Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2023
Summary of Signficant Accounting Policies
Nature of Business Policy	General Auburn National Bancorporation, Inc. (the “Company”) provides a full range of banking services to individuals and commercial customers in Lee County, Alabama and surrounding areas through its wholly owned subsidiary, AuburnBank (the “Bank”). The Company does not have any segments other than banking that are considered material.
Basis of Presentation Policy	Basis of Presentation and Use of Estimates The unaudited consolidated financial statements in this report have been prepared in accordance with U.S. generally accepted accounting principles (“GAAP”) for interim financial information. Accordingly, these financial statements do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. The unaudited consolidated financial statements include, in the opinion of management, all adjustments necessary to present a fair statement of the financial position and the results of operations for all periods presented. All such adjustments are of a normal recurring nature. The results of operations in the interim statements are not necessarily indicative of the results of operations that the Company and its subsidiaries may achieve for future interim periods or the entire year. For further information, refer to the consolidated financial statements and footnotes included in the Company's Annual Report on Form 10-K for the year ended December 31, 2022.
Consolidation Policy	The unaudited consolidated financial statements include the accounts of the Company and its wholly-owned subsidiaries. Significant intercompany transactions and accounts are eliminated in consolidation.
Use of Estimates Policy	The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosures of contingent assets and liabilities as of the balance sheet date and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term include the determination of allowance for credit losses on investment securities and loans, fair value of financial instruments, and the valuation of deferred tax assets and other real estate owned (“OREO”).
Reclassification Policy	Reclassifications Certain amounts reported in prior periods have been reclassified to conform to the current -period presentation. These reclassifications had no material effect on the Company’s previously reported net earnings or total stockholders’ equity.
Revenue Recognition Policy	Revenue Recognition On January 1, 2018, the Company implemented Accounting Standards Update (“ASU” or “updates”) 2014-09, Revenue from Contracts with Customers , codified at Accounting Standards Codification (“ASC”) 606. The Company adopted ASC 606 using the modified retrospective transition method. The majority of the Company’s revenue stream is generated from interest income on loans and securities which are outside the scope of ASC 606. The Company’s sources of income that fall within the scope of ASC 606 include service charges on deposits, interchange fees and gains and losses on sales of other real estate, all of which are presented as components of noninterest income. The following is a summary of the revenue streams that fall within the scope of ASC 606: ● Service charges on deposits, investment services, ATM and interchange fees – Fees from these services are either (i) transaction-based, for which the performance obligations are satisfied when the individual transaction is processed, or (ii) set periodic service charges, for which the performance obligations are satisfied over the period the service is provided. Transaction-based fees are recognized at the time the transaction is processed, and periodic service charges are recognized over the service period. ● Gains on sales of OREO – A gain on sale should be recognized when a contract for sale exists and control of the asset has been transferred to the buyer. ASC 606 lists several criteria required to conclude that a contract for sale exists, including a determination that the institution will collect substantially all of the consideration to which it is entitled. In addition to the loan-to-value ratio, where the seller provides the purchaser with financing, the analysis is based on various other factors, including the credit quality of the purchaser, the structure of the loan, and any other factors that we believe may affect collectability.
Subsequent Events Policy	Subsequent Events The Company has evaluated the effects of events and transactions through the date of this filing that have occurred subsequent to September 30, 2023. The Company does not believe there were any material subsequent events during this period that would have required further recognition or disclosure in the unaudited consolidated financial statements included in this report.
Accounting Developments	Accounting Standards Adopted in 2023 On January 1, 2023, the Company adopted ASU 2016-13 Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments (ASC 326). This standard replaced the incurred loss methodology with an expected loss methodology that is referred to as the current expected credit loss (“CECL”) methodology. CECL requires an estimate of credit losses for the remaining estimated life of the financial asset using historical experience, current conditions, and reasonable and supportable forecasts and generally applies to financial assets measured at amortized cost, including loan receivables and held-to-maturity debt securities, and some off -balance sheet credit exposures such as unfunded commitments to extend credit. Financial assets measured at amortized cost will be presented at the net amount expected to be collected by using an allowance for credit losses. In addition, CECL made changes to the accounting for available for sale debt securities. One such change is to require credit losses to be presented as an allowance rather than as a write-down on available for sale debt securities if management does not intend to sell and does not believe that it is more likely than not, they will be required to sell. The Company adopted ASC 326 and all related subsequent amendments thereto effective January 1, 2023 using the modified retrospective approach for all financial assets measured at amortized cost and off-balance sheet credit exposures. The transition adjustment upon the adoption of CECL on January 1, 2023 included an increase in the allowance for credit losses on loans of $ 1.0 million, which is presented as a reduction to net loans outstanding, and an increase in the allowance for credit losses on unfunded loan commitments of $ 0.1 million, which is recorded within other liabilities. The Company recorded a net decrease to retained earnings of $ 0.8 million as of January 1, 2023 for the cumulative effect of adopting CECL, which reflects the transition adjustments noted above, net of the applicable deferred tax assets recorded. Results for reporting periods beginning after January 1, 2023 are presented under CECL while prior period amounts continue to be reported in accordance with previously applicable accounting standards. The Company adopted ASC 326 using the prospective transition approach for debt securities for which other-than- temporary impairment had been recognized prior to January 1, 2023. As of December 31, 2022, the Company did not have any other-than-temporarily impaired investment securities. Therefore, upon adoption of ASC 326, the Company determined that an allowance for credit losses on available for sale securities was not deemed material. The Company elected not to measure an allowance for credit losses for accrued interest receivable and instead elected to reverse interest income on loans or securities that are placed on nonaccrual status, which is generally when the instrument is 90 days past due, or earlier if the Company believes the collection of interest is doubtful. The Company has concluded that this policy results in the timely reversal of uncollectible interest. The Company also adopted ASU 2022-02, “Financial Instruments - Credit Losses (Topic 326): Troubled Debt Restructurings and Vintage Disclosures” on January 1, 2023, the effective date of the guidance, on a prospective basis. ASU 2022-02 eliminated the accounting guidance for TDRs, while enhancing disclosure requirements for certain loan refinancings and restructurings by creditors when a borrower is experiencing financial difficulty. Specifically, rather than applying the recognition and measurement guidance for TDRs, an entity must apply the loan refinancing and restructuring guidance to determine whether a modification results in a new loan or a continuation of an existing loan. Additionally, ASU 2022-02 requires an entity to disclose current-period gross write-offs by year of origination for financing receivables within the scope of Subtopic 326-20, Financial Instruments—Credit Losses—Measured at Amortized Cost. ASU 2022-02 did not have a material impact on the Company’s consolidated financial statements. Loans Loans that management has the intent and ability to hold for the foreseeable future or until maturity or payoff are reported at amortized cost. Amortized cost is the principal balance outstanding, net of purchase premiums and discounts and deferred fees and costs. Accrued interest receivable related to loans is recorded in other assets on the consolidated balance sheets. Interest income is accrued on the unpaid principal balance. Loan origination fees, net of certain direct origination costs, are deferred and recognized in interest income using methods that approximate a level yield without anticipating prepayments. The accrual of interest is generally discontinued when a loan becomes 90 days past due and is not well collateralized and in the process of collection, or when management believes, after considering economic and business conditions and collection efforts, that the principal or interest will not be collectible in the normal course of business. Past due status is based on contractual terms of the loan. A loan is considered to be past due when a scheduled payment has not been received 30 days after the contractual due date. All accrued interest is reversed against interest income when a loan is placed on nonaccrual status. Interest received on such loans is accounted for using the cost-recovery method, until qualifying for return to accrual. Under the cost-recovery method, interest income is not recognized until the loan balance is reduced to zero. Loans are returned to accrual status when all the principal and interest amounts contractually due are brought current, there is a sustained period of repayment performance, and future payments are reasonably assured. Allowance for Credit Losses – Loans The allowance for credit losses 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. Loans are charged off against the allowance when management believes the uncollectibility of a loan balance is confirmed. Expected recoveries do not exceed the aggregate of amounts previously charged-off and expected to be charged-off. Accrued interest receivable is excluded from the estimate of credit losses. The allowance for credit losses represents management’s estimate of lifetime credit losses inherent in loans as of the balance sheet date. The allowance for credit losses is estimated by management using relevant available information, from both internal and external sources, relating to past events, current conditions, and reasonable and supportable forecasts. The Company’s loan loss estimation process includes procedures to appropriately consider the unique characteristics of its respective loan segments (commercial and industrial, construction and land development, commercial real estate, residential real estate, and consumer loans). These segments are further disaggregated into loan classes, the level at which credit quality is monitored. See Note 5, Loans and Allowance for Credit Losses, for additional information about our loan portfolio. Credit loss assumptions are estimated using a discounted cash flow ("DCF") model for each loan segment, except consumer loans. The weighted average remaining life method is used to estimate credit loss assumptions for consumer loans. The DCF model calculates an expected life-of-loan loss percentage by considering the forecasted probability that a borrower will default (the “PD”), adjusted for relevant forecasted macroeconomic factors, and LGD, which is the estimate of the amount of net loss in the event of default. This model utilizes historical correlations between default experience and certain macroeconomic factors as determined through a statistical regression analysis. The forecasted Alabama unemployment rate is considered in the model for commercial and industrial, construction and land development, commercial real estate, and residential real estate loans. In addition, forecasted changes in the Alabama home price index is considered in the model for construction and land development and residential real estate loans; forecasted changes in the national commercial real estate (“CRE”) price index is considered in the model for commercial real estate and multifamily loans; and forecasted changes in the Alabama gross state product is considered in the model for multifamily loans. Projections of these macroeconomic factors, obtained from an independent third party, are utilized to predict quarterly rates of default based on the statistical PD models. Expected credit losses are estimated over the contractual term of the loan, adjusted for expected prepayments and principal payments (“curtailments”) when appropriate. Management's determination of the contract term excludes expected extensions, renewals, and modifications unless the extension or renewal option is included in the contract at the reporting date and is not unconditionally cancellable by the Company. To the extent the lives of the loans in the portfolio extend beyond the period for which a reasonable and supportable forecast can be made (which is 4 quarters for the Company), the Company reverts, on a straight-line basis back to the historical rates over an 8 quarter reversion period. The weighted average remaining life method was deemed most appropriate for the consumer loan segment because consumer loans contain many different payment structures, payment streams and collateral. The weighted average remaining life method uses an annual charge-off rate over several vintages to estimate credit losses. The average annual charge-off rate is applied to the contractual term adjusted for prepayments. Additionally, the allowance for credit losses calculation includes subjective adjustments for qualitative risk factors that are believed likely to cause estimated credit losses to differ from historical experience. These qualitative adjustments may increase reserve levels and include adjustments for lending management experience and risk tolerance, loan review and audit results, asset quality and portfolio trends, loan portfolio growth, industry concentrations, trends in underlying collateral, external factors and economic conditions not already captured. Loans secured by real estate with balances equal to or greater than $500 thousand and loans not secured by real estate with balances equal to or greater than $250 thousand that do not share risk characteristics are evaluated on an individual basis. When management determines that foreclosure is probable and the borrower is experiencing financial difficulty, the expected credit losses are based on the estimated fair value of collateral held at the reporting date, adjusted for selling costs as appropriate. Allowance for Credit Losses – Unfunded Commitments Financial instruments include off-balance sheet credit instruments, such as commitments to make loans and commercial letters of credit issued to meet customer financing needs. The Company’s exposure to credit loss in the event of nonperformance by the other party to the financial instrument for off-balance sheet loan commitments is represented by the contractual amount of those instruments. Such financial instruments are recorded when they are funded. The Company records an allowance for credit losses on off-balance sheet credit exposures, unless the commitments to extend credit are unconditionally cancelable, through a charge to provision for credit losses in the Company’s consolidated statements of earnings. The allowance for credit losses on off-balance sheet credit exposures is estimated by loan segment at each balance sheet date under the current expected credit loss model using the same methodologies as portfolio loans, taking into consideration the likelihood that funding will occur as well as any third-party guarantees. The allowance for unfunded commitments is included in other liabilities on the Company’s consolidated balance sheets. On January 1, 2023, the Company recorded an adjustment for unfunded commitments of $77 thousand upon the adoption of ASC 326. At September 30, 2023, the liability for credit losses on off-balance-sheet credit exposures included in other liabilities was $ 0.2 million.