Basis of Presentation and Accounting Policies	12 Months Ended
Dec. 31, 2013
Accounting Policies [Abstract]
Basis of Presentation and Accounting Policies	BASIS OF PRESENTATION AND ACCOUNTING POLICIES Organization Comerica Incorporated (the Corporation) is a registered financial holding company headquartered in Dallas, Texas. The Corporation’s major business segments are the Business Bank, the Retail Bank and Wealth Management. The Corporation operates in three primary geographic markets: Michigan, California and Texas. For further discussion of each business segment and primary geographic market, refer to Note 22. The Corporation and its banking subsidiaries are regulated at both the state and federal levels. The accounting and reporting policies of the Corporation conform to United States (U.S.) generally accepted accounting principles (GAAP). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect reported amounts and disclosures. Actual results could differ from these estimates. The following summarizes the significant accounting policies of the Corporation applied in the preparation of the accompanying consolidated financial statements. Principles of Consolidation The consolidated financial statements include the accounts of the Corporation and the accounts of those subsidiaries that are majority owned and in which the Corporation has a controlling financial interest. The Corporation consolidates entities not determined to be variable interest entities (VIEs) when it holds a controlling interest in the entity's outstanding voting stock and uses the cost or equity method when it holds less than a controlling interest. In consolidation, all significant intercompany accounts and transactions are eliminated. The results of operations of companies acquired are included from the date of acquisition. Certain amounts in the financial statements for prior years have been reclassified to conform to current financial statement presentation. The Corporation holds investments in certain legal entities that are considered VIEs. In general, a VIE is an entity that either (1) has an insufficient amount of equity to carry out its principal activities without additional subordinated financial support, (2) has a group of equity owners that are unable to make significant decisions about its activities, or (3) has a group of equity owners that do not have the obligation to absorb losses or the right to receive returns generated by its operations. If any of these characteristics are present, the entity is subject to a variable interests consolidation model, and consolidation is based on variable interests, not on ownership of the entity’s outstanding voting stock. Variable interests are defined as contractual ownership or other money interests in an entity that change with fluctuations in the entity’s net asset value. The primary beneficiary is required to consolidate the VIE. The primary beneficiary is defined as the party that has both the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and the obligation to absorb losses or the right to receive benefits that could be significant to the VIE. The maximum potential exposure to losses relative to investments in VIEs is generally limited to the sum of the outstanding book basis and unfunded commitments for future investments. The Corporation evaluates its investments in VIEs, both at inception and when there is a change in circumstances that requires reconsideration, to determine if the Corporation is the primary beneficiary and consolidation is required. The Corporation accounts for unconsolidated VIEs using either the cost or equity method. The equity method is used for investments where the Corporation has the ability to exercise significant influence over the entity’s operation and financial policies, which is generally presumed to exist if the Corporation owns more than a 20 percent voting interest in the entity. Equity method investments are included in “accrued income and other assets” on the consolidated balance sheets, with income and losses recorded in “other noninterest income” on the consolidated statements of income. Unconsolidated equity investments that do not meet the criteria to be accounted for under the equity method are accounted for under the cost method. Cost method investments are included in “accrued income and other assets” on the consolidated balance sheets, with income (net of write-downs) recorded in “other noninterest income” on the consolidated statements of income. Assets held in an agency or fiduciary capacity are not assets of the Corporation and are not included in the consolidated financial statements. See Note 9 for additional information about the Corporation’s involvement with VIEs. Fair Value Measurements Fair value measurement applies whenever accounting guidance requires or permits assets or liabilities to be measured at fair value. Fair value is defined as the exchange price that would be received to sell an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction (i.e., not a forced transaction, such as a liquidation or distressed sale) between market participants at the measurement date. Fair value is based on the assumptions market participants would use when pricing an asset or liability. Fair value measurements and disclosures guidance establishes a three-level fair value hierarchy based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The fair value hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. Fair value measurements are separately disclosed by level within the fair value hierarchy. For assets and liabilities recorded at fair value, it is the Corporation’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements. Fair value measurements for assets and liabilities where limited or no observable market data exists are based primarily upon estimates, often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, the results cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values. For further information about fair value measurements refer to Note 2. Other Short-Term Investments Other short-term investments include trading securities and loans held-for-sale. Trading securities are carried at fair value. Realized and unrealized gains or losses on trading securities are included in “other noninterest income” on the consolidated statements of income. Loans held-for-sale, typically residential mortgages originated with the intent to sell, are carried at the lower of cost or fair value. Fair value is determined in the aggregate for each portfolio. Changes in fair value are included in “other noninterest income” on the consolidated statements of income. Investment Securities Securities that are not held for trading purposes are accounted for as securities available-for-sale and recorded at fair value, with unrealized gains and losses, net of income taxes, reported as a separate component of other comprehensive income (loss) (OCI). Investment securities are reviewed quarterly for possible other-than-temporary impairment (OTTI). In determining whether OTTI exists for debt securities in an unrealized loss position, the Corporation assesses the likelihood of selling the security prior to the recovery of its amortized cost basis. If the Corporation intends to sell the debt security or it is more likely than not that the Corporation will be required to sell the debt security prior to the recovery of its amortized cost basis, the debt security is written down to fair value, and the full amount of any impairment charge is recorded as a loss in “net securities gains” in the consolidated statements of income. If the Corporation does not intend to sell the debt security and it is more likely than not that the Corporation will not be required to sell the debt security prior to recovery of its amortized cost basis, only the credit component of any impairment of a debt security is recognized as a loss in “net securities gains” on the consolidated statements of income, with the remaining impairment recorded in OCI. The OTTI review for equity securities includes an analysis of the facts and circumstances of each individual investment and focuses on the severity of loss, the length of time the fair value has been below cost, the expectation for that security’s performance, the financial condition and near-term prospects of the issuer, and management’s intent and ability to hold the security to recovery. A decline in value of an equity security that is considered to be other-than-temporary is recorded as a loss in “net securities (losses) gains” on the consolidated statements of income. Gains or losses on the sale of securities are computed based on the adjusted cost of the specific security sold. For further information on investment securities, refer to Note 3. Loans Loans and leases originated and held for investment are recorded at the principal balance outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Interest income is recognized on loans and leases using the interest method. Loans and leases acquired in business combinations are initially recorded at fair value with no carryover of any existing allowance for loan losses. Acquired loans with evidence of credit quality deterioration at acquisition are reviewed to determine if it is probable that the Corporation will not be able to collect all contractual amounts due, including both principal and interest. When both conditions exist, such loans are accounted for as purchased credit-impaired (PCI) loans. The Corporation generally aggregates PCI loans into pools of loans based on common risk characteristics. The Corporation estimates the total cash flows expected to be collected from the pools of acquired PCI loans, which include undiscounted expected principal and interest, using credit risk, interest rate and prepayment risk models that incorporate management's best estimate of current key assumptions such as default rates, loss severity and payment speeds. The excess of the undiscounted total cash flows expected to be collected over the fair value of the related PCI loans represents the accretable yield, which is recognized as interest income on a level-yield basis over the life of the related loan pools. The difference between the undiscounted contractual principal and interest and the undiscounted total cash flows expected to be collected is the nonaccretable difference, which reflects the impact of estimated credit losses and other factors. Subsequent increases in expected cash flows will result in a recovery of any previously recorded allowance for loan losses, to the extent applicable, and a reclassification from nonaccretable difference to accretable yield, which is recognized prospectively over the then remaining lives of the loan pools. Subsequent decreases in expected cash flows will result in an impairment charge to the provision for loan losses, resulting in an addition to the allowance for loan losses, and a reclassification from accretable yield to nonaccretable difference. A loan disposal, which may include a loan sale, receipt of payment in full from the borrower or foreclosure, results in removal of the loan from the acquired PCI loan pool at its allocated carrying amount. Refinanced or restructured loans remain within the acquired PCI loan pools. For acquired loans not deemed credit-impaired at acquisition, the difference between the initial fair value and the unpaid principal balance is recognized as interest income on a level-yield basis over the lives of the related loans. The Corporation assesses all loan modifications to determine whether a restructuring constitutes a troubled debt restructuring (TDR). A restructuring is considered a TDR when a borrower is experiencing financial difficulty and the Corporation grants a concession to the borrower. TDRs on accrual status at the original contractual rate of interest are considered performing. Nonperforming TDRs include TDRs on nonaccrual status and loans which have been renegotiated to less than the original contractual rates (reduced-rate loans). All TDRs are considered impaired loans. Loan Origination Fees and Costs Substantially all loan origination fees and costs are deferred and amortized to net interest income of over the life of the related loan or over the commitment period as a yield adjustment. Net deferred income on originated loans, including unearned income and unamortized costs, fees, premiums and discounts, totaled $287 million and $310 million at December 31, 2013 and 2012, respectively. Loan fees on unused commitments and net origination fees related to loans sold are recognized in noninterest income. Allowance for Credit Losses The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments. The Corporation disaggregates the loan portfolio into segments for purposes of determining the allowance for credit losses. These segments are based on the level at which the Corporation develops, documents and applies a systematic methodology to determine the allowance for credit losses. The Corporation's portfolio segments are business loans and retail loans. Business loans are defined as those belonging to the commercial, real estate construction, commercial mortgage, lease financing and international loan portfolios. Retail loans consist of traditional residential mortgage, home equity and other consumer loans. For further information on the Allowance for Credit Losses, refer to Note 4. Allowance for Loan Losses The allowance for loan losses represents management’s assessment of probable, estimable losses inherent in the Corporation’s loan portfolio. The allowance for loan losses includes specific allowances, based on individual evaluations of certain loans, and allowances for homogeneous pools of loans with similar risk characteristics. The Corporation individually evaluates certain impaired loans on a quarterly basis and establishes specific allowances for such loans, if required. A loan is considered impaired when it is probable that interest or principal payments will not be made in accordance with the contractual terms of the loan agreement. Consistent with this definition, all loans for which the accrual of interest has been discontinued (nonaccrual loans) are considered impaired. The Corporation individually evaluates nonaccrual loans with book balances of $2 million or more and accruing loans whose terms have been modified in a TDR. The threshold for individual evaluation is revised on an infrequent basis, generally when economic circumstances change significantly. Specific allowances for impaired loans are estimated using one of several methods, including the estimated fair value of underlying collateral, observable market value of similar debt or discounted expected future cash flows. Collateral values supporting individually evaluated impaired loans are evaluated quarterly. Either appraisals are obtained or appraisal assumptions are updated at least annually unless conditions dictate increased frequency. Appraisals on impaired construction loans are generally based on “as-is” collateral values. In certain circumstances, the Corporation may believe that the highest and best use of the collateral, and thus the most advantageous exit strategy, requires completion of the construction project. In these situations, the Corporation uses an “as-developed” appraisal to evaluate alternatives. However, the “as-developed” collateral value is appropriately adjusted to reflect the cost to complete the construction project and to prepare the property for sale. The Corporation may reduce the collateral value based upon the age of the appraisal and adverse developments in market conditions. Loans which do not meet the criteria to be evaluated individually are evaluated in homogeneous pools of loans with similar risk characteristics. For business loans not individually evaluated, losses inherent to the pool are estimated by applying standard reserve factors to outstanding principal balances, giving consideration to the estimated loss emergence period. Standard reserve factors are based on estimated probabilities of default and loss given default. These factors are evaluated and updated quarterly based on borrower risk rating migration experience and trends, recent charge-off experience, current economic conditions and trends, changes in collateral values of properties securing loans, and trends with respect to past due and nonaccrual amounts. The Corporation also periodically reviews its loss emergence period estimates to determine the most appropriate default horizon associated with the calculation of probabilities of default. Probabilities of default and loss given default factors are estimated for each internal risk rating. Internal risk ratings are assigned to each business loan at the time of approval and are subjected to subsequent periodic reviews by the Corporation’s senior management, generally at least annually or more frequently upon the occurrence of a circumstance that affects the credit risk of the loan. The Corporation considers the inherent imprecision in the risk rating system resulting from inaccuracy in assigning and/or entering risk ratings in the loan accounting system. An additional allowance is established to capture the probable losses which could result from such risk rating errors. This additional allowance is calculated based on the results of risk rating accuracy assessments performed on samples of business loans conducted by the Corporation's asset quality review function, a function independent of the lending and credit groups responsible for assigning the initial internal risk rating at the time of approval. Incremental reserves may be established to cover losses in industries and/or portfolios experiencing elevated loss levels. The allowance for business loans not individually evaluated also may include a qualitative adjustment, which is determined based on an established framework. The determination of the appropriate adjustment is based on management's analysis of observable macroeconomic metrics, including consideration of regional metrics within the Corporation's footprint, internal credit risk movement and a qualitative assessment of the lending environment, including underwriting standards, current economic and political conditions, and other factors affecting credit quality. The framework enables management to develop a view of the uncertainties that exist but are not yet reflected in the standard reserve factors. In the first quarter 2013, the Corporation enhanced the approach utilized for determining standard reserve factors by changing from a dollar-based migration method for developing probability of default statistics to a count-based method. Under the dollar-based method, each dollar that moved to default received equal weight in the determination of standard reserve factors for each internal risk rating. As a result, the movement of larger loans impacted standard reserve factors more than the movement of smaller loans. By moving to a count-based approach, where each loan that moves to default receives equal weighting, unusually large or small loans will not have a disproportionate influence on the standard reserve factors. The change resulted in a $40 million increase to the allowance for loan losses at March 31, 2013. The allowance for retail loans not individually evaluated is determined by applying estimated loss rates to various pools of loans within the portfolios with similar risk characteristics. Estimated loss rates for all pools are updated quarterly, incorporating factors such as recent charge-off experience, current economic conditions and trends, changes in collateral values of properties securing loans (using index-based estimates), and trends with respect to past due and nonaccrual amounts. Loans acquired in business combinations are initially recorded at fair value, which includes an estimate of credit losses expected to be realized over the remaining lives of the loans, and therefore no corresponding allowance for loan losses is recorded for these loans at acquisition. Methods utilized to estimate any subsequently required allowance for loan losses for acquired loans not deemed credit-impaired at acquisition are similar to originated loans; however, the estimate of loss is based on the unpaid principal balance less any remaining purchase discount. The total allowance for loan losses is sufficient to absorb incurred losses inherent in the total portfolio. Unanticipated economic events, including political, economic and regulatory instability in countries where the Corporation has loans, could cause changes in the credit characteristics of the portfolio and result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures, as well as the inclusion of additional industry-specific portfolio exposures in the allowance, could also increase the amount of the allowance. Any of these events, or some combination thereof, may result in the need for additional provision for credit losses in order to maintain an allowance that complies with credit risk and accounting policies. Loans deemed uncollectible are charged off and deducted from the allowance. The provision for loan losses and recoveries on loans previously charged off are added to the allowance. Allowance for Credit Losses on Lending-Related Commitments The allowance for credit losses on lending-related commitments provides for probable losses inherent in lending-related commitments, including unused commitments to extend credit and letters of credit. The allowance for credit losses on lending-related commitments includes specific allowances, based on individual evaluations of certain letters of credit in a manner consistent with business loans, and allowances based on the pool of the remaining letters of credit and all unused commitments to extend credit within each internal risk rating. A probability of draw estimate is applied to the commitment amount, and the result is multiplied by standard reserve factors consistent with business loans. In general, the probability of draw for letters of credit is considered certain for all letters of credit supporting loans and for letters of credit assigned an internal risk rating generally consistent with regulatory defined substandard or doubtful. Other letters of credit and all unfunded commitments have a lower probability of draw. The allowance for credit losses on lending-related commitments is included in “accrued expenses and other liabilities” on the consolidated balance sheets, with the corresponding charge reflected in the “provision for credit losses” on the consolidated statements of income. Nonperforming Assets Nonperforming assets consist of nonaccrual loans, including loans held-for-sale, reduced-rate loans and foreclosed property. Business loans are generally placed on nonaccrual status when management determines full collection of principal or interest is unlikely or when principal or interest payments are 90 days past due, unless the loan is fully collateralized and in the process of collection. There is no past-due status threshold in the determination of when a business loan should be charged-off. Business loans typically require individual evaluation and management judgment to determine the timing and amount of principal charge-offs. The past-due status of a business loan is one of many indicative factors considered in determining the collectibility of the credit. The primary driver of when the principal amount of a business loan should be fully or partially charged-off is based on a qualitative assessment of the recoverability of the principal amount from collateral and other cash flow sources. In 2012, the Corporation modified its residential mortgage and home equity nonaccrual policies. Under the new policies, residential mortgage and home equity loans are generally placed on nonaccrual status once they become 90 days past due (previously no later than 180 days past due) and charged off to current appraised values less costs to sell no later than 180 days past due. In addition, junior lien home equity loans less than 90 days past due are placed on nonaccrual status if they have underlying risk characteristics that place full collection of the loan in doubt, such as when the related senior lien position is seriously delinquent. In connection with regulatory guidance issued during 2012, the Corporation further modified its nonaccrual and charge-off policy regarding residential mortgage and consumer loans in bankruptcy for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt. Such loans are placed on nonaccrual status and written down to estimated collateral value, without regard to the actual payment status of the loan, and are classified as TDRs. All other consumer loans are generally not placed on nonaccrual status and are charged off at no later than 120 days past due, earlier if deemed uncollectible. At the time a loan is placed on nonaccrual status, interest previously accrued but not collected is charged against current income. Income on such loans is then recognized only to the extent that cash is received and future collection of principal is probable. Generally, a loan may be returned to accrual status when all delinquent principal and interest have been received and the Corporation expects repayment of the remaining contractual principal and interest, or when the loan or debt security is both well secured and in the process of collection. PCI loans are recorded at fair value at acquisition date. Although the PCI loans may be contractually delinquent, the Corporation does not classify these loans as past due or nonperforming as the loans were written down to fair value at the acquisition date and the accretable yield is recognized in interest income over the remaining life of the loan. Foreclosed property (primarily real estate) is initially recorded at fair value, less costs to sell, at the date of foreclosure and subsequently carried at the lower of cost or fair value, less estimated costs to sell. Independent appraisals are obtained to substantiate the fair value of foreclosed property at the time of foreclosure and updated at least annually or upon evidence of deterioration in the property’s value. At the time of foreclosure, any excess of the related loan balance over fair value (less estimated costs to sell) of the property acquired is charged to the allowance for loan losses. Subsequent write-downs, operating expenses and losses upon sale, if any, are charged to noninterest expenses. Foreclosed property is included in “accrued income and other assets” on the consolidated balance sheets. Premises and Equipment Premises and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation, computed on the straight-line method, is charged to operations over the estimated useful lives of the assets. Estimated useful lives are generally 3 years to 33 years for premises that the Corporation owns and 3 years to 8 years for furniture and equipment. Leasehold improvements are generally amortized over the terms of their respective leases or 10 years, whichever is shorter. Software Capitalized software is stated at cost, less accumulated amortization. Capitalized software includes purchased software and capitalizable application development costs associated with internally-developed software. Amortization, computed on the straight-line method, is charged to operations over 5 years, the estimated useful life of the software. Capitalized software is included in “accrued income and other assets” on the consolidated balance sheets. Goodwill and Core Deposit Intangibles Goodwill, included in "accrued income and other assets" on the consolidated balance sheets, is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Business Bank, the Retail Bank and Wealth Management. The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and on an interim basis if events or changes in circumstances between annual tests suggest additional testing may be warranted to determine if goodwill might be impaired. The goodwill impairment test is a two-step test. The first step of the goodwill impairment test compares the estimated fair value of identified reporting units with their carrying amount, including goodwill. If the estimated fair value of the reporting unit is less than the carrying value, the second step must be performed to determine the implied fair value of the reporting unit's goodwill and the amount of goodwill impairment, if any. The implied fair value of goodwill is determined as if the reporting unit were being acquired in a business combination. If the implied fair value of goodwill exceeds the goodwill assigned to the reporting unit, there is no impairment. If the goodwill assigned to a reporting unit exceeds the implied fair value of goodwill, an impairment charge would be recorded for the excess. In performing the annual impairment test, the carrying value of each reporting unit is the greater of economic or regulatory capital. The Corporation assigns economic capital using internal management methodologies on the basis of each reporting unit's credit, operational and interest rate risks, as well as goodwill. To determine regulatory capital, each reporting unit is assigned sufficient capital such that their respective Tier 1 ratio, based on allocated risk-weighted assets, is the same as that of the Corporation. Using this two-pronged approach, the Corporation's equity is fully allocated to its reporting units except for capital held primarily for the risk associated with the securities portfolio which is assigned to the Finance segment of the Corporation. The estimated fair values of the reporting units are determined using a blend of two commonly used valuation techniques: the market approach and the income approach. For the market approach, valuations of reporting units consider a combination of earnings, equity and other multiples from companies with characteristics similar to the reporting unit. Since the fair values determined under the market approach are representative of noncontrolling interests, the valuations accordingly incorporate a control premium. For the income approach, estimated future cash flows and terminal value are discounted. Estimated future cash flows are derived from internal forecasts and economic expectations for each reporting unit which incorporate uncertainty factors inherent to long-term projections. The applicable discount rate is based on the imputed cost of equity capital appropriate for each reporting unit, which incorporates the risk-free rate of return, the level of non-diversified risk associated with companies with characteristics similar to the reporting unit, an entity-specific risk premium and a market equity risk premium. Determining the fair value of reporting units is a subjective process involving the use of estimates and judgments related to the selection of inputs such as future cash flows, discount rates, comparable public company multiples, applicable control premiums and economic expectations used in determining the interest rate environment. The Corporation may choose to perform a qualitative assessment to determine whether the first step of the impairment test should be performed in future periods if certain factors indicate that impairment is unlikely. Factors which could be considered in the assessment of the likelihood of impairment include macroeconomic conditions, industry and market considerations, stock performance of the Corporation and its peers, financial performance, events affecting the Corporation as a whole or its reporting units individually and previous results of goodwill impairment tests. Core deposit intangibles are amortized on an accelerated basis, based on the estimated period the economic benefits are expected to be received. Core deposit intangibles are reviewed for impairment when events or changes in circumstances indicate that their carrying amounts may not be recoverable. Impairment for a finite-lived intangible asset exists if the sum of the undiscounted cash flows expected to result from the use of the asset exceeds its carrying value. Additional information regarding goodwill and core deposit intangibles can be found in Note 7. Nonmarketable Equity Securities The Corporation has certain investments that are not readily marketable. These investments include a portfolio of investments in indirect private equity and venture capital funds and restricted equity investments, which are securities the Corporation is required to hold for various reasons, primarily Federal Home Loan Bank of Dallas (FHLB) and Federal Reserve Bank (FRB) stock. These investments are accounted for on the cost or equity method and are included in “accrued income and other assets” on the consolidated balance sheets. The investments are individually reviewed for impairment on a quarterly basis. Indirect private equity and venture capital funds are evaluated by comparing the carrying value to the estimated fair value. The amount by which the carrying value exceeds the fair value that is determined to be other-than-temporary impairment is charged to current earnings and the carrying value of the investment is written down accordingly. FHLB and FRB stock are recorded at cost (par value) and evaluated for impairment based on the ultimate recoverability of the par value. If the Corporation does not expect to recover the full par value, the amount by which the par value exceeds the ultimately recoverable value would be charged to current earnings and the carrying value of the investment would be written down accordingly. Derivative Instruments and Hedging Activities Derivative instruments are carried at fair value in either “accrued income and other assets” or “accrued expenses and other liabilities” on the consolidated balance sheets. The accounting for changes in the fair value (i.e., gains or losses) of a derivative instrument is determined by whether it has been designated and qualifies as part of a hedging relationship and, further, by the type of hedging relationship. The Corporation presents derivative instruments at fair value in the consolidated balance sheets on a net basis when a right of offset exists, based on transactions with a single counterparty and any cash collateral paid to and/or received from that counterparty for derivative contracts that are subject to legally enforceable master netting arrangements. For derivative instruments designated and qualifying as fair value hedges (i.e., hedging the exposure to changes in the fair value of an asset or a liability or an identified portion thereof that is attributable to a particular risk), the gain or loss on the derivative instrument, as well as the offsetting loss or gain on the hedged item attributable to the hedged risk, are recognized in current earnings during the period of the change in fair values. For derivative instruments that are designated and qualify as cash flow hedges (i.e., hedging the exposure to variability in expected future cash flows that is attributable to a particular risk), the effective portion of the gain or loss on the derivative instrument is reported as a component of other comprehensive income and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. The remaining gain or loss on the derivative instrument in excess of the cumulative change in the present value of future cash flows of the hedged item (i.e., the ineffective portion), if any, is recognized in current earnings during the period of change. For derivative instruments not designated as hedging instruments, the gain or loss is recognized in current earnings during the period of change. In 2013, the Corporation adopted amendments to GAAP which require enhanced disclosures about the nature and effect or potential effect of an entity's rights of setoff associated with its derivative and certain other financial instruments. The required disclosures are provided in Note 8. For derivatives designated as hedging instruments at inception, the Corporation uses either the short-cut method or applies statistical regression analysis to assess effectiveness. The short-cut method is used for certain fair value hedges of medium and long-term debt issued prior to 2006. This method allows for the assumption of zero hedge ineffectiveness and eliminates the requirement to further assess hedge effectiveness on these transactions. For hedge relationships to which the Corporation does not apply the short-cut method, statistical regression analysis is used at inception and for each reporting period thereafter to assess whether the derivative used has been and is expected to be highly effective in offsetting changes in the fair value or cash flows of the hedged item. All components of each derivative instrument’s gain or loss are included in the assessment of hedge effectiveness. Net hedge ineffectiveness is recorded in “other noninterest income” on the consolidated statements of income. In 2013, the Financial Accounting Standards Board (FASB) issued an amendment to GAAP which permits the Overnight Index Swap Rate, also referred to as the Fed Funds Effective Swap Rate, to be used as a benchmark interest rate for hedge accounting purposes, effective for qualifying new or re-designated hedging relationships entered into on or after July 17, 2013. The amendment also removed the restriction on using different benchmark rates for similar hedges. While the adoption of this amendment had no impact on the Corporation's financial condition and results of operations, to the extent to Corporation enters into new or re-designates existing hedging relationships in the future, the Overnight Index Swap Rate will be included in the spectrum of available benchmark interest rates for hedge accounting. Further information on the Corporation’s derivative instruments and hedging activities is included in Note 8. Short-Term Borrowings Securities sold under agreements to repurchase are treated as collateralized borrowings and are recorded at amounts equal to the cash received. The contractual terms of the agreements to repurchase may require the Corporation to provide additional collateral if the fair value of the securities underlying the borrowings declines during the term of the agreement. Financial Guarantees Certain guarantee contracts or indemnification agreements that contingently require the Corporation, as guarantor, to make payments to the guaranteed party are initially measured at fair value and included in “accrued expenses and other liabilities” on the consolidated balance sheets. The subsequent accounting for the liability depends on the nature of the underlying guarantee. The release from risk is accounted for under a particular guarantee when the guarantee expires or is settled, or by a systematic and rational amortization method. Further information on the Corporation’s obligations under guarantees is included in Note 8. Share-Based Compensation The Corporation recognizes share-based compensation expense using the straight-line method over the requisite service period for all stock awards, including those with graded vesting. The requisite service period is the period an employee is required to provide service in order to vest in the award, which cannot extend beyond the date at which the employee is no longer required to perform any service to receive the share-based compensation (the retirement-eligible date). Certain awards are contingent upon performance conditions, which affect the number of awards ultimately granted. The Corporation periodically evaluates the probable outcome of the performance conditions and makes cumulative adjustments to compensation expense as appropriate. Further information on the Corporation’s share-based compensation plans is included in Note 16. Revenue Recognition The following summarizes the Corporation’s revenue recognition policies as they relate to certain noninterest income line items in the consolidated statements of income. Service charges on deposit accounts include fees for banking services provided, overdrafts and non-sufficient funds. Revenue is generally recognized in accordance with published deposit account agreements for retail accounts or contractual agreements for commercial accounts. Fiduciary income includes fees and commissions from asset management, custody, recordkeeeping, investment advisory and other services provided to personal and institutional trust customers. Revenue is recognized on an accrual basis at the time the services are performed and are based on either the market value of the assets managed or the services provided. Commercial lending fees primarily include fees assessed on the unused portion of commercial lines of credit ("unused commitment fees") and syndication agent fees. Unused commitment fees are recognized when earned. Syndication agent fees are generally recognized when the transaction is complete. Card fees includes primarily bankcard interchange revenue which is recorded as revenue when earned. Defined Benefit Pension and Other Postretirement Costs Defined benefit pension costs are charged to “employee benefits” expense on the consolidated statements of income and are funded consistent with the requirements of federal laws and regulations. Inherent in the determination of defined benefit pension costs are assumptions concerning future events that will affect the amount and timing of required benefit payments under the plans. These assumptions include demographic assumptions such as retirement age and mortality, a compensation rate increase, a discount rate used to determine the current benefit obligation and a long-term expected rate of return on plan assets. Net periodic defined benefit pension expense includes service cost, interest cost based on the assumed discount rate, an expected return on plan assets based on an actuarially derived market-related value of assets, amortization of prior service cost and amortization of net actuarial gains or losses. The market-related value of plan assets is determined by amortizing the current year’s investment gains and losses (the actual investment return net of the expected investment return) over 5 years. The amortization adjustment cannot exceed 10 percent of the fair value of assets. Prior service costs include the impact of plan amendments on the liabilities and are amortized over the future service periods of active employees expected to receive benefits under the plan. Actuarial gains and losses result from experience different from that assumed and from changes in assumptions (excluding asset gains and losses not yet reflected in market-related value). Amortization of actuarial gains and losses is included as a component of net periodic defined benefit pension cost for a year if the actuarial net gain or loss exceeds 10 percent of the greater of the projected benefit obligation or the market-related value of plan assets. If amortization is required, the excess is amortized over the average remaining service period of participating employees expected to receive benefits under the plan. Postretirement benefits are recognized in “employee benefits” expense on the consolidated statements of income during the average remaining service period of participating employees expected to receive benefits under the plan or the average remaining future lifetime of retired participants currently receiving benefits under the plan. For further information regarding the Corporation’s defined benefit pension and other postretirement plans, refer to Note 17. Income Taxes The provision for income taxes is the sum of income taxes due for the current year and deferred taxes. Deferred taxes arise from temporary differences between the income tax basis and financial accounting basis of assets and liabilities. Deferred tax assets are evaluated for realization based on available evidence of loss carry-back capacity, future reversals of existing taxable temporary differences, and assumptions made regarding future events. A valuation allowance is provided when it is more likely than not that some portion of the deferred tax asset will not be realized. The Corporation classifies interest and penalties on income tax liabilities in the “provision for income taxes” on the consolidated statements of income. Earnings Per Share Basic income per common share and net income per common share are calculated using the two-class method. The two-class method is an earnings allocation formula that determines earnings per share for each share of common stock and participating securities according to dividends declared (distributed earnings) and participation rights in undistributed earnings. Distributed and undistributed earnings are allocated between common and participating security shareholders based on their respective rights to receive dividends. Nonvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents are considered participating securities (e.g., nonvested restricted stock and restricted stock units). Undistributed net losses are not allocated to nonvested restricted shareholders, as these shareholders do not have a contractual obligation to fund the losses incurred by the Corporation. Income attributable to common shares and net income attributable to common shares are then divided by the weighted-average number of common shares outstanding during the period. Diluted income per common share and net income per common share consider common stock issuable under the assumed exercise of stock options granted under the Corporation’s stock plans and warrants. Diluted income attributable to common shares and net income attributable to common shares are then divided by the total of weighted-average number of common shares and common stock equivalents outstanding during the period. Statements of Cash Flows Cash and cash equivalents are defined as those amounts included in “cash and due from banks”, “federal funds sold” and “interest-bearing deposits with banks” on the consolidated balance sheets. Comprehensive Income (Loss) The Corporation presents on an annual basis the components of net income and other comprehensive income in two separate, but consecutive statements and presents on an interim basis the components of net income and a total for comprehensive income in one continuous consolidated statement of comprehensive income. Pending Accounting Pronouncements In January 2014, the FASB issued ASU No. 2014-01, “Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects,” (ASU 2014-01), which enables companies that invest in affordable housing projects that qualify for the low-income housing tax credit (LIHTC) to elect to use the proportional amortization method if certain conditions are met. Under the proportional amortization method, the initial investment cost of the project is amortized in proportion to the amount of tax credits and benefits received, with the results of the investment presented on a net basis as a component of income tax expense (benefit). ASU 2014-01 is effective for interim and annual periods beginning after December 15, 2014, with early adoption permitted. The Corporation is currently evaluating the impact of adopting ASU 2014-01, but does not expect the adoption to have a material effect on the Corporation’s financial condition and results of operations. Also in January 2014, the FASB issued ASU No. 2014-04, “Receivables – Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure,” (ASU 2014-04), which clarifies when an in-substance foreclosure or repossession of residential real estate property occurs, requiring a creditor to reclassify the loan to other real estate. According to ASU 2014-04, a consumer mortgage loan should be reclassified to other real estate either upon the creditor obtaining legal title to the real estate collateral or when the borrower voluntarily conveys all interest in the real estate property to the creditor through a deed in lieu of foreclosure or similar legal agreement. ASU 2014-04 also clarifies that a creditor should not delay reclassification when a borrower has a legal right of redemption. The Corporation's current practice is to delay reclassification of foreclosed residential real estate to other real estate until the redemption period, if any, has expired. The Corporation expects to prospectively adopt ASU 2014-04 in the first quarter 2015 and does not expect the adoption to have a material effect on the Corporation's financial condition and results of operations. At December 31, 2013, approximately $5 million of foreclosed residential real estate property subject to a redemption period was classified in nonperforming loans.

BASIS OF PRESENTATION AND ACCOUNTING POLICIES

Organization

Comerica Incorporated (the Corporation) is a registered financial holding company headquartered in Dallas, Texas. The Corporation’s major business segments are the Business Bank, the Retail Bank and Wealth Management. The Corporation operates in three primary geographic markets: Michigan, California and Texas. For further discussion of each business segment and primary geographic market, refer to Note 22. The Corporation and its banking subsidiaries are regulated at both the state and federal levels.

The accounting and reporting policies of the Corporation conform to United States (U.S.) generally accepted accounting principles (GAAP). The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect reported amounts and disclosures. Actual results could differ from these estimates.

The following summarizes the significant accounting policies of the Corporation applied in the preparation of the accompanying consolidated financial statements.

Principles of Consolidation

The consolidated financial statements include the accounts of the Corporation and the accounts of those subsidiaries that are majority owned and in which the Corporation has a controlling financial interest. The Corporation consolidates entities not determined to be variable interest entities (VIEs) when it holds a controlling interest in the entity's outstanding voting stock and uses the cost or equity method when it holds less than a controlling interest. In consolidation, all significant intercompany accounts and transactions are eliminated. The results of operations of companies acquired are included from the date of acquisition. Certain amounts in the financial statements for prior years have been reclassified to conform to current financial statement presentation.

The Corporation holds investments in certain legal entities that are considered VIEs. In general, a VIE is an entity that either (1) has an insufficient amount of equity to carry out its principal activities without additional subordinated financial support, (2) has a group of equity owners that are unable to make significant decisions about its activities, or (3) has a group of equity owners that do not have the obligation to absorb losses or the right to receive returns generated by its operations. If any of these characteristics are present, the entity is subject to a variable interests consolidation model, and consolidation is based on variable interests, not on ownership of the entity’s outstanding voting stock. Variable interests are defined as contractual ownership or other money interests in an entity that change with fluctuations in the entity’s net asset value. The primary beneficiary is required to consolidate the VIE. The primary beneficiary is defined as the party that has both the power to direct the activities of the VIE that most significantly impact the entity’s economic performance and the obligation to absorb losses or the right to receive benefits that could be significant to the VIE. The maximum potential exposure to losses relative to investments in VIEs is generally limited to the sum of the outstanding book basis and unfunded commitments for future investments.

The Corporation evaluates its investments in VIEs, both at inception and when there is a change in circumstances that requires reconsideration, to determine if the Corporation is the primary beneficiary and consolidation is required. The Corporation accounts for unconsolidated VIEs using either the cost or equity method.

The equity method is used for investments where the Corporation has the ability to exercise significant influence over the entity’s operation and financial policies, which is generally presumed to exist if the Corporation owns more than a 20 percent voting interest in the entity. Equity method investments are included in “accrued income and other assets” on the consolidated balance sheets, with income and losses recorded in “other noninterest income” on the consolidated statements of income. Unconsolidated equity investments that do not meet the criteria to be accounted for under the equity method are accounted for under the cost method. Cost method investments are included in “accrued income and other assets” on the consolidated balance sheets, with income (net of write-downs) recorded in “other noninterest income” on the consolidated statements of income.

Assets held in an agency or fiduciary capacity are not assets of the Corporation and are not included in the consolidated financial statements.

See Note 9 for additional information about the Corporation’s involvement with VIEs.

Fair Value Measurements

Fair value measurement applies whenever accounting guidance requires or permits assets or liabilities to be measured at fair value. Fair value is defined as the exchange price that would be received to sell an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction (i.e., not a forced transaction, such as a liquidation or distressed sale) between market participants at the measurement date. Fair value is based on the assumptions market participants would use when pricing an asset or liability. Fair value measurements and disclosures guidance establishes a three-level fair value hierarchy based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. The fair value hierarchy gives the highest priority to quoted prices in active markets and the lowest priority to unobservable data. Fair value measurements are separately disclosed by level within the fair value hierarchy. For assets and liabilities recorded at fair value, it is the Corporation’s policy to maximize the use of observable inputs and minimize the use of unobservable inputs when developing fair value measurements.

Fair value measurements for assets and liabilities where limited or no observable market data exists are based primarily upon estimates, often calculated based on the economic and competitive environment, the characteristics of the asset or liability and other factors. Therefore, the results cannot be determined with precision and may not be realized in an actual sale or immediate settlement of the asset or liability. Additionally, there may be inherent weaknesses in any calculation technique, and changes in the underlying assumptions used, including discount rates and estimates of future cash flows, could significantly affect the results of current or future values.

For further information about fair value measurements refer to Note 2.

Other Short-Term Investments

Other short-term investments include trading securities and loans held-for-sale.

Trading securities are carried at fair value. Realized and unrealized gains or losses on trading securities are included in “other noninterest income” on the consolidated statements of income.

Loans held-for-sale, typically residential mortgages originated with the intent to sell, are carried at the lower of cost or fair value. Fair value is determined in the aggregate for each portfolio. Changes in fair value are included in “other noninterest income” on the consolidated statements of income.

Investment Securities

Securities that are not held for trading purposes are accounted for as securities available-for-sale and recorded at fair value, with unrealized gains and losses, net of income taxes, reported as a separate component of other comprehensive income (loss) (OCI).

Investment securities are reviewed quarterly for possible other-than-temporary impairment (OTTI). In determining whether OTTI exists for debt securities in an unrealized loss position, the Corporation assesses the likelihood of selling the security prior to the recovery of its amortized cost basis. If the Corporation intends to sell the debt security or it is more likely than not that the Corporation will be required to sell the debt security prior to the recovery of its amortized cost basis, the debt security is written down to fair value, and the full amount of any impairment charge is recorded as a loss in “net securities gains” in the consolidated statements of income. If the Corporation does not intend to sell the debt security and it is more likely than not that the Corporation will not be required to sell the debt security prior to recovery of its amortized cost basis, only the credit component of any impairment of a debt security is recognized as a loss in “net securities gains” on the consolidated statements of income, with the remaining impairment recorded in OCI.

The OTTI review for equity securities includes an analysis of the facts and circumstances of each individual investment and focuses on the severity of loss, the length of time the fair value has been below cost, the expectation for that security’s performance, the financial condition and near-term prospects of the issuer, and management’s intent and ability to hold the security to recovery. A decline in value of an equity security that is considered to be other-than-temporary is recorded as a loss in “net securities (losses) gains” on the consolidated statements of income.

Gains or losses on the sale of securities are computed based on the adjusted cost of the specific security sold.

For further information on investment securities, refer to Note 3.

Loans

Loans and leases originated and held for investment are recorded at the principal balance outstanding, net of unearned income, charge-offs and unamortized deferred fees and costs. Interest income is recognized on loans and leases using the interest method.

Loans and leases acquired in business combinations are initially recorded at fair value with no carryover of any existing allowance for loan losses. Acquired loans with evidence of credit quality deterioration at acquisition are reviewed to determine if it is probable that the Corporation will not be able to collect all contractual amounts due, including both principal and interest. When both conditions exist, such loans are accounted for as purchased credit-impaired (PCI) loans. The Corporation generally aggregates PCI loans into pools of loans based on common risk characteristics.

The Corporation estimates the total cash flows expected to be collected from the pools of acquired PCI loans, which include undiscounted expected principal and interest, using credit risk, interest rate and prepayment risk models that incorporate management's best estimate of current key assumptions such as default rates, loss severity and payment speeds. The excess of the undiscounted total cash flows expected to be collected over the fair value of the related PCI loans represents the accretable yield, which is recognized as interest income on a level-yield basis over the life of the related loan pools. The difference between the undiscounted contractual principal and interest and the undiscounted total cash flows expected to be collected is the nonaccretable difference, which reflects the impact of estimated credit losses and other factors. Subsequent increases in expected cash flows will result in a recovery of any previously recorded allowance for loan losses, to the extent applicable, and a reclassification from nonaccretable difference to accretable yield, which is recognized prospectively over the then remaining lives of the loan pools. Subsequent decreases in expected cash flows will result in an impairment charge to the provision for loan losses, resulting in an addition to the allowance for loan losses, and a reclassification from accretable yield to nonaccretable difference. A loan disposal, which may include a loan sale, receipt of payment in full from the borrower or foreclosure, results in removal of the loan from the acquired PCI loan pool at its allocated carrying amount. Refinanced or restructured loans remain within the acquired PCI loan pools.

For acquired loans not deemed credit-impaired at acquisition, the difference between the initial fair value and the unpaid principal balance is recognized as interest income on a level-yield basis over the lives of the related loans.

The Corporation assesses all loan modifications to determine whether a restructuring constitutes a troubled debt restructuring (TDR). A restructuring is considered a TDR when a borrower is experiencing financial difficulty and the Corporation grants a concession to the borrower. TDRs on accrual status at the original contractual rate of interest are considered performing. Nonperforming TDRs include TDRs on nonaccrual status and loans which have been renegotiated to less than the original contractual rates (reduced-rate loans). All TDRs are considered impaired loans.

Loan Origination Fees and Costs

Substantially all loan origination fees and costs are deferred and amortized to net interest income of over the life of the related loan or over the commitment period as a yield adjustment. Net deferred income on originated loans, including unearned income and unamortized costs, fees, premiums and discounts, totaled $287 million and $310 million at December 31, 2013 and 2012, respectively.

Loan fees on unused commitments and net origination fees related to loans sold are recognized in noninterest income.

Allowance for Credit Losses

The allowance for credit losses includes both the allowance for loan losses and the allowance for credit losses on lending-related commitments.

The Corporation disaggregates the loan portfolio into segments for purposes of determining the allowance for credit losses. These segments are based on the level at which the Corporation develops, documents and applies a systematic methodology to determine the allowance for credit losses. The Corporation's portfolio segments are business loans and retail loans. Business loans are defined as those belonging to the commercial, real estate construction, commercial mortgage, lease financing and international loan portfolios. Retail loans consist of traditional residential mortgage, home equity and other consumer loans.

For further information on the Allowance for Credit Losses, refer to Note 4.

Allowance for Loan Losses

The allowance for loan losses represents management’s assessment of probable, estimable losses inherent in the Corporation’s loan portfolio. The allowance for loan losses includes specific allowances, based on individual evaluations of certain loans, and allowances for homogeneous pools of loans with similar risk characteristics.

The Corporation individually evaluates certain impaired loans on a quarterly basis and establishes specific allowances for such loans, if required. A loan is considered impaired when it is probable that interest or principal payments will not be made in accordance with the contractual terms of the loan agreement. Consistent with this definition, all loans for which the accrual of interest has been discontinued (nonaccrual loans) are considered impaired. The Corporation individually evaluates nonaccrual loans with book balances of $2 million or more and accruing loans whose terms have been modified in a TDR. The threshold for individual evaluation is revised on an infrequent basis, generally when economic circumstances change significantly. Specific allowances for impaired loans are estimated using one of several methods, including the estimated fair value of underlying collateral, observable market value of similar debt or discounted expected future cash flows.

Collateral values supporting individually evaluated impaired loans are evaluated quarterly. Either appraisals are obtained or appraisal assumptions are updated at least annually unless conditions dictate increased frequency. Appraisals on impaired construction loans are generally based on “as-is” collateral values. In certain circumstances, the Corporation may believe that the highest and best use of the collateral, and thus the most advantageous exit strategy, requires completion of the construction project. In these situations, the Corporation uses an “as-developed” appraisal to evaluate alternatives. However, the “as-developed” collateral value is appropriately adjusted to reflect the cost to complete the construction project and to prepare the property for sale. The Corporation may reduce the collateral value based upon the age of the appraisal and adverse developments in market conditions.

Loans which do not meet the criteria to be evaluated individually are evaluated in homogeneous pools of loans with similar risk characteristics. For business loans not individually evaluated, losses inherent to the pool are estimated by applying standard reserve factors to outstanding principal balances, giving consideration to the estimated loss emergence period. Standard reserve factors are based on estimated probabilities of default and loss given default. These factors are evaluated and updated quarterly based on borrower risk rating migration experience and trends, recent charge-off experience, current economic conditions and trends, changes in collateral values of properties securing loans, and trends with respect to past due and nonaccrual amounts. The Corporation also periodically reviews its loss emergence period estimates to determine the most appropriate default horizon associated with the calculation of probabilities of default. Probabilities of default and loss given default factors are estimated for each internal risk rating. Internal risk ratings are assigned to each business loan at the time of approval and are subjected to subsequent periodic reviews by the Corporation’s senior management, generally at least annually or more frequently upon the occurrence of a circumstance that affects the credit risk of the loan. The Corporation considers the inherent imprecision in the risk rating system resulting from inaccuracy in assigning and/or entering risk ratings in the loan accounting system. An additional allowance is established to capture the probable losses which could result from such risk rating errors. This additional allowance is calculated based on the results of risk rating accuracy assessments performed on samples of business loans conducted by the Corporation's asset quality review function, a function independent of the lending and credit groups responsible for assigning the initial internal risk rating at the time of approval. Incremental reserves may be established to cover losses in industries and/or portfolios experiencing elevated loss levels.

The allowance for business loans not individually evaluated also may include a qualitative adjustment, which is determined based on an established framework. The determination of the appropriate adjustment is based on management's analysis of observable macroeconomic metrics, including consideration of regional metrics within the Corporation's footprint, internal credit risk movement and a qualitative assessment of the lending environment, including underwriting standards, current economic and political conditions, and other factors affecting credit quality. The framework enables management to develop a view of the uncertainties that exist but are not yet reflected in the standard reserve factors.

In the first quarter 2013, the Corporation enhanced the approach utilized for determining standard reserve factors by changing from a dollar-based migration method for developing probability of default statistics to a count-based method. Under the dollar-based method, each dollar that moved to default received equal weight in the determination of standard reserve factors for each internal risk rating. As a result, the movement of larger loans impacted standard reserve factors more than the movement of smaller loans. By moving to a count-based approach, where each loan that moves to default receives equal weighting, unusually large or small loans will not have a disproportionate influence on the standard reserve factors. The change resulted in a $40 million increase to the allowance for loan losses at March 31, 2013.

The allowance for retail loans not individually evaluated is determined by applying estimated loss rates to various pools of loans within the portfolios with similar risk characteristics. Estimated loss rates for all pools are updated quarterly, incorporating factors such as recent charge-off experience, current economic conditions and trends, changes in collateral values of properties securing loans (using index-based estimates), and trends with respect to past due and nonaccrual amounts.

Loans acquired in business combinations are initially recorded at fair value, which includes an estimate of credit losses expected to be realized over the remaining lives of the loans, and therefore no corresponding allowance for loan losses is recorded for these loans at acquisition. Methods utilized to estimate any subsequently required allowance for loan losses for acquired loans not deemed credit-impaired at acquisition are similar to originated loans; however, the estimate of loss is based on the unpaid principal balance less any remaining purchase discount.

The total allowance for loan losses is sufficient to absorb incurred losses inherent in the total portfolio. Unanticipated economic events, including political, economic and regulatory instability in countries where the Corporation has loans, could cause changes in the credit characteristics of the portfolio and result in an unanticipated increase in the allowance. Significant increases in current portfolio exposures, as well as the inclusion of additional industry-specific portfolio exposures in the allowance, could also increase the amount of the allowance. Any of these events, or some combination thereof, may result in the need for additional provision for credit losses in order to maintain an allowance that complies with credit risk and accounting policies.

Loans deemed uncollectible are charged off and deducted from the allowance. The provision for loan losses and recoveries on loans previously charged off are added to the allowance.

Allowance for Credit Losses on Lending-Related Commitments

The allowance for credit losses on lending-related commitments provides for probable losses inherent in lending-related commitments, including unused commitments to extend credit and letters of credit. The allowance for credit losses on lending-related commitments includes specific allowances, based on individual evaluations of certain letters of credit in a manner consistent with business loans, and allowances based on the pool of the remaining letters of credit and all unused commitments to extend credit within each internal risk rating. A probability of draw estimate is applied to the commitment amount, and the result is multiplied by standard reserve factors consistent with business loans. In general, the probability of draw for letters of credit is considered certain for all letters of credit supporting loans and for letters of credit assigned an internal risk rating generally consistent with regulatory defined substandard or doubtful. Other letters of credit and all unfunded commitments have a lower probability of draw. The allowance for credit losses on lending-related commitments is included in “accrued expenses and other liabilities” on the consolidated balance sheets, with the corresponding charge reflected in the “provision for credit losses” on the consolidated statements of income.

Nonperforming Assets

Nonperforming assets consist of nonaccrual loans, including loans held-for-sale, reduced-rate loans and foreclosed property.

Business loans are generally placed on nonaccrual status when management determines full collection of principal or interest is unlikely or when principal or interest payments are 90 days past due, unless the loan is fully collateralized and in the process of collection. There is no past-due status threshold in the determination of when a business loan should be charged-off. Business loans typically require individual evaluation and management judgment to determine the timing and amount of principal charge-offs. The past-due status of a business loan is one of many indicative factors considered in determining the collectibility of the credit. The primary driver of when the principal amount of a business loan should be fully or partially charged-off is based on a qualitative assessment of the recoverability of the principal amount from collateral and other cash flow sources.

In 2012, the Corporation modified its residential mortgage and home equity nonaccrual policies. Under the new policies, residential mortgage and home equity loans are generally placed on nonaccrual status once they become 90 days past due (previously no later than 180 days past due) and charged off to current appraised values less costs to sell no later than 180 days past due. In addition, junior lien home equity loans less than 90 days past due are placed on nonaccrual status if they have underlying risk characteristics that place full collection of the loan in doubt, such as when the related senior lien position is seriously delinquent. In connection with regulatory guidance issued during 2012, the Corporation further modified its nonaccrual and charge-off policy regarding residential mortgage and consumer loans in bankruptcy for which the court has discharged the borrower's obligation and the borrower has not reaffirmed the debt. Such loans are placed on nonaccrual status and written down to estimated collateral value, without regard to the actual payment status of the loan, and are classified as TDRs.

All other consumer loans are generally not placed on nonaccrual status and are charged off at no later than 120 days past due, earlier if deemed uncollectible. At the time a loan is placed on nonaccrual status, interest previously accrued but not collected is charged against current income. Income on such loans is then recognized only to the extent that cash is received and future collection of principal is probable. Generally, a loan may be returned to accrual status when all delinquent principal and interest have been received and the Corporation expects repayment of the remaining contractual principal and interest, or when the loan or debt security is both well secured and in the process of collection.

PCI loans are recorded at fair value at acquisition date. Although the PCI loans may be contractually delinquent, the Corporation does not classify these loans as past due or nonperforming as the loans were written down to fair value at the acquisition date and the accretable yield is recognized in interest income over the remaining life of the loan.

Foreclosed property (primarily real estate) is initially recorded at fair value, less costs to sell, at the date of foreclosure and subsequently carried at the lower of cost or fair value, less estimated costs to sell. Independent appraisals are obtained to substantiate the fair value of foreclosed property at the time of foreclosure and updated at least annually or upon evidence of deterioration in the property’s value. At the time of foreclosure, any excess of the related loan balance over fair value (less estimated costs to sell) of the property acquired is charged to the allowance for loan losses. Subsequent write-downs, operating expenses and losses upon sale, if any, are charged to noninterest expenses. Foreclosed property is included in “accrued income and other assets” on the consolidated balance sheets.

Premises and Equipment

Premises and equipment are stated at cost, less accumulated depreciation and amortization. Depreciation, computed on the straight-line method, is charged to operations over the estimated useful lives of the assets. Estimated useful lives are generally 3 years to 33 years for premises that the Corporation owns and 3 years to 8 years for furniture and equipment. Leasehold improvements are generally amortized over the terms of their respective leases or 10 years, whichever is shorter.

Software

Capitalized software is stated at cost, less accumulated amortization. Capitalized software includes purchased software and capitalizable application development costs associated with internally-developed software. Amortization, computed on the straight-line method, is charged to operations over 5 years, the estimated useful life of the software. Capitalized software is included in “accrued income and other assets” on the consolidated balance sheets.

Goodwill and Core Deposit Intangibles

Goodwill, included in "accrued income and other assets" on the consolidated balance sheets, is initially recorded as the excess of the purchase price over the fair value of net assets acquired in a business combination and is subsequently evaluated at least annually for impairment. Goodwill impairment testing is performed at the reporting unit level, equivalent to a business segment or one level below. The Corporation has three reporting units: the Business Bank, the Retail Bank and Wealth Management.

The Corporation performs its annual evaluation of goodwill impairment in the third quarter of each year and on an interim basis if events or changes in circumstances between annual tests suggest additional testing may be warranted to determine if goodwill might be impaired. The goodwill impairment test is a two-step test. The first step of the goodwill impairment test compares the estimated fair value of identified reporting units with their carrying amount, including goodwill. If the estimated fair value of the reporting unit is less than the carrying value, the second step must be performed to determine the implied fair value of the reporting unit's goodwill and the amount of goodwill impairment, if any. The implied fair value of goodwill is determined as if the reporting unit were being acquired in a business combination. If the implied fair value of goodwill exceeds the goodwill assigned to the reporting unit, there is no impairment. If the goodwill assigned to a reporting unit exceeds the implied fair value of goodwill, an impairment charge would be recorded for the excess.

In performing the annual impairment test, the carrying value of each reporting unit is the greater of economic or regulatory capital. The Corporation assigns economic capital using internal management methodologies on the basis of each reporting unit's credit, operational and interest rate risks, as well as goodwill. To determine regulatory capital, each reporting unit is assigned sufficient capital such that their respective Tier 1 ratio, based on allocated risk-weighted assets, is the same as that of the Corporation. Using this two-pronged approach, the Corporation's equity is fully allocated to its reporting units except for capital held primarily for the risk associated with the securities portfolio which is assigned to the Finance segment of the Corporation.

The estimated fair values of the reporting units are determined using a blend of two commonly used valuation techniques: the market approach and the income approach. For the market approach, valuations of reporting units consider a combination of earnings, equity and other multiples from companies with characteristics similar to the reporting unit. Since the fair values determined under the market approach are representative of noncontrolling interests, the valuations accordingly incorporate a control premium. For the income approach, estimated future cash flows and terminal value are discounted. Estimated future cash flows are derived from internal forecasts and economic expectations for each reporting unit which incorporate uncertainty factors inherent to long-term projections. The applicable discount rate is based on the imputed cost of equity capital appropriate for each reporting unit, which incorporates the risk-free rate of return, the level of non-diversified risk associated with companies with characteristics similar to the reporting unit, an entity-specific risk premium and a market equity risk premium. Determining the fair value of reporting units is a subjective process involving the use of estimates and judgments related to the selection of inputs such as future cash flows, discount rates, comparable public company multiples, applicable control premiums and economic expectations used in determining the interest rate environment.

The Corporation may choose to perform a qualitative assessment to determine whether the first step of the impairment test should be performed in future periods if certain factors indicate that impairment is unlikely. Factors which could be considered in the assessment of the likelihood of impairment include macroeconomic conditions, industry and market considerations, stock performance of the Corporation and its peers, financial performance, events affecting the Corporation as a whole or its reporting units individually and previous results of goodwill impairment tests.

Core deposit intangibles are amortized on an accelerated basis, based on the estimated period the economic benefits are expected to be received. Core deposit intangibles are reviewed for impairment when events or changes in circumstances indicate that their carrying amounts may not be recoverable. Impairment for a finite-lived intangible asset exists if the sum of the undiscounted cash flows expected to result from the use of the asset exceeds its carrying value.

Additional information regarding goodwill and core deposit intangibles can be found in Note 7.

Nonmarketable Equity Securities

The Corporation has certain investments that are not readily marketable. These investments include a portfolio of investments in indirect private equity and venture capital funds and restricted equity investments, which are securities the Corporation is required to hold for various reasons, primarily Federal Home Loan Bank of Dallas (FHLB) and Federal Reserve Bank (FRB) stock. These investments are accounted for on the cost or equity method and are included in “accrued income and other assets” on the consolidated balance sheets. The investments are individually reviewed for impairment on a quarterly basis. Indirect private equity and venture capital funds are evaluated by comparing the carrying value to the estimated fair value. The amount by which the carrying value exceeds the fair value that is determined to be other-than-temporary impairment is charged to current earnings and the carrying value of the investment is written down accordingly. FHLB and FRB stock are recorded at cost (par value) and evaluated for impairment based on the ultimate recoverability of the par value. If the Corporation does not expect to recover the full par value, the amount by which the par value exceeds the ultimately recoverable value would be charged to current earnings and the carrying value of the investment would be written down accordingly.

Derivative Instruments and Hedging Activities

Derivative instruments are carried at fair value in either “accrued income and other assets” or “accrued expenses and other liabilities” on the consolidated balance sheets. The accounting for changes in the fair value (i.e., gains or losses) of a derivative instrument is determined by whether it has been designated and qualifies as part of a hedging relationship and, further, by the type of hedging relationship. The Corporation presents derivative instruments at fair value in the consolidated balance sheets on a net basis when a right of offset exists, based on transactions with a single counterparty and any cash collateral paid to and/or received from that counterparty for derivative contracts that are subject to legally enforceable master netting arrangements. For derivative instruments designated and qualifying as fair value hedges (i.e., hedging the exposure to changes in the fair value of an asset or a liability or an identified portion thereof that is attributable to a particular risk), the gain or loss on the derivative instrument, as well as the offsetting loss or gain on the hedged item attributable to the hedged risk, are recognized in current earnings during the period of the change in fair values. For derivative instruments that are designated and qualify as cash flow hedges (i.e., hedging the exposure to variability in expected future cash flows that is attributable to a particular risk), the effective portion of the gain or loss on the derivative instrument is reported as a component of other comprehensive income and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. The remaining gain or loss on the derivative instrument in excess of the cumulative change in the present value of future cash flows of the hedged item (i.e., the ineffective portion), if any, is recognized in current earnings during the period of change. For derivative instruments not designated as hedging instruments, the gain or loss is recognized in current earnings during the period of change. In 2013, the Corporation adopted amendments to GAAP which require enhanced disclosures about the nature and effect or potential effect of an entity's rights of setoff associated with its derivative and certain other financial instruments. The required disclosures are provided in Note 8.

For derivatives designated as hedging instruments at inception, the Corporation uses either the short-cut method or applies statistical regression analysis to assess effectiveness. The short-cut method is used for certain fair value hedges of medium and long-term debt issued prior to 2006. This method allows for the assumption of zero hedge ineffectiveness and eliminates the requirement to further assess hedge effectiveness on these transactions. For hedge relationships to which the Corporation does not apply the short-cut method, statistical regression analysis is used at inception and for each reporting period thereafter to assess whether the derivative used has been and is expected to be highly effective in offsetting changes in the fair value or cash flows of the hedged item. All components of each derivative instrument’s gain or loss are included in the assessment of hedge effectiveness. Net hedge ineffectiveness is recorded in “other noninterest income” on the consolidated statements of income.

In 2013, the Financial Accounting Standards Board (FASB) issued an amendment to GAAP which permits the Overnight Index Swap Rate, also referred to as the Fed Funds Effective Swap Rate, to be used as a benchmark interest rate for hedge accounting purposes, effective for qualifying new or re-designated hedging relationships entered into on or after July 17, 2013. The amendment also removed the restriction on using different benchmark rates for similar hedges. While the adoption of this amendment had no impact on the Corporation's financial condition and results of operations, to the extent to Corporation enters into new or re-designates existing hedging relationships in the future, the Overnight Index Swap Rate will be included in the spectrum of available benchmark interest rates for hedge accounting.

Further information on the Corporation’s derivative instruments and hedging activities is included in Note 8.

Short-Term Borrowings

Securities sold under agreements to repurchase are treated as collateralized borrowings and are recorded at amounts equal to the cash received. The contractual terms of the agreements to repurchase may require the Corporation to provide additional collateral if the fair value of the securities underlying the borrowings declines during the term of the agreement.

Financial Guarantees

Certain guarantee contracts or indemnification agreements that contingently require the Corporation, as guarantor, to make payments to the guaranteed party are initially measured at fair value and included in “accrued expenses and other liabilities” on the consolidated balance sheets. The subsequent accounting for the liability depends on the nature of the underlying guarantee. The release from risk is accounted for under a particular guarantee when the guarantee expires or is settled, or by a systematic and rational amortization method.

Further information on the Corporation’s obligations under guarantees is included in Note 8.

Share-Based Compensation

The Corporation recognizes share-based compensation expense using the straight-line method over the requisite service period for all stock awards, including those with graded vesting. The requisite service period is the period an employee is required to provide service in order to vest in the award, which cannot extend beyond the date at which the employee is no longer required to perform any service to receive the share-based compensation (the retirement-eligible date). Certain awards are contingent upon performance conditions, which affect the number of awards ultimately granted. The Corporation periodically evaluates the probable outcome of the performance conditions and makes cumulative adjustments to compensation expense as appropriate.

Further information on the Corporation’s share-based compensation plans is included in Note 16.

Revenue Recognition

The following summarizes the Corporation’s revenue recognition policies as they relate to certain noninterest income line items in the consolidated statements of income.

Service charges on deposit accounts include fees for banking services provided, overdrafts and non-sufficient funds. Revenue is generally recognized in accordance with published deposit account agreements for retail accounts or contractual agreements for commercial accounts.

Fiduciary income includes fees and commissions from asset management, custody, recordkeeeping, investment advisory and other services provided to personal and institutional trust customers. Revenue is recognized on an accrual basis at the time the services are performed and are based on either the market value of the assets managed or the services provided.

Commercial lending fees primarily include fees assessed on the unused portion of commercial lines of credit ("unused commitment fees") and syndication agent fees. Unused commitment fees are recognized when earned. Syndication agent fees are generally recognized when the transaction is complete.

Card fees includes primarily bankcard interchange revenue which is recorded as revenue when earned.

Defined Benefit Pension and Other Postretirement Costs

Defined benefit pension costs are charged to “employee benefits” expense on the consolidated statements of income and are funded consistent with the requirements of federal laws and regulations. Inherent in the determination of defined benefit pension costs are assumptions concerning future events that will affect the amount and timing of required benefit payments under the plans. These assumptions include demographic assumptions such as retirement age and mortality, a compensation rate increase, a discount rate used to determine the current benefit obligation and a long-term expected rate of return on plan assets. Net periodic defined benefit pension expense includes service cost, interest cost based on the assumed discount rate, an expected return on plan assets based on an actuarially derived market-related value of assets, amortization of prior service cost and amortization of net actuarial gains or losses. The market-related value of plan assets is determined by amortizing the current year’s investment gains and losses (the actual investment return net of the expected investment return) over 5 years. The amortization adjustment cannot exceed 10 percent of the fair value of assets. Prior service costs include the impact of plan amendments on the liabilities and are amortized over the future service periods of active employees expected to receive benefits under the plan. Actuarial gains and losses result from experience different from that assumed and from changes in assumptions (excluding asset gains and losses not yet reflected in market-related value). Amortization of actuarial gains and losses is included as a component of net periodic defined benefit pension cost for a year if the actuarial net gain or loss exceeds 10 percent of the greater of the projected benefit obligation or the market-related value of plan assets. If amortization is required, the excess is amortized over the average remaining service period of participating employees expected to receive benefits under the plan.

Postretirement benefits are recognized in “employee benefits” expense on the consolidated statements of income during the average remaining service period of participating employees expected to receive benefits under the plan or the average remaining future lifetime of retired participants currently receiving benefits under the plan.

For further information regarding the Corporation’s defined benefit pension and other postretirement plans, refer to Note 17.

Income Taxes

The provision for income taxes is the sum of income taxes due for the current year and deferred taxes. Deferred taxes arise from temporary differences between the income tax basis and financial accounting basis of assets and liabilities. Deferred tax assets are evaluated for realization based on available evidence of loss carry-back capacity, future reversals of existing taxable temporary differences, and assumptions made regarding future events. A valuation allowance is provided when it is more likely than not that some portion of the deferred tax asset will not be realized.

The Corporation classifies interest and penalties on income tax liabilities in the “provision for income taxes” on the consolidated statements of income.

Earnings Per Share

Basic income per common share and net income per common share are calculated using the two-class method. The two-class method is an earnings allocation formula that determines earnings per share for each share of common stock and participating securities according to dividends declared (distributed earnings) and participation rights in undistributed earnings. Distributed and undistributed earnings are allocated between common and participating security shareholders based on their respective rights to receive dividends. Nonvested share-based payment awards that contain nonforfeitable rights to dividends or dividend equivalents are considered participating securities (e.g., nonvested restricted stock and restricted stock units). Undistributed net losses are not allocated to nonvested restricted shareholders, as these shareholders do not have a contractual obligation to fund the losses incurred by the Corporation. Income attributable to common shares and net income attributable to common shares are then divided by the weighted-average number of common shares outstanding during the period.

Diluted income per common share and net income per common share consider common stock issuable under the assumed exercise of stock options granted under the Corporation’s stock plans and warrants. Diluted income attributable to common shares and net income attributable to common shares are then divided by the total of weighted-average number of common shares and common stock equivalents outstanding during the period.

Statements of Cash Flows

Cash and cash equivalents are defined as those amounts included in “cash and due from banks”, “federal funds sold” and “interest-bearing deposits with banks” on the consolidated balance sheets.

Comprehensive Income (Loss)

The Corporation presents on an annual basis the components of net income and other comprehensive income in two separate, but consecutive statements and presents on an interim basis the components of net income and a total for comprehensive income in one continuous consolidated statement of comprehensive income.

Pending Accounting Pronouncements

In January 2014, the FASB issued ASU No. 2014-01, “Investments-Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Qualified Affordable Housing Projects,” (ASU 2014-01), which enables companies that invest in affordable housing projects that qualify for the low-income housing tax credit (LIHTC) to elect to use the proportional amortization method if certain conditions are met. Under the proportional amortization method, the initial investment cost of the project is amortized in proportion to the amount of tax credits and benefits received, with the results of the investment presented on a net basis as a component of income tax expense (benefit). ASU 2014-01 is effective for interim and annual periods beginning after December 15, 2014, with early adoption permitted. The Corporation is currently evaluating the impact of adopting ASU 2014-01, but does not expect the adoption to have a material effect on the Corporation’s financial condition and results of operations.

Also in January 2014, the FASB issued ASU No. 2014-04, “Receivables – Troubled Debt Restructurings by Creditors (Subtopic 310-40): Reclassification of Residential Real Estate Collateralized Consumer Mortgage Loans upon Foreclosure,” (ASU 2014-04), which clarifies when an in-substance foreclosure or repossession of residential real estate property occurs, requiring a creditor to reclassify the loan to other real estate. According to ASU 2014-04, a consumer mortgage loan should be reclassified to other real estate either upon the creditor obtaining legal title to the real estate collateral or when the borrower voluntarily conveys all interest in the real estate property to the creditor through a deed in lieu of foreclosure or similar legal agreement. ASU 2014-04 also clarifies that a creditor should not delay reclassification when a borrower has a legal right of redemption. The Corporation's current practice is to delay reclassification of foreclosed residential real estate to other real estate until the redemption period, if any, has expired. The Corporation expects to prospectively adopt ASU 2014-04 in the first quarter 2015 and does not expect the adoption to have a material effect on the Corporation's financial condition and results of operations. At December 31, 2013, approximately $5 million of foreclosed residential real estate property subject to a redemption period was classified in nonperforming loans.