $32
Earnings (loss) per common share – basic$0.42
 $0.79
 $1.19
 $(0.24)  $0.43
 $0.61
 $1.52
 $0.13
Earnings (loss) per common share – diluted(b)
$0.42
 $0.79
 $1.18
 $(0.24)  $0.43
 $0.61
 $1.52
 $0.13
(a)
The December 31, 2014 balance primarily consists of deferredIncludes an increase to income tax assets related toexpense of $154 million recorded in 2017 as a result of the abandoned Meredosia and Hutsonville energy centers.TCJA.
(b)The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is because of the effects of rounding and the changes in the number of weighted-average diluted shares outstanding each period.

Ameren Missouri
Quarter ended
 
Operating
Revenues
 
Operating
Income
 Net Income (Loss) 
Net Income (Loss)
Available
to Common
Shareholder
March 31, 2017 $790
 $53
 $6
 $5
March 31, 2016 741
 63
 15
 14
June 30, 2017 935
 237
 121
 120
June 30, 2016 867
 197
 93
 92
September 30, 2017 1,115
 417
 235
 234
September 30, 2016 1,165
 431
 242
 241
December 31, 2017 699
 40
 (36)
(a) 
(36)
December 31, 2016 750
 54
 10
 10
(a)Includes AROsan increase to income tax expense of $32 million recorded in 2017 as a result of the TCJA.    
Ameren Illinois
Quarter ended(a)
 
Operating
Revenues
 
Operating
Income
 Net Income 
Net Income
Available
to Common
Shareholder
March 31, 2017 $703
 $172
 $80
 $79
March 31, 2016 677
 133
 60
 59
June 30, 2017 576
 130
 58
 57
June 30, 2016 542
 107
 46
 45
September 30, 2017 575
 128
 55
 55
September 30, 2016 676
 230
 119
 119
December 31, 2017 674
 150
 78
 77
December 31, 2016 595
 74
 30
 29
(a)In 2017, in connection with the decoupling provisions of the FEJA, Ameren Illinois changed the method it used to recognize its interim-period revenue. Ameren Illinois now recognizes revenue consistent with the timing of incurred electric distribution recoverable costs, and it recognizes revenue associated with the abandoned Meredosiaexpected return on its rate base ratably over the year. As a result of this change in recognition of the interim period revenue for the IEIMA formula rate framework, as modified by the FEJA, Ameren Illinois incurred quarterly year-over-year increases to earnings in 2017 in comparison to 2016 for the first, second, and Hutsonville energy centers of $32 millionfourth quarters and $31 million at December 31, 2014 and 2013, respectively.a decrease to earnings in the third quarter. The change in interim period revenue recognition did not affect 2017 annual earnings.
Ameren has continuing transactions with New AER. Ameren Illinois has power supply agreements with Marketing Company, which are a result of the power procurement process in Illinois administered by the IPA, as required by the Illinois Public Utilities Act. Ameren Illinois continues to purchase power and to purchase trade receivables as required by Illinois law. Ameren Illinois and ATXI continue to sell transmission services to Marketing Company. Also, the transaction agreement requires Ameren (parent) to maintain certain guarantees discussed below. Immediately prior to the transaction agreement closing, the money pool borrowings through which Ameren provided cash collateral to Marketing Company were converted to a note payable to Ameren, with interest, on December 2, 2015, or sooner, as cash collateral requirements are reduced. Ameren has determined that the continuing cash flows generated by these arrangements are not significant and, accordingly, are not deemed to be direct cash flows of the divested business.

Additionally, these arrangements do not provide Ameren with the ability to significantly influence the operating results of New AER. Ameren did not have significant continuing involvement with or material cash flows from the Elgin, Gibson City, or Grand Tower energy centers after their sale.
Pursuant to the IPH transaction agreement, as amended, Ameren is obligated to pay up to $29 million for certain contingent liabilities as of December 31, 2014, which were included in "Other current liabilities" on Ameren's December 31, 2014 consolidated balance sheet.
The note receivable from Marketing Company related to the cash collateral support provided to New AER was $12 million and $18 million at December 31, 2014 and 2013, respectively, and was reflected on Ameren's consolidated balance sheet in "Miscellaneous accounts and notes receivable" at December 31,


142


2014. This receivable is due to Ameren, with interest, on December 2, 2015, or sooner as cash collateral requirements are reduced. In addition, as of December 31, 2014, if Ameren’s credit ratings had been below investment grade, Ameren could have been required to post additional cash collateral in support of New AER in the amount of $26 million, which includes $11 million currently covered by Ameren guarantees. This cash collateral support is part of Ameren’s obligation to provide certain limited credit support to New AER until December 2, 2015, as discussed below.
Ameren Guarantees and Letters of Credit
The IPH transaction agreement, as amended, requires Ameren to maintain its financial obligations with respect to all credit support provided to New AER as of the December 2, 2013 closing date of the divestiture. Ameren must also provide such additional credit support as required by contracts entered into prior to the closing date, in each case until December 2, 2015. IPH shall indemnify Ameren for any payments Ameren makes pursuant to these credit support obligations if the counterparty does not return the posted collateral to Ameren. IPH's indemnification obligation is secured by certain AERG and Genco assets. In addition, Dynegy has provided a limited guarantee of $25 million to Ameren pursuant to which Dynegy will, among other things, guarantee IPH's indemnification obligations until December 2, 2015.
In addition to the $29 million of contingent liabilities recorded on Ameren’s December 31, 2014 consolidated balance sheet, Ameren had a total of $114 million in guarantees outstanding for New AER that were not recorded on Ameren’s December 31, 2014 consolidated balance sheet, which included:
$106 million related to guarantees supporting Marketing Company for physically and financially settled power transactions with its counterparties that were in place at the December 2, 2013 closing of the divestiture, as well as for
Marketing Company's clearing broker and other service agreements. If Marketing Company did not fulfill its obligations to these counterparties who had active open positions as of December 31, 2014, Ameren would have been required under its guarantees to provide $11 million to the counterparties.
$8 million related to requirements for lease agreements and potential environmental obligations. If New AER had not fulfilled its lease obligation as of December 31, 2014, Ameren would have been required to provide approximately $7 million to the leasing counterparty.
Additionally, at December 31, 2014, Ameren had issued letters of credit totaling $9 million as credit support on behalf of New AER.
Ameren has not recorded a reserve for these contingent obligations because it does not believe a payment with respect to any of these guarantees or letters of credit was probable as of December 31, 2014.
NOTE 17 SEGMENT INFORMATION
Ameren has two reportable segments: Ameren Missouri and Ameren Illinois. Ameren Missouri and Ameren Illinois each have one reportable segment. The Ameren Missouri segment for both Ameren and Ameren Missouri includes all the operations of Ameren Missouri as described in Note 1 – Summary of Significant Accounting Policies. The Ameren Illinois segment for both Ameren and Ameren Illinois consists of all of the operations of Ameren Illinois as described in Note 1 – Summary of Significant Accounting Policies. The category called Other primarily includes Ameren parent company activities, Ameren Services, and ATXI. The Other category also includes certain corporate activities previously included in the Merchant Generation segment. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information.


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The following table presents information about the reported revenues and specified items reflected in Ameren’s net income attributable to Ameren Corporation and capital expenditures from continuing operations for the years ended December 31, 2014, 2013, and 2012, and total assets in continuing operations as of December 31, 2014, 2013, and 2012:
 
Ameren
Missouri
 
Ameren
Illinois
 Other 
Intersegment
Eliminations
 Consolidated 
2014          
External revenues$3,526
 $2,496
 $31
 $
 $6,053
 
Intersegment revenues27
 2
 2
 (31) 
 
Depreciation and amortization473
 263
 9
 
 745
 
Interest and dividend income28
 7
 2
 
 37
 
Interest charges211
 112
 18
 
 341
 
Income taxes229
 143
 5
 
 377
 
Net income (loss) attributable to Ameren Corporation from continuing operations390
 201
 (4) 
 587
 
Capital expenditures747
 835
 203
(a) 

 1,785
 
Total assets13,541
 8,381
 942
 (203) 22,661
(b) 
2013          
External revenues$3,516
 $2,307
 $15
 $
 $5,838
 
Intersegment revenues25
 4
 2
 (31) 
 
Depreciation and amortization454
 243
 9
 
 706
 
Interest and dividend income27
 2
 1
 
 30
 
Interest charges210
 143
 45
 
 398
 
Income taxes (benefit)242
 110
 (41) 
 311
 
Net income (loss) attributable to Ameren Corporation from continuing operations395
 160
 (43) 
 512
 
Capital expenditures648
 701
 30
(a) 

 1,379
 
Total assets12,904
 7,454
 752
 (233) 20,877
(b) 
2012          
External revenues$3,252
 $2,524
 $5
 $
 $5,781
 
Intersegment revenues20
 1
 3
 (24) 
 
Depreciation and amortization440
 221
 12
 
 673
 
Interest and dividend income32
 
 
 
 32
 
Interest charges223
 129
 40
 
 392
 
Income taxes (benefit)252
 94
 (39) 
 307
 
Net income (loss) attributable to Ameren Corporation from continuing operations416
 141
 (41) 
 516
 
Capital expenditures595
 442
 26
(a) 

 1,063
 
Total assets13,043
 7,282
 1,228
 (934) 20,619
(b) 
.
(a)ITEM 9.Includes the elimination of intercompany transfers.
(b)
Excludes total assets from discontinued operations of $15 million, $165 million, and $1,611 million as of December 31, 2014, 2013, and 2012, respectively.

144


SELECTED QUARTERLY INFORMATION (Unaudited) (In millions, except per share amounts)
Ameren2014  2013
Quarter ended (a)
March 31 June 30 September 30 December 31  March 31 June 30 September 30 December 31
Operating revenues$1,594
 $1,419
 $1,670
 $1,370
  $1,475
 $1,403
 $1,638
 $1,322
Operating income246
 322
 561
 125
  185
 261
 567
 171
Net income (loss)98
 150
 295
 49
  (143) 96
 304
 38
Net income attributable to Ameren Corporation – continuing operations$97
 $150
 $294
 $46
  $54
 $105
 $305
 $48
Net income (loss) attributable to Ameren Corporation – discontinued operations(1) (1) (1) 2
  (199) (10) (3) (11)
Net income (loss) attributable to Ameren Corporation$96
 $149
 $293
 $48
  $(145) $95
 $302
 $37
Earnings per common share – basic – continuing operations$0.40
 $0.62
 $1.21
 $0.19
  $0.22
 $0.44
 $1.26
 $0.19
Earnings (loss) per common share – basic – discontinued operations
 (0.01) 
 0.01
  (0.82) (0.05) (0.01) (0.04)
Earnings (loss) per common share – basic$0.40
 $0.61
 $1.21
 $0.20
  $(0.60) $0.39
 $1.25
 $0.15
Earnings per common share – diluted – continuing operations$0.40
 $0.62
 $1.20
 $0.19
  $0.22
 $0.44
 $1.25
 $0.19
Earnings (loss) per common share – diluted – discontinued operations
 (0.01) 
 0.01
  (0.82) (0.05) (0.01) (0.04)
Earnings (loss) per common share – diluted$0.40
 $0.61
 $1.20
 $0.20
  $(0.60) $0.39
 $1.24
 $0.15
(a)
The sum of quarterly amounts, including per share amounts, may not equal amounts reported for year-to-date periods. This is due to the effects of rounding and to changes in the number of weighted-average shares outstanding each period.CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE

None.
Ameren Missouri Quarter ended 
Operating
Revenues
 
Operating
Income
 
Net Income
 (Loss)
 
Net Income (Loss)
Available
to Common
Stockholder
March 31, 2014 $817
 $119
 $48
 $47
March 31, 2013 796
 111
 41
 40
June 30, 2014 900
 243
 127
 126
June 30, 2013 889
 179
 85
 84
September 30, 2014 1,097
 394
 223
 222
September 30, 2013 1,093
 417
 239
 238
December 31, 2014 739
 29
 (5) (5)
December 31, 2013 763
 96
 33
 33
Ameren Illinois Quarter ended 
Operating
Revenues
 
Operating
Income
 Net Income 
Net Income
Available
to Common
Stockholder
March 31, 2014 $774
 $120
 $54
 $53
March 31, 2013 684
 85
 32
 31
June 30, 2014 519
 75
 29
 28
June 30, 2013 516
 87
 32
 31
September 30, 2014 572
 158
 75
 75
September 30, 2013 547
 158
 77
 77
December 31, 2014 633
 97
 46
 45
December 31, 2013 564
 85
 22
 21
ITEM 9.CHANGES IN AND DISAGREEMENTS WITH ACCOUNTANTS ON ACCOUNTING AND FINANCIAL DISCLOSURE
None.
ITEM 9A.CONTROLS AND PROCEDURES
(a)Evaluation of Disclosure Controls and Procedures

145


As of December 31, 2014,2017, evaluations were performed under the supervision and with the participation of management, including the principal executive officer and the principal financial officer of each of the Ameren Companies, of the effectiveness of the design and operation of such registrant’s disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) of the Exchange Act). Based on those evaluations, as of December 31, 2014,2017, the principal executive officer and the principal financial officer of each of the Ameren Companies concluded that such disclosure controls and procedures are effective to provide assurance that information required to be disclosed in such registrant’s reports filed or submitted under the Exchange Act is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms, and that such information is accumulated and communicated to its management, including its principal executive and principal financial officers, to allow timely decisions regarding required disclosure.
(b)Management’s Report on Internal Control over Financial Reporting
Management is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Exchange Act Rules 13a-15(f) and 15d-15(f). Under the supervision of and with the participation of management, including the principal executive officer and the principal financial officer, an evaluation was conducted of the effectiveness of each of the Ameren Companies’ internal control over financial reporting based on the framework in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO). After making that evaluation, management concluded that each of the Ameren Companies’ internal control over financial reporting was effective as of December 31, 2014.2017. The effectiveness of Ameren’s internal control over financial reporting as of December 31, 2014,2017, has been audited by PricewaterhouseCoopers LLP, an independent registered public accounting firm, as stated in its report herein under Part II, Item 8. This annual report does not include an attestation report of Ameren Missouri’s or Ameren Illinois’ (the Subsidiary Registrants) independent registered public accounting firm regarding internal control over

financial reporting. Management’s report for each of the Subsidiary Registrants is not subject to attestation by an independent registered public accounting firm.
Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements. Also, projections of any evaluation of effectiveness into future periods are subject to the risk that internal controls might become inadequate because of changes in conditions, orand to the risk that the degree of compliance with the policies or procedures might deteriorate.
(c)Change in Internal Control
There has been no change in the Ameren Companies’ internal control over financial reporting during their most recent fiscal quarter that has materially affected, or is reasonably likely to materially affect, their internal control over financial reporting.
ITEM 9B.OTHER INFORMATION
The Ameren Companies have no information reportable under this item that was required to be disclosed in a report on SEC Form 8-K during the fourth quarter of 20142017 that has not previously been reported on an SEC Form 8-K.
PART III
ITEM 10.DIRECTORS, EXECUTIVE OFFICERS, AND CORPORATE GOVERNANCE
Information required by Items 401, 405, 406 and 407(c)(3),(d)(4) and (d)(5) of SEC Regulation S-K for Ameren will be included in its definitive proxy statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14A; it is incorporated herein by reference. Information required by these SEC Regulation S-K items for Ameren Missouri and Ameren Illinois will be included in each company’s definitive information statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14C; it is incorporated herein by reference. Specifically, reference is made to the following sections of Ameren’s definitive proxy statement and to each of Ameren Missouri’s and Ameren Illinois’ definitive information statement:statements: “Information Concerning Nominees to the Board of Directors,” “Section 16(a) Beneficial Ownership Reporting Compliance,” “Corporate Governance” and “Board Structure.”
Information concerning executive officers of the Ameren Companies required by Item 401 of SEC Regulation S-K is reported under a separate caption entitled “Executive Officers of
the Registrants” in Part I of this report.
Ameren Missouri and Ameren Illinois do not have separately designated standing audit committees, but instead use Ameren’s audit and risk committee to perform such committee functions for their boards of directors. These companies do not have securities listed on the NYSE and therefore are not subject to the NYSE listing standards. Walter J. Galvin serves as chairman of Ameren’s audit and risk committee and Catherine S. Brune, J. Edward Coleman, and Ellen M. Fitzsimmons and Stephen R. Wilson serve as members. The board of directors of Ameren has determined that Walter J. Galvin qualifiesand J. Edward Coleman each qualify as an audit committee financial expert and that heeach is “independent” as that term is used in SEC Regulation 14A.
Also, on the same basis as reported above, the boards of directors of Ameren Missouri and Ameren Illinois use the nominating and corporate governance committee of Ameren’s board of directors to perform such committee functions. This committee is responsible for the nomination of directors and for corporate governance practices. Ameren’s nominating and corporate governance committee will consider director nominations from shareholders in accordance with its Policy


146


Regarding Nominations of Directors, which can be found on Ameren’s website: www.ameren.com.www.ameren.com.
To encourage ethical conduct in its financial management and reporting, Ameren has adopted a code of ethics that applies to the principal executive officer, the president, the principal financial officer, the principal accounting officer, the controller, and the treasurer of each of the Ameren Companies. Ameren has also adopted a code of business conduct that applies to the directors, officers, and employees of the Ameren Companies. It is referred to as the Principles of Business Conduct. The Ameren
Companies make available free of charge through Ameren’s website (www.ameren.com)(www.ameren.com) the Code of Ethics and the Principles of Business Conduct. Any amendment to the Code of Ethics or the Principles of Business Conduct and any waiver from a provision of the Code of Ethics or the Principles of Business Conduct as it relates to the principal executive officer, the president, the principal financial officer, the principal accounting officer, the controller, andor the treasurer of each of the Ameren Companies will be posted on Ameren’s website within four business days following the date of the amendment or waiver.

ITEM 11.EXECUTIVE COMPENSATION
Information required by Items 402 and 407(e)(4) and (e)(5) of SEC Regulation S-K for Ameren will be included in its definitive proxy statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14A; it is incorporated herein by reference. Information required by these SEC Regulation S-K items for Ameren Missouri and Ameren Illinois will be included in each company’s definitive information statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14C; it is incorporated herein by reference. Specifically, reference is made to the following sections of Ameren’s definitive proxy statement and to each of Ameren

Missouri’s and Ameren Illinois’ definitive information statement:statements: “Executive Compensation” and “Human Resources Committee Interlocks and Insider Participation.”
ITEM 12.SECURITY OWNERSHIP OF CERTAIN BENEFICIAL OWNERS AND MANAGEMENT AND RELATED STOCKHOLDER MATTERS
Equity Compensation Plan Information
The following table presents information as of December 31, 2014,2017, with respect to the shares of Ameren’s common stock that may be issued under its existing equity compensation plans.
Plan
Category
 
Column A Number of Securities To Be
Issued Upon Exercise of
Outstanding Options,
Warrants and Rights
 
Column B            Weighted-Average
Exercise Price of
Outstanding Options,
Warrants and Rights
 
Column C Number of Securities Remaining
Available for Future Issuance
Equity Compensation  Plans (excluding
securities reflected in Column A)
 
Column A
Number of Securities To Be
Issued Upon Exercise of
Outstanding Options,
Warrants and Rights(a)
 
Column B
Weighted-Average
Exercise Price of
Outstanding Options,
Warrants and Rights
 
Column C
Number of Securities Remaining
Available for Future Issuance
Equity Compensation  Plans (excluding
securities reflected in Column A)
Equity compensation plans approved by security holders(a)(b)
 2,335,780
 (b)
 7,964,166
 1,834,043
 (c)
 4,893,953
Equity compensation plans not approved by security holders 
 
 
 
 
 
Total 2,335,780
 (b)
 7,964,166
 1,834,043
 (c)
 4,893,953
(a)Consists of the 2006 Incentive Plan, which was approved by shareholders in May 2006, and the 2014 Incentive Plan, which was approved by shareholders in April 2014, and expires April 2024. The 2014 Plan replaced the 2006 Plan for any new grants made after April 24, 2014. Pursuant to grants of performance share units (PSUs) under the 20062014 Incentive Plan, 649,0181,767,462 of the securities represent PSUs that vested asthe target number of December 31, 2014 (including accrued and reinvested dividends), and 1,622,649 of the securities represent target PSUs granted but not vested (including accrued and reinvested dividends) as of December 31, 20142017 (including outstanding awards under the 2014 Incentive Plan as of December 31, 2014)2017). The actual number of shares issued in respect of the PSUs will vary from 0% to 200% of the target level, depending upon the achievement of total shareholder return objectives established for such awards. For additional information about the PSUs, including payout calculations, see “Compensation Discussion and Analysis – Long-Term Incentives: Performance Share Unit Program ("PSUP"(“PSUP”)” in Ameren’s definitive proxy statement for its 20152018 annual meeting of shareholders, which will be filed pursuant to SEC Regulation 14A. 64,113Also, 66,581 of the securities represent shares that may be issued as of December 31, 2014,2017, to satisfy obligations under the Ameren Corporation Deferred Compensation Plan for members of the board of directors.
(b)Consists of the 2014 Incentive Plan.
(c)Earned PSUs and deferred compensation stock units are paid in shares of Ameren common stock on a one-for-one basis. Accordingly, the PSUs and deferred compensation stock units do not have a weighted-average exercise price.
Ameren Missouri and Ameren Illinois do not have separate equity compensation plans.
Security Ownership of Certain Beneficial Owners and Management
The information required by Item 403 of SEC Regulation S-K for Ameren will be included in its definitive proxy statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14A; it is incorporated herein by reference. Information required by this SEC Regulation S-K item for Ameren Missouri and Ameren Illinois will be included in each company’s definitive information statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14C; it is incorporated herein by reference. Specifically, reference is made to the following section of Ameren’s definitive proxy statement and each of Ameren Missouri’s and Ameren Illinois’ definitive information statement: “Security Ownership.”

147


ITEM 13.CERTAIN RELATIONSHIPS AND RELATED TRANSACTIONS AND DIRECTOR INDEPENDENCE
Information required by ItemItems 404 and Item 407(a) of SEC Regulation S-K for Ameren will be included in its definitive proxy statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14A; it is incorporated herein by reference. Information required by these SEC Regulation S-K items for Ameren Missouri and Ameren Illinois will be included in each company’s definitive information statement for its 20152018 annual meeting of shareholders filed pursuant to SEC Regulation 14C; it is incorporated herein by reference. Specifically, reference is made to the following sections of Ameren’s definitive proxy statement and to each of Ameren Missouri’s and Ameren Illinois’ definitive information statement:statements: “Policy and Procedures With Respect to Related Person Transactions” and “Director Independence.”
ITEM 14.PRINCIPAL ACCOUNTING FEES AND SERVICES
Information required by Item 9(e) of SEC Schedule 14A for the Ameren Companies will be included in the definitive proxy statement of Ameren and the definitive information statements of Ameren Missouri and Ameren Illinois for their 20152018 annual meetings of shareholders filed pursuant to SEC Regulations 14A and 14C, respectively; it is incorporated herein by reference. Specifically, reference is made to the following section of Ameren’s definitive proxy statement and each of Ameren Missouri’s and Ameren Illinois’ definitive information statement: “Independent Registered Public Accounting Firm.”

PART IV

ITEM 15.EXHIBITS AND FINANCIAL STATEMENT SCHEDULES
  
 Page No.
(a)(1) Financial Statements 
Ameren 
Report of Independent Registered Public Accounting Firm
Consolidated Statement of Income (Loss) – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Consolidated Statement of Comprehensive Income (Loss) – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Consolidated Balance Sheet – December 31, 20142017 and 20132016
Consolidated Statement of Cash Flows – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Consolidated Statement of Stockholders’Shareholders’ Equity – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Ameren Missouri 
Report of Independent Registered Public Accounting Firm
Statement of Income and Comprehensive Income – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Balance Sheet – December 31, 20142017 and 20132016
Statement of Cash Flows – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Statement of Stockholders’Shareholders’ Equity – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Ameren Illinois 
Report of Independent Registered Public Accounting Firm
Statement of Income and Comprehensive Income – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Balance Sheet – December 31, 20142017 and 20132016
Statement of Cash Flows – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Statement of Stockholders’Shareholders’ Equity – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
  
(a)(2) Financial Statement Schedules 
Schedule I
Condensed Financial Information of Parent – Ameren: 
Condensed Statement of Income (Loss) and Comprehensive Income (Loss) – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Condensed Balance Sheet – December 31, 20142017 and 20132016
Condensed Statement of Cash Flows – Years Ended December 31, 2014, 2013,2017, 2016, and 20122015
Schedule II
Ameren
Valuation and Qualifying Accounts for the years ended December 31, 2014, 2013,2017, 2016, and 20122015
Ameren Missouri
Valuation and Qualifying Accounts for the years ended December 31, 2017, 2016, and 2015
Ameren Illinois
Valuation and Qualifying Accounts for the years ended December 31, 2017, 2016, and 2015
Schedule I and II should be read in conjunction with the aforementioned financial statements. Certain schedules have been omitted because they are not applicable or because the required data is shown in the aforementioned financial statements.
    
(a)(3) Exhibits - reference is made to the Exhibit Index
(b) Exhibit Index

148


SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF INCOME (LOSS) AND COMPREHENSIVE INCOME (LOSS)
For the Years Ended December 31, 2014, 2013, and 2012
(In millions)2014 2013 2012
Operating revenues$
 $
 $
Operating expenses11
 26
 17
Operating loss(11) (26) (17)
Equity in earnings of subsidiaries607
 546
 546
Interest income from affiliates3
 3
 3
Total other income (expense), net2
 (5) (4)
Interest charges16
 42
 39
Income tax (benefit)(2) (36) (27)
Net Income Attributable to Ameren Corporation – Continuing Operations587
 512
 516
Net Loss Attributable to Ameren Corporation – Discontinued Operations(1) (223) (1,490)
Net Income (Loss) Attributable to Ameren Corporation$586
 $289
 $(974)
      
Net Income Attributable to Ameren Corporation – Continuing Operations$587
 $512
 $516
Other Comprehensive Income (Loss), Net of Taxes:     
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $(7), $16, and $(6), respectively(12) 30
 (8)
Comprehensive Income from Continuing Operations Attributable to Ameren Corporation575
 542
 508
Net Loss Attributable to Ameren Corporation – Discontinued Operations(1) (223) (1,490)
Other Comprehensive Income (Loss) from Discontinued Operations, Net of Income Taxes
 (19) 50
Comprehensive Loss from Discontinued Operations Attributable to Ameren Corporation(1) (242) (1,440)
Comprehensive Income (Loss) Attributable to Ameren Corporation$574
 $300
 $(932)
SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF INCOME AND COMPREHENSIVE INCOME
For the Years Ended December 31, 2017, 2016, and 2015
(In millions)2017 2016 2015
Operating revenues$
 $
 $
Operating expenses13
 14
 14
Operating loss(13) (14) (14)
Equity in earnings of subsidiaries659
 663
 600
Interest income from affiliates9
 10
 6
Total other expense, net
 (5) (5)
Interest charges31
 28
 3
Income tax (benefit)101
 (27) 5
Net Income Attributable to Ameren Common Shareholders – Continuing Operations523
 653
 579
Net Income Attributable to Ameren Common Shareholders – Discontinued Operations
 
 51
Net Income Attributable to Ameren Common Shareholders$523
 $653
 $630
      
Net Income Attributable to Ameren Common Shareholders – Continuing Operations$523
 $653
 $579
Other Comprehensive Income, Net of Taxes:     
Pension and other postretirement benefit plan activity, net of income taxes (benefit) of $3, $(7), and $3, respectively5
 (20) 6
Comprehensive Income from Continuing Operations Attributable to Ameren Common Shareholders528
 633
 585
Comprehensive Income from Discontinued Operations Attributable to Ameren Common Shareholders
 
 51
Comprehensive Income Attributable to Ameren Common Shareholders$528
 $633
 $636
 

149


SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED BALANCE SHEET
(In millions)December 31, 2014 December 31, 2013December 31, 2017 December 31, 2016
Assets:      
Cash and cash equivalents$1
 $11
$
 $1
Advances to money pool55
 334
13
 27
Accounts receivable – affiliates28
 18
46
 31
Notes receivable – affiliates94
 9
Miscellaneous accounts and notes receivable39
 125

 26
Current accumulated deferred income taxes, net143
 41
Other current assets14
 1
8
 8
Total current assets374
 539
67
 93
Investments in subsidiaries – continuing operations6,680
 6,336
Investments in subsidiaries – discontinued operations(4) (5)
Investments in subsidiaries7,944
 7,498
Note receivable – ATXI100
 51
75
 350
Accumulated deferred income taxes, net264
 570
222
 419
Other assets152
 141
140
 135
Total assets$7,566
 $7,632
$8,448
 $8,495
Liabilities and Stockholders’ Equity:   
Current maturities of long-term debt$
 $425
Liabilities and Shareholders’ Equity:   
Short-term debt585
 368
383
 507
Accounts payable
 119
Borrowings from money pool28
 33
Accounts payable – affiliates88
 4
6
 13
Other current liabilities52
 20
27
 17
Total current liabilities725
 936
444
 570
Long-term debt696
 694
Pension and other postretirement benefits37
 45
Other deferred credits and liabilities128
 152
87
 83
Total liabilities853
 1,088
1,264
 1,392
Commitments and Contingencies (Notes 4 and 5)   
Stockholders’ Equity:   
Common stock, $.01 par value, 400.0 shares authorized – shares outstanding of 242.62
 2
Commitments and Contingencies (Note 4)   
Shareholders’ Equity:   
Common stock, $.01 par value, 400.0 shares authorized – 242.6 shares outstanding2
 2
Other paid-in capital, principally premium on common stock5,617
 5,632
5,540
 5,556
Retained earnings1,103
 907
1,660
 1,568
Accumulated other comprehensive income (loss)(9) 3
Total stockholders’ equity6,713
 6,544
Total liabilities and stockholders’ equity$7,566
 $7,632
Accumulated other comprehensive loss(18) (23)
Total shareholders’ equity7,184
 7,103
Total liabilities and shareholders’ equity$8,448
 $8,495
 

150


SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF CASH FLOWS
For the Years Ended December 31, 2014, 2013, and 2012
SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF CASH FLOWS
For the Years Ended December 31, 2017, 2016, and 2015
SCHEDULE I – CONDENSED FINANCIAL INFORMATION OF PARENT
AMEREN CORPORATION
CONDENSED STATEMENT OF CASH FLOWS
For the Years Ended December 31, 2017, 2016, and 2015
(In millions)2014 2013 2012 2017 2016 2015
Net cash flows provided by operating activities$514
 $453
 $532
 $454
 $483
 $551
Cash flows from investing activities:           
Money pool advances, net279
 (371) 24
 14
 (27) 55
Notes receivable – affiliates, net(134) (23) (20)
Notes receivable – ATXI, net 275
 (60) (96)
Investments in subsidiaries(280) (50) (2) (151) (123) (509)
Distributions from subsidiaries215
 1
 21
Proceeds from note receivable – Marketing Company95
 6
 
Contributions to note receivable – Marketing Company(89) (5) 
Other(12) (3) (5) 6
 2
 (12)
Net cash flows provided by (used in) investing activities74
 (445) 18
 144
 (208) (562)
Cash flows from financing activities:           
Dividends on common stock(390) (388) (382) (431) (416) (402)
Short-term debt, net217
 368
 (148) (124) 206
 (284)
Maturities of long-term debt(425) 
 
Net cash flows used in financing activities(598) (20) (530)
Money pool borrowings, net (5) 19
 14
Issuances of long-term debt 
 
 700
Debt issuance costs 
 
 (6)
Share-based payments (39) (83) (12)
Net cash flows provided by (used in) financing activities (599) (274) 10
Net change in cash and cash equivalents$(10) $(12) $20
 $(1) $1
 $(1)
Cash and cash equivalents at beginning of year11
 23
 3
 1
 
 1
Cash and cash equivalents at end of year$1
 $11
 $23
 $
 $1
 $
           
Cash dividends received from consolidated subsidiaries$340
 $570
 $610
 $362
 $465
 $575
           
Noncash investing activity – divestiture$
 $494
 $
Noncash investing activity – investments in subsidiaries(19) 
 
 
 
 (38)
Noncash financing activity – dividends on common stock
 
 (7)
AMEREN CORPORATION (parent company only)
NOTES TO CONDENSED FINANCIAL STATEMENTS
December 31, 20142017
NOTE 1 BASIS OF PRESENTATION
Ameren Corporation (parent company only) is a public utility holding company that conducts substantially all of its business operations through its subsidiaries. In accordance with authoritative accounting guidance, Ameren Corporation (parent company only) has accounted for wholly ownedits subsidiaries using the equity method. These financial statements are presented on a condensed basis.
Beginning in 2014, unrecognized tax benefits are recorded as a reduction to the deferred tax assets for net operating losses and tax credit carryforwards within "Accumulated deferred income taxes, net" on Ameren Corporation's (parent company only) balance sheets. At December 31, 2014, unrecognized tax benefits of $53 million were recorded in "Accumulated deferred income taxes, net" on Ameren Corporation's (parent company only) balance sheet. At December 31, 2013, unrecognized tax benefits of $53 million previously recorded in "Other deferred credits and liabilities" on Ameren Corporation's (parent company only) balance sheet were reclassified to "Accumulated deferred income taxes, net" for comparative purposes. See Note 1 – Summary of Significant Accounting Policies under Part II, Item 8, of this report for additional information.
Additional disclosures relating to the parent company financial statements are included within the combined notes under Part II, Item 8, of this report. See Note 113 – Summary of Significant Accounting Policies and Note 14 – Related PartyRelated-party Transactions under Part II, Item 8, of this report for information on the tax allocation agreement between Ameren (parent)Corporation (parent company only) and its subsidiaries.
NOTE 2 – SHORT-TERM DEBT AND LIQUIDITY
Ameren, Ameren Services, and other non-state-regulated Ameren subsidiaries have the ability, subject to Ameren parent company and applicable regulatory short-term borrowing authorizations, to access funding from the Credit Agreements and the commercial paper programs through a non-state-regulated subsidiary money pool agreement. All participants may borrow from or lend to the non-state-regulated money pool. The total amount available to pool participants from the non-state-regulated subsidiary money pool at any given time is reduced by the amount of borrowings made by participants, but is increased to the extent that the pool participants advance surplus funds to the non-state-regulated subsidiary money pool or remit funds from other external sources. The non-state-regulated subsidiary money pool was established to coordinate and to provide short-term cash and working capital for the participants. Participants receiving a loan under the non-state-regulated subsidiary money pool agreement must repay the principal amount of such loan, together with accrued interest. The rate of interest depends on the composition of internal and external funds in the non-state-regulated subsidiary money pool. Interest revenues and interest charges related to non-state-regulated money pool advances and borrowings were immaterial in 2015, 2016, and 2017.
Ameren Corporation (parent company only) had a total of $46 million in guarantees outstanding, primarily for ATXI, that were not recorded on its December 31, 2017 balance sheet. The ATXI guarantees were issued to local governments as assurance for potential remediation of damage caused by ATXI construction.

See Note 4 – Short-term Debt and Liquidity under Part II, Item 8, of this report for a description and details of short-term debt and liquidity needs of Ameren Corporation (parent company only).
NOTE 3 LONG-TERM OBLIGATIONS

151


In May 2014,this report for additional information on Ameren (parent) repaid at maturity $425 million of its 8.875% senior unsecured notes, plus accrued interest. The notes were repaid with proceeds from commercial paper issuances.Corporation’s (parent company only) long-term debt, indenture provisions, and restricted cash balance.
NOTE 4 COMMITMENTS AND CONTINGENCIES
See Note 1514 – Commitments and Contingencies and Note 16 – Divestiture Transactions and Discontinued Operations under Part II, Item 8, of this report for a description of all material contingencies guarantees, and letters of credit outstanding of Ameren Corporation (parent company only).
NOTE 5 NEW AER DIVESTITURE TRANSACTIONS AND DISCONTINUED OPERATIONS
In December 2012, Ameren determined that it intended to, and it was probable that it would, exit its Merchant Generation business before the end of the previously estimated useful lives of that business's long-lived assets. As a result of the 2012 determination, Ameren Corporation (parent company only) recorded a pretax impairment charge of $1.88 billion to reduce its investment in certain of the Merchant Generation segment's coal and natural-gas-fired energy centers to their estimated fair values. In December 2013, Ameren completed a divestiture that included a significant portion of that business. As a result of the divestiture in 2013, Ameren Corporation (parent company only) recorded a pretax loss on disposal of $201 million. These charges were included within "Net Loss Attributable to Ameren Corporation – Discontinued Operations" in the Ameren Corporation (parent company only) Condensed Statement of Income (Loss) and Comprehensive Income (Loss) for the years ended December 31, 2013 and 2012.
The "Miscellaneous accounts and notes receivable" on the December 31, 2013 Ameren Corporation (parent company only) Condensed Balance Sheet included a receivable from Dynegy related to the non-state-regulated subsidiary money pool borrowing balance as of the divestiture date of certain New AER subsidiaries. Additionally, a payable to Dynegy of the estimated working capital adjustment required under the terms of the agreement with IPH was reflected in "Accounts payable" on the December 31, 2013 Ameren Corporation (parent company only) Condensed Balance Sheet. In 2014, the receivable and payable were finalized and settled, along with certain contingent liabilities associated with the New AER divestiture, resulting in a net $13 million payment to IPH.
See Note 161 – Divestiture Transactions and Discontinued OperationsSummary of Significant Accounting Policies under Part II, Item 8, of this report for additional information regarding the divestiture transactions and discontinued operations.
NOTE 6 INCOME TAXES
See Note 12 – Income Taxes under Part II, Item 8, of this report for information regarding the impacts of the TCJA on the impairment charges recognized in 2013 and 2012 as well as the divestiture.Ameren Corporation (parent company only).

152


SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS
FOR THE YEARS ENDED DECEMBER 31, 2014, 2013, AND 2012
(in millions)         
Column AColumn B Column C Column D Column E
Description
Balance at
Beginning
of Period
 
(1)
Charged to Costs
and Expenses
 
(2)
Charged to Other
Accounts(a)
 
Deductions(b)
 
Balance at End
of Period
Ameren:         
Deducted from assets – allowance for doubtful accounts:         
2014$18
 $36
 $4
 $37
 $21
201317
 35
 4
 38
 18
201220
 30
 2
 35
 17
Deferred tax valuation allowance:         
2014$7
 $3
 $
 $
 $10
20132
 5
 
 
 7
20121
 1
 
 
 2
Ameren Missouri:         
Deducted from assets – allowance for doubtful accounts:         
2014$5
 $16
 $
 $13
 $8
20135
 16
 
 16
 5
20127
 11
 
 13
 5
Deferred tax valuation allowance:         
2014$1
 $
 $
 $
 $1
20131
 
 
 
 1
20121
 
 
 
 1
Ameren Illinois:         
Deducted from assets – allowance for doubtful accounts:         
2014$13
 $20
 $4
 $24
 $13
201312
 19
 4
 22
 13
201213
 19
 2
 22
 12
Deferred tax valuation allowance:         
2014$1
 $
 $
 $
 $1
20131
 
 
 
 1
2012
 1
 
 
 1
SCHEDULE II – VALUATION AND QUALIFYING ACCOUNTS
FOR THE YEARS ENDED DECEMBER 31, 2017, 2016, AND 2015
(in millions)         
Column AColumn B Column C Column D Column E
Description
Balance at
Beginning
of Period
 
(1)
Charged to Costs
and Expenses
 
(2)
Charged to Other
Accounts(a)
 
Deductions(b)
 
Balance at End
of Period
Ameren:         
Deducted from assets – allowance for doubtful accounts:         
2017$19
 $26
 $7
 $33
 $19
201619
 32
 3
 35
 19
201521
 33
 5
 40
 19
Deferred tax valuation allowance:         
2017$11
 $(6)
(c) 
$
 $
 $5
20166
 7
 (2) 
 11
201510
 4
 (8) 
 6
Ameren Missouri:         
Deducted from assets – allowance for doubtful accounts:         
2017$7
 $9
 $
 $9
 $7
20167
 10
 
 10
 7
20158
 13
 
 14
 7
Deferred tax valuation allowance:         
2017$
 $
 $
 $
 $
2016
 
 
 
 
20151
 
 (1) 
 
Ameren Illinois:         
Deducted from assets – allowance for doubtful accounts:         
2017$12
 $17
 $7
 $24
 $12
201612
 22
 3
 25
 12
201513
 20
 5
 26
 12
Deferred tax valuation allowance:         
2017$
 $
 $
 $
 $
2016
 
 
 
 
20151
 
 (1) 
 
(a)UncollectibleAmounts associated with the allowance for doubtful accounts relate to the uncollectible account reserve associated with receivables purchased by Ameren Illinois from alternative retail electric suppliers, as required by the Illinois Public Utilities Act. The amounts relating to the deferred tax valuation allowance are for items that have expired and were removed from both the underlying accumulated deferred income tax account as well as the offsetting valuation account.
(b)Uncollectible accounts charged off, less recoveries.
(c)Includes an adjustment of $3 million to Ameren (parent)’s valuation allowance for certain deferred tax assets existing at December 31, 2017, for the reduction in the income tax rate.
ITEM 16.FORM 10-K SUMMARY
The Ameren Companies elected not to provide a summary of the Form 10-K.

EXHIBIT INDEX
The documents listed below are being filed or have previously been filed on behalf of the Ameren Companies and are incorporated herein by reference from the documents indicated and made a part hereof. Exhibits not identified as previously filed are filed herewith: 
Exhibit DesignationRegistrant(s)Nature of ExhibitPreviously Filed as Exhibit to:
Articles of Incorporation/ By-Laws
3.1(i)AmerenAnnex F to Part I of the Registration Statement on Form S-4, File No. 33-64165
3.2(i)Ameren
1998 Form 10-K, Exhibit 3(i),
File No. 1-14756
3.3(i)Ameren
April 21, 2011 Form 8-K, Exhibit 3(i),
File No. 1-14756
3.4(i)Ameren
December 18, 2012 Form 8-K, Exhibit 3.1(i),
File No. 1-14756
3.5(i)Ameren Missouri
1993 Form 10-K, Exhibit 3(i),
File No. 1-2967
3.6(i)Ameren Illinois
2010 Form 10-K, Exhibit 3.4(i),
File No. 1-3672
3.7(ii)Ameren
February 14, 2017 Form 8-K, Exhibit 3,
File No. 1-14756
3.8(ii)Ameren Missouri
December 18, 2014 Form 8-K,
Exhibit 3.1, File No. 1-2967
3.9(ii)Ameren Illinois
December 18, 2014 Form 8-K,
Exhibit 3.2, File No. 1-3672
Instruments Defining Rights of Security Holders, Including Indentures
4.1AmerenExhibit 4.5, File No. 333-81774
4.2Ameren
June 30, 2008 Form 10-Q, Exhibit 4.1,
File No. 1-14756
4.3AmerenNovember 24, 2015 Form 8-K, Exhibits 4.3, 4.4 and 4.5, File No. 1-14756
4.4
Ameren
Ameren Missouri
Indenture of Mortgage and Deed of Trust, dated June 15, 1937 (Ameren Missouri Mortgage), from Ameren Missouri to The Bank of New York Mellon, as successor trustee, as amended May 1, 1941, and Second Supplemental Indenture dated May 1, 1941Exhibit B-1, File No. 2-4940
4.5
Ameren
Ameren Missouri
Exhibit 4.22, File No. 333-222108
4.6
Ameren
Ameren Missouri
Exhibit 4.23, File No. 333-222108
4.7
Ameren
Ameren Missouri
Exhibit 4.24, File No. 333-222108
4.8
Ameren
Ameren Missouri
Exhibit 4.25, File No. 333-222108
4.9
Ameren
Ameren Missouri
1993 Form 10-K, Exhibit 4.8,
File No. 1-2967
4.10
Ameren
Ameren Missouri
2000 Form 10-K, Exhibit 4.1,
File No. 1-2967
4.11
Ameren
Ameren Missouri
August 23, 2002 Form 8-K, Exhibit 4.3,
File No. 1-2967
4.12
Ameren
Ameren Missouri
March 11, 2003 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.13
Ameren
Ameren Missouri
August 4, 2003 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.14
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.1,
File No. 1-2967

153

4.15
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.2,
File No. 1-2967
4.16
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.3,
File No. 1-2967
4.17
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.8,
File No. 1-2967
4.18
Ameren
Ameren Missouri
September 23, 2004 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.19
Ameren
Ameren Missouri
January 27, 2005 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.20
Ameren
Ameren Missouri
July 21, 2005 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.21
Ameren
Ameren Missouri
April 8, 2008 Form 8-K, Exhibit 4.7,
File No. 1-2967
4.22
Ameren
Ameren Missouri
June 19, 2008 Form 8-K, Exhibit 4.5,
File No. 1-2967
4.23
Ameren
Ameren Missouri
March 23, 2009 Form 8-K, Exhibit 4.5,
File No. 1-2967
4.24
Ameren
Ameren Missouri
Exhibit 4.45, File No. 333-182258
4.25
Ameren
Ameren Missouri
September 11, 2012 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.26
Ameren
Ameren Missouri
April 4, 2014 Form 8-K, Exhibit 4.5,
File No. 1-2967
4.27
Ameren
Ameren Missouri
April 6, 2015 Form 8-K, Exhibit 4.5, File No. 1-2967
4.28
Ameren
Ameren Missouri
June 15, 2017 Form 8-K, Exhibit 4.5, File No. 1-2967
4.29
Ameren
Ameren Missouri
Loan Agreement, dated as of December 1, 1992, between the Missouri Environmental Authority and Ameren Missouri, together with Indenture of Trust dated as of December 1, 1992, between the Missouri Environmental Authority and UMB Bank, N.A. as successor trustee to Mercantile Bank of St. Louis, N.A.
1992 Form 10-K, Exhibit 4.38,
File No. 1-2967
4.30
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.10,
File No. 1-2967
4.31
Ameren
Ameren Missouri
September 30, 1998 Form 10-Q,
Exhibit 4.28, File No. 1-2967
4.32
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.11,
File No. 1-2967
4.33
Ameren
Ameren Missouri
September 30, 1998 Form 10-Q,
Exhibit 4.29, File No. 1-2967
4.34
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.12,
File No. 1-2967
4.35
Ameren
Ameren Missouri
September 30, 1998 Form 10-Q,
Exhibit 4.30, File No. 1-2967
4.36
Ameren
Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.13,
File No. 1-2967
4.37
Ameren
Ameren Missouri
August 23, 2002 Form 8-K, Exhibit 4.1,
File No. 1-2967
4.38
Ameren
Ameren Missouri
Exhibit 4.48, File No. 333-182258

4.39
Ameren
Ameren Missouri
March 11, 2003 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.40
Ameren
Ameren Missouri
August 4, 2003 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.41
Ameren
Ameren Missouri
September 23, 2004 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.42
Ameren
Ameren Missouri
January 27, 2005 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.43
Ameren
Ameren Missouri
July 21, 2005 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.44
Ameren
Ameren Missouri
April 8, 2008 Form 8-K, Exhibits 4.3 and 4.5, File No. 1-2967
4.45
Ameren
Ameren Missouri
June 19, 2008 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.46
Ameren
Ameren Missouri
March 23, 2009 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.47
Ameren
Ameren Missouri
September 30, 2012 Form 10-Q, Exhibit 4.1 and September 11, 2012 Form 8-K, Exhibit 4.2, File No. 1-2967
4.48
Ameren
Ameren Missouri
April 4, 2014 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.49
Ameren
Ameren Missouri
April 6, 2015 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.50
Ameren
Ameren Missouri
June 23, 2016 Form 8-K, Exhibits 4.3, and 4.4, File No. 1-2967
4.51
Ameren
Ameren Missouri
June 15, 2017 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.52
Ameren
Ameren Illinois
Exhibit 4.4, File No. 333-59438
4.53
Ameren
Ameren Illinois
June 19, 2006 Form 8-K, Exhibit 4.2, File No. 1-3672
4.54
Ameren
Ameren Illinois
Exhibit 4.17, File No. 333-166095
4.55
Ameren
Ameren Illinois
2010 Form 10-K, Exhibit 4.59, File No. 1-3672
4.56
Ameren
Ameren Illinois
2010 Form 10-K, Exhibit 4.60, File No. 1-3672
4.57
Ameren
Ameren Illinois
2010 Form 10-K, Exhibit 4.62, File No. 1-3672
4.58
Ameren
Ameren Illinois
Indenture of Mortgage and Deed of Trust between Ameren Illinois (successor in interest to Central Illinois Light Company and Illinois Power Company) and Deutsche Bank Trust Company Americas (formerly Bankers Trust Company), as trustee, dated as of April 1, 1933 (CILCO Mortgage), Supplemental Indenture between the same parties dated as of June 30, 1933, Supplemental Indenture between CILCO (predecessor in interest to Ameren Illinois) and the trustee, dated as of July 1, 1933, Supplemental Indenture between the same parties dated as of January 1, 1935, and Supplemental Indenture between the same parties dated as of April 1, 1940Exhibit B-1, Registration No. 2-1937; Exhibit B-1(a), Registration No. 2-2093; and Exhibit A, April 1940 Form 8-K, File No. 1-2732
4.59
Ameren
Ameren Illinois
4.60
Ameren
Ameren Illinois

4.61
Ameren
Ameren Illinois
4.62
Ameren
Ameren Illinois
4.63
Ameren
Ameren Illinois
June 19, 2006 Form 8-K, Exhibit 4.11, File No. 1-2732
4.64
Ameren
Ameren Illinois
October 7, 2010 Form 8 K, Exhibit 4.4, File No. 1-14756
4.65
Ameren
Ameren Illinois
June 19, 2006 Form 8-K, Exhibit 4.3, File No. 1-2732
4.66
Ameren
Ameren Illinois
October 7, 2010 Form 8 K, Exhibit 4.1, File No. 1-3672
4.67
Ameren
Ameren Illinois
September 30, 2011 Form 10-Q, Exhibit 4.1,
File No. 1-3672
4.68
Ameren
Ameren Illinois
June 19, 2006 Form 8-K, Exhibit 4.6, File No. 1-2732
4.69
Ameren
Ameren Illinois
General Mortgage Indenture and Deed of Trust, dated as of November 1, 1992 between Ameren Illinois (successor in interest to Illinois Power Company) and The Bank of New York Mellon Trust Company, N.A., as successor trustee (Ameren Illinois Mortgage)1992 Form 10-K, Exhibit 4(cc), File No. 1-3004
4.70
Ameren
Ameren Illinois
June 30, 1999 Form 10-Q, Exhibit 4.2, File No. 1-3004
4.71
Ameren
Ameren Illinois
December 23, 2002 Form 8-K, Exhibit 4.1, File No. 1-3004
4.72
Ameren
Ameren Illinois
April 8, 2008 Form 8-K, Exhibit 4.9, File No. 1-3004
4.73
Ameren
Ameren Illinois
October 23, 2008 Form 8-K, Exhibit 4.4, File No. 1-3004
4.74
Ameren
Ameren Illinois
October 7, 2010 Form 8 K, Exhibit 4.9, File No. 1-3672
4.75
Ameren
Ameren Illinois
Exhibit 4.78, File No. 333-182258
4.76
Ameren
 Ameren Illinois
August 20, 2012 Form 8-K, Exhibit 4.5, File No. 1-3672
4.77
Ameren
Ameren Illinois
December 10, 2013 Form 8-K, Exhibit 4.5, File No. 1-3672
4.78
Ameren
Ameren Illinois
June 30, 2014 Form 8-K, Exhibit 4.5, File No. 1-3672
4.79
Ameren
Ameren Illinois
December 10, 2014 Form 8-K, Exhibit 4.5, File No. 1-3672
4.80
Ameren
Ameren Illinois
December 14, 2015 Form 8-K, Exhibit 4.5, File No. 1-3672
4.81
Ameren
Ameren Illinois
September 30, 2017 Form 10-Q, Exhibit 4.1, File No. 1-3672
4.82
Ameren
Ameren Illinois
November 28, 2017 Form 8-K, Exhibit 4.2, File No. 1-3672
4.83
Ameren
Ameren Illinois
June 19, 2006 Form 8-K, Exhibit 4.4, File No. 1-3004
4.84
Ameren
Ameren Illinois
October 7, 2010 Form 8 K, Exhibit 4.5, File No. 1-14756
4.85
Ameren
Ameren Illinois
September 30, 2011 Form 10-Q, Exhibit 4.2, File No. 1-3672
4.86
Ameren
Ameren Illinois
Exhibit 4.83, File No. 333-182258

4.87
Ameren
Ameren Illinois
April 8, 2008 Form 8-K, Exhibit 4.4, File No. 1-3004
4.88
Ameren
Ameren Illinois
October 23, 2008 Form 8-K, Exhibit 4.2, File No. 1-3004
4.89
Ameren
Ameren Illinois
August 20, 2012 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-3672
4.90
Ameren
Ameren Illinois
December 10, 2013 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-3672
4.91
Ameren
Ameren Illinois
June 30, 2014 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-3672
4.92
Ameren
Ameren Illinois
December 10, 2014 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-3672
4.93
Ameren
Ameren Illinois
December 14, 2015 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-3672
4.94
Ameren
Ameren Illinois
December 6, 2016 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-3672
Material Contracts
10.1Ameren CompaniesJune 30, 2015 Form 10-Q, Exhibit 10.1, File No. 1-14756
10.2
Ameren
Ameren Missouri
December 8, 2016 Form 8-K, Exhibit 10.1, File No. 1-2967
10.3
Ameren
Ameren Illinois
December 8, 2016 Form 8-K, Exhibit 10.2, File No. 1-3672
10.4Ameren
10.5AmerenJune 30, 2008 Form 10-Q, Exhibit 10.3, File No. 1-14756
10.6Ameren2009 Form 10-K, Exhibit 10.15, File No. 1-14756
10.7Ameren2010 Form 10-K, Exhibit 10.15, File No. 1-14756
10.8AmerenOctober 14, 2009 Form 8-K, Exhibit 10.1, File No. 1-14756
10.9Ameren2010 Form 10-K, Exhibit 10.17, File No. 1-14756
10.10Ameren Companies2014 Form 10-K, Exhibit 10.13, File No. 1-14756
10.11Ameren Companies2015 Form 10-K, Exhibit 10.13, File No. 1-14756
10.12Ameren Companies2016 Form 10-K, Exhibit 10.13, File No. 1-14756
10.13Ameren Companies
10.14Ameren Companies2014 Form 10-K, Exhibit 10.17, File No. 1-14756
10.15Ameren Companies2015 Form 10-K, Exhibit 10.17, File No. 1-14756
10.16Ameren Companies2016 Form 10-K, Exhibit 10.17, File No. 1-14756
10.17Ameren Companies
10.18Ameren Companies2008 Form 10-K, Exhibit 10.37, File No. 1-14756
10.19Ameren CompaniesOctober 14, 2009 Form 8-K, Exhibit 10.2, File No. 1-14756
10.20Ameren Companies

10.21Ameren Companies2014 Form 10-K, Exhibit 10.24, File No. 1-14756
10.22Ameren Companies2015 Form 10-K, Exhibit 10.24, File No. 1-14756
10.23Ameren Companies2016 Form 10-K, Exhibit 10.24, File No. 1-14756
10.24Ameren Companies
10.25Ameren CompaniesExhibit 99, File No. 333-196515
10.26Ameren Companies2014 Form 10-K, Exhibit 10.31, File No. 1-14756
10.27Ameren Companies2015 Form 10-K, Exhibit 10.31, File No. 1-14756
10.28Ameren Companies2016 Form 10-K, Exhibit 10.31, File No. 1-14756
10.29Ameren CompaniesDecember 13, 2017 Form 8-K, Exhibit 10.1, File No. 1-14756
10.30Ameren CompaniesDecember 13, 2017 Form 8-K, Exhibit 10.2, File No. 1-14756
10.31Ameren CompaniesDecember 13, 2017 Form 8-K, Exhibit 10.3, File No. 1-14756
10.32Ameren CompaniesJune 30, 2008 Form 10-Q, Exhibit 10.1, File No. 1-14756
10.33Ameren Companies2008 Form 10-K, Exhibit 10.44, File No. 1-14756
Statement re: Computation of Ratios
12.1Ameren
12.2Ameren Missouri
12.3Ameren Illinois
Subsidiaries of the Registrant
21.1Ameren Companies
Consent of Experts and Counsel
23.1Ameren
23.2Ameren Missouri
23.3Ameren Illinois
Power of Attorney
24.1Ameren
24.2Ameren Missouri
24.3Ameren Illinois
Rule 13a-14(a)/15d-14(a) Certifications
31.1Ameren
31.2Ameren
31.3Ameren Missouri
31.4Ameren Missouri

31.5Ameren Illinois
31.6Ameren Illinois
Section 1350 Certifications
32.1Ameren
32.2Ameren Missouri
32.3Ameren Illinois
Additional Exhibits
99.1Ameren Companies2013 Form 10-K, Exhibit 99.1, File No. 1-14756
Interactive Data File
101.INSAmeren CompaniesXBRL Instance Document
101.SCHAmeren CompaniesXBRL Taxonomy Extension Schema Document
101.CALAmeren CompaniesXBRL Taxonomy Extension Calculation Linkbase Document
101.LABAmeren CompaniesXBRL Taxonomy Extension Label Linkbase Document
101.PREAmeren CompaniesXBRL Taxonomy Extension Presentation Linkbase Document
101.DEFAmeren CompaniesXBRL Taxonomy Extension Definition Document

The file number references for the Ameren Companies’ filings with the SEC are: Ameren, 1-14756; Ameren Missouri, 1-2967; and Ameren Illinois, 1-3672.
*Compensatory plan or arrangement.
Each registrant hereby undertakes to furnish to the SEC upon request a copy of Contentsany long-term debt instrument not listed above that such registrant has not filed as an exhibit pursuant to the exemption provided by Item 601(b)(4)(iii)(A) of Regulation S-K.



SIGNATURES
Pursuant to the requirements of Section 13 or 15(d) of the Securities Exchange Act of 1934, each registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized. The signatures for each undersigned company shall be deemed to relate only to matters having reference to such company or its subsidiaries.
  
AMEREN CORPORATION (registrant)
    
Date:March 2, 2015February 28, 2018By /s/ Warner L. Baxter
    
Warner L. Baxter
Chairman, President and Chief Executive Officer
Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the date indicated.
/s/ Warner L. Baxter Chairman, President and Chief Executive Officer, and Director (Principal Executive Officer) March 2, 2015February 28, 2018
Warner L. Baxter    
    
/s/ Martin J. Lyons, Jr. 
Executive Vice President and Chief Financial Officer (Principal
(Principal Financial Officer)
 March 2, 2015February 28, 2018
Martin J. Lyons, Jr.     
      
/s/ Bruce A. Steinke Senior Vice President, Finance, and Chief Accounting Officer (Principal Accounting Officer) March 2, 2015February 28, 2018
Bruce A. Steinke    
      
* Director March 2, 2015February 28, 2018
Catherine S. Brune     
      
* Director March 2, 2015February 28, 2018
J. Edward Coleman    
    
* Director March 2, 2015February 28, 2018
Ellen M. Fitzsimmons     
    
* Director March 2, 2015February 28, 2018
Rafael Flores
*DirectorFebruary 28, 2018
Walter J. Galvin     
    
* Director March 2, 2015February 28, 2018
Richard J. Harshman     
    
* Director March 2, 2015February 28, 2018
Gayle P.W.P. W. Jackson     
    
* Director March 2, 2015February 28, 2018
James C. Johnson     
    
* Director March 2, 2015February 28, 2018
Steven H. Lipstein     
    
* Director March 2, 2015
Patrick T. Stokes
*DirectorMarch 2, 2015February 28, 2018
Stephen R. Wilson     
*DirectorMarch 2, 2015
Jack D. Woodard    
    
*By/s/ Martin J. Lyons, Jr.    March 2, 2015February 28, 2018
 Martin J. Lyons, Jr.    
 Attorney-in-Fact    

154


  
UNION ELECTRIC COMPANY (registrant)
    
Date:March 2, 2015February 28, 2018By /s/ Michael L. Moehn
    
Michael L. Moehn
Chairman and President
Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the date indicated.

/s/ Michael L. Moehn Chairman and President, and Director (Principal Executive Officer) March 2, 2015February 28, 2018
Michael L. Moehn     
    

/s/ Martin J. Lyons, Jr.
 Executive Vice President and Chief Financial Officer, and Director (Principal Financial Officer) March 2, 2015February 28, 2018
Martin J. Lyons, Jr.     
    

/s/ Bruce A. Steinke
 Senior Vice President, Finance, and Chief Accounting Officer (Principal Accounting Officer) March 2, 2015February 28, 2018
Bruce A. Steinke    
      
* Director March 2, 2015February 28, 2018
Daniel F. ColeMark C. Birk     
    
* Director March 2, 2015February 28, 2018
Fadi M. Diya     
    
* Director March 2, 2015February 28, 2018
Gregory L. Nelson
*DirectorFebruary 28, 2018
David N. Wakeman     
    
*By/s/ Martin J. Lyons, Jr.    March 2, 2015February 28, 2018
 Martin J. Lyons, Jr.    
 Attorney-in-Fact    


155


  
AMEREN ILLINOIS COMPANY (registrant)
     
Date:March 2, 2015February 28, 2018By  /s/ Richard J. Mark
    
Richard J. Mark
Chairman and President
Pursuant to the requirements of the Securities Exchange Act of 1934, this report has been signed below by the following persons on behalf of the registrant and in the capacities and on the date indicated.
 
/s/ Richard J. Mark Chairman and President, and Director (Principal Executive Officer) March 2, 2015February 28, 2018
Richard J. Mark     
    
/s/ Martin J. Lyons, Jr. Executive Vice President and Chief Financial Officer, and Director (Principal Financial Officer) March 2, 2015February 28, 2018
Martin J. Lyons, Jr.     
    
/s/ Bruce A. Steinke Senior Vice President, Finance, and Chief Accounting Officer (Principal Accounting Officer) March 2, 2015February 28, 2018
Bruce A. Steinke    
      
* Director March 2, 2015February 28, 2018
Daniel F. ColeCraig D. Nelson     
    
* Director March 2, 2015February 28, 2018
Craig D.Gregory L. Nelson     
      
* 
Director

 
March 2, 2015

February 28, 2018
Gregory L. NelsonDavid N. Wakeman    
    
*By/s/ Martin J. Lyons, Jr.    March 2, 2015February 28, 2018
 Martin J. Lyons, Jr.    
 Attorney-in-Fact    


156


EXHIBIT INDEX
The documents listed below are being filed or have previously been filed on behalf of the Ameren Companies and are incorporated herein by reference from the documents indicated and made a part hereof. Exhibits not identified as previously filed are filed herewith: 
Exhibit DesignationRegistrant(s)Nature of ExhibitPreviously Filed as Exhibit  to:
Plan of Acquisition, Reorganization, Arrangement, Liquidation or Succession
2.1AmerenTransaction Agreement, dated as of March 14, 2013, between Ameren Corporation and Illinois Power Holdings, LLCMarch 19, 2013 Form 8-K, Exhibit 2.1, File No. 1-14756
2.2AmerenLetter Agreement, dated December 2, 2013, between Ameren Corporation and Illinois Power Holdings, LLC, amending the Transaction Agreement, dated as of March 14, 2013December 4, 2013 Form 8-K, Exhibit 2.2, File No. 1-14756
Articles of Incorporation/ By-Laws
3.1(i)AmerenRestated Articles of Incorporation of AmerenAnnex F to Part I of the Registration Statement on Form S-4, File No. 33-64165
3.2(i)AmerenCertificate of Amendment to Ameren's Restated Articles of Incorporation filed December 14, 1998
1998 Form 10-K, Exhibit 3(i),
File No. 1-14756
3.3(i)AmerenCertificate of Amendment to Ameren's Restated Articles of Incorporation filed April 21, 2011
April 21, 2011 Form 8-K, Exhibit 3(i),
File No. 1-14756
3.4(i)AmerenCertificate of Amendment to Ameren's Restated Articles of Incorporation filed December 18, 2012
December 18, 2012 Form 8-K, Exhibit 3.1(i),
File No. 1-14756
3.5(i)Ameren MissouriRestated Articles of Incorporation of Ameren Missouri
1993 Form 10-K, Exhibit 3(i),
File No. 1-2967
3.6(i)Ameren IllinoisRestated Articles of Incorporation of Ameren Illinois
2010 Form 10-K, Exhibit 3.4(i),
File No. 1-3672
3.7(ii)AmerenBy-Laws of Ameren, as amended December 14, 2012
December 18, 2012 Form 8-K, Exhibit 3.1(ii),
File No. 1-14756
3.8(ii)Ameren MissouriBylaws of Ameren Missouri, as amended December 12, 2014
December 18, 2014 Form 8-K,
Exhibit 3.1, File No. 1-2967
3.9(ii)Ameren IllinoisBylaws of Ameren Illinois, as amended December 12, 2014
December 18, 2014 Form 8-K,
Exhibit 3.2, File No. 1-3672
Instruments Defining Rights of Security Holders, Including Indentures
4.1AmerenIndenture, dated as of December 1, 2001 from Ameren to The Bank of New York Mellon Trust Company, N.A., as successor trustee, relating to senior debt securities (Ameren Indenture)Exhibit 4.5, File No. 333-81774
4.2AmerenFirst Supplemental Indenture to Ameren Senior Indenture dated as of May 19, 2008
June 30, 2008 Form 10-Q, Exhibit 4.1,
File No. 1-14756
4.3
Ameren
Ameren Missouri
Indenture of Mortgage and Deed of Trust, dated June 15, 1937 (Ameren Missouri Mortgage), from Ameren Missouri to The Bank of New York Mellon, as successor trustee, as amended May 1, 1941, and Second Supplemental Indenture dated May 1, 1941Exhibit B-1, File No. 2-4940
4.4
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated as of July 1, 1956August 2, 1956 Form 8-K, Exhibit 2, File No. 1-2967
4.5
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated as of April 1, 1971
April 1971 Form 8-K, Exhibit 6,
File No. 1-2967
4.6
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated as of February 1, 1974
February 1974 Form 8-K, Exhibit 3,
File No. 1-2967
4.7
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated as of July 7, 1980Exhibit 4.6, File No. 2-69821
4.8
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated as of October 1, 1993, relative to Series 2028
1993 Form 10-K, Exhibit 4.8,
File No. 1-2967
4.9
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated as of February 1, 2000
2000 Form 10-K, Exhibit 4.1,
File No. 1-2967
4.10
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated August 15, 2002
August 23, 2002 Form 8-K, Exhibit 4.3,
File No. 1-2967
4.11
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated March 5, 2003, relative to Series BB
March 11, 2003 Form 8-K, Exhibit 4.4,
File No. 1-2967

157


4.12
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated April 1, 2003, relative to Series CC
April 10, 2003 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.13
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated July 15, 2003, relative to Series DD
August 4, 2003 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.14
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated October 1, 2003, relative to Series EE
October 8, 2003 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.15
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated February 1, 2004, relative to Series 2004A (1998A)
March 31, 2004 Form 10-Q, Exhibit 4.1,
File No. 1-2967
4.16
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated February 1, 2004, relative to Series 2004B (1998B)
March 31, 2004 Form 10-Q, Exhibit 4.2,
File No. 1-2967
4.17
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated February 1, 2004, relative to Series 2004C (1998C)
March 31, 2004 Form 10-Q, Exhibit 4.3,
File No. 1-2967
4.18
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated February 1, 2004, relative to Series 2004H (1992)
March 31, 2004 Form 10-Q, Exhibit 4.8,
File No. 1-2967
4.19
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated May 1, 2004 relative to Series FF
May 18, 2004 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.20
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated September 1, 2004 relative to Series GG
September 23, 2004 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.21
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated January 1, 2005 relative to Series HH
January 27, 2005 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.22
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated July 1, 2005 relative to Series II
July 21, 2005 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.23
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated December 1, 2005 relative to Series JJ
December 9, 2005 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.24
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated June 1, 2007 relative to Series KK
June 15, 2007 Form 8-K, Exhibit 4.5,
File No. 1-2967
4.25
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated April 1, 2008 relative to Series LL
April 8, 2008 Form 8-K, Exhibit 4.7,
File No. 1-2967
4.26
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated June 1, 2008 relative to Series MM
June 19, 2008 Form 8-K, Exhibit 4.5,
File No. 1-2967
4.27
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated March 1, 2009 relative to Series NN
March 23, 2009 Form 8-K, Exhibit 4.5,
File No. 1-2967
4.28
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated May 15, 2012Exhibit 4.45, File No. 333-182258
4.29
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated September 1, 2012 relative to Series OO
September 11, 2012 Form 8-K, Exhibit 4.4,
File No. 1-2967
4.30
Ameren
Ameren Missouri
Supplemental Indenture to the Ameren Missouri Mortgage dated April 1, 2014 relative to Series PP
April 4, 2014 Form 8-K, Exhibit 4.5,
File No. 1-2967
4.31
Ameren
Ameren Missouri
Loan Agreement, dated as of December 1, 1992, between the Missouri Environmental Authority and Ameren Missouri, together with Indenture of Trust dated as of December 1, 1992, between the Missouri Environmental Authority and UMB Bank, N.A. as successor trustee to Mercantile Bank of St. Louis, N.A.
1992 Form 10-K, Exhibit 4.38,
File No. 1-2967
4.32
Ameren
Ameren Missouri
First Amendment, dated as of February 1, 2004, to Loan Agreement dated as of December 1, 1992, between the Missouri Environmental Authority and Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.10,
File No. 1-2967
4.33
Ameren
Ameren Missouri
Series 1998A Loan Agreement, dated as of September 1, 1998, between the Missouri Environmental Authority and Ameren Missouri
September 30, 1998 Form 10-Q,
Exhibit 4.28, File No. 1-2967
4.34
Ameren
Ameren Missouri
First Amendment, dated as of February 1, 2004, to Series 1998A Loan Agreement dated as of September 1, 1998, between the Missouri Environmental Authority and Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.11,
File No. 1-2967
4.35
Ameren
Ameren Missouri
Series 1998B Loan Agreement, dated as of September 1, 1998, between the Missouri Environmental Authority and Ameren Missouri
September 30, 1998 Form 10-Q,
Exhibit 4.29, File No. 1-2967
4.36
Ameren
Ameren Missouri
First Amendment, dated as of February 1, 2004, to Series 1998B Loan Agreement dated as of September 1, 1998, between the Missouri Environmental Authority and Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.12,
File No. 1-2967

158


4.37
Ameren
Ameren Missouri
Series 1998C Loan Agreement, dated as of September 1, 1998, between the Missouri Environmental Authority and Ameren Missouri
September 30, 1998 Form 10-Q,
Exhibit 4.30, File No. 1-2967
4.38
Ameren
Ameren Missouri
First Amendment, dated as of February 1, 2004, to Series 1998C Loan Agreement dated as of September 1, 1998, between the Missouri Environmental Authority and Ameren Missouri
March 31, 2004 Form 10-Q, Exhibit 4.13,
File No. 1-2967
4.39
Ameren
Ameren Missouri
Indenture, dated as of August 15, 2002, from Ameren Missouri to The Bank of New York Mellon, as successor trustee (relating to senior secured debt securities) (Ameren Missouri Indenture)
August 23, 2002 Form 8-K, Exhibit 4.1,
File No. 1-2967
4.40
Ameren
Ameren Missouri
First Supplemental Indenture to the Ameren Missouri Indenture, dated as of May 15, 2012Exhibit 4.48, File No. 333-182258
4.41
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated March 10, 2003, establishing the 5.50% Senior Secured Notes due 2034 (including the global note)March 11, 2003 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.42
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated April 9, 2003, establishing the 4.75% Senior Secured Notes due 2015 (including the global note)April 10, 2003 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.43
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated July 28, 2003, establishing the 5.10% Senior Secured Notes due 2018 (including the global note)August 4, 2003 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.44
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated October 7, 2003, establishing the 4.65% Senior Secured Notes due 2013 (including the global note)October 8, 2003 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.45
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated May 13, 2004, establishing the 5.50% Senior Secured Notes due 2014 (including the global note)May 18, 2004 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.46
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated September 1, 2004, establishing the 5.10% Senior Secured Notes due 2019 (including the global note)September 23, 2004 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.47
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated January 27, 2005, establishing the 5.00% Senior Secured Notes due 2020 (including the global note)January 27, 2005 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.48
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated July 21, 2005, establishing the 5.30% Senior Secured Notes due 2037 (including the global note)July 21, 2005 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.49
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated December 8, 2005, establishing the 5.40% Senior Secured Notes due 2016 (including the global note)December 9, 2005 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.50
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated June 15, 2007, establishing the 6.40% Senior Secured Notes due 2017 (including the global note)June 15, 2007 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.51
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated April 8, 2008, establishing the 6.00% Senior Secured Notes due 2018 (including the global note)April 8, 2008 Form 8-K, Exhibits 4.3 and 4.5, File No. 1-2967
4.52
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated June 19, 2008, establishing the 6.70% Senior Secured Notes due 2019 (including the global note)June 19, 2008 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.53
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated March 20, 2009, establishing 8.45% Senior Secured Notes due 2039 (including the global note)March 23, 2009 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-2967
4.54
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated September 11, 2012, establishing 3.90% Senior Secured Notes due 2042 (including the global note)September 11, 2012 Form 8-K, Exhibit 4.2, File No. 1-2967
4.55
Ameren
Ameren Missouri
Ameren Missouri Indenture Company Order, dated April 4, 2014, establishing 3.50% Senior Secured Notes due 2024 (including the global note)April 4, 2014 Form 8-K, Exhibit 4.2, File No. 1-2967
4.56
Ameren
Ameren Illinois
Indenture, dated as of December 1, 1998, from Central Illinois Public Service Company (now known as Ameren Illinois) to The Bank of New York Mellon Trust Company, N.A., as successor trustee (CIPS Indenture)Exhibit 4.4, File No. 333-59438
4.57
Ameren
Ameren Illinois
First Supplemental Indenture to the CIPS Indenture, dated as of June 14, 2006June 19, 2006 Form 8-K, Exhibit 4.2, File No. 1-3672
4.58
Ameren
Ameren Illinois
Second Supplemental Indenture to the CIPS Indenture, dated as of March 1, 2010Exhibit 4.17, File No. 333-166095
4.59
Ameren
Ameren Illinois
Third Supplemental Indenture to the CIPS Indenture, dated as of October 1, 20102010 Form 10-K, Exhibit 4.59, File No. 1-3672
4.60
Ameren
Ameren Illinois
Ameren Illinois Global Note, dated October 1, 2010, representing CIPS Indenture Senior Notes, 6.125% due 20282010 Form 10-K, Exhibit 4.60, File No. 1-3672

159


4.61
Ameren
Ameren Illinois
Ameren Illinois Global Note, dated October 1, 2010, representing CIPS Indenture Senior Notes, 6.70% Series Secured Notes due 20362010 Form 10-K, Exhibit 4.62, File No. 1-3672
4.62
Ameren
Ameren Illinois
Indenture of Mortgage and Deed of Trust between Illinois Power Company (predecessor in interest to CILCO and Ameren Illinois) and Bankers Trust Company (now known as Deutsche Bank Trust Company Americas), as trustee, dated as of April 1, 1933 (CILCO Mortgage), Supplemental Indenture between the same parties dated as of June 30, 1933, Supplemental Indenture between CILCO (predecessor in interest to Ameren Illinois) and the trustee, dated as of July 1, 1933, Supplemental Indenture between the same parties dated as of January 1, 1935, and Supplemental Indenture between the same parties dated as of April 1, 1940Exhibit B-1, Registration No. 2-1937; Exhibit B-1(a), Registration No. 2-2093; and Exhibit A, April 1940 Form 8-K, File No. 1-2732
4.63
Ameren
Ameren Illinois
Supplemental Indenture to the CILCO Mortgage, dated December 1, 1949December 1949 Form 8-K, Exhibit A, File No. 1-2732
4.64
Ameren
Ameren Illinois
Supplemental Indenture to the CILCO Mortgage, dated July 1, 1957July 1957 Form 8-K, Exhibit A, File No. 1-2732
4.65
Ameren
Ameren Illinois
Supplemental Indenture to the CILCO Mortgage, dated February 1, 1966February 1966 Form 8-K, Exhibit A, File No. 1-2732
4.66
Ameren
Ameren Illinois
Supplemental Indenture to the CILCO Mortgage, dated January 15, 1992January 30, 1992 Form 8-K, Exhibit 4(b), File No. 1-2732
4.67
Ameren
Ameren Illinois
Supplemental Indenture to the CILCO Mortgage, dated June 1, 2006 for the Series AA and BBJune 19, 2006 Form 8-K, Exhibit 4.11, File No. 1-2732
4.68
Ameren
Ameren Illinois
Supplemental Indenture to the CILCO Mortgage, dated December 1, 2008 for the Series CCDecember 9, 2008 Form 8-K, Exhibit 4.5, File No. 1-2732
4.69
Ameren
Ameren Illinois
Supplemental Indenture to the CILCO Mortgage, dated as of October 1, 2010October 7, 2010 Form 8 K, Exhibit 4.4, File No. 1-14756
4.70
Ameren
Ameren Illinois
Indenture, dated as of June 1, 2006, from CILCO (predecessor in interest to Ameren Illinois) to The Bank of New York Mellon Trust Company, N.A., as successor trustee (CILCO Indenture)June 19, 2006 Form 8-K, Exhibit 4.3, File No. 1-2732
4.71
Ameren
Ameren Illinois
First Supplemental Indenture to the CILCO Indenture, dated October 1, 2010October 7, 2010 Form 8 K, Exhibit 4.1, File No. 1-3672
4.72
Ameren
Ameren Illinois
Second Supplemental Indenture to the CILCO Indenture dated as of July 21, 2011
September 30, 2011 Form 10-Q, Exhibit 4.1,
File No. 1-3672
4.73
Ameren
Ameren Illinois
CILCO Indenture Company Order, dated June 14, 2006, establishing the 6.20% Senior Secured Notes due 2016 (including the global note) and the 6.70% Senior Secured Notes due 2036 (including the global note)June 19, 2006 Form 8-K, Exhibit 4.6, File No. 1-2732
4.74
Ameren
Ameren Illinois
CILCO Indenture Company Order, dated December 9, 2008, establishing the 8.875% Senior Secured Notes due 2013 (including the global note)
December 9, 2008 Form 8-K, Exhibits 4.2 and 4.3,
File No. 1-2732
4.75
Ameren
Ameren Illinois
General Mortgage Indenture and Deed of Trust, dated as of November 1, 1992 between Illinois Power Company (predecessor in interest to Ameren Illinois) and The Bank of New York Mellon Trust Company, N.A., as successor trustee (Ameren Illinois Mortgage)1992 Form 10-K, Exhibit 4(cc), File No. 1-3004
4.76
Ameren
Ameren Illinois
Supplemental Indenture, dated as of March 1, 1998, to Ameren Illinois Mortgage for Series SExhibit 4.41, File No. 333-71061
4.77
Ameren
Ameren Illinois
Supplemental Indenture, dated as of March 1, 1998, to Ameren Illinois Mortgage for Series TExhibit 4.42, File No. 333-71061
4.78
Ameren
Ameren Illinois
Supplemental Indenture amending the Ameren Illinois Mortgage dated as of June 15, 1999June 30, 1999 Form 10-Q, Exhibit 4.2, File No. 1-3004
4.79
Ameren
Ameren Illinois
Supplemental Indenture, dated as of July 15, 1999, to Ameren Illinois Mortgage for Series UJune 30, 1999 Form 10-Q, Exhibit 4.4, File No. 1-3004
4.80
Ameren
Ameren Illinois
Supplemental Indenture amending the Ameren Illinois Mortgage dated as of December 15, 2002December 23, 2002 Form 8-K, Exhibit 4.1, File No. 1-3004
4.81
Ameren
Ameren Illinois
Supplemental Indenture, dated as of June 1, 2006, to Ameren Illinois Mortgage for Series AAJune 19, 2006 Form 8-K, Exhibit 4.13, File No. 1-3004
4.82
Ameren
Ameren Illinois
Supplemental Indenture, dated as of November 15, 2007, to Ameren Illinois Mortgage for Series BBNovember 20, 2007 Form 8-K, Exhibit 4.4, File No. 1-3004
4.83
Ameren
Ameren Illinois
Supplemental Indenture, dated as of April 1, 2008, to Ameren Illinois Mortgage for Series CCApril 8, 2008 Form 8-K, Exhibit 4.9, File No. 1-3004
4.84
Ameren
Ameren Illinois
Supplemental Indenture, dated as of October 1, 2008, to Ameren Illinois Mortgage for Series DDOctober 23, 2008 Form 8-K, Exhibit 4.4, File No. 1-3004

160


4.85
Ameren
Ameren Illinois
Supplemental Indenture, dated as of October 1, 2010, to Ameren Illinois Mortgage for Series CIPS-AA, CIPS-BB and CIPS-CCOctober 7, 2010 Form 8 K, Exhibit 4.9, File No. 1-3672
4.86
Ameren
Ameren Illinois
Supplemental Indenture, dated as of January 15, 2011, to Ameren Illinois MortgageExhibit 4.78, File No. 333-182258
4.87
Ameren
 Ameren Illinois
Supplemental Indenture, dated as of August 1, 2012, to Ameren Illinois Mortgage for Series EEAugust 20, 2012 Form 8-K, Exhibit 4.4, File No. 1-3672
4.88
Ameren
Ameren Illinois
Supplemental Indenture, dated as of December 1, 2013, to Ameren Illinois Mortgage for Series FFDecember 10, 2013 Form 8-K, Exhibit 4.5, File No. 1-3672
4.89
Ameren
Ameren Illinois
Supplemental Indenture, dated as of June 1, 2014, to Ameren Illinois Mortgage for Series GGJune 30, 2014 Form 8-K, Exhibit 4.5, File No. 1-3672
4.90
Ameren
Ameren Illinois
Supplemental Indenture, dated as of December 1, 2014, to Ameren Illinois Mortgage for Series HHDecember 10, 2014 Form 8-K, Exhibit 4.5, File No. 1-3672
4.91
Ameren
Ameren Illinois
Indenture, dated as of June 1, 2006, from IP (predecessor in interest to Ameren Illinois) to The Bank of New York Mellon Trust Company, N.A., as successor trustee (Ameren Illinois Indenture)June 19, 2006 Form 8-K, Exhibit 4.4, File No. 1-3004
4.92
Ameren
Ameren Illinois
First Supplemental Indenture, dated as of October 1, 2010, to the Ameren Illinois Indenture for Series CIPS-AA, CIPS-BB and CIPS-CCOctober 7, 2010 Form 8 K, Exhibit 4.5, File No. 1-14756
4.93
Ameren
Ameren Illinois
Second Supplemental Indenture to the Ameren Illinois Indenture dated as of July 21, 2011September 30, 2011 Form 10-Q, Exhibit 4.2, File No. 1-3672
4.94
Ameren
Ameren Illinois
Third Supplemental Indenture to the Ameren Illinois Indenture dated as of May 15, 2012Exhibit 4.83, File No. 333-182258
4.95
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order, dated June 14, 2006, establishing the 6.25% Senior Secured Notes due 2016 (including the global note)June 19, 2006 Form 8-K, Exhibit 4.7, File No. 1-3004
4.96
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order, dated November 15, 2007, establishing 6.125% Senior Secured Notes due 2017 (including the global note)November 20, 2007 Form 8-K, Exhibit 4.2, File No. 1-3004
4.97
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order, dated April 8, 2008, establishing 6.25% Senior Secured Notes due 2018 (including the global note)April 8, 2008 Form 8-K, Exhibit 4.4, File No. 1-3004
4.98
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order dated October 23, 2008, establishing 9.75% Senior Secured Notes due 2018 (including the global note)October 23, 2008 Form 8-K, Exhibit 4.2, File No. 1-3004
4.99
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order dated August 20, 2012, establishing 2.70% Senior Secured Notes due 2022 (including the global note)August 20, 2012 Form 8-K, Exhibits 4.2 and 4.3, File No. 1-3004
4.100
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order dated December 10, 2013, establishing 4.80% Senior Secured Notes due 2043 (including the global note)December 10, 2013 Form 8-K, Exhibit 4.2, File No. 1-3672
4.101
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order dated June 30, 2014, establishing 4.30% Senior Secured Notes due 2044 (including the global note)June 30, 2014 Form 8-K, Exhibit 4.2, File No. 1-3672
4.102
Ameren
Ameren Illinois
Ameren Illinois Indenture Company Order dated December 10, 2014, establishing 3.25% Senior Secured Notes due 2025 (including the global note)December 10, 2014 Form 8-K, Exhibit 4.2, File No. 1-3672
Material Contracts
10.1Ameren CompaniesThird Amended Ameren Corporation System Utility Money Pool Agreement, as amended September 30, 2004October 1, 2004 Form 8-K, Exhibit 10.2, File No. 1-14756
10.2
Ameren
Ameren Missouri
Amended and Restated Credit Agreement, dated as of December 11, 2014, by and among Ameren, Ameren Missouri and JPMorgan Chase Bank, N.A., as agent, and the lenders party thereto.December 11, 2014 Form 8-K, Exhibit 10.1, File No. 1-14756
10.3
Ameren
Ameren Illinois
Amended and Restated Credit Agreement, dated as of December 11, 2014, by and among Ameren, Ameren Illinois and JPMorgan Chase Bank, N.A., as agent, and the lenders party thereto.December 11, 2014 Form 8-K, Exhibit 10.2, File No. 1-14756
10.4Ameren*Summary Sheet of Ameren Corporation Non-Management Director Compensation revised on August 9, 2013 and effective as of August 12, 2013September 30, 2013 Form 10-Q, Exhibit 10.1, File No. 1-14756
10.5Ameren*Ameren's Deferred Compensation Plan for Members of the Board of Directors amended and restated effective January 1, 2009, dated June 13, 2008June 30, 2008 Form 10-Q, Exhibit 10.3, File No. 1-14756
10.6Ameren Companies*Amendment dated October 12, 2009, to Ameren's Deferred Compensation Plan for Members of the Board of Directors, effective January 1, 20102009 Form 10-K, Exhibit 10.15, File No. 1-14756

161


10.7Ameren Companies*Amendment dated October 14, 2010, to Ameren's Deferred Compensation Plan for Members of the Board of Directors2010 Form 10-K, Exhibit 10.15, File No. 1-14756
10.8Ameren Companies*Ameren's Deferred Compensation Plan as amended and restated effective January 1, 2010October 14, 2009 Form 8-K, Exhibit 10.1, File No. 1-14756
10.9Ameren Companies*Amendment dated October 14, 2010 to Ameren's Deferred Compensation Plan2010 Form 10-K, Exhibit 10.17, File No. 1-14756
10.10Ameren Companies*2012 Ameren Executive Incentive PlanDecember 14, 2011 Form 8-K, Exhibit 10.1, File No. 1-14756
10.11Ameren Companies*2013 Ameren Executive Incentive PlanDecember 18, 2012 Form 8-K, Exhibit 10.1, File No. 1-14756
10.12Ameren Companies*2014 Ameren Executive Incentive PlanMarch 31, 2014 Form 10-Q, Exhibit 10.1, File No. 1-14756
10.13Ameren Companies*2015 Ameren Executive Incentive Plan
10.14Ameren Companies*2012 Base Salary Table for Named Executive Officers2011 Form 10-K, Exhibit 10.23, File No. 1-14756
10.15Ameren Companies*2013 Base Salary Table for Named Executive Officers2012 Form 10-K, Exhibit 10.17, File No. 1-14756
10.16Ameren Companies*2014 Base Salary Table for Named Executive Officers2013 Form 10-K, Exhibit 10.15, File No. 1-14756
10.17Ameren Companies*2015 Base Salary Table for Named Executive Officers
10.18Ameren Companies*Second Amended and Restated Ameren Corporation Change of Control Severance Plan2008 Form 10-K, Exhibit 10.37, File No. 1-14756
10.19Ameren Companies*First Amendment dated October 12, 2009, to the Second Amended and Restated Ameren Change of Control Severance PlanOctober 14, 2009 Form 8-K, Exhibit 10.2, File No. 1-14756
10.20Ameren Companies*Revised Schedule I to Second Amended and Restated Ameren Change of Control Severance Plan, as amendedSeptember 30, 2014 Form 10-Q, Exhibit 10.1, File No. 1-14756
10.21Ameren Companies*Formula for Determining 2012 Target Performance Share Unit Awards to be Issued to Named Executive OfficersDecember 14, 2011 Form 8-K, Exhibit 99.1, File No. 1-14756
10.22Ameren Companies*Formula for Determining 2013 Target Performance Share Unit Awards to be Issued to Named Executive OfficersDecember 18, 2012 Form 8-K, Exhibit 99.1, File No. 1-14756
10.23Ameren Companies*Formula for Determining 2014 Target Performance Share Unit Awards to be Issued to Named Executive OfficersMarch 31, 2014 Form 10-Q, Exhibit 10.2, File No. 1-14756
10.24Ameren Companies*Formula for Determining 2015 Target Performance Share Unit Awards to be Issued to Named Executive Officers
10.25Ameren Companies*Ameren Corporation 2006 Omnibus Incentive Compensation PlanFebruary 16, 2006 Form 8-K, Exhibit 10.3, File No. 1-14756
10.26Ameren Companies*Form of Performance Share Unit Award Agreement for Awards Issued in 2012 pursuant to 2006 Omnibus Incentive Compensation PlanDecember 14, 2011 Form 8-K, Exhibit 10.2, File No. 1-14756
10.27Ameren Companies*Form of Performance Share Unit Award Agreement for Awards Issued in 2013 pursuant to 2006 Omnibus Incentive Compensation PlanDecember 18, 2012 Form 8-K, Exhibit 10.2, File No. 1-14756
10.28Ameren Companies*Form of Performance Share Unit Award Agreement for Awards Issued in 2014 pursuant to 2006 Omnibus Incentive Compensation PlanMarch 31, 2014 Form 10-Q, Exhibit 10.3, File No. 1-14756
10.29Ameren Companies*Ameren Corporation 2014 Omnibus Incentive Compensation PlanExhibit 99, File No. 333-196515
10.30Ameren Companies*Form of Performance Share Unit Award Agreement for Awards Issued in 2014 pursuant to 2014 Omnibus Incentive Compensation Plan
10.31Ameren Companies*Form of Performance Share Unit Award Agreement for Awards Issued in 2015 pursuant to 2014 Omnibus Incentive Compensation Plan
10.32Ameren Companies*Ameren Supplemental Retirement Plan amended and restated effective January 1, 2008, dated June 13, 2008June 30, 2008 Form 10-Q, Exhibit 10.1, File No. 1-14756
10.33Ameren Companies*First Amendment to amended and restated Ameren Supplemental Retirement Plan, dated October 24, 20082008 Form 10-K, Exhibit 10.44, File No. 1-14756
10.34
Ameren
Ameren Illinois
*CILCO Executive Deferral Plan as amended effective August 15, 19991999 Form 10-K, Exhibit 10, File No. 1-2732
10.35
Ameren
Ameren Illinois
*CILCO Executive Deferral Plan II as amended effective April 1, 19991999 Form 10-K, Exhibit 10(a), File No. 1-2732
10.36
Ameren
Ameren Illinois
*CILCO Restructured Executive Deferral Plan (approved August 15, 1999)1999 Form 10-K, Exhibit 10(e), File No. 1-2732
10.37AmerenNovation and Amendment of Put Option Agreement, dated March 14, 2013, by and among Medina Valley, AERG, Genco and AmerenMarch 19, 2013 Form 8-K, Exhibit 10.3, File No. 1-14756

162


10.38Ameren*Employment and Change of Control Agreement, dated March 13, 2013, between Steven R. Sullivan, AER and AmerenMarch 19, 2013 Form 8-K, Exhibit 10.4, File No. 1-14756
Statement re: Computation of Ratios
12.1AmerenAmeren's Statement of Computation of Ratio of Earnings to Fixed Charges
12.2Ameren MissouriAmeren Missouri's Statement of Computation of Ratio of Earnings to Fixed Charges and Combined Fixed Charges and Preferred Stock Dividend Requirements
12.3Ameren IllinoisAmeren Illinois' Statement of Computation of Ratio of Earnings to Fixed Charges and Combined Fixed Charges and Preferred Stock Dividend Requirements
Subsidiaries of the Registrant
21.1Ameren CompaniesSubsidiaries of Ameren
Consent of Experts and Counsel
23.1AmerenConsent of Independent Registered Public Accounting Firm with respect to Ameren
23.2Ameren MissouriConsent of Independent Registered Public Accounting Firm with respect to Ameren Missouri
23.3Ameren IllinoisConsent of Independent Registered Public Accounting Firm with respect to Ameren Illinois
Power of Attorney
24.1AmerenPowers of Attorney with respect to Ameren
24.2Ameren MissouriPowers of Attorney with respect to Ameren Missouri
24.3Ameren IllinoisPowers of Attorney with respect to Ameren Illinois
Rule 13a-14(a)/15d-14(a) Certifications
31.1AmerenRule 13a-14(a)/15d-14(a) Certification of Principal Executive Officer of Ameren
31.2AmerenRule 13a-14(a)/15d-14(a) Certification of Principal Financial Officer of Ameren
31.3Ameren MissouriRule 13a-14(a)/15d-14(a) Certification of Principal Executive Officer of Ameren Missouri
31.4Ameren MissouriRule 13a-14(a)/15d-14(a) Certification of Principal Financial Officer of Ameren Missouri
31.5Ameren IllinoisRule 13a-14(a)/15d-14(a) Certification of Principal Executive Officer of Ameren Illinois
31.6Ameren IllinoisRule 13a-14(a)/15d-14(a) Certification of Principal Financial Officer of Ameren Illinois
Section 1350 Certifications
32.1AmerenSection 1350 Certification of Principal Executive Officer and Principal Financial Officer of Ameren
32.2Ameren MissouriSection 1350 Certification of Principal Executive Officer and Principal Financial Officer of Ameren Missouri
32.3Ameren IllinoisSection 1350 Certification of Principal Executive Officer and Principal Financial Officer of Ameren Illinois
Additional Exhibits
99.1Ameren CompaniesAmended and Restated Tax Allocation Agreement, dated as of November 21, 20132013 Form 10-K, Exhibit 99.1, File No. 1-14756
Interactive Data File
101.INS**Ameren CompaniesXBRL Instance Document
101.SCH**Ameren CompaniesXBRL Taxonomy Extension Schema Document
101.CAL**Ameren CompaniesXBRL Taxonomy Extension Calculation Linkbase Document
101.LAB**Ameren CompaniesXBRL Taxonomy Extension Label Linkbase Document
101.PRE**Ameren CompaniesXBRL Taxonomy Extension Presentation Linkbase Document
101.DEF**Ameren CompaniesXBRL Taxonomy Extension Definition Document

The file number references for the Ameren Companies' filings with the SEC are: Ameren, 1-14756; Ameren Missouri, 1-2967; and Ameren Illinois, 1-3672.
*Compensatory plan or arrangement.

163165


Each registrant hereby undertakes to furnish to the SEC upon request a copy of any long-term debt instrument not listed above that such registrant has not filed as an exhibit pursuant to the exemption provided by Item 601(b)(4)(iii)(A) of Regulation S-K.



164