Statement of Accounting Policies (Policies)	12 Months Ended
Dec. 31, 2020
Accounting Policies [Abstract]
Business Combinations Policy [Policy Text Block]	Business Combinations Business combinations are accounted for by using the acquisition method of accounting. Under the acquisition method, identifiable assets acquired and liabilities assumed at the acquisition date are measured at their fair values as of that date, and are recognized separately from goodwill. The difference between the purchase price and the fair value of the net assets acquired is recorded as goodwill. Results of operations of the acquired entities are included in the consolidated statement of income from the date of acquisition. Acquisition costs are expensed when incurred.
General	General The following summary of accounting and reporting policies is presented to aid the reader in obtaining a better understanding of the consolidated financial statements of First Commonwealth Financial Corporation and its subsidiaries (“First Commonwealth”) contained in this report. First Commonwealth's subsidiaries include, First Commonwealth Bank ("FCB" or the "Bank"), First Commonwealth Insurance Agency, Inc. ("FCIA"), FRAMAL and First Commonwealth Financial Advisors, Inc ("FCFA"). The financial information is presented in accordance with generally accepted accounting principles and general practice for financial institutions in the United States of America. In preparing financial statements, management is required to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. In addition, these estimates and assumptions affect revenues and expenses in the financial statements and as such, actual results could differ from those estimates. Through its subsidiaries, which include a commercial bank and an insurance agency, First Commonwealth provides a full range of loan, deposit, trust, insurance and personal financial planning services primarily to individuals and small to middle market businesses in 26 counties in central and western Pennsylvania as well as throughout Ohio. First Commonwealth has determined that it has one business segment. First Commonwealth is subject to regulations of certain state and federal agencies. These regulatory agencies periodically examine First Commonwealth for adherence to laws and regulations.
Basis of Presentation	Basis of Presentation The accompanying Consolidated Financial Statements include the accounts of First Commonwealth previously defined above. All material intercompany transactions have been eliminated in consolidation. Certain prior period amounts have been reclassified to conform to the current period's presentation. Equity investments of less than a majority but at least 20% ownership are accounted for by the equity method and classified as “Other assets.” Earnings on these investments are reflected in “Other income” on the Consolidated Statements of Income, as appropriate, in the period earned.
Securities	Securities Debt securities that First Commonwealth has the positive intent and ability to hold to maturity are classified as securities held to maturity and are reported at amortized cost adjusted for amortization of premium and accretion of discount on a level yield basis. Debt and equity securities that are bought and held principally for the purpose of selling them in the near term are to be classified as trading securities and reported at fair value, with unrealized gains and losses included in earnings. Debt securities not classified as either held-to-maturity securities or trading securities are classified as securities available for sale and are reported at fair value, with unrealized gains and losses that are not related to impairment excluded from earnings and reported as a component of other comprehensive income, which is included in shareholders’ equity, net of deferred taxes. First Commonwealth has securities classified as held to maturity and available for sale and does not engage in trading activities. First Commonwealth utilizes the specific identification method to determine the net gain or loss on debt securities and the average cost method to determine the net gain or loss on the equity securities. First Commonwealth conducts a comprehensive review of the investment portfolio on a quarterly basis to evaluate for expected credit losses. When evaluating available-for-sale securities, management first considers whether we intend to sell the security, or if it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis. If there is intent to sell, the security's amortized cost is written down to fair value through income. Otherwise, available-for-sale securities whose market values have fallen below their book value are evaluated at the issuer-specific level to determine if the decline in value is a result of credit losses. Issuer-specific securities include obligations of U.S. Government agencies and sponsored enterprises, single issue trust preferred securities, corporate debentures and obligations of states and political subdivisions. Further analysis of these securities includes a review of research reports, analysts’ recommendations, credit rating changes, news stories, annual reports, impact of interest rate changes and any other relevant information pertaining to the affected security. Any loss not determined to be a credit loss is recorded as a reduction to shareholders equity, through other comprehensive income. Held-to-maturity securities are evaluated for impairment on a quarterly basis using historical probability of default and loss given default information specific to the investment category. If this evaluation determines that credit losses exist an allowance for credit loss is recorded and included in earnings as a component of credit loss expense.
Financing Receivable, Held-for-sale [Policy Text Block]	Mortgage Loans Held for SaleCertain residential mortgage loans are originated for sale in the secondary mortgage loan market with the majority sold with servicing rights released. These loans are classified as loans held for sale and are carried at the estimated market value on an aggregate basis. Market value is determined on the basis of rates obtained in the respective secondary market for the type of loan held for sale. Loans are generally sold at a premium or discount from the carrying amount of the loan. Such premium or discount is recognized at the date of sale. Gain or loss on the sale of loans is recorded in non-interest income at the time consideration is received and all other criteria for sales treatment have been met.
Loans	Loans Loans are carried at the principal amount outstanding. Interest is accrued as earned. Loans held for sale are carried at the lower of cost or fair market value determined on an individual basis. First Commonwealth considers a loan to be past due and still accruing interest when payment of interest or principal is contractually past due but the loan is both well secured and in the process of collection. For installment, mortgage, term and other loans with amortizing payments that are scheduled monthly, 90 days past due is reached when four monthly payments are due and unpaid. For demand, time and other multi-payment obligations with payments scheduled other than monthly, delinquency status is calculated using number of days instead of number of payments. Revolving credit loans, including personal credit lines and home equity lines, are considered to be 90 days past due when the borrower has not made the minimum payment for four monthly cycles. A loan is placed in nonaccrual status when, based on current information and events, it is probable that First Commonwealth will be unable to fully collect principal or interest due according to the contractual terms of the loan. A loan is also placed in nonaccrual status when, based on regulatory definitions, the loan is maintained on a “cash basis” due to the weakened financial condition of the borrower. When a determination is made to place a loan in nonaccrual status, all accrued and unpaid interest is reversed. Nonaccrual loans are restored to accrual status when, based on a sustained period of repayment by the borrower in accordance with the contractual terms of the loan, First Commonwealth expects repayment of the remaining contractual principal and interest or when the loan otherwise becomes well-secured and in the process of collection. First Commonwealth considers a loan to be a troubled debt restructured loan when the loan terms have been renegotiated to provide a reduction or deferral of principal or interest as a result of the financial difficulties experienced by the borrower, who could not obtain comparable terms from alternate financing sources. Troubled debt restructured loans are considered to be nonperforming loans. A loan is considered to be nonperforming when, based on current information and events, it is expected that First Commonwealth will be unable to collect principal or interest that is due in accordance with contractual terms of the loan. Nonperforming loans include nonaccrual loans and troubled debt restructured loans. Loan impairment is measured based on the present value of expected cash flows discounted at the loan’s effective interest rate or, as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent. For loans other than those that First Commonwealth expects repayment through liquidation of the collateral, when the remaining recorded investment in the loan is less than or equal to the present value of the expected cash flows, income is applied as a reduction to loan principal rather than interest income. Loans deemed uncollectible are charged off through the allowance for credit losses. Factors considered in assessing ultimate collectability include past due status, financial condition of the borrower, collateral values and debt covenants including secondary sources of repayment by guarantors. Payments received on previously charged off loans are recorded as recoveries in the allowance for credit losses. Acquired loans are recorded at estimated fair value on the date of acquisition with no carryover of the related allowance for credit losses. The fair value of acquired loans is determined by estimating the principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The estimated fair value considers factors such as loan term, internal risk rating, delinquency status, prepayment rates, estimated value of the underlying collateral and the current interest rate environment.
Loan Fees	Loan Fees Loan origination and commitment fees, net of associated direct costs, are deferred and the net amount is amortized as an adjustment to the related loan yield on the interest method, generally over the contractual life of the related loans or commitments.
Other Real Estate Owned	Other Real Estate OwnedReal estate, other than bank premises, is recorded at fair value less estimated selling costs at the time of acquisition. After that time, other real estate is carried at the lower of cost or fair value less estimated costs to sell. Fair value is determined based on an independent appraisal. Expenses related to holding the property and rental income earned on the property are generally reflected in earnings in the current period. Depreciation is not recorded on the other real estate owned properties.
Allowance for Credit Losses	Allowance for Credit Losses for Loans On January 1, 2020, First Commonwealth adopted ASU 2016-13 Financial Instruments - Credit Losses ("Topic 326"), which replaces the incurred loss methodology for determining our allowance for credit losses and related provision for credit losses with an expected loss methodology that is referred to as the Current Expected Credit Loss ("CECL") model. The measurement of expected credit losses under the CECL methodology is applicable to financial assets measured at amortized cost, including our loans. We adopted ASU 2016-13 using the modified retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures and recognized a cumulative effect adjustment reducing retained earnings by $11.2 million, net of tax. First Commonwealth made the accounting policy election to exclude accrued interest from the allowance for credit loss calculation because these balances are written off or reversed when a loan is placed in non-accrual status. In connection with our adoption of ASU 2016-13, we made changes to our loan portfolio segments, as compared to loan segments under the incurred model, to align with the methodology applied in determining the allowance under CECL. Refer to Note 9, " Loans and Allowance for Credit Losses" for further discussion of these portfolio segments. Under CECL, the allowance for credit losses is calculated by pooling loans of similar credit risk characteristics and applying a discounted cash flow methodology after incorporating probability of default and loss given default estimates. Probability of default represents an estimate of the likelihood of default and loss given default measures the expected loss upon default. Inputs impacting the expected losses includes a forecast of macroeconomic factors, using a weighted forecast from a nationally recognized firm. Our model incorporates a one-year forecast of macroeconomic factors, after which the factors revert back to the historical mean over a one-year period. Results for reporting periods beginning after January 1, 2020 are presented under ASU 2016-13 while prior period amounts continue to be reported in accordance with previously applicable GAAP. Prior to January 1, 2020, the allowance for credit losses was estimated based on managements assessment of probable estimated losses. In addition to loan category, the major loan classifications used in the allowance for credit losses calculation include pass, other assets especially mentioned (“OAEM”), substandard and doubtful. Additional information related to these credit quality categories is provided in Note 9, "Loans and Allowance for Credit Losses." Under this incurred methodology, the allowance calculation uses net historical charge-off trends to estimate probable unconfirmed losses for each loan category. A multiplier known as the emergence factor is applied to the historical loss rates for non-criticized loans. The emergence factor is calculated by loan category and represents the average time period from when a loss is incurred until the bank experiences a charge-off against the loan. Before applying the adjusted historical loss experience percentages, loan balances are reduced by the portion of the loan balances which are subject to guarantee by a government agency. Under the incurred model, loans acquired with evidence of credit deterioration were evaluated and not considered to be significant. The premium or discount estimated through the loan fair value calculation is recognized in interest income on a level yield or straight-line basis over the remaining contractual life of the loans. Additional credit deterioration on acquired loans, in excess of the original credit discount embedded in the fair value determination on the date of acquisition, was recognized in the allowance for credit losses through the provision for loan losses. As part of both CECL and the incurred methodology, all nonperforming credits, which includes nonaccrual loans and all troubled debt restructurings ("TDRs"), in excess of $250 thousand are individually evaluated on a quarterly basis. A specific reserve is established for individually evaluated loans in an amount equal to the total amount of estimated losses for the loans that are reviewed. Based on this reserve as a percentage of reviewed loan balances, a reserve is also established for the nonperforming loan balances that are not individually reviewed. An additional component of the allowance is determined by management based on a qualitative analysis of certain factors related to portfolio risks that are not incorporated in the calculated model. Factors considered by management include lending practices, ability and experience of the credit staff, the overall lending environment and external factors such as the regulatory environment and competition. Portfolio risks include unusual changes or recent trends in specific portfolios such as unexpected changes in the trends or levels of delinquency. No matter how detailed an analysis of potential credit losses is performed, these estimates are inherently imprecise. Management must make estimates using assumptions and information that is often subjective and changes rapidly.
Allowance for Off-Balance Sheet Credit Exposures	Allowance for Off-Balance Sheet Credit ExposuresFirst Commonwealth maintains an allowance for off-balance sheet credit exposure at a level deemed sufficient to absorb losses that are inherent to off-balance sheet credit risk. Off-balance sheet credit exposure includes commitments to extend credit, standby letters of credit and commercial letters of credit. The Company’s methodology for assessing the appropriateness of the allowance for off-balance sheet credit exposure consists of analysis of historical usage trends. The calculation begins with historical usage trends related to lines of credit as well as letters of credit and then utilizes those figures to determine the probable usage of available lines. These values are then adjusted by the expected loss percentage calculated for comparable loan categories as part of the allowance for credit losses for loans. This amount is adjusted quarterly and any change to the allowance is reported as part of provision expense on the Consolidated Statements of Income. The allowance for off-balance sheet credit exposures is reflected in "Other Liabilities" in the Consolidated Statements of Finance Condition.
Bank Owned Life Insurance	Bank Owned Life InsuranceFirst Commonwealth and the banks that First Commonwealth has acquired have purchased insurance on the lives of certain groups of employees. The policies accumulate asset values to meet future liabilities, including the payment of employee benefits such as health care. Increases in the cash surrender value are recorded as non-interest income in the Consolidated Statements of Income and cash receipts and disbursements are included in "Operating Activities" in the Consolidated Statements of Cash Flows. Under some of these policies, the beneficiaries receive a portion of the death benefit.
Premises and Equipment	Premises, Equipment and Lease Commitments Premises and equipment are carried at cost less accumulated depreciation on First Commonwealth’s Consolidated Statements of Financial Condition. Depreciation is computed on the straight-line and accelerated methods over the estimated useful life of the asset. A straight-line depreciation method was used for substantially all furniture and equipment. The straight-line depreciation method was used for buildings and improvements. Charges for maintenance and repairs are expensed as incurred. Leasehold improvements are expensed over the term of the lease or the estimated useful life of the improvement, whichever is shorter. Software costs are amortized on a straight-line basis over a period not to exceed 7 years
Goodwill	Goodwill Intangible assets resulting from acquisitions under the purchase method of accounting consist of goodwill and other intangible assets (see “Other Intangible Assets” section below). Goodwill is not amortized and is subject to at least annual assessments for impairment. First Commonwealth reviews goodwill annually and again at any quarter-end if a material event occurs during the quarter that may affect goodwill. When circumstances indicate that it is more likely than not that fair value is less than carrying value, a triggering event has occurred and a quantitative impairment test is performed. Goodwill is evaluated for potential impairment by determining if our fair value has fallen below carrying value.
Other Intangible Assets	Other Intangible Assets Other intangible assets consist of core deposits and customer lists obtained through acquisitions. Core deposit intangibles are amortized over their estimated lives using the present value of the benefit of the core deposits and straight-line methods of amortization. Customer list intangibles are amortized over the expected lives using expected cash flows based on retention of the customer base. These intangibles are evaluated for impairment on an annual basis and when events or changes in circumstances indicate that the carrying amount may not be recoverable.
Accounting for the Impairment of Long-Lived Assets	Accounting for the Impairment of Long-Lived Assets First Commonwealth reviews long-lived assets, such as premises and equipment and intangibles, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. These changes in circumstances may include a significant decrease in the market value of an asset or the extent or manner in which an asset is used. If there is an indication that the carrying amount of an asset may not be recoverable, future undiscounted cash flows expected to result from the use of the asset are estimated. If the sum of the expected cash flows is less than the carrying value of the asset, a loss is recognized for the difference between the carrying value and fair value of the asset. Long-lived assets classified as held for sale are measured at the lower of their carrying amount or fair value less cost to sell. Depreciation or amortization is discontinued on long-lived assets classified as held for sale.
Income Taxes	Income TaxesFirst Commonwealth records taxes in accordance with the asset and liability method of FASB ASC Topic 740, “Income Taxes,” whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amount of existing assets and liabilities and their respective tax bases given the provisions of the enacted tax laws. Deferred tax assets are reduced, if necessary, by the amount of such benefits that are more likely than not expected to be realized based upon available evidence. In accordance with FASB ASC Topic 740, interest or penalties incurred for taxes will be recorded as a component of noninterest expense.
Comprehensive Income Disclosures	Comprehensive Income Disclosures“Other Comprehensive Income” (comprehensive income, excluding net income) includes the after-tax effect of changes in unrealized holding gains and losses on available-for-sale securities, changes in the funded status of defined benefit postretirement plans and changes in the fair value of cash flow hedges. Comprehensive income is reported in the accompanying Consolidated Statements of Comprehensive Income, net of tax.
Cash and Cash Equivalents	Cash and Cash Equivalents For purposes of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks, federal funds sold and interest-bearing bank deposits. Generally, federal funds are sold for one-day periods.
Derivatives and Hedging Activities	Derivatives and Hedging Activities First Commonwealth accounts for derivative instruments and hedging activities in accordance with FASB ASC Topic 815, “Derivatives and Hedging.” All derivatives are evaluated at inception as to whether or not they are hedging or non-hedging activities, and appropriate documentation is maintained to support the final determination. First Commonwealth recognizes all derivatives as either assets or liabilities on the Consolidated Statements of Financial Condition and measures those instruments at fair value. For derivatives designated as fair value hedges, changes in the fair value of the derivative and the hedged item related to the hedged risk are recognized in earnings. Any hedge ineffectiveness would be recognized in the income statement line item pertaining to the hedged item. For derivatives designated as cash flow hedges, changes in fair value of the effective portion of the cash flow hedges are reported in other comprehensive income ("OCI"). When the cash flows associated with the hedged item are realized, the gain or loss included in OCI is recognized in the Consolidated Statement of Income. When First Commonwealth purchases a portion of a commercial loan that has an existing interest rate swap, it enters a Risk Participation Agreement with the counterparty and assumes the credit risk of the loan customer related to the swap. Any fee paid to First Commonwealth as a result of the risk participation agreement is offset by credit risk of the counterparties and is recognized in the income statement. Credit risk on the risk participation agreements is determined after considering the risk rating, probability of default and loss given default of the counterparties. Management periodically reviews contracts from various functional areas of First Commonwealth to identify potential derivatives embedded within selected contracts. As of December 31, 2020, First Commonwealth has interest rate derivative positions that are designated as hedging instruments and others that are not designated as hedging instruments. See Note 7, “Derivatives,” for a description of these instruments.
Earnings Per Common Share	Earnings Per Common Share Basic earnings per share excludes dilution and is computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding for the period. Diluted earnings per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of the entity. For all periods presented, the dilutive effect on average shares outstanding is the result of unvested restricted stock grants.
Fair Value Measurements	Fair Value Measurements In accordance with FASB ASC Topic 820, “Fair Value Measurements and Disclosures,” First Commonwealth groups financial assets and financial liabilities measured at fair value into three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are: •Level 1—Valuations for assets and liabilities traded in active exchange markets, such as the New York Stock Exchange. Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities. •Level 2—Valuations for assets and liabilities traded in less active dealer or broker markets. Valuations are obtained for identical or comparable assets or liabilities from alternative pricing sources with reasonable levels of price transparency. Level 2 securities include U.S. Government securities issued by Agencies and Sponsored Enterprises, Obligations of States and Political Subdivisions, certain corporate securities, FHLB stock, loans held for sale, interest rate derivatives that include interest rate swaps, risk participation agreements and foreign currency contracts, certain other real estate owned and certain nonperforming loans. •Level 3—Valuations for assets and liabilities that are derived from other valuation methodologies, including option pricing models, discounted cash flow models and similar techniques, and not based on market exchange, dealer or broker traded transactions. If the inputs used to provide the evaluation are unobservable and/or there is very little, if any, market activity for the security or similar securities, the securities would be considered Level 3 securities. Level 3 valuations incorporate certain assumptions and projections in determining the fair value assigned to such assets or liabilities. The assets included in Level 3 are nonmarketable equity investments, certain other real estate owned and certain nonperforming loans. In general, fair values of financial instruments are based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon pricing models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality and our creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. See Note 17 “Fair Values of Assets and Liabilities” for additional information.
Revenue from Contract with Customer [Policy Text Block]	Revenue from Contracts with Customers First Commonwealth records revenue from contracts with customers in accordance with ASC Topic 606, “Revenue from Contracts with Customers” (“Topic 606”). Under Topic 606, the Company must identify the contract with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the Company satisfies a performance obligation. A significant component of the Company's revenue, net interest earned on financial assets and liabilities, is excluded from the scope of Topic 606. First Commonwealth generally fully satisfies its performance obligations on its contracts with customers as services are rendered and the transaction prices are typically fixed; charged either on a periodic basis or based on activity. Because performance obligations are satisfied as services are rendered and the transaction prices are fixed, the Company has made no significant judgments in applying the revenue guidance prescribed in Topic 606 that affect the determination of the amount and timing of revenue from contracts with customers.

Statement of Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Business Combinations Policy [Policy Text Block]

Business Combinations

Business combinations are accounted for by using the acquisition method of accounting. Under the acquisition method, identifiable assets acquired and liabilities assumed at the acquisition date are measured at their fair values as of that date, and are recognized separately from goodwill. The difference between the purchase price and the fair value of the net assets acquired is recorded as goodwill. Results of operations of the acquired entities are included in the consolidated statement of income from the date of acquisition. Acquisition costs are expensed when incurred.

General

The following summary of accounting and reporting policies is presented to aid the reader in obtaining a better understanding of the consolidated financial statements of First Commonwealth Financial Corporation and its subsidiaries (“First Commonwealth”) contained in this report. First Commonwealth's subsidiaries include, First Commonwealth Bank ("FCB" or the "Bank"), First Commonwealth Insurance Agency, Inc. ("FCIA"), FRAMAL and First Commonwealth Financial Advisors, Inc ("FCFA").

The financial information is presented in accordance with generally accepted accounting principles and general practice for financial institutions in the United States of America. In preparing financial statements, management is required to make estimates and assumptions that affect the reported amount of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements. In addition, these estimates and assumptions affect revenues and expenses in the financial statements and as such, actual results could differ from those estimates.

Through its subsidiaries, which include a commercial bank and an insurance agency, First Commonwealth provides a full range of loan, deposit, trust, insurance and personal financial planning services primarily to individuals and small to middle market businesses in 26 counties in central and western Pennsylvania as well as throughout Ohio. First Commonwealth has determined that it has one business segment.

First Commonwealth is subject to regulations of certain state and federal agencies. These regulatory agencies periodically examine First Commonwealth for adherence to laws and regulations.

Basis of Presentation

The accompanying Consolidated Financial Statements include the accounts of First Commonwealth previously defined above. All material intercompany transactions have been eliminated in consolidation. Certain prior period amounts have been reclassified to conform to the current period's presentation.

Equity investments of less than a majority but at least 20% ownership are accounted for by the equity method and classified as “Other assets.” Earnings on these investments are reflected in “Other income” on the Consolidated Statements of Income, as appropriate, in the period earned.

Securities

Debt securities that First Commonwealth has the positive intent and ability to hold to maturity are classified as securities held to maturity and are reported at amortized cost adjusted for amortization of premium and accretion of discount on a level yield basis. Debt and equity securities that are bought and held principally for the purpose of selling them in the near term are to be classified as trading securities and reported at fair value, with unrealized gains and losses included in earnings. Debt securities not classified as either held-to-maturity securities or trading securities are classified as securities available for sale and are reported at fair value, with unrealized gains and losses that are not related to impairment excluded from earnings and reported as a component of other comprehensive income, which is included in shareholders’ equity, net of deferred taxes.

First Commonwealth has securities classified as held to maturity and available for sale and does not engage in trading activities. First Commonwealth utilizes the specific identification method to determine the net gain or loss on debt securities and the average cost method to determine the net gain or loss on the equity securities.

First Commonwealth conducts a comprehensive review of the investment portfolio on a quarterly basis to evaluate for expected credit losses. When evaluating available-for-sale securities, management first considers whether we intend to sell the security, or if it is more likely than not that we will be required to sell the security before recovery of its amortized cost basis. If there is intent to sell, the security's amortized cost is written down to fair value through income. Otherwise, available-for-sale securities whose market values have fallen below their book value are evaluated at the issuer-specific level to determine if the decline in value is a result of credit losses. Issuer-specific securities include obligations of U.S. Government agencies and sponsored enterprises, single issue trust preferred securities, corporate debentures and obligations of states and political subdivisions. Further analysis of these securities includes a review of research reports, analysts’ recommendations, credit rating changes, news stories, annual reports, impact of interest rate changes and any other relevant information pertaining to the affected security. Any loss not determined to be a credit loss is recorded as a reduction to shareholders equity, through other comprehensive income. Held-to-maturity securities are evaluated for impairment on a quarterly basis using historical probability of default and loss given default information specific to the investment category. If this evaluation determines that credit losses exist an allowance for credit loss is recorded and included in earnings as a component of credit loss expense.

Financing Receivable, Held-for-sale [Policy Text Block]

Mortgage Loans Held for SaleCertain residential mortgage loans are originated for sale in the secondary mortgage loan market with the majority sold with servicing rights released. These loans are classified as loans held for sale and are carried at the estimated market value on an aggregate basis. Market value is determined on the basis of rates obtained in the respective secondary market for the type of loan held for sale. Loans are generally sold at a premium or discount from the carrying amount of the loan. Such premium or discount is recognized at the date of sale. Gain or loss on the sale of loans is recorded in non-interest income at the time consideration is received and all other criteria for sales treatment have been met.

Loans

Loans are carried at the principal amount outstanding. Interest is accrued as earned. Loans held for sale are carried at the lower of cost or fair market value determined on an individual basis.

First Commonwealth considers a loan to be past due and still accruing interest when payment of interest or principal is contractually past due but the loan is both well secured and in the process of collection. For installment, mortgage, term and other loans with amortizing payments that are scheduled monthly, 90 days past due is reached when four monthly payments are due and unpaid. For demand, time and other multi-payment obligations with payments scheduled other than monthly, delinquency status is calculated using number of days instead of number of payments. Revolving credit loans, including personal credit lines and home equity lines, are considered to be 90 days past due when the borrower has not made the minimum payment for four monthly cycles.

A loan is placed in nonaccrual status when, based on current information and events, it is probable that First Commonwealth will be unable to fully collect principal or interest due according to the contractual terms of the loan. A loan is also placed in nonaccrual status when, based on regulatory definitions, the loan is maintained on a “cash basis” due to the weakened financial condition of the borrower. When a determination is made to place a loan in nonaccrual status, all accrued and unpaid interest is reversed. Nonaccrual loans are restored to accrual status when, based on a sustained period of repayment by the borrower in accordance with the contractual terms of the loan, First Commonwealth expects repayment of the remaining contractual principal and interest or when the loan otherwise becomes well-secured and in the process of collection.

First Commonwealth considers a loan to be a troubled debt restructured loan when the loan terms have been renegotiated to provide a reduction or deferral of principal or interest as a result of the financial difficulties experienced by the borrower, who could not obtain comparable terms from alternate financing sources. Troubled debt restructured loans are considered to be nonperforming loans.

A loan is considered to be nonperforming when, based on current information and events, it is expected that First Commonwealth will be unable to collect principal or interest that is due in accordance with contractual terms of the loan. Nonperforming loans include nonaccrual loans and troubled debt restructured loans. Loan impairment is measured based on the present value of expected cash flows discounted at the loan’s effective interest rate or, as a practical expedient, at the loan’s observable market price or the fair value of the collateral if the loan is collateral dependent.

For loans other than those that First Commonwealth expects repayment through liquidation of the collateral, when the remaining recorded investment in the loan is less than or equal to the present value of the expected cash flows, income is applied as a reduction to loan principal rather than interest income.

Loans deemed uncollectible are charged off through the allowance for credit losses. Factors considered in assessing ultimate collectability include past due status, financial condition of the borrower, collateral values and debt covenants including secondary sources of repayment by guarantors. Payments received on previously charged off loans are recorded as recoveries in the allowance for credit losses.

Acquired loans are recorded at estimated fair value on the date of acquisition with no carryover of the related allowance for credit losses. The fair value of acquired loans is determined by estimating the principal and interest cash flows expected to be collected on the loans and discounting those cash flows at a market rate of interest. The estimated fair value considers factors such as loan term, internal risk rating, delinquency status, prepayment rates, estimated value of the underlying collateral and the current interest rate environment.

Loan Fees

Loan origination and commitment fees, net of associated direct costs, are deferred and the net amount is amortized as an adjustment to the related loan yield on the interest method, generally over the contractual life of the related loans or commitments.

Other Real Estate Owned

Other Real Estate OwnedReal estate, other than bank premises, is recorded at fair value less estimated selling costs at the time of acquisition. After that time, other real estate is carried at the lower of cost or fair value less estimated costs to sell. Fair value is determined based on an independent appraisal. Expenses related to holding the property and rental income earned on the property are generally reflected in earnings in the current period. Depreciation is not recorded on the other real estate owned properties.

Allowance for Credit Losses

Allowance for Credit Losses for Loans

On January 1, 2020, First Commonwealth adopted ASU 2016-13 Financial Instruments - Credit Losses ("Topic 326"), which replaces the incurred loss methodology for determining our allowance for credit losses and related provision for credit losses with an expected loss methodology that is referred to as the Current Expected Credit Loss ("CECL") model. The measurement of expected credit losses under the CECL methodology is applicable to financial assets measured at amortized cost, including our loans.

We adopted ASU 2016-13 using the modified retrospective method for all financial assets measured at amortized cost and off-balance sheet credit exposures and recognized a cumulative effect adjustment reducing retained earnings by $11.2 million, net of tax. First Commonwealth made the accounting policy election to exclude accrued interest from the allowance for credit loss calculation because these balances are written off or reversed when a loan is placed in non-accrual status.

In connection with our adoption of ASU 2016-13, we made changes to our loan portfolio segments, as compared to loan segments under the incurred model, to align with the methodology applied in determining the allowance under CECL. Refer to Note 9, " Loans and Allowance for Credit Losses" for further discussion of these portfolio segments.

Under CECL, the allowance for credit losses is calculated by pooling loans of similar credit risk characteristics and applying a discounted cash flow methodology after incorporating probability of default and loss given default estimates. Probability of default represents an estimate of the likelihood of default and loss given default measures the expected loss upon default. Inputs impacting the expected losses includes a forecast of macroeconomic factors, using a weighted forecast from a nationally recognized firm. Our model incorporates a one-year forecast of macroeconomic factors, after which the factors revert back to the historical mean over a one-year period.

Results for reporting periods beginning after January 1, 2020 are presented under ASU 2016-13 while prior period amounts continue to be reported in accordance with previously applicable GAAP.

Prior to January 1, 2020, the allowance for credit losses was estimated based on managements assessment of probable estimated losses. In addition to loan category, the major loan classifications used in the allowance for credit losses calculation include pass, other assets especially mentioned (“OAEM”), substandard and doubtful. Additional information related to these credit quality categories is provided in Note 9, "Loans and Allowance for Credit Losses." Under this incurred methodology, the allowance calculation uses net historical charge-off trends to estimate probable unconfirmed losses for each loan category.

A multiplier known as the emergence factor is applied to the historical loss rates for non-criticized loans. The emergence factor

is calculated by loan category and represents the average time period from when a loss is incurred until the bank experiences a

charge-off against the loan. Before applying the adjusted historical loss experience percentages, loan balances are reduced by

the portion of the loan balances which are subject to guarantee by a government agency.

Under the incurred model, loans acquired with evidence of credit deterioration were evaluated and not considered to be significant. The premium or discount estimated through the loan fair value calculation is recognized in interest income on a level yield or straight-line basis over the remaining contractual life of the loans. Additional credit deterioration on acquired loans, in excess of the original credit discount embedded in the fair value determination on the date of acquisition, was recognized in the allowance for credit losses through the provision for loan losses.

As part of both CECL and the incurred methodology, all nonperforming credits, which includes nonaccrual loans and all troubled debt restructurings ("TDRs"), in excess of $250 thousand are individually evaluated on a quarterly basis. A specific reserve is established for individually evaluated loans in an amount equal to the total amount of estimated losses for the loans that are reviewed. Based on this reserve as a percentage of reviewed loan balances, a reserve is also established for the nonperforming loan balances that are not individually reviewed.

An additional component of the allowance is determined by management based on a qualitative analysis of certain factors related to portfolio risks that are not incorporated in the calculated model. Factors considered by management include lending practices, ability and experience of the credit staff, the overall lending environment and external factors such as the regulatory environment and competition. Portfolio risks include unusual changes or recent trends in specific portfolios such as unexpected changes in the trends or levels of delinquency. No matter how detailed an analysis of potential credit losses is performed, these estimates are inherently imprecise. Management must make estimates using assumptions and information that is often subjective and changes rapidly.

Allowance for Off-Balance Sheet Credit Exposures

Allowance for Off-Balance Sheet Credit ExposuresFirst Commonwealth maintains an allowance for off-balance sheet credit exposure at a level deemed sufficient to absorb losses that are inherent to off-balance sheet credit risk. Off-balance sheet credit exposure includes commitments to extend credit, standby letters of credit and commercial letters of credit. The Company’s methodology for assessing the appropriateness of the allowance for off-balance sheet credit exposure consists of analysis of historical usage trends. The calculation begins with historical usage trends related to lines of credit as well as letters of credit and then utilizes those figures to determine the probable usage of available lines. These values are then adjusted by the expected loss percentage calculated for comparable loan categories as part of the allowance for credit losses for loans. This amount is adjusted quarterly and any change to the allowance is reported as part of provision expense on the Consolidated Statements of Income. The allowance for off-balance sheet credit exposures is reflected in "Other Liabilities" in the Consolidated Statements of Finance Condition.

Bank Owned Life Insurance

Bank Owned Life InsuranceFirst Commonwealth and the banks that First Commonwealth has acquired have purchased insurance on the lives of certain groups of employees. The policies accumulate asset values to meet future liabilities, including the payment of employee benefits such as health care. Increases in the cash surrender value are recorded as non-interest income in the Consolidated Statements of Income and cash receipts and disbursements are included in "Operating Activities" in the Consolidated Statements of Cash Flows. Under some of these policies, the beneficiaries receive a portion of the death benefit.

Premises and Equipment

Premises, Equipment and Lease Commitments

Premises and equipment are carried at cost less accumulated depreciation on First Commonwealth’s Consolidated Statements of Financial Condition. Depreciation is computed on the straight-line and accelerated methods over the estimated useful life of the asset. A straight-line depreciation method was used for substantially all furniture and equipment. The straight-line depreciation method was used for buildings and improvements. Charges for maintenance and repairs are expensed as incurred. Leasehold improvements are expensed over the term of the lease or the estimated useful life of the improvement, whichever is shorter.

Software costs are amortized on a straight-line basis over a period not to exceed 7 years

Goodwill

Intangible assets resulting from acquisitions under the purchase method of accounting consist of goodwill and other intangible assets (see “Other Intangible Assets” section below). Goodwill is not amortized and is subject to at least annual assessments for impairment. First Commonwealth reviews goodwill annually and again at any quarter-end if a material event occurs during the quarter that may affect goodwill. When circumstances indicate that it is more likely than not that fair value is less than carrying value, a triggering event has occurred and a quantitative impairment test is performed. Goodwill is evaluated for potential impairment by determining if our fair value has fallen below carrying value.

Other Intangible Assets

Other intangible assets consist of core deposits and customer lists obtained through acquisitions. Core deposit intangibles are amortized over their estimated lives using the present value of the benefit of the core deposits and straight-line methods of amortization. Customer list intangibles are amortized over the expected lives using expected cash flows based on retention of the customer base. These intangibles are evaluated for impairment on an annual basis and when events or changes in circumstances indicate that the carrying amount may not be recoverable.

Accounting for the Impairment of Long-Lived Assets

First Commonwealth reviews long-lived assets, such as premises and equipment and intangibles, for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. These changes in circumstances may include a significant decrease in the market value of an asset or the extent or manner in which an asset is used. If there is an indication that the carrying amount of an asset may not be recoverable, future undiscounted cash flows expected to result from the use of the asset are estimated. If the sum of the expected cash flows is less than the carrying value of the asset, a loss is recognized for the difference between the carrying value and fair value of the asset. Long-lived assets classified as held for sale are measured at the lower of their carrying amount or fair value less cost to sell. Depreciation or amortization is discontinued on long-lived assets classified as held for sale.

Income Taxes

Income TaxesFirst Commonwealth records taxes in accordance with the asset and liability method of FASB ASC Topic 740, “Income Taxes,” whereby deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amount of existing assets and liabilities and their respective tax bases given the provisions of the enacted tax laws. Deferred tax assets are reduced, if necessary, by the amount of such benefits that are more likely than not expected to be realized based upon available evidence. In accordance with FASB ASC Topic 740, interest or penalties incurred for taxes will be recorded as a component of noninterest expense.

Comprehensive Income Disclosures

Comprehensive Income Disclosures“Other Comprehensive Income” (comprehensive income, excluding net income) includes the after-tax effect of changes in unrealized holding gains and losses on available-for-sale securities, changes in the funded status of defined benefit postretirement plans and changes in the fair value of cash flow hedges. Comprehensive income is reported in the accompanying Consolidated Statements of Comprehensive Income, net of tax.

Cash and Cash Equivalents

For purposes of reporting cash flows, cash and cash equivalents include cash on hand, amounts due from banks, federal funds sold and interest-bearing bank deposits. Generally, federal funds are sold for one-day periods.

Derivatives and Hedging Activities

First Commonwealth accounts for derivative instruments and hedging activities in accordance with FASB ASC Topic 815, “Derivatives and Hedging.” All derivatives are evaluated at inception as to whether or not they are hedging or non-hedging activities, and appropriate documentation is maintained to support the final determination. First Commonwealth recognizes all derivatives as either assets or liabilities on the Consolidated Statements of Financial Condition and measures those instruments at fair value. For derivatives designated as fair value hedges, changes in the fair value of the derivative and the hedged item related to the hedged risk are recognized in earnings. Any hedge ineffectiveness would be recognized in the income statement line item pertaining to the hedged item. For derivatives designated as cash flow hedges, changes in fair value of the effective portion of the cash flow hedges are reported in other comprehensive income ("OCI"). When the cash flows associated with the hedged item are realized, the gain or loss included in OCI is recognized in the Consolidated Statement of Income.

When First Commonwealth purchases a portion of a commercial loan that has an existing interest rate swap, it enters a Risk Participation Agreement with the counterparty and assumes the credit risk of the loan customer related to the swap. Any fee paid to First Commonwealth as a result of the risk participation agreement is offset by credit risk of the counterparties and is recognized in the income statement. Credit risk on the risk participation agreements is determined after considering the risk rating, probability of default and loss given default of the counterparties.

Management periodically reviews contracts from various functional areas of First Commonwealth to identify potential derivatives embedded within selected contracts. As of December 31, 2020, First Commonwealth has interest rate derivative positions that are designated as hedging instruments and others that are not designated as hedging instruments. See Note 7, “Derivatives,” for a description of these instruments.

Earnings Per Common Share

Basic earnings per share excludes dilution and is computed by dividing income available to common shareholders by the weighted-average number of common shares outstanding for the period.

Diluted earnings per share reflects the potential dilution that could occur if securities or other contracts to issue common stock were exercised or converted into common stock or resulted in the issuance of common stock that then shared in the earnings of

the entity. For all periods presented, the dilutive effect on average shares outstanding is the result of unvested restricted stock grants.

Fair Value Measurements

In accordance with FASB ASC Topic 820, “Fair Value Measurements and Disclosures,” First Commonwealth groups financial assets and financial liabilities measured at fair value into three levels, based on the markets in which the assets and liabilities are traded and the reliability of the assumptions used to determine fair value. These levels are:

•Level 1—Valuations for assets and liabilities traded in active exchange markets, such as the New York Stock Exchange. Valuations are obtained from readily available pricing sources for market transactions involving identical assets or liabilities.

•Level 2—Valuations for assets and liabilities traded in less active dealer or broker markets. Valuations are obtained for identical or comparable assets or liabilities from alternative pricing sources with reasonable levels of price transparency. Level 2 securities include U.S. Government securities issued by Agencies and Sponsored Enterprises, Obligations of States and Political Subdivisions, certain corporate securities, FHLB stock, loans held for sale, interest rate derivatives that include interest rate swaps, risk participation agreements and foreign currency contracts, certain other real estate owned and certain nonperforming loans.

•Level 3—Valuations for assets and liabilities that are derived from other valuation methodologies, including option pricing models, discounted cash flow models and similar techniques, and not based on market exchange, dealer or broker traded transactions. If the inputs used to provide the evaluation are unobservable and/or there is very little, if any, market activity for the security or similar securities, the securities would be considered Level 3 securities. Level 3 valuations incorporate certain assumptions and projections in determining the fair value assigned to such assets or liabilities. The assets included in Level 3 are nonmarketable equity investments, certain other real estate owned and certain nonperforming loans.

In general, fair values of financial instruments are based upon quoted market prices, where available. If such quoted market prices are not available, fair value is based upon pricing models that primarily use, as inputs, observable market-based parameters. Valuation adjustments may be made to ensure that financial instruments are recorded at fair value. These adjustments may include amounts to reflect counterparty credit quality and our creditworthiness, among other things, as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. See Note 17 “Fair Values of Assets and Liabilities” for additional information.

Revenue from Contract with Customer [Policy Text Block]

Revenue from Contracts with Customers

First Commonwealth records revenue from contracts with customers in accordance with ASC Topic 606, “Revenue from Contracts with Customers” (“Topic 606”). Under Topic 606, the Company must identify the contract with a customer, identify the performance obligations in the contract, determine the transaction price, allocate the transaction price to the performance obligations in the contract, and recognize revenue when (or as) the Company satisfies a performance obligation.

A significant component of the Company's revenue, net interest earned on financial assets and liabilities, is excluded from the scope of Topic 606. First Commonwealth generally fully satisfies its performance obligations on its contracts with customers as services are rendered and the transaction prices are typically fixed; charged either on a periodic basis or based on activity. Because performance obligations are satisfied as services are rendered and the transaction prices are fixed, the Company has made no significant judgments in applying the revenue guidance prescribed in Topic 606 that affect the determination of the amount and timing of revenue from contracts with customers.