Summary of Significant Accounting Policies (Policies)	6 Months Ended
Jun. 30, 2023
Accounting Policies [Abstract]
CECL Adoption and Updated Significant Accounting Policy	CECL Adoption and Updated Significant Accounting Policy On January 1, 2023, the Corporation adopted ASU 2016-13, Financial Instruments - Credit Losses (ASC Topic 326): Measurement of Credit Losses on Financial Instruments, which replaces the incurred loss methodology, and is referred to as CECL. The measurement of expected credit losses under CECL is applicable to financial assets measured at amortized cost, including loans and HTM debt securities. It also applies to OBS credit exposures (loan commitments, standby letters of credit, financial guarantees, and other similar instruments) and net investments in leases recognized by a lessor in accordance with ASC Topic 842. The Corporation adopted CECL using the modified retrospective method for all financial assets measured at amortized cost, net of investments in leases and OBS credit exposures. Results for reporting periods beginning after January 1, 2023 are presented under CECL, while prior period results are reported in accordance with the previously applicable incurred loss methodology. The Corporation recorded an overall increase of $15.0 million to the ACL on January 1, 2023 as a result of the adoption of CECL. Retained earnings decreased $11.5 million and deferred tax assets increased by $3.1 million. Included in the $15.0 million increase to the ACL was $3.1 million for certain OBS credit exposures that were previously recognized in other liabilities before the adoption of CECL. On January 1, 2023, the Corporation adopted ASU 2022-02, Financial Instruments - Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures, which eliminates the accounting guidance for troubled debt restructurings in Accounting Standards Codification ("ASC") Subtopic 310-40, Receivables - Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Additionally, ASU 2022-02 requires entities to disclose current-period gross write-offs by year of origination for financing receivables and net investments in leases within the scope of ASC Subtopic 326-20, Financial Instruments - Credit Losses - Measured at Amortized Cost. See "Note 4 - Loans and Allowance for Credit Losses - Loans" for the new financial statement disclosures applicable under this update. The updates to the significant accounting policies related to CECL are further discussed in "Note 3 - Investment Securities", "Note 4 - Loans and Allowance for Credit Losses - Loans" and "Note 8 - Commitments and Contingencies". All other significant accounting policies used in preparation of the Consolidated Financial Statements are disclosed in the 2022 Annual Report. Those significant accounting policies are unchanged at June 30, 2023. Accounting Standards Pending Adoption ASU No. 2023-02: The FASB issued ASU 2023-02, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method. The amendments in this update permit reporting entities to elect to account for their tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. A reporting entity may make an accounting policy election to apply the proportional amortization method on a tax-credit-program-by-tax-credit-program basis rather than electing to apply the proportional amortization method at the reporting entity level or to individual investments. The amendments in this update also remove certain guidance for Qualified Affordable Housing Project investments and require the application of the delayed equity contribution guidance to all tax equity investments. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and must be applied on either a modified retrospective or a retrospective basis. Early adoption is permitted in any interim period, however if adopted in an interim period the entity shall adopt the amendments in this update as of the beginning of the fiscal year that includes the interim period. The Corporation does not expect the adoption of ASU No. 2023-02 to have a material impact on its consolidated financial statements.
AFS and HTM Securities	AFS Securities ASU 2016-13 makes targeted improvements to the accounting for credit losses on AFS securities. The concept of other-than-temporarily impaired has been replaced with the allowance for credit losses. Unlike HTM securities, AFS securities are evaluated on an individual level and pooling of securities is not allowed. Quarterly, Mid Penn evaluates if any security has a fair value less than its amortized cost. Once these securities are identified, in order to determine whether a decline in fair value resulted from a credit loss or other factors, Mid Penn performs further analysis as outlined below: •Review the extent to which the fair value is less than the amortized cost and observe the security’s lowest credit rating as reported by third-party credit ratings companies. •The securities that violate the credit loss triggers above would be subjected to additional analysis that may include, but is not limited to: changes in market interest rates, changes in securities credit ratings, security type, service area economic factors, financial performance of the issuer/or obligor of the underlying issue and third-party guarantee. •If Mid Penn determines that a credit loss exists, the credit portion of the allowance will be measured using a DCF analysis using the effective interest rate as of the security’s purchase date. The amount of credit loss Mid Penn records will be limited to the amount by which the amortized cost exceeds the fair value. The DCF analysis utilizes contractual maturities, as well as third-party credit ratings and cumulative default rates published annually by a reputable third-party. HTM Securities ASU 2016-13 requires institutions to measure expected credit losses on financial assets carried at amortized cost on a collective or pool basis when similar risks exist. Mid Penn uses several levels of segmentation in order to measure expected credit losses: •The portfolio is segmented into agency and non-agency securities. •The non-agency securities are separated into state and political subdivision obligations and corporate debt securities. Each individual segment is categorized by third-party credit ratings. As discussed above, Mid Penn has determined that for certain classes of securities it would be appropriate to assume the expected credit loss to be zero, which include debt issuances of the U.S. Treasury and agencies and instrumentalities of the United States government. This assumption will be reviewed and attested to quarterly.
Collateral Dependent Loans	Collateral-Dependent Loans A financial asset is considered to be collateral-dependent when the debtor is experiencing financial difficulty and repayment is expected to be provided substantially through the sale or operation of the collateral. For all classes of financial assets deemed collateral-dependent, Mid Penn elected the practical expedient to estimate expected credit losses based on the collateral’s fair value less cost to sell. In most cases, Mid Penn records a partial charge-off to reduce the loan’s carrying value to the collateral’s fair value less cost to sell. Substantially all of the collateral supporting collateral-dependent financial assets consists of various types of real estate, including residential properties; commercial properties such as retail centers, office buildings, and lodging; agriculture land; and vacant land. Allowance for Credit Losses, effective January 1, 2023 Mid Penn’s ACL - loans methodology is based upon guidance within FASB ASC Subtopic 326-20, as well as regulatory guidance from the FDIC, its primary federal regulator. The ACL - loans is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected on the loans. Credit quality within the loan portfolio is continuously monitored by management and is reflected within the ACL - loans. The ACL - loans is an estimate of expected losses inherent within Mid Penn’s existing loan portfolio. The ACL - loans is adjusted through the PCL and reduced by the charge off of loan amounts, net of recoveries. The loan loss estimation process involves procedures to appropriately consider the unique characteristics of Mid Penn’s loan portfolio segments. When computing allowance levels, credit loss assumptions are estimated using a model that categorizes loan pools based on loss history and other credit trends and risk characteristics, including current conditions and reasonable and supportable forecasts about the future. Evaluations of the portfolio and individual credits are inherently subjective, as they require estimates, assumptions and judgments as to the facts and circumstances of particular situations. Determining the appropriateness of the allowance is complex and requires judgement by management about the effect of matters that are inherently uncertain. In future periods, evaluations of the overall loan portfolio, in light of the factors and forecasts then prevailing, may result in significant changes in the ACL and credit loss expense. Mid Penn estimates the ACL using relevant available information, from internal and external sources, relating to past events, current conditions and reasonable and supportable forecasts. Mid Penn uses a third-party software application to calculate the quantitative portion of the ACL using a methodology and assumptions specific to each loan pool. The qualitative portion of the allowance is based on general economic conditions and other internal and external factors affecting Mid Penn as a whole, as well as specific loans. Factors considered include the following: lending process, concentrations of credit, and credit quality. The quantitative and qualitative portions of the allowance are added together to determine the total ACL, which reflects management’s expectations of future conditions based on reasonable and supportable forecasts. The methodology for estimating the amount of expected credit losses reported in the ACL has two basic components: a collective, or pooled, component for estimated expected credit losses for pools of loans that share similar risk characteristics, and an asset-specific component involving individual loans that do not share risk characteristics with other loans and the measurement of expected credit losses for such individual loans. In estimating the ACL for the collective component, loans are segregated into loan pools based on loan purpose codes and similar risk characteristics. The commercial real estate and residential mortgage loan portfolio segments include loans for both commercial and residential properties that are secured by real estate. The underwriting process for these loans includes analysis of the financial position and strength of both the borrower and, if applicable, guarantor, experience with similar projects in the past, market demand and prospects for successful completion of the proposed project within the established budget and schedule, values of underlying collateral, availability of permanent financing, maximum loan-to-value ratios, minimum equity requirements, acceptable amortization periods and minimum debt service coverage requirements, based on property type. The borrower’s financial strength and capacity to repay their obligations remain the primary focus of underwriting. Financial strength is evaluated based upon analytical tools that consider historical and projected cash flows and performance, in addition to analysis of the proposed project for income-producing properties. Additional support offered by guarantors is also considered when applicable. Ultimate repayment of these loans is sensitive to interest rate changes, general economic conditions, liquidity and availability of long-term financing. The commercial and industrial loan portfolio segment includes commercial loans made to many types of businesses for various purposes, such as short-term working capital loans that are usually secured by accounts receivable and inventory, equipment and fixed asset purchases that are secured by those assets, and term financing for those within Mid Penn’s geographic markets. Mid Penn’s credit underwriting process for commercial and industrial loans includes analysis of historical and projected cash flows and performance, evaluation of financial strength of both borrowers and guarantors as reflected in current and detailed financial information, and evaluation of underlying collateral to support the credit. The consumer loan portfolio segment is comprised of loans which are underwritten after evaluating a borrower’s capacity, credit and collateral. Several factors are considered when assessing a borrower’s capacity, including the borrower’s employment, income, current debt, assets and level of equity in the property. Credit is assessed using a credit report that provides credit scores and the borrower’s current and past information about their credit history. Loan-to-value and debt-to-income ratios, loan amount and lien position are also considered in assessing whether to originate a loan. These borrowers are particularly susceptible to downturns in economic trends, such as conditions that negatively affect housing prices and demand and levels of unemployment. Mid Penn utilizes a DCF method to estimate the quantitative portion of the allowance for credit losses for loan pools. The DCF is based off of historical losses, including peer data, which is correlated to national unemployment and GDP. The PD and LGD measures are used in conjunction with prepayment data as inputs into the DCF model to calculate the cash flows at the individual loan level. Contractual cash flows based on loan terms are adjusted for PD, LGD and prepayments to derive loss cash flows. These loss cash flows are discounted by the loan’s coupon rate to arrive at the discounted cash flow based quantitative loss. The prepayment studies are updated quarterly by a third-party for each applicable pool. Mid Penn determined that reasonable and supportable forecasts could be made for a twelve-month period for all of its loan pools. To the extent the lives of the loans in the LHFI portfolio extend beyond this forecast period, Mid Penn uses a reversion period of four quarters and reverts to the historical mean on a straight-line basis over the remaining life of the loans. Qualitative factors used in the ACL methodology include the following: •Lending process •Concentrations of credit •Credit Quality The ACL for individual loans, such as non-accrual and PCD, that do not share risk characteristics with other loans is measured as the difference between the discounted value of expected future cash flows, based on the effective interest rate at origination, and the amortized cost basis of the loan, or the net realizable value. The ACL is the difference between the loan’s net realizable value and its amortized cost basis (net of previous charge-offs and deferred loan fees and costs), except for collateral-dependent loans. A loan is collateral dependent when the borrower is experiencing financial difficulty and repayment of the loan is expected to be provided substantially through the sale of the collateral. The expected credit loss for collateral-dependent loans is measured as the difference between the amortized cost basis of the loan and the fair value of the collateral, adjusted for the estimated cost to sell. Fair value estimates for collateral-dependent loans are derived from appraised values based on the current market value or the "as is" value of the collateral, normally from recently received and reviewed appraisals. Current appraisals are ordered on a regular basis based on the inspection date or more often if market conditions necessitate. Appraisals are obtained from state-certified appraisers and are based on certain assumptions, which may include construction or development status and the highest and best use of the property. These appraisals are reviewed by Mid Penn’s Appraisal Review Department to ensure they are acceptable, and values are adjusted down for costs associated with asset disposal. If the calculated expected credit loss is determined to be permanent or not recoverable, the amount of the expected credit loss is charged off. Mid Penn may also purchase loans or acquire loans through a business combination. At the purchase or acquisition date, loans are evaluated to determine whether there has been more than insignificant credit deterioration since origination. Loans that have experienced more than insignificant credit deterioration since origination are referred to as PCD loans. In its evaluation of whether a loan has experienced more than insignificant deterioration in credit quality since origination, Mid Penn takes into consideration loan grades, past due and nonaccrual status. Mid Penn may also consider external credit rating agency ratings for borrowers and for non-commercial loans, FICO score or band, probability of default levels, and number of times past due. At the purchase or acquisition date, the amortized cost basis of PCD loans is equal to the purchase price and an initial estimate of credit losses. The initial recognition of expected credit losses on PCD loans has no impact on net income. When the initial measurement of expected credit losses on PCD loans is calculated on a pooled loan basis, the expected credit losses are allocated to each loan within the pool. Any difference between the initial amortized cost basis and the unpaid principal balance of the loan represents a noncredit discount or premium, which is accreted (or amortized) into interest income over the life of the loan. Subsequent changes to the ACL on PCD loans are recorded through the PCL. For purchased loans that are not deemed to have experienced more than insignificant credit deterioration since origination and are therefore not deemed PCD, any discounts or premiums included in the purchase price are accreted (or amortized) over the contractual life of the individual loan. Loans are charged off against the ACL, with any subsequent recoveries credited back to the ACL account. Expected recoveries may not exceed the aggregate of amounts previously charged off and expected to be charged off.
Fair Value Measurement	The Corporation uses estimates of fair value in applying various accounting standards for its consolidated financial statements on either a recurring or non-recurring basis. Fair value is defined as the price to sell an asset or transfer a liability in an orderly transaction between willing and able market participants. Mid Penn groups its assets and liabilities measured at fair value in three hierarchy levels, based on the observability and transparency of the inputs. The fair value hierarchy is as follows: Level 1 - Inputs that represent quoted prices for identical instruments in active markets. Level 2 - Inputs that represent quoted prices in markets that are not active, or inputs that are observable either directly or indirectly, for substantially the full term of the asset or liability. Level 3 - Inputs that are largely unobservable, as little or no market data exists for the instrument being valued.

Summary of Significant Accounting Policies (Policies)

6 Months Ended

Jun. 30, 2023

CECL Adoption and Updated Significant Accounting Policy

On January 1, 2023, the Corporation adopted ASU 2016-13, Financial Instruments - Credit Losses (ASC Topic 326): Measurement of Credit Losses on Financial Instruments, which replaces the incurred loss methodology, and is referred to as CECL. The measurement of expected credit losses under CECL is applicable to financial assets measured at amortized cost, including loans and HTM debt securities. It also applies to OBS credit exposures (loan commitments, standby letters of credit, financial guarantees, and other similar instruments) and net investments in leases recognized by a lessor in accordance with ASC Topic 842.

The Corporation adopted CECL using the modified retrospective method for all financial assets measured at amortized cost, net of investments in leases and OBS credit exposures. Results for reporting periods beginning after January 1, 2023 are presented under CECL, while prior period results are reported in accordance with the previously applicable incurred loss methodology. The Corporation recorded an overall increase of $15.0 million to the ACL on January 1, 2023 as a result of the adoption of CECL. Retained earnings decreased $11.5 million and deferred tax assets increased by $3.1 million. Included in the $15.0 million increase to the ACL was $3.1 million for certain OBS credit exposures that were previously recognized in other liabilities before the adoption of CECL.

On January 1, 2023, the Corporation adopted ASU 2022-02, Financial Instruments - Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures, which eliminates the accounting guidance for troubled debt restructurings in Accounting Standards Codification ("ASC") Subtopic 310-40, Receivables - Troubled Debt Restructurings by Creditors, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Additionally, ASU 2022-02 requires entities to disclose current-period gross write-offs by year of origination for financing receivables and net investments in leases within the scope of ASC Subtopic 326-20, Financial Instruments - Credit Losses - Measured at Amortized Cost. See "Note 4 - Loans and Allowance for Credit Losses - Loans" for the new financial statement disclosures applicable under this update.

The updates to the significant accounting policies related to CECL are further discussed in "Note 3 - Investment Securities", "Note 4 - Loans and Allowance for Credit Losses - Loans" and "Note 8 - Commitments and Contingencies".

All other significant accounting policies used in preparation of the Consolidated Financial Statements are disclosed in the 2022 Annual Report. Those significant accounting policies are unchanged at June 30, 2023.

Accounting Standards Pending Adoption

ASU No. 2023-02: The FASB issued ASU 2023-02, Investments - Equity Method and Joint Ventures (Topic 323): Accounting for Investments in Tax Credit Structures Using the Proportional Amortization Method.

The amendments in this update permit reporting entities to elect to account for their tax equity investments, regardless of the tax credit program from which the income tax credits are received, using the proportional amortization method if certain conditions are met. A reporting entity may make an accounting policy election to apply the proportional amortization method on a tax-credit-program-by-tax-credit-program basis rather than electing to apply the proportional amortization method at the reporting entity level or to individual investments. The amendments in this update also remove certain guidance for Qualified Affordable Housing Project investments and require the application of the delayed equity contribution guidance to all tax equity investments. The amendments in this update are effective for fiscal years beginning after December 15, 2023, and must be applied on either a modified retrospective or a retrospective basis. Early adoption is permitted in any interim period, however if adopted in an interim period the entity shall adopt the amendments in this update as of the beginning of the fiscal year that includes the interim period. The Corporation does not expect the adoption of ASU No. 2023-02 to have a material impact on its consolidated financial statements.

AFS and HTM Securities

AFS Securities

ASU 2016-13 makes targeted improvements to the accounting for credit losses on AFS securities. The concept of other-than-temporarily impaired has been replaced with the allowance for credit losses. Unlike HTM securities, AFS securities are evaluated on an individual level and pooling of securities is not allowed.

Quarterly, Mid Penn evaluates if any security has a fair value less than its amortized cost. Once these securities are identified, in order to determine whether a decline in fair value resulted from a credit loss or other factors, Mid Penn performs further analysis as outlined below:

•Review the extent to which the fair value is less than the amortized cost and observe the security’s lowest credit rating as reported by third-party credit ratings companies.

•The securities that violate the credit loss triggers above would be subjected to additional analysis that may include, but is not limited to: changes in market interest rates, changes in securities credit ratings, security type, service area economic factors, financial performance of the issuer/or obligor of the underlying issue and third-party guarantee.

•If Mid Penn determines that a credit loss exists, the credit portion of the allowance will be measured using a DCF analysis using the effective interest rate as of the security’s purchase date. The amount of credit loss Mid Penn records will be limited to the amount by which the amortized cost exceeds the fair value.

The DCF analysis utilizes contractual maturities, as well as third-party credit ratings and cumulative default rates published annually by a reputable third-party.

HTM Securities

ASU 2016-13 requires institutions to measure expected credit losses on financial assets carried at amortized cost on a collective or pool basis when similar risks exist. Mid Penn uses several levels of segmentation in order to measure expected credit losses:

•The portfolio is segmented into agency and non-agency securities.

•The non-agency securities are separated into state and political subdivision obligations and corporate debt securities.

Each individual segment is categorized by third-party credit ratings.

As discussed above, Mid Penn has determined that for certain classes of securities it would be appropriate to assume the expected credit loss to be zero, which include debt issuances of the U.S. Treasury and agencies and instrumentalities of the United States government. This assumption will be reviewed and attested to quarterly.

Collateral Dependent Loans

Collateral-Dependent Loans

A financial asset is considered to be collateral-dependent when the debtor is experiencing financial difficulty and repayment is expected to be provided substantially through the sale or operation of the collateral. For all classes of financial assets deemed collateral-dependent, Mid Penn elected the practical expedient to estimate expected credit losses based on the collateral’s fair value less cost to sell. In most cases, Mid Penn records a partial charge-off to reduce the loan’s carrying value to the collateral’s fair value less cost to sell. Substantially all of the collateral supporting collateral-dependent financial assets consists of various types of real estate, including residential properties; commercial properties such as retail centers, office buildings, and lodging; agriculture land; and vacant land.

Allowance for Credit Losses, effective January 1, 2023

Mid Penn’s ACL - loans methodology is based upon guidance within FASB ASC Subtopic 326-20, as well as regulatory guidance from the FDIC, its primary federal regulator. The ACL - loans is a valuation account that is deducted from the loans’ amortized cost basis to present the net amount expected to be collected on the loans. Credit quality within the loan portfolio is continuously monitored by management and is reflected within the ACL - loans. The ACL - loans is an estimate of expected losses inherent within Mid Penn’s existing loan portfolio. The ACL - loans is adjusted through the PCL and reduced by the charge off of loan amounts, net of recoveries.

The loan loss estimation process involves procedures to appropriately consider the unique characteristics of Mid Penn’s loan portfolio segments. When computing allowance levels, credit loss assumptions are estimated using a model that categorizes loan pools based on loss history and other credit trends and risk characteristics, including current conditions and reasonable and supportable forecasts about the future. Evaluations of the portfolio and individual credits are inherently subjective, as they require estimates, assumptions and judgments as to the facts and circumstances of particular situations. Determining the appropriateness of the allowance is complex and requires judgement by management about the effect of matters that are inherently uncertain. In future periods, evaluations of the overall loan portfolio, in light of the factors and forecasts then prevailing, may result in significant changes in the ACL and credit loss expense.

Mid Penn estimates the ACL using relevant available information, from internal and external sources, relating to past events, current conditions and reasonable and supportable forecasts. Mid Penn uses a third-party software application to calculate the quantitative portion of the ACL using a methodology and assumptions specific to each loan pool. The qualitative portion of the allowance is based on general economic conditions and other internal and external factors affecting Mid Penn as a whole, as well as specific loans. Factors considered include the following: lending process, concentrations of credit, and credit quality. The quantitative and qualitative portions of the allowance are added together to determine the total ACL, which reflects management’s expectations of future conditions based on reasonable and supportable forecasts.

The methodology for estimating the amount of expected credit losses reported in the ACL has two basic components: a collective, or pooled, component for estimated expected credit losses for pools of loans that share similar risk characteristics, and an asset-specific component involving individual loans that do not share risk characteristics with other loans and the measurement of expected credit losses for such individual loans. In estimating the ACL for the collective component, loans are segregated into loan pools based on loan purpose codes and similar risk characteristics.

The commercial real estate and residential mortgage loan portfolio segments include loans for both commercial and residential properties that are secured by real estate. The underwriting process for these loans includes analysis of the financial position and strength of both the borrower and, if applicable, guarantor, experience with similar projects in the past, market demand and prospects for successful completion of the proposed project within the established budget and schedule, values of underlying collateral, availability of permanent financing, maximum loan-to-value ratios, minimum equity requirements, acceptable amortization periods and minimum debt service coverage requirements, based on property type. The borrower’s financial strength and capacity to repay their obligations remain the primary focus of underwriting. Financial strength is evaluated based upon analytical tools that consider historical and projected cash flows and performance, in addition to analysis of the proposed project for income-producing properties. Additional support offered by guarantors is also considered when applicable. Ultimate repayment of these loans is sensitive to interest rate changes, general economic conditions, liquidity and availability of long-term financing.

The commercial and industrial loan portfolio segment includes commercial loans made to many types of businesses for various purposes, such as short-term working capital loans that are usually secured by accounts receivable and inventory, equipment and fixed asset purchases that are secured by those assets, and term financing for those within Mid Penn’s

geographic markets. Mid Penn’s credit underwriting process for commercial and industrial loans includes analysis of historical and projected cash flows and performance, evaluation of financial strength of both borrowers and guarantors as reflected in current and detailed financial information, and evaluation of underlying collateral to support the credit.

The consumer loan portfolio segment is comprised of loans which are underwritten after evaluating a borrower’s capacity, credit and collateral. Several factors are considered when assessing a borrower’s capacity, including the borrower’s employment, income, current debt, assets and level of equity in the property. Credit is assessed using a credit report that provides credit scores and the borrower’s current and past information about their credit history. Loan-to-value and debt-to-income ratios, loan amount and lien position are also considered in assessing whether to originate a loan. These borrowers are particularly susceptible to downturns in economic trends, such as conditions that negatively affect housing prices and demand and levels of unemployment.

Mid Penn utilizes a DCF method to estimate the quantitative portion of the allowance for credit losses for loan pools. The DCF is based off of historical losses, including peer data, which is correlated to national unemployment and GDP.

The PD and LGD measures are used in conjunction with prepayment data as inputs into the DCF model to calculate the cash flows at the individual loan level. Contractual cash flows based on loan terms are adjusted for PD, LGD and prepayments to derive loss cash flows. These loss cash flows are discounted by the loan’s coupon rate to arrive at the discounted cash flow based quantitative loss. The prepayment studies are updated quarterly by a third-party for each applicable pool.

Mid Penn determined that reasonable and supportable forecasts could be made for a twelve-month period for all of its loan pools. To the extent the lives of the loans in the LHFI portfolio extend beyond this forecast period, Mid Penn uses a reversion period of four quarters and reverts to the historical mean on a straight-line basis over the remaining life of the loans.

Qualitative factors used in the ACL methodology include the following:

•Lending process

•Concentrations of credit

•Credit Quality

The ACL for individual loans, such as non-accrual and PCD, that do not share risk characteristics with other loans is measured as the difference between the discounted value of expected future cash flows, based on the effective interest rate at origination, and the amortized cost basis of the loan, or the net realizable value. The ACL is the difference between the loan’s net realizable value and its amortized cost basis (net of previous charge-offs and deferred loan fees and costs), except for collateral-dependent loans. A loan is collateral dependent when the borrower is experiencing financial difficulty and repayment of the loan is expected to be provided substantially through the sale of the collateral. The expected credit loss for collateral-dependent loans is measured as the difference between the amortized cost basis of the loan and the fair value of the collateral, adjusted for the estimated cost to sell. Fair value estimates for collateral-dependent loans are derived from appraised values based on the current market value or the "as is" value of the collateral, normally from recently received and reviewed appraisals. Current appraisals are ordered on a regular basis based on the inspection date or more often if market conditions necessitate. Appraisals are obtained from state-certified appraisers and are based on certain assumptions, which may include construction or development status and the highest and best use of the property. These appraisals are reviewed by Mid Penn’s Appraisal Review Department to ensure they are acceptable, and values are adjusted down for costs associated with asset disposal. If the calculated expected credit loss is determined to be permanent or not recoverable, the amount of the expected credit loss is charged off.

Mid Penn may also purchase loans or acquire loans through a business combination. At the purchase or acquisition date, loans are evaluated to determine whether there has been more than insignificant credit deterioration since origination. Loans that have experienced more than insignificant credit deterioration since origination are referred to as PCD loans. In its evaluation of whether a loan has experienced more than insignificant deterioration in credit quality since origination, Mid Penn takes into consideration loan grades, past due and nonaccrual status. Mid Penn may also consider external credit rating agency ratings for borrowers and for non-commercial loans, FICO score or band, probability of default levels, and number of times past due. At the purchase or acquisition date, the amortized cost basis of PCD loans is equal to the purchase price and an initial estimate of credit losses. The initial recognition of expected credit losses on PCD loans has no impact on net income. When the initial measurement of expected credit losses on PCD loans is calculated on a pooled loan basis, the expected credit losses are allocated to each loan within the pool. Any difference between the initial amortized cost basis and the unpaid principal balance of the loan represents a noncredit discount or premium, which is accreted (or

amortized) into interest income over the life of the loan. Subsequent changes to the ACL on PCD loans are recorded through the PCL. For purchased loans that are not deemed to have experienced more than insignificant credit deterioration since origination and are therefore not deemed PCD, any discounts or premiums included in the purchase price are accreted (or amortized) over the contractual life of the individual loan.

Loans are charged off against the ACL, with any subsequent recoveries credited back to the ACL account. Expected recoveries may not exceed the aggregate of amounts previously charged off and expected to be charged off.

Fair Value Measurement

The Corporation uses estimates of fair value in applying various accounting standards for its consolidated financial statements on either a recurring or non-recurring basis. Fair value is defined as the price to sell an asset or transfer a liability in an orderly transaction between willing and able market participants. Mid Penn groups its assets and liabilities measured at fair value in three hierarchy levels, based on the observability and transparency of the inputs. The fair value hierarchy is as follows:

Level 1 - Inputs that represent quoted prices for identical instruments in active markets.

Level 2 - Inputs that represent quoted prices in markets that are not active, or inputs that are observable either directly or indirectly, for substantially the full term of the asset or liability.

Level 3 - Inputs that are largely unobservable, as little or no market data exists for the instrument being valued.