Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Dec. 31, 2024
Summary of Significant Accounting Policies [Abstract]
Summary of Significant Accounting Policies	(1) Summary of Significant Accounting Policies Principles of Consolidation and Basis of Presentation Within the accompanying unaudited interim consolidated financial statements and related notes to the consolidated financial statements, the June 30, 2024 data was derived from the audited consolidated financial statements and notes of Greene County Bancorp, Inc. (the “Company”) and its wholly owned subsidiaries, the Bank of Greene County (the “Bank”) and the Bank’s wholly owned subsidiaries, Greene County Commercial Bank (the “Commercial Bank”) and Greene Property Holdings, Ltd. The interim consolidated financial statements at and for the three and six months ended December 31, 2024 and 2023 are unaudited. The unaudited interim consolidated financial statements include the accounts of certain Variable Interest Entities (“VIE(s)”). In accordance with the applicable accounting guidance for consolidations, the Company consolidates a VIE if it has (i) a variable interest in the entity; (ii) the power to direct activities of the VIE that most significantly affect the entity’s economic performance; and (iii) the obligation to absorb losses of the entity or the right to receive benefits from the entity that could potentially be significant to the VIE (i.e., we are considered to be the primary beneficiary). The Company uses the equity method to account for unconsolidated investments in VIEs if it has significant influence over the entity’s operating and financing decision. Unconsolidated investments in VIEs in which the Company does not have significant influence, are carried at a cost measurement alternative. See Note 14, Variable Interest Entities for information on our involvement with VIEs. The financial statements have been prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with the instructions to Form 10-Q and Article 8 of Regulation S-X. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. To the extent that information and notes required by GAAP for complete financial statements are contained in or are consistent with the audited financial statements incorporated by reference to Greene County Bancorp, Inc.’s Annual Report on Form 10-K for the year ended June 30, 2024, such information and notes have not been duplicated herein. In the opinion of management, all adjustments (consisting of only normal recurring items) necessary for a fair presentation of the financial position and results of operations and cash flows at and for the periods presented have been included. Certain previous years’ amounts in the unaudited consolidated financial statements and notes thereto, have been reclassified to conform to the current year’s presentation. All material inter-company accounts and transactions have been eliminated in the consolidation. The results of operations and other data for the three and six months ended December 31, 2024 are not necessarily indicative of results that may be expected for the entire fiscal year ending June 30, 2025. These consolidated financial statements consider events that occurred through the date the consolidated financial statements were issued and should be read in conjunction with the audited consolidated financial statements and notes included in the Company’s Annual Report on Form 10-K. Nature of Operations The Company’s primary business is the ownership and operation of its subsidiaries. At December 31, 2024, the Bank has 18 full-service offices, lending centers, an operations center, customer call center, and wealth management center, located in its market area consisting of the Hudson Valley and Capital District Regions of New York State. The Bank is primarily engaged in the business of attracting deposits from the general public in the Bank’s market area, and investing such deposits, together with other sources of funds, in loans and investment securities. The Commercial Bank’s primary business is to attract deposits from, and provide banking services to, local municipalities. Greene Property Holdings, Ltd. was formed as a New York corporation that has elected under the Internal Revenue Code to be a real estate investment trust. Currently, certain mortgages and loan notes held by the Bank are transferred and beneficially owned by Greene Property Holdings, Ltd. The Bank continues to service these loans. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States of America requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could materially differ from those estimates. Material estimates that are particularly susceptible to significant change in the near term relate to the determination of the allowance for credit losses (“ACL”) on loans and on unfunded commitments. Accrued Interest Receivable Accrued interest receivable balances are presented separately on the consolidated statements of financial condition and are not included in amortized cost when determining the allowance for credit losses. Accrued interest receivable that is deemed uncollectible is written off timely. For loans, write off typically occurs upon becoming over 90 to 120 days past due and therefore, the amount of such write offs are immaterial. Historically, the Company has not experienced uncollectible accrued interest receivable on investment securities. Income Taxes The Company uses the proportional amortization method for solar tax credit investments, whereby the associated tax credits are recognized as a reduction to tax expense. Certain federal tax credits that are non-refundable and transferable under applicable regulations are accounted for as government grants and recorded as a reduction to the amortized cost or net investment in the applicable asset generating the credit, generally within “other assets.” Amounts are amortized through depreciation or as an adjustment to yield over the estimated life of the asset. Any gain or loss on the transfer of a tax credit is recorded within “other income.”