SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

General

Ameren, headquartered in St. Louis, Missouri, is a public utility holding company under PUHCA 2005. Ameren’s primary assets are its equity interests in its subsidiaries, including Ameren Missouri and Ameren Illinois. Ameren’s subsidiaries are separate, independent legal entities with separate businesses, assets, and liabilities. Dividends on Ameren’s common stock and the payment of expenses by Ameren depend on distributions made to it by its subsidiaries. Ameren’s principal subsidiaries are listed below.

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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-mile area in central and eastern Missouri. This area has an estimated population of 2.8 million and includes the Greater St. Louis area. Ameren Missouri supplies electric service to 1.2 million customers and natural gas service to 0.1 million customers.

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Ameren Illinois Company, doing business as Ameren Illinois, operates rate-regulated electric 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 was 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 of central and southern Illinois having an estimated population of 3.1 million in an area of 40,000 square miles. Ameren Illinois supplies electric service to 1.2 million customers and natural gas service to 0.8 million customers.

Ameren has various other subsidiaries that conduct 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 projects to improve electric transmission system reliability within Ameren Missouri's 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, in 2013, Ameren abandoned the Meredosia and Hutsonville energy centers upon the completion of the divestiture of New AER to IPH. Ameren is demolishing the Hutsonville energy center and expects to demolish the Meredosia energy center beginning in 2016. As a result of these events, Ameren has 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. Unless otherwise stated, these notes to the financial statements exclude discontinued operations for all periods presented. See Note 16 – Divestiture Transactions and Discontinued Operations for additional information regarding these transactions.

Ameren's financial statements are prepared on a consolidated basis, and therefore include the accounts 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.

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. In addition to the cost recovery mechanisms discussed in the Purchased Gas, Power, and Fuel Rate-adjustment Mechanisms section below, Ameren Missouri and Ameren Illinois have approvals from rate regulators to use other cost recovery mechanisms. Ameren Missouri has a pension and postretirement benefit cost tracker, an uncertain tax positions tracker, a renewable energy standards cost tracker, a solar rebate program tracker, and the MEEIA energy efficiency rider. Ameren Illinois' and ATXI's electric transmission rates are determined pursuant to formula ratemaking. Additionally, Ameren Illinois' electric distribution business participates in the performance-based formula ratemaking process established pursuant to the IEIMA. Ameren Illinois also has an environmental cost rider, an asbestos-related litigation rider, an 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 regulatory assets and liabilities.

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 bad debt rider that adjusts rates for net write-offs of customer accounts receivable above or below those being collected in rates.

Materials and Supplies

Materials and supplies are recorded at the lower of cost or market. Cost is determined by the average-cost method. Materials and supplies are capitalized as inventory when purchased and then expensed or capitalized as plant assets when installed, as appropriate. The following table presents a breakdown of materials and supplies for each of the Ameren Companies at December 31, 2015 and 2014:



	Ameren Missouri		Ameren Illinois		Ameren
2015
Fuel^(a)	$	173	$	—	$	173
Gas stored underground	10		87		97
Other materials and supplies	204		64		268
Total materials and supplies	$	387	$	151	$	538
2014
Fuel^(a)	$	134	$	—	$	134
Gas stored underground	16		111		127
Other materials and supplies	197		66		263
Total materials and supplies	$	347	$	177	$	524


(a)	Consists of coal, oil, and propane.

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, 2015 and 2014, 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. As of May 30, 2015, transmission revenues and substantially all transmission charges are excluded from net energy costs as a result of the April 2015 MoPSC electric rate order.

Property and Plant, Net

We capitalize the cost of additions to and betterments of units of property and plant. 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 below and Note 3 – Property and Plant, 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 2015, 2014, and 2013 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 shareholders’ equity) applicable to rate-regulated construction expenditures, in accordance with the utility industry'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 rates that were applied to construction projects in 2015, 2014, and 2013:



	2015		2014		2013
Ameren Missouri	7	%	7	%	8	%
Ameren Illinois	6	%	2	%	8	%

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' carrying amount of goodwill was $411 million at December 31, 2015, and 2014. All of Ameren's and Ameren Illinois' goodwill at December 31, 2015 and 2014, was assigned to the Ameren Illinois reporting unit.

We evaluate goodwill for impairment as of October 31 each year, or more frequently if events and circumstances change that would more likely than not reduce the fair value of the Ameren Illinois reporting unit below its carrying amount. Entities assessing goodwill for impairment have the option of first performing a qualitative assessment before calculating the fair value of the reporting unit. If an entity determines, on the basis of qualitative factors, that the fair value of the reporting unit is more likely than not less than the carrying amount, a two-step quantitative test is required. An entity has the option to bypass the qualitative assessment in any period and proceed directly to the first step of the quantitative test, which compares the fair value of the reporting unit to its carrying amount. If the carrying amount of the reporting unit exceeds its estimated fair value, the entity performs the second step, which requires an assignment of the reporting unit's fair value to the individual assets and liabilities in order to determine the implied fair value of the reporting unit's goodwill. If the implied fair value of goodwill is less than its carrying amount, an impairment loss is recorded.

Ameren and Ameren Illinois elected to bypass the qualitative assessment and completed the first step of the quantitative test as of October 31, 2015. Based on the results, Ameren and Ameren Illinois determined that the estimated fair value of the Ameren Illinois reporting unit significantly exceeded its carrying value as of October 31, 2015, indicating no impairment of Ameren’s or Ameren Illinois’ goodwill. Ameren's and Ameren Illinois' valuation approach is based on a market participant view. It uses a weighted combination of a discounted cash flow analysis and a market multiples analysis. Significant assumptions used in estimating the fair value of the Ameren Illinois reporting unit include discount and growth rates, utility sector market performance and transactions, and projected operating results and cash flows.

The goodwill assigned to the Ameren Illinois reporting unit on the December 31, 2015 balance sheets of Ameren and Ameren Illinois had no accumulated goodwill impairment losses. Ameren and Ameren Illinois will continue to monitor internal and external factors for signs of possible declines in estimated fair value and potential goodwill impairment.

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. 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 2015 and 2014.

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 to AROs based on changes in the estimated fair values of the obligations. Corresponding increases in asset book values are depreciated over the remaining useful life of the related asset. 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, CCR facilities, and river structures. Also, Ameren, Ameren Missouri, and Ameren Illinois have recorded AROs for retirement costs associated with asbestos removal and the disposal of certain transformers. Ameren and Ameren Missouri have a nuclear decommissioning trust fund for the decommissioning of the Callaway energy center. 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.

The following table provides a reconciliation of the beginning and ending carrying amount of AROs for the years ended December 31, 2015 and 2014:



	Ameren Missouri				Ameren Illinois				Ameren
Balance at December 31, 2013	$	366			$	3			$	369
Liabilities incurred	2				—				2
Liabilities settled	(2		)		(a)				(2		)
Accretion in 2014^(b)	21				(a)				21
Change in estimates^(c)	2				4				6
Balance at December 31, 2014	$	389			$	7		^(d)	$	396
Liabilities incurred	3				—				3
Liabilities settled	(1		)		(1		)		(2		)
Accretion in 2015^(b)	23				(a)				23
Change in estimates^(e)	203				(a)				203
Balance at December 31, 2015	$	617		^(f)	$	6		^(d)	$	623		^(f)


(a)	Less than $1 million.


(b)	Accretion expense was recorded as an increase to regulatory assets at Ameren Missouri and Ameren Illinois.


(c)	The ARO increase resulted in a corresponding increase recorded to "Property and Plant, Net." Ameren Illinois changed its fair value estimate for asbestos removal.


(d)	Included in “Other deferred credits and liabilities” on the balance sheet.

(e)

The ARO increase resulted in a corresponding increase recorded to "Property and Plant, Net." Ameren and Ameren Missouri increased their AROs related to the decommissioning of the Callaway energy center by $99 million to reflect the 2015 cost study and funding analysis filed with the MoPSC, the extension of the estimated operating life until 2044, and a reduction in the discount rate assumption. See Note 10 – Callaway Energy Center for additional information. In addition, as a result of new federal regulations, Ameren and Ameren Missouri recorded an increase of $100 million to their AROs associated with CCR storage facilities. See Note 15 – Commitments and Contingencies for additional information. Ameren and Ameren Missouri also increased their AROs by $4 million due to a change in the estimated retirement dates of the Meramec and Rush Island energy centers as a result of the MoPSC's April 2015 electric rate order.


(f)	Balance included $5 million in "Other current liabilities" on the balance sheet as of December 31, 2015.

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, 2015 and 2014, 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. In addition, Ameren Illinois' and ATXI's electric transmission delivery service operating revenues are regulated by the FERC. The provisions of the IEIMA and the FERC's electric transmission formula rate framework provide for annual reconciliations of the electric delivery and electric transmission service revenue requirements necessary to reflect the actual recoverable costs incurred in a given year with the revenue requirements in customer rates for that year, including an allowed return on equity. In each of those electric jurisdictions, 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 amounts from customers within the next two years. In each jurisdiction, 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 for information regarding Ameren Illinois' revenue requirement reconciliation pursuant to the IEIMA.

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's and Ameren 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 revenues once the resettlement amount is received.

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 Expenses – Fuel" in the statement of income.

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 service period. See Note 12 – Stock-based Compensation for additional information.

Excise Taxes

Ameren Missouri and Ameren Illinois collect from their customers certain excise taxes that are levied on the sale or distribution of natural gas and electricity. Excise taxes are levied on Ameren Missouri's electric and natural gas businesses and on Ameren Illinois' natural gas business. They are recorded gross in “Operating Revenues – Electric,” “Operating Revenues – 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 customers and are therefore not included in Ameren Illinois' revenues and expenses. The following table presents the excise taxes recorded in “Operating Revenues – Electric,” “Operating Revenues – Gas,” and “Operating Expenses – Taxes other than income taxes” for the years ended December 31, 2015, 2014, and 2013:



	2015		2014		2013
Ameren Missouri	$	156	$	151	$	152
Ameren Illinois	57		64		61
Ameren	$	213	$	215	$	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 facility fees are amortized over the credit facility term.

Income Taxes

Ameren uses an asset and liability approach for its financial accounting and reporting of income taxes, in accordance with authoritative accounting guidance. 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 recognize 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 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.

Investment tax credits used on tax returns for prior years have been deferred as a noncurrent liability. The credits are being amortized over the useful lives of the related investment. Deferred income taxes were recorded on the temporary difference represented by the deferred investment tax credits and a corresponding regulatory liability. This recognizes the expected reduction in rates for future lower income taxes associated with the amortization of the investment tax credits. See Note 13 – Income Taxes.

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 similar to that which would be owed or refunded had the party been separately subject to tax. Any net benefit attributable to the parent is reallocated to the other parties. This reallocation is treated as a capital contribution to the party receiving the benefit.

Earnings per Share

Basic earnings per share is computed by dividing net income attributable to Ameren common shareholders by the weighted-average number of common shares outstanding during the period. Earnings per diluted share is computed by dividing net income attributable to Ameren common shareholders by the weighted-average number of diluted common shares outstanding during the period. Earnings per diluted share reflects the potential dilution that would occur if certain stock-based performance share units were settled. The number of performance share units assumed to be settled was 1.0 million, 1.8 million, and 1.9 million for the years ended December 31, 2015, 2014, and 2013, respectively. There were no potentially dilutive securities excluded from the diluted earnings per share calculations for the years ended December 31, 2015, 2014, and 2013.

Capital Contributions and Return of Capital

In 2015, Ameren Missouri and Ameren Illinois received cash capital contributions of $224 million and $25 million, respectively, from Ameren (parent) as a result of the tax allocation agreement. Additionally, as of December 31, 2015, Ameren Missouri accrued a $38 million capital contribution related to the same agreement.

In 2014, Ameren Missouri 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 contribution related to the same agreement. Also in 2014, Ameren Missouri returned capital of $215 million to 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, 2015, 2014, and 2013:



	2015			2014			2013
Cash paid (refunded) during the year:
Interest
Continuing operations^(a)	$	335		$	333		$	362
Discontinued operations^(b)	—			—			31
	$	335		$	333		$	393

Income taxes, net
Continuing Operations	$	(17	)	$	(41	)	$	116
Discontinued Operations	2			14			(108		)
	$	(15	)	$	(27	)	$	8


(a)	Net of $17 million, $18 million, and $20 million capitalized, respectively.


(b)	Net of $- million, $- million, and $17 million capitalized, respectively.

See Note 3 – Property and Plant, Net, for information on accrued capital expenditures.

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.

Revenue from Contracts with Customers

In May 2014, the FASB issued authoritative accounting guidance that changes the criteria for recognizing revenue from a contract with a customer. The underlying principle of the guidance is that an entity will recognize revenue for the transfer of promised goods or services to customers at an amount that the entity expects to be entitled to 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. Entities can apply the guidance retrospectively to each reporting period presented or retrospectively by recording a cumulative effect adjustment to retained earnings in the period of initial adoption. The Ameren Companies are currently assessing the impacts of this guidance on their results of operations, financial position, and disclosures, including their accounting for contributions in aid of construction and similar arrangements, as well as the transition method that they will use to adopt the guidance. In August 2015, the FASB deferred the effective date of this revenue guidance to the first quarter of 2018, with an option for entities to early adopt in the first quarter of 2017. The Ameren Companies do not expect to early adopt this guidance.

Amendments to the Consolidation Analysis

In February 2015, the FASB issued authoritative accounting guidance that amends the consolidation analysis for variable interest entities and voting interest entities. The new guidance affects (1) limited partnerships and similar legal entities, (2) evaluating fees paid to a decision maker or service provider as a variable interest, (3) the effect of fee arrangements on the primary beneficiary determination, (4) the effect of related parties on the primary beneficiary determination, and (5) certain investment funds. The guidance is effective for the Ameren Companies in the first quarter of 2016, and can be applied retrospectively to each reporting period presented or retrospectively by recording a cumulative effect adjustment to retained earnings in the period of initial adoption. The Ameren Companies are currently assessing this guidance and do not expect any material impacts to their results of operations, financial position or cash flows.

Presentation of Debt Issuance Costs

In April 2015, the FASB issued authoritative accounting guidance to simplify the presentation of debt issuance costs in the balance sheet. The guidance requires debt issuance costs to be presented as a reduction to the associated debt liability. Previously, debt issuance costs were presented in "Other assets" on the Ameren Companies' balance sheets. The Ameren Companies early adopted this standard in 2015 and applied the guidance retrospectively. At December 31, 2015, debt issuance costs of $43 million, $19 million, and $18 million were presented in "Long-term debt, net" on Ameren's, Ameren Missouri's, and Ameren Illinois' balance sheets, respectively. At December 31, 2014, debt issuance costs of $35 million, $18 million, and $17 million previously presented in "Other assets" on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets were reclassified to Long-term debt, net" for comparative purposes. See Note 5 – Long-Term Debt and Equity Financings for additional information. The implementation of this authoritative accounting guidance did not affect the Ameren Companies' results of operations or cash flows.

Balance Sheet Classification of Deferred Income Taxes

In November 2015, the FASB issued authoritative accounting guidance to simplify the presentation of deferred income taxes in the balance sheet. The guidance requires all deferred tax assets and liabilities, along with any related valuation allowances, to be classified as noncurrent on the balance sheet. Previously, the current portion of deferred taxes was presented as "Current accumulated deferred income taxes, net" and the noncurrent portion of deferred taxes was presented as "Accumulated deferred income taxes, net" on the Ameren Companies' balance sheets. The Ameren Companies early adopted this standard in 2015 and applied the guidance retrospectively. At December 31, 2014, the current deferred income taxes of $352 million, $49 million, and $160 million, which were previously presented as "Current accumulated deferred income taxes, net" on Ameren's, Ameren Missouri's, and Ameren Illinois' respective balance sheets, were reclassified and presented in "Accumulated deferred income taxes, net" for comparative purposes. The implementation of this authoritative accounting guidance did not affect the Ameren Companies' results of operations or cash flows.

Leases

In February 2016, the FASB issued authoritative accounting guidance that will require an entity to recognize assets and liabilities arising from a lease. Consistent with current GAAP, the recognition, measurement, and presentation of expenses and cash flows arising from a lease will depend primarily on its classification as a finance or operating lease. The guidance also requires additional disclosures to enable users of financial statements to understand the amount, timing, and uncertainty of cash flows arising from leases. The guidance will be effective for the Ameren Companies in the first quarter of 2019, and includes an option for entities to early adopt. The guidance requires a retrospective cumulative adjustment to retained earnings in the period of initial adoption. The Ameren Companies are currently assessing the impacts of this guidance on their results of operations, financial position, cash flows and disclosures.