Basis of Presentation (Policies)	3 Months Ended
Basis of Presentation (Policies)	Mar. 31, 2018
Accounting Policies [Abstract]
Principles of Consolidation	Principles of Consolidation The interim Consolidated Financial Statements include the accounts of S&T Bancorp, Inc., or S&T, and its wholly owned subsidiaries. All significant intercompany transactions have been eliminated in consolidation. Investments of 20 percent to 50 percent of the outstanding common stock of investees are accounted for using the equity method of accounting.
Basis of Presentation	Basis of Presentation The accompanying unaudited interim Consolidated Financial Statements of S&T have been prepared in accordance with generally accepted accounting principles, or GAAP, in the United States for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X. Accordingly, they do not include all of the information and footnotes required by GAAP for complete financial statements and should be read in conjunction with the audited consolidated financial statements included in our annual report on Form 10-K for the year ended December 31, 2017, filed with the Securities and Exchange Commission, or SEC, on March 1, 2018. In the opinion of management, the accompanying interim financial information reflects all adjustments, consisting of normal recurring adjustments, necessary to present fairly our financial position and the results of operations for each of the interim periods presented. Results of operations for interim periods are not necessarily indicative of the results of operations that may be expected for a full year or any future period.
Reclassification	Reclassification Amounts in prior period financial statements and footnotes are reclassified whenever necessary to conform to the current period presentation. Reclassifications had no effect on our results of operations or financial condition.
Use of Estimates	Use of Estimates The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities at the date of the financial statements. Actual results could differ from those estimates.
Recently Adopted Accounting Standards Updates, or ASU or Update	Recently Adopted Accounting Standards Updates, or ASU or Update Income Taxes - Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118 In March 2018, the FASB issued ASU No. 2018-05 Income Taxes - Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 118. The amendments in this ASU add various SEC paragraphs pursuant to the issuance of the SEC Staff Accounting Bulletin to the Accounting Standards Codification Subtopic 740-10. We adopted the amendments in this ASU in conjunction with ASU 2018-02 Reclassification of Certain Tax Effects from AOCI. This ASU had no impact to our Balance Sheets or Statements of Comprehensive Income. Investments - Debt Securities and Regulated Operations - Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 117 and SEC Release No. 33-9273 In March 2018, the FASB issued ASU No. 2018-04 Investments - Debt Securities and Regulated Operations - Amendments to SEC Paragraphs Pursuant to SEC Staff Accounting Bulletin No. 117 and SEC Release No. 33-9273. The amendments in this ASU add various SEC paragraphs pursuant to the issuance of the SEC Staff Accounting Bulletin to the Accounting Standards Codification Subtopics 320 and 980. We adopted the amendments in this ASU in conjunction with ASU 2016-01 as it relates to equity securities. Income Statement -- Reporting Comprehensive Income - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the FASB issued ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220), Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. The amendments in this Update allow a reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act, or Tax Act. The amendments eliminate the stranded tax effects resulting from the Tax Act and will improve the usefulness of information reported to financial statement users and will require certain disclosures about the stranded tax effects. This Update is effective for all entities for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period, for public business entities for reporting periods for which financial statements have not been issued or made available for issuance. We have elected to reclassify all tax effects related to the Tax Act from accumulated other comprehensive income, or AOCI, to retained earnings as of January 1, 2018. As such, we have early adopted this Update and reclassified $3.7 million for the release of stranded income tax effects relating to unrealized gains and losses on our securities portfolio and our pension plan from AOCI, to retained earnings as of March 31, 2018. The adoption of this ASU had no impact on our Statements of Comprehensive Income. Our policy for releasing income tax effects from AOCI is to release them as investments are sold or mature and liabilities are extinguished. Compensation - Retirement Benefits - Improving the Presentation of Net Periodic Pension Costs and Net Periodic Post Retirement Benefit Costs In March 2017, the FASB issued ASU No. 2017-07, Compensation Retirement Benefits - Improving the Presentation of Net Periodic Pension Costs and Net Periodic Post Retirement Benefit Costs (Topic 715). The main objective of this ASU is to provide financial statement users with clearer and disaggregated information related to the components of net periodic benefit cost and improve transparency of the presentation of net periodic benefit cost in the financial statements. This Update is effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual period for which financial statements have not been issued or made available for issuance. Effective March 31, 2016, our qualified and nonqualified defined benefit plans were amended to freeze benefit accruals for all persons entitled to benefits under the plan; as such, the adoption of this ASU had no impact on our Consolidated Balance Sheets or Consolidated Statements of Comprehensive Income. Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets - Clarifying the Scope of Assets Derecognition Guidance and Accounting for Partial Sales of Nonfinancial Assets In February 2017, the FASB issued ASU No. 2017-05, Other Income - Gains and Losses from the Derecognition of Nonfinancial Assets (Subtopic 610-20). The main objective of this ASU is intended to provide greater detail on what types of transactions should be accounted for as partial sales of nonfinancial assets. The scope of this ASU, as originally issued in ASU No. 2014-09, is intended to reduce the complexity of current GAAP requirements by clarifying which accounting guidance applies to various types of contracts that transfer assets or ownership interest to another entity. This Update was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017 and at the same time that ASU No. 2014-09 was effective. Early adoption was permitted, but only as of annual reporting periods beginning after December 15, 2016, including interim reporting periods within that reporting period. The adoption of this ASU was applied to the partial sale of our insurance subsidiary. As such, the subsidiary is no longer included in our consolidated financial statements and we recognized a $1.9 million gain on the transaction. Business Combinations - Clarifying the Definition of a Business In January 2017, the FASB issued ASU No. 2017-01, Business Combinations - Clarifying the Definition of a Business (Topic 805). The main objective of this ASU is to help financial statement preparers evaluate whether a set of transferred assets and activities (either acquired or disposed of) is a business under Topic 805, Business Combinations by changing the definition of a business. The revised definition will result in fewer acquisitions being accounted for as business combinations than under existing guidance. The definition of a business is significant because it affects the accounting for acquisitions, the identification of reporting units, consolidation evaluations and the accounting for dispositions. This Update was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption was permitted for transactions not yet reflected in financial statements that have been issued or made available for issuance. The adoption of this ASU had no impact on our Balance Sheets or Statements of Comprehensive Income. Income Taxes - Intra-Entity Transfers of Assets Other Than Inventory In October 2016, the FASB issued ASU No. 2016-16, Intra-Entity Transfers of Assets Other Than Inventory. The main objective of this ASU is to require companies to recognize the income tax effects of intercompany sales and transfers of assets other than inventory in the period in which the transfer occurs. This represents a change from existing guidance, which requires companies to defer the income tax effects of intercompany transfers of assets until the asset has been sold to an outside party or otherwise recognized. The new guidance will require companies to defer the income tax effects only of intercompany transfers of inventory. This Update is effective for annual periods beginning after December 15, 2017. Early adoption is permitted as of the beginning of an annual period. If an entity chooses to early adopt the amendments in the ASU, it must do so in the first interim period of its annual financial statements. That is, an entity cannot adopt the amendments in the ASU in a later interim period and apply them as if they were in effect as of the beginning of the year. The adoption of this ASU had no impact on our Balance Sheets or Statements of Comprehensive Income. Statement of Cash Flows - Classification of Certain Cash Receipts and Cash Payments In August 2016, the FASB issued ASU No. 2016-15, Classification of Certain Cash Receipts and Cash Payments. The main objective of this ASU is to reduce diversity in practice in how certain transactions are classified in the statement of cash flows. The amendments in this Update provide guidance on the following eight specific cash flow issues: debt prepayment or debt extinguishment costs, settlement of zero-coupon debt instruments, contingent consideration payments made after a business combination, proceeds from the settlement of insurance claims, proceeds from the settlement of bank-owned life insurance (BOLI) policies, distributions received from equity method investments, beneficial interests in securitization transactions, and separately identifiable cash flows and application of the predominance principle. This Update was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption was permitted, provided that all of the amendments are adopted in the same period. The adoption of this ASU had no material impact to the presentation of activities in our Statements of Cash Flows. Revenue from Contracts with Customers In May 2014, the FASB issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). The new revenue pronouncement creates a single source of revenue guidance for all companies in all industries and is more principles-based than current revenue guidance. The pronouncement provides a five-step model for a company to recognize revenue when it transfers control of goods or services to customers at an amount that reflects the consideration to which it expects to be entitled in exchange for those goods or services. The five steps are: 1. identify the contract with the customer; 2. identify the separate performance obligations in the contract; 3. determine the transaction price; 4. allocate the transaction price to the separate performance obligations; and 5. recognize revenue when each performance obligation is satisfied. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date. This ASU defers the effective date of ASU No. 2014-09 for all entities by one year. In March 2016, the FASB issued ASU No. 2016-08, Principal versus Agent Considerations (Reporting Revenue Gross versus Net), as an amendment to ASU No. 2014-09 to improve Topic 606, Revenue from Contracts with Customers, by reducing: 1. the potential for diversity in practice arising from inconsistent application of the principal versus agent guidance, and; 2. the cost and complexity of applying Topic 606 both at transition and on an ongoing basis. In April 2016, the FASB issued ASU No. 2016-10, Identifying Performance Obligations and Licensing, as an amendment to ASU No. 2014-09 to improve Topic 606, Revenue from Contracts with Customers, by reducing: 1. the potential for diversity in practice at initial application and; 2. the cost and complexity of applying Topic 606 both at transition and on an ongoing basis. In May 2016, the FASB issued ASU No. 2016-12, Narrow-scope Improvements and Practical Expedients. The amendments in this ASU do not change the core principles of Topic 606, Revenue from Contracts with Customers. These amendments affect only the narrow aspects of Topic 606: 1. Collectibility Criterion; 2. Presentation of Sales Taxes and Other Similar Taxes Collected from Customers; 3. Noncash Consideration; 4. Contract Modifications at Transition and; 5. Completed Contracts at Transition. ASU 2014-09, including transition requirements for all amendments, was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption was permitted as of the original effective date for interim and annual reporting periods in fiscal years beginning after December 15, 2016. As of January 1, 2018, we adopted ASU 2014-09 Revenue from Contracts with Customers — Topic 606 and all subsequent ASUs that modified Topic 606. The ASU requires that we identify the contract with a customer, identity 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 we satisfy a performance obligation. We generally satisfy our performance obligations on our contracts with customers as services are rendered and the transaction prices are typically fixed; charged whether on a periodic basis or based on activity. Because performance obligations are satisfied as services are rendered and the transaction prices are fixed, there is little judgment involved in applying Topic 606 that significantly affects the determination of the amount and timing of revenue from contracts with customers. Significant revenue has not been recognized in the current reporting period that results from performance obligations satisfied in previous periods. The implementation guidance had no material impact on the measurement or timing of revenue recognition. Our primary sources of revenue are derived from interest and dividends earned on loans, investment securities and other financial instruments that are not within the scope of Topic 606. We have evaluated the nature of our contracts with customers and related revenue streams, including services charges on deposit accounts, debit and credit cards and wealth management and determined that further disaggregation of revenue from contracts with customers into more granular categories beyond what is presented in the Consolidated Statements of Comprehensive Income was not necessary. We have also completed our evaluation of certain costs related to these revenue streams to determine whether such costs should be presented as expenses or contra-revenue. The adoption of this ASU had no material impact on our Balance Sheets or Statements of Comprehensive Income. Accounting for Financial Instruments - Overall: Classification and Measurement In January 2016, the FASB issued ASU No. 2016-01, Accounting for Financial Instruments - Overall: Classification and Measurement (Subtopic 825-10). The amendments in this ASU address the following: 1. require equity investments to be measured at fair value with changes in fair value recognized in net income; 2. simplify the impairment assessment of equity investments without readily-determinable fair values by requiring a qualitative assessment to identify impairment; 3. eliminate the requirement to disclose the method(s) and significant assumptions used to estimate the fair value that is required to be disclosed for financial instruments measured at amortized cost on the balance sheet; 4. require entities to use the exit price notion when measuring the fair value of financial instruments for disclosure purposes; 5. require separate presentation in other comprehensive income for the portion of the total change in the fair value of a liability resulting from a change in the instrument-specific credit risk when the entity has elected to measure the liability at fair value in accordance with the fair value option for financial instruments; 6. require separate presentation of financial assets and financial liabilities by measurement category and form of financial asset (that is, securities or loans and receivables) on the balance sheet or in the accompanying notes to the financial statements; and 7. clarify that an entity should evaluate the need for a valuation allowance on a deferred tax asset related to available-for-sale securities in combination with the entity's other deferred tax assets. This ASU was effective for annual and interim periods in fiscal years beginning after December 15, 2017. We adopted ASU No. 2016-01 January 1, 2018 and have concluded that the provisions of this ASU did not materially impact our Balance Sheets or Statements of Comprehensive Income. The new guidance resulted in a change in the fair value measurement of our loan portfolio as of March 31, 2018 using an exit price notion (see Note 3: Fair Value Measurements). The new guidance also resulted in a cumulative-effect adjustment of $0.9 million from AOCI, to retained earnings at January 1, 2018 for net unrealized gains on our marketable equities portfolio. As a result of the new guidance we recognized $0.1 million of net unrealized gains in our Statements of Comprehensive Income during the three months ended March 31, 2018 on our marketable equity securities portfolio. Recently Issued Accounting Standards Leases - Land Easement Practical Expedient for Transition to Topic 842 In January 2018, the FASB issued ASU No. 2018-01 Leases - Land Easement Practical Expedient for Transition to Topic 842. The amendments in this ASU permit an entity to elect an optional transition practical expedient to not evaluate under Topic 842 land easements, that exist or expired before the entity's adoption of Topic 842 and that were not previously accounted for as leases under Topic 840. We are evaluating the amendments in this ASU; however, we do not anticipate that these amendments will materially impact to our Balance Sheets or Statements of Comprehensive Income. Intangibles - Goodwill and Other - Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU No. 2017-04, Intangibles - Goodwill and Other - Simplifying the Test for Goodwill Impairment (Topic 350). The main objective in this ASU is intended to simplify the current requirements for testing goodwill for impairment by eliminating step two from the goodwill impairment test. The amendments are expected to reduce the complexity and costs associated with performing the goodwill impairment test, which could result in recording impairment charges sooner than under the current guidance. This Update is effective for any interim and annual impairment tests in reporting periods in fiscal years beginning after December 15, 2019. Early adoption is permitted for interim or annual goodwill impairment tests performed on testing dates after January 1, 2017. We are evaluating the provisions of this ASU; however, we do not anticipate that this ASU will materially impact our Balance Sheets or Statements of Comprehensive Income. Financial Instruments - Credit Losses In June 2016, the FASB issued ASU No. 2016-13, Measurement of Credit Losses on Financial Instruments. The main objective of this ASU is to provide financial statement users with more decision-useful information about the expected credit losses on financial instruments and other commitments to extend credit held by a reporting entity at each reporting date. The amendments of this Update replace the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. The collective changes to the recognition and measurement accounting standards for financial instruments and their anticipated impact on the allowance for credit losses modeling have been universally referred to as the CECL, or current expected credit loss, model. This Update is effective for interim and annual reporting periods in fiscal years beginning after December 15, 2019. Early adoption is permitted as of fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. We have created a CECL Committee to govern the implementation of these amendments consisting of key stakeholders from Credit Administration, Finance, Risk Management and Audit. We have engaged a third-party to assist us in developing our CECL methodology. We continue to evaluate the provisions of this ASU to determine the potential impact on our Balance Sheets and Statements of Comprehensive Income. Leases - Section A-Amendments to the FASB Accounting Standards Codification, Section B-Conforming Amendments Related to Leases and Section C-Background Information and Basis for Conclusions In February 2016, the FASB issued ASU No. 2016-02, Leases, which requires lessees to recognize a right-to-use asset and a lease obligation for all leases on the balance sheet. Lessor accounting remains substantially similar to current GAAP. ASU 2016-02 supersedes Topic 840, Leases. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2018. ASU 2016-02 mandates a modified retrospective transition method for all entities. Early adoption of this ASU is permitted. We anticipate that this ASU will impact our financial statements as it relates to the recognition of right-to-use assets and lease obligations on our Consolidated Balance Sheets. We have numerous lease agreements for our branch and loan production offices, which are currently accounted for as operating leases. We expect the new guidance will require these lease agreements to be included on our Balance Sheets as right-to-use assets with a corresponding lease liability. We expect that these changes to our Balance Sheets will impact our regulatory capital ratios. We have compiled a preliminary inventory of our leases and continue to evaluate the standard. We anticipate that this ASU will impact total assets and total liabilities presented on our Balance Sheets; however, we do not believe that it will materially impact our Statements of Comprehensive Income.
Fair Value Measurements	We use fair value measurements when recording and disclosing certain financial assets and liabilities. Debt securities, equity securities, trading assets and derivative financial instruments are recorded at fair value on a recurring basis. Additionally, from time to time, we may be required to record other assets at fair value on a nonrecurring basis, such as loans held for sale, impaired loans, other real estate owned, or OREO, and other repossessed assets, mortgage servicing rights, or MSRs, and certain other assets. Fair value is the price that would be received to sell an asset or paid to transfer a liability in the principal or most advantageous market in an orderly transaction between market participants at the measurement date. An orderly transaction is a transaction that assumes exposure to the market for a period prior to the measurement date to allow for marketing activities that are usual and customary for transactions involving such assets or liabilities; it is not a forced transaction. In determining fair value, we use various valuation approaches, including market, income and cost approaches. The fair value standard establishes a hierarchy for inputs used in measuring fair value that maximizes the use of observable inputs and minimizes the use of unobservable inputs by requiring that observable inputs be used when available. Observable inputs are inputs that market participants would use in pricing an asset or liability, which are developed based on market data that we have obtained from independent sources. Unobservable inputs reflect our estimates of assumptions that market participants would use in pricing an asset or liability, which are developed based on the best information available in the circumstances. The fair value hierarchy gives the highest priority to unadjusted quoted market prices in active markets for identical assets or liabilities (Level 1 measurement) and the lowest priority to unobservable inputs (Level 3 measurement). The fair value hierarchy is broken down into three levels based on the reliability of inputs as follows: Level 1: valuation is based upon unadjusted quoted market prices for identical instruments traded in active markets. Level 2: valuation is based upon quoted market prices for similar instruments traded in active markets, quoted market prices for identical or similar instruments traded in markets that are not active and model-based valuation techniques for which all significant assumptions are observable in the market or can be corroborated by market data. Level 3: valuation is derived from other valuation methodologies, including discounted cash flow models and similar techniques that use significant assumptions not observable in the market. These unobservable assumptions reflect estimates of assumptions that market participants would use in determining fair value. A financial instrument’s level within the fair value hierarchy is based on the lowest level of input that is significant to the fair value measurement. Our policy is to recognize transfers between any of the fair value hierarchy levels at the end of the reporting period in which the transfer occurred. The following are descriptions of the valuation methodologies that we use for financial instruments recorded at fair value on either a recurring or nonrecurring basis. Recurring Basis Debt Securities Available-for-Sale We obtain fair values for debt securities from a third-party pricing service which utilizes several sources for valuing fixed-income securities. We validate prices received from our pricing service through comparison to a secondary pricing service and broker quotes. We review the methodologies of the pricing service which provides us with a sufficient understanding of the valuation models, assumptions, inputs and pricing to reasonably measure the fair value of our debt securities. The market evaluation sources for debt securities include observable inputs rather than significant unobservable inputs and are classified as Level 2. The service provider utilizes pricing models that vary by asset class and include available trade, bid and other market information. Generally, the methodologies include broker quotes, proprietary models, and vast descriptive terms and conditions databases, and extensive quality control programs. Equity Securities Marketable equity securities that have an active, quotable market are classified as Level 1. Marketable equity securities that are quotable, but are thinly traded or inactive, are classified as Level 2. Marketable equity securities that are not readily traded and do not have a quotable market are classified as Level 3. Trading Assets We use quoted market prices to determine the fair value of our trading assets. Our trading assets are held in a Rabbi Trust under a deferred compensation plan and are invested in readily quoted mutual funds. Accordingly, these assets are classified as Level 1. Rabbi Trust assets are reported in other assets in the Consolidated Balance Sheets. Derivative Financial Instruments We use derivative instruments, including interest rate swaps for commercial loans with our customers, interest rate lock commitments and the sale of mortgage loans in the secondary market. We calculate the fair value for derivatives using widely accepted valuation techniques, including discounted cash flow analysis on the expected cash flows of each derivative. Each valuation considers the contractual terms of the derivative, including the period to maturity, and uses observable market-based inputs, such as interest rate curves and implied volatilities. Accordingly, derivatives are classified as Level 2. We incorporate credit valuation adjustments into the valuation models to appropriately reflect both our own nonperformance risk and the respective counterparties' nonperformance risk in calculating fair value measurements. In adjusting the fair value of our derivative contracts for the effect of nonperformance risk, we have considered the impact of netting and any applicable credit enhancements and collateral postings. Nonrecurring Basis Loans Held for Sale Loans held for sale consist of 1-4 family residential loans originated for sale in the secondary market and, from time to time, certain loans transferred from the loan portfolio to loans held for sale, all of which are carried at the lower of cost or fair value. The fair value of 1-4 family residential loans is based on the principal or most advantageous market currently offered for similar loans using observable market data. The fair value of the loans transferred from the loan portfolio is based on the amounts offered for these loans in currently pending sales transactions. Loans held for sale carried at fair value are classified as Level 3. Impaired Loans Impaired loans are carried at the lower of carrying value or fair value. Fair value is determined as the recorded investment balance less any specific reserve. We establish specific reserves based on the following three impairment methods: 1) the present value of expected future cash flows discounted at the loan’s original effective interest rate; 2) the loan’s observable market price; or 3) the fair value of the collateral less estimated selling costs when the loan is collateral dependent and we expect to liquidate the collateral. However, if repayment is expected to come from the operation of the collateral, rather than liquidation, then we do not consider estimated selling costs in determining the fair value of the collateral. Collateral values are generally based upon appraisals by approved, independent state certified appraisers. Appraisals may be discounted based on our historical knowledge, changes in market conditions from the time of appraisal or our knowledge of the borrower and the borrower’s business. Impaired loans carried at fair value are classified as Level 3. OREO and Other Repossessed Assets OREO and other repossessed assets obtained in partial or total satisfaction of a loan are recorded at the lower of recorded investment in the loan or fair value less cost to sell. Subsequent to foreclosure, these assets are carried at the lower of the amount recorded at acquisition date or fair value less cost to sell. Accordingly, it may be necessary to record nonrecurring fair value adjustments. Fair value, when recorded, is generally based upon appraisals by approved, independent state certified appraisers. Like impaired loans, appraisals on OREO may be discounted based on our historical knowledge, changes in market conditions from the time of appraisal or other information available to us. OREO and other repossessed assets carried at fair value are classified as Level 3. Mortgage Servicing Rights The fair value of MSRs is determined by calculating the present value of estimated future net servicing cash flows, considering expected mortgage loan prepayment rates, discount rates, servicing costs and other economic factors, which are determined based on current market conditions. The expected rate of mortgage loan prepayments is the most significant factor driving the value of MSRs. MSRs are considered impaired if the carrying value exceeds fair value. The valuation model includes significant unobservable inputs; therefore, MSRs are classified as Level 3. MSRs are reported in other assets in the Consolidated Balance Sheets and are amortized into noninterest income in the Consolidated Statements of Comprehensive Income. Other Assets We measure certain other assets at fair value on a nonrecurring basis. Fair value is based on the application of lower of cost or fair value accounting, or write-downs of individual assets. Valuation methodologies used to measure fair value are consistent with overall principles of fair value accounting and consistent with those described above. Financial Instruments In addition to financial instruments recorded at fair value in our financial statements, fair value accounting guidance requires disclosure of the fair value of all of an entity’s assets and liabilities that are considered financial instruments. The majority of our assets and liabilities are considered financial instruments. Many of these instruments lack an available trading market as characterized by a willing buyer and willing seller engaged in an exchange transaction. Also, it is our general practice and intent to hold our financial instruments to maturity and to not engage in trading or sales activities with respect to such financial instruments. For fair value disclosure purposes, we substantially utilize the fair value measurement criteria as required and explained above. In cases where quoted fair values are not available, we use present value methods to determine the fair value of our financial instruments. Cash and Cash Equivalents The carrying amounts reported in the Consolidated Balance Sheets for cash and due from banks, including interest-bearing deposits, approximate fair value. Loans With the adoption of ASU 2016-01 on January 1, 2018, we refined our methodology to estimate the fair value of our loan portfolio to use the exit price notion as required by the standard. The guidance was applied on a prospective basis resulting in prior-periods no longer being comparable. The fair value of variable rate loans that may reprice frequently at short-term market rates is based on carrying values adjusted for liquidity and credit risk. The fair value of variable rate loans that reprice at intervals of one year or longer, such as adjustable rate mortgage products, is estimated using discounted cash flow analyses that utilize interest rates currently being offered for similar loans and adjusted for liquidity and credit risk. The fair value of fixed rate loans is estimated using a discounted cash flow analysis that utilizes interest rates currently being offered for similar loans adjusted for liquidity and credit risk. Bank Owned Life Insurance Fair value approximates net cash surrender value of bank owned life insurance, or BOLI. Federal Home Loan Bank, or FHLB, and Other Restricted Stock It is not practical to determine the fair value of our FHLB and other restricted stock due to the restrictions placed on the transferability of these stocks; it is presented at carrying value. Deposits The fair values disclosed for deposits without defined maturities (e.g., noninterest and interest-bearing demand, money market and savings accounts) are by definition equal to the amounts payable on demand. The carrying amounts for variable rate, fixed-term time deposits approximate their fair values. Estimated fair values for fixed rate and other time deposits are based on discounted cash flow analysis using interest rates currently offered for time deposits with similar terms. The carrying amount of accrued interest approximates fair value. Short-Term Borrowings The carrying amounts of securities sold under repurchase agreements, or REPOs, and other short-term borrowings approximate their fair values. Long-Term Borrowings The fair values disclosed for fixed rate long-term borrowings are determined by discounting their contractual cash flows using current interest rates for long-term borrowings of similar remaining maturities. The carrying amounts of variable rate long-term borrowings approximate their fair values. Junior Subordinated Debt Securities The interest rate on the variable rate junior subordinated debt securities is reset quarterly; therefore, the carrying values approximate their fair values. Loan Commitments and Standby Letters of Credit Off-balance sheet financial instruments consist of commitments to extend credit and letters of credit. Except for interest rate lock commitments, estimates of the fair value of these off-balance sheet items are not made because of the short-term nature of these arrangements and the credit standing of the counterparties. Other Estimates of fair value are not made for items that are not defined as financial instruments, including such items as our core deposit intangibles and the value of our trust operations.
Allowance for Loans Losses	We maintain an allowance for loan losses, or ALL, at a level determined to be adequate to absorb estimated probable credit losses inherent within the loan portfolio as of the balance sheet date. We develop and document a systematic ALL methodology based on the following portfolio segments: 1) CRE, 2) C&I, 3) Commercial Construction, 4) Consumer Real Estate and 5) Other Consumer. The following are key risks within each portfolio segment: CRE—Loans secured by commercial purpose real estate, including both owner-occupied properties and investment properties for various purposes such as hotels, strip malls and apartments. Operations of the individual projects and global cash flows of the debtors are the primary sources of repayment for these loans. The condition of the local economy is an important indicator of risk, but there are also more specific risks depending on the collateral type and the business prospects of the lessee, if the project is not owner-occupied. C&I—Loans made to operating companies or manufacturers for the purpose of production, operating capacity, accounts receivable, inventory or equipment financing. Cash flow from the operations of the company is the primary source of repayment for these loans. The condition of the local economy is an important indicator of risk, but there are also more specific risks depending on the industry of the company. Collateral for these types of loans often do not have sufficient value in a distressed or liquidation scenario to satisfy the outstanding debt. Commercial Construction—Loans made to finance construction of buildings or other structures, as well as to finance the acquisition and development of raw land for various purposes. While the risk of these loans is generally confined to the construction period, if there are problems, the project may not be completed, and as such, may not provide sufficient cash flow on its own to service the debt or have sufficient value in a liquidation to cover the outstanding principal. The condition of the local economy is an important indicator of risk, but there are also more specific risks depending on the type of project and the experience and resources of the developer. Consumer Real Estate—Loans secured by first and second liens such as home equity loans, home equity lines of credit and 1-4 family residential mortgages, including purchase money mortgages. The primary source of repayment for these loans is the income and assets of the borrower. The condition of the local economy, in particular the unemployment rate, is an important indicator of risk for this segment. The state of the local housing market can also have a significant impact on this segment because low demand and/or declining home values can limit the ability of borrowers to sell a property and satisfy the debt. Other Consumer—Loans made to individuals that may be secured by assets other than 1-4 family residences, as well as unsecured loans. This segment includes auto loans, unsecured loans and lines and credit cards. The primary source of repayment for these loans is the income and assets of the borrower. The condition of the local economy, in particular the unemployment rate, is an important indicator of risk for this segment. The value of the collateral, if there is any, is less likely to be a source of repayment due to less certain collateral values. We further assess risk within each portfolio segment by pooling loans with similar risk characteristics. For the commercial loan classes, the most important indicator of risk is the internally assigned risk rating, including pass, special mention and substandard. Consumer loans are pooled by type of collateral, lien position and loan to value, or LTV, for Consumer Real Estate loans. Historical loss rates are applied to these loan pools to determine the reserve for loans collectively evaluated for impairment. The ALL methodology for groups of loans collectively evaluated for impairment is comprised of both a quantitative and qualitative analysis. A key assumption in the quantitative component of the reserve is the loss emergence period, or LEP. The LEP is an estimate of the average amount of time from the point at which a loss is incurred on a loan to the point at which the loss is confirmed. Another key assumption is the look-back period, or LBP, which represents the historical data period utilized to calculate loss rates. Management monitors various credit quality indicators for both the commercial and consumer loan portfolios, including delinquency, nonperforming status and changes in risk ratings on a monthly basis.
Loans Credit Risk Rating	We continually monitor the commercial loan portfolio through an internal risk rating system. Loan risk ratings are assigned based upon the creditworthiness of the borrower and are reviewed on an ongoing basis according to our internal policies. Loans within the pass rating generally have a lower risk of loss than loans risk rated as special mention or substandard. Our risk ratings are consistent with regulatory guidance and are as follows: Pass—The loan is currently performing and is of high quality. Special Mention—A special mention loan has potential weaknesses that warrant management’s close attention. If left uncorrected, these potential weaknesses may result in deterioration of the repayment prospects or in the strength of our credit position at some future date. Economic and market conditions, beyond the borrower’s control, may in the future necessitate this classification. Substandard—A substandard loan is not adequately protected by the net worth and/or paying capacity of the borrower or by the collateral pledged, if any. Substandard loans have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. These loans are characterized by the distinct possibility that we will sustain some loss if the deficiencies are not corrected.
Derivative Financial Instruments	Interest Rate Swaps In accordance with applicable accounting guidance for derivatives and hedging, all derivatives are recognized as either assets or liabilities on the balance sheet at fair value. Interest rate swaps are contracts in which a series of interest rate flows (fixed and variable) are exchanged over a prescribed period. The notional amounts on which the interest payments are based are not exchanged. These derivative positions relate to transactions in which we enter into an interest rate swap with a commercial customer while at the same time entering into an offsetting interest rate swap with another financial institution. In connection with each transaction, we agree to pay interest to the customer on a notional amount at a variable interest rate and receive interest from the customer on the same notional amount at a fixed rate. At the same time, we agree to pay another financial institution the same fixed interest rate on the same notional amount and receive the same variable interest rate on the same notional amount. The transaction allows our customer to effectively convert a variable rate loan to a fixed rate loan with us receiving a variable rate. These agreements could have floors or caps on the contracted interest rates. Pursuant to our agreements with various financial institutions, we may receive collateral or may be required to post collateral based upon mark-to-market positions. Beyond unsecured threshold levels, collateral in the form of cash or securities may be made available to counterparties of interest rate swap transactions. Based upon our current positions and related future collateral requirements relating to them, we believe any effect on our cash flow or liquidity position to be immaterial. Derivatives contain an element of credit risk, the possibility that we will incur a loss because a counterparty, which may be a financial institution or a customer, fails to meet its contractual obligations. All derivative contracts with financial institutions may be executed only with counterparties approved by our Asset and Liability Committee, or ALCO, and derivatives with customers may only be executed with customers within credit exposure limits approved by our Senior Loan Committee. Interest rate swaps are considered derivatives, but are not accounted for using hedge accounting. As such, changes in the estimated fair value of the derivatives are recorded in current earnings and included in other noninterest income in the Consolidated Statements of Comprehensive Income. Interest Rate Lock Commitments and Forward Sale Contracts In the normal course of business, we sell originated mortgage loans into the secondary mortgage loan market. We also offer interest rate lock commitments to potential borrowers. The commitments are generally for a period of 60 days and guarantee a specified interest rate for a loan if underwriting standards are met, but the commitment does not obligate the potential borrower to close on the loan. Accordingly, some commitments expire prior to becoming loans. We may encounter pricing risks if interest rates increase significantly before the loan can be closed and sold. We may utilize forward sale contracts in order to mitigate this pricing risk. Whenever a customer desires these products, a mortgage originator quotes a secondary market rate guaranteed for that day by the investor. The rate lock is executed between the mortgagee and us and in turn a forward sale contract may be executed between us and the investor. Both the rate lock commitment and the corresponding forward sale contract for each customer are considered derivatives, but are not accounted for using hedge accounting. As such, changes in the estimated fair value of the derivatives during the commitment period are recorded in current earnings and included in mortgage banking in the Consolidated Statements of Comprehensive Income.