Basis of Presentation	9 Months Ended
Sep. 30, 2018
Accounting Policies [Abstract]
BASIS OF PRESENTATION	BASIS OF PRESENTATION 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 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. On January 1, 2018, we sold a 70 percent majority interest in the assets of our wholly-owned subsidiary S&T Evergreen Insurance, LLC. We transferred our remaining 30 percent ownership interest in the net assets of S&T Evergreen Insurance, LLC to a new entity for a 30 percent ownership interest in a new insurance entity (see Note 13: Sale of a Majority Interest of Insurance Business). We use the equity method of accounting to recognize our partial ownership interest in the new entity. 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 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. Revenue from Contracts with Customers We earn revenue from contracts with our customers when we have completed our performance obligations and recognize that revenue when services are provided to our customers. Our contracts with customers are primarily in the form of account agreements. Generally our services are transferred at a point in time in response to transactions initiated and controlled by our customers under service agreements with an expected duration of one year or less. Our customers have the right to terminate their services agreements at any time. We do not defer incremental direct costs to obtain contracts with customers that would be amortized in one year or less. These costs are primarily salaries and employee benefits recognized as expense in the period incurred. Service charges on deposit accounts - We recognize monthly service charges for both commercial and personal banking customers based on account fee schedules. Our performance obligation is generally satisfied and the related revenue recognized over the period in which the service is provided. Other fees are earned based on specific transactions or customer activity within the customers' deposit accounts. These are earned at the time the transaction or customer activity occurs. Debit and credit card services - Interchange fees are earned whenever debit and credit cards are processed through third-party card payment networks. ATM fees are based on transactions by our customers' and other customers' use of our ATMs or other ATMs. Debit and credit card revenue is recognized at a point in time when the transaction is settled. Wealth management services - Wealth management services is primarily comprised of fees earned from the management and administration of trusts, assets under management, brokerage and other financial advisory services. Fees are earned over a period of time per the related fee schedules. The fees are based on a fixed amount or a scale based on the level of services provided or assets under management. Recently Adopted Accounting Standards Updates, or ASU or Update Income Statement - Reporting Comprehensive Income - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income In February 2018, the Financial Accounting Standards Board, or 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, or AOCI, 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 AOCI to retained earnings as of January 1, 2018. As such, we have early adopted this Update and reclassified $3.4 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 Consolidated 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 was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption was 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 to provide greater detail on what types of transactions should be accounted for as partial sales of nonfinancial assets. 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 interests to another entity. This Update was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017 which is 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 in January 2018. 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 results in fewer acquisitions being accounted for as business combinations than under previous 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 Consolidated Balance Sheets or Consolidated 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 previous guidance, which required 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 requires companies to defer the income tax effects only of intercompany transfers of inventory. This Update was effective for annual periods beginning after December 15, 2017. Early adoption was permitted as of the beginning of an annual period. If an entity chose to early adopt the amendments in the ASU, it had to do so in the first interim period of its annual financial statements. That is, an entity could not have adopted 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 Consolidated Balance Sheets or Consolidated 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 Consolidated 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). This revenue pronouncement established a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and superseded most previous revenue recognition guidance in GAAP. We adopted the new standard as of January 1, 2018. 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 ASU No. 2014-09. We evaluated the nature of our contracts with customers and related revenue streams, including service charges on deposit accounts, debit and credit cards and wealth management and determined that revenue recognition did not change significantly from current practice. We evaluated 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 Consolidated Balance Sheets or Consolidated 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 as of January 1, 2018 and have concluded that the provisions of this ASU did not materially impact our Consolidated Balance Sheets or Consolidated 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 losses during the three months ended September 30, 2018 and $0.2 million of net unrealized gains during the nine months ended September 30, 2018 on our marketable equity securities portfolio in our Consolidated Statements of Comprehensive Income. Accounting Standards Issued But Not Yet Adopted Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The amendments in this ASU apply to entities that are a customer in a hosting arrangement that is a service contract. These amendments relate to accounting for implementation costs (e.g. implementation, setup and other upfront costs.) These amendments require an entity in a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which cost to capitalize and which costs to expense. These amendments require the entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. This ASU is effective for annual and interim periods beginning after December 15, 2019. Early adoption of the amendments is permitted, including adoption in any interim period. We are evaluating the amendments in this ASU; however, we do not anticipate that these amendments will materially impact our Consolidated Balance Sheets or Consolidated Statements of Comprehensive Income. Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans In August 2018, the FASB issued ASU No. 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans. The amendments in this ASU apply to all employers that sponsor defined benefit pension or other postretirement plans. These amendments remove certain disclosures from Topic 715-20 and require additional disclosures. The amendments in this ASU will require S&T to update our employee benefits disclosures beginning with our Form 10-Q for the period ended March 31, 2021. The amendments in this ASU will have no impact on our Consolidated Balance Sheets or Consolidated Statements of Comprehensive Income. Fair Value Measurement - Changes to the Disclosure Requirements for Fair Value Measurement In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement - Changes to the Disclosure Requirements for Fair Value Measurement. The amendments in this ASU remove certain disclosures from Topic 820, modify and/or require additional disclosures. The amendments in this Update will require us to change our Fair Value disclosures beginning with our Form 10-Q for the period ended March 31, 2020. The amendments in this ASU will have no impact on our Consolidated Balance Sheets or Consolidated Statements of Comprehensive Income. 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 existed or expired before the entity's adoption of Topic 842 and that were not previously accounted for as leases under Topic 840. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2018. We are evaluating the amendments in this ASU; however, we do not anticipate that these amendments will materially impact our Consolidated Balance Sheets or Consolidated 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 of this ASU is 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 Consolidated Balance Sheets or Consolidated 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 form 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 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 for 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 Internal 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 Consolidated Balance Sheets and Consolidated 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 No. 2016-02 supersedes Topic 840, Leases. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2018. ASU No. 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 approximately 50 lease agreements for our branch and loan production offices, which are currently accounted for as operating leases. We expect the new guidance will require recognition of right-to-use assets and corresponding lease liabilities in the range of $30 million to $35 million on our Consolidated Balance Sheets in the first quarter of 2019. We expect that these changes to our Consolidated Balance Sheets will have a minor impact to our regulatory capital ratios. We have compiled a preliminary inventory of our leases and continue to evaluate the standard as additional lease accounting guidance continues to be released. 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 Consolidated Statements of Comprehensive Income.

BASIS OF PRESENTATION

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

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.

On January 1, 2018, we sold a 70 percent majority interest in the assets of our wholly-owned subsidiary S&T Evergreen Insurance, LLC. We transferred our remaining 30 percent ownership interest in the net assets of S&T Evergreen Insurance, LLC to a new entity for a 30 percent ownership interest in a new insurance entity (see Note 13: Sale of a Majority Interest of Insurance Business). We use the equity method of accounting to recognize our partial ownership interest in the new entity.

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

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.

Revenue from Contracts with Customers

We earn revenue from contracts with our customers when we have completed our performance obligations and recognize that revenue when services are provided to our customers. Our contracts with customers are primarily in the form of account agreements. Generally our services are transferred at a point in time in response to transactions initiated and controlled by our customers under service agreements with an expected duration of one year or less. Our customers have the right to terminate their services agreements at any time.

We do not defer incremental direct costs to obtain contracts with customers that would be amortized in one year or less. These costs are primarily salaries and employee benefits recognized as expense in the period incurred.

Service charges on deposit accounts - We recognize monthly service charges for both commercial and personal banking customers based on account fee schedules. Our performance obligation is generally satisfied and the related revenue recognized over the period in which the service is provided. Other fees are earned based on specific transactions or customer activity within the customers' deposit accounts. These are earned at the time the transaction or customer activity occurs.

Debit and credit card services - Interchange fees are earned whenever debit and credit cards are processed through third-party card payment networks. ATM fees are based on transactions by our customers' and other customers' use of our ATMs or other ATMs. Debit and credit card revenue is recognized at a point in time when the transaction is settled.

Wealth management services - Wealth management services is primarily comprised of fees earned from the management and administration of trusts, assets under management, brokerage and other financial advisory services. Fees are earned over a period of time per the related fee schedules. The fees are based on a fixed amount or a scale based on the level of services provided or assets under management.

Recently Adopted Accounting Standards Updates, or ASU or Update

Income Statement - Reporting Comprehensive Income - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income

In February 2018, the Financial Accounting Standards Board, or 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, or AOCI, 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 AOCI to retained earnings as of January 1, 2018. As such, we have early adopted this Update and reclassified $3.4 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 Consolidated 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 was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017. Early adoption was 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 to provide greater detail on what types of transactions should be accounted for as partial sales of nonfinancial assets. 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 interests to another entity. This Update was effective for interim and annual reporting periods in fiscal years beginning after December 15, 2017 which is 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 in January 2018. 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 results in fewer acquisitions being accounted for as business combinations than under previous 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 Consolidated Balance Sheets or Consolidated 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 previous guidance, which required 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 requires companies to defer the income tax effects only of intercompany transfers of inventory. This Update was effective for annual periods beginning after December 15, 2017. Early adoption was permitted as of the beginning of an annual period. If an entity chose to early adopt the amendments in the ASU, it had to do so in the first interim period of its annual financial statements. That is, an entity could not have adopted 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 Consolidated Balance Sheets or Consolidated 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 Consolidated 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). This revenue pronouncement established a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and superseded most previous revenue recognition guidance in GAAP. We adopted the new standard as of January 1, 2018. 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 ASU No. 2014-09. We evaluated the nature of our contracts with customers and related revenue streams, including service charges on deposit accounts, debit and credit cards and wealth management and determined that revenue recognition did not change significantly from current practice. We evaluated 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 Consolidated Balance Sheets or Consolidated 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 as of January 1, 2018 and have concluded that the provisions of this ASU did not materially impact our Consolidated Balance Sheets or Consolidated 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 losses during the three months ended September 30, 2018 and $0.2 million of net unrealized gains during the nine months ended September 30, 2018 on our marketable equity securities portfolio in our Consolidated Statements of Comprehensive Income.

Accounting Standards Issued But Not Yet Adopted

Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract

In August 2018, the FASB issued ASU No. 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The amendments in this ASU apply to entities that are a customer in a hosting arrangement that is a service contract. These amendments relate to accounting for implementation costs (e.g. implementation, setup and other upfront costs.) These amendments require an entity in a hosting arrangement that is a service contract to follow the guidance in Subtopic 350-40 to determine which cost to capitalize and which costs to expense. These amendments require the entity to expense the capitalized implementation costs of a hosting arrangement that is a service contract over the term of the hosting arrangement. This ASU is effective for annual and interim periods beginning after December 15, 2019. Early adoption of the amendments is permitted, including adoption in any interim period. We are evaluating the amendments in this ASU; however, we do not anticipate that these amendments will materially impact our Consolidated Balance Sheets or Consolidated Statements of Comprehensive Income.

Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans

In August 2018, the FASB issued ASU No. 2018-14, Compensation—Retirement Benefits—Defined Benefit Plans—General (Subtopic 715-20): Changes to the Disclosure Requirements for Defined Benefit Plans. The amendments in this ASU apply to all employers that sponsor defined benefit pension or other postretirement plans. These amendments remove certain disclosures from Topic 715-20 and require additional disclosures. The amendments in this ASU will require S&T to update our employee benefits disclosures beginning with our Form 10-Q for the period ended March 31, 2021. The amendments in this ASU will have no impact on our Consolidated Balance Sheets or Consolidated Statements of Comprehensive Income.

Fair Value Measurement - Changes to the Disclosure Requirements for Fair Value Measurement

In August 2018, the FASB issued ASU No. 2018-13, Fair Value Measurement - Changes to the Disclosure Requirements for Fair Value Measurement. The amendments in this ASU remove certain disclosures from Topic 820, modify and/or require additional disclosures. The amendments in this Update will require us to change our Fair Value disclosures beginning with our Form 10-Q for the period ended March 31, 2020. The amendments in this ASU will have no impact on our Consolidated Balance Sheets or Consolidated Statements of Comprehensive Income.

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 existed or expired before the entity's adoption of Topic 842 and that were not previously accounted for as leases under Topic 840. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2018. We are evaluating the amendments in this ASU; however, we do not anticipate that these amendments will materially impact our Consolidated Balance Sheets or Consolidated 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 of this ASU is 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 Consolidated Balance Sheets or Consolidated 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 form 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 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 for 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 Internal 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 Consolidated Balance Sheets and Consolidated 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 No. 2016-02 supersedes Topic 840, Leases. This ASU is effective for annual and interim periods in fiscal years beginning after December 15, 2018. ASU No. 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 approximately 50 lease agreements for our branch and loan production offices, which are currently accounted for as operating leases. We expect the new guidance will require recognition of right-to-use assets and corresponding lease liabilities in the range of $30 million to $35 million on our Consolidated Balance Sheets in the first quarter of 2019. We expect that these changes to our Consolidated Balance Sheets will have a minor impact to our regulatory capital ratios. We have compiled a preliminary inventory of our leases and continue to evaluate the standard as additional lease accounting guidance continues to be released. 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 Consolidated Statements of Comprehensive Income.