Summary Of Significant Accounting Policies	9 Months Ended
Jun. 30, 2026
Accounting Policies [Abstract]
Summary Of Significant Accounting Policies	SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (a) Basis of Presentation: The accompanying unaudited consolidated financial statements of Timberland Bancorp, Inc. and its wholly-owned subsidiary, Timberland Bank (the "Bank") (collectively, "the Company") were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with instructions for Form 10-Q and, therefore, do not include all disclosures necessary for a complete presentation of consolidated financial condition, results of operations, and cash flows in conformity with GAAP. However, all adjustments which are, in the opinion of management, necessary for a fair presentation of the interim consolidated financial statements have been included. All such adjustments are of a normal recurring nature. The unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2025 (“2025 Form 10-K”). The unaudited consolidated results of operations for the nine months ended June 30, 2026 are not necessarily indicative of the results that may be expected for the entire fiscal year ending September 30, 2026. (b) Principles of Consolidation: The unaudited consolidated financial statements include the accounts of the Company, its wholly-owned subsidiary, the Bank, and the Bank's wholly owned subsidiary, Timberland Service Corp. All significant inter-company transactions and balances have been eliminated in consolidation. (c) Operating Segment: The Company's revenue is primarily derived from the business of banking. Management has assigned certain responsibilities by business-line and evaluates financial performance on a Company-wide basis. The Company's financial performance is monitored on a consolidated basis by the Company's Chief Executive Officer, President and Chief Financial Officer, which are considered the Company's chief operating decision makers ("CODMs") for financial oversight. The primary measure of performance is consolidated net income. Financial performance is reviewed monthly by the CODMs. The presentation of financial performance is consistent with amounts and financial statement line items shown in the Company's consolidated balance sheets and consolidated statements of income. All of the Company's operations are considered by management to be aggregated in one reportable operating segment. (d) The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities, as of the date of the consolidated balance sheets, and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates. (e) Certain prior period amounts have been reclassified to conform to the June 30, 2026 presentation with no change to previously reported net income or total shareholders’ equity.

(a) Basis of Presentation: The accompanying unaudited consolidated financial statements of Timberland Bancorp, Inc. and its wholly-owned subsidiary, Timberland Bank (the "Bank") (collectively, "the Company") were prepared in accordance with accounting principles generally accepted in the United States of America (“GAAP”) for interim financial information and with instructions for Form 10-Q and, therefore, do not include all disclosures necessary for a complete presentation of consolidated financial condition, results of operations, and cash flows in conformity with GAAP. However, all adjustments which are, in the opinion of management, necessary for a fair presentation of the interim consolidated financial statements have been included. All such adjustments are of a normal recurring nature. The unaudited consolidated financial statements should be read in conjunction with the audited consolidated financial statements included in the Company’s Annual Report on Form 10-K for the fiscal year ended September 30, 2025 (“2025 Form 10-K”). The unaudited consolidated results of operations for the nine months ended June 30, 2026 are not necessarily indicative of the results that may be expected for the entire fiscal year ending September 30, 2026.

(b) Principles of Consolidation: The unaudited consolidated financial statements include the accounts of the Company, its wholly-owned subsidiary, the Bank, and the Bank's wholly owned subsidiary, Timberland Service Corp. All significant inter-company transactions and balances have been eliminated in consolidation.

(c) Operating Segment: The Company's revenue is primarily derived from the business of banking. Management has assigned certain responsibilities by business-line and evaluates financial performance on a Company-wide basis. The Company's financial performance is monitored on a consolidated basis by the Company's Chief Executive Officer, President and Chief Financial Officer, which are considered the Company's chief operating decision makers ("CODMs") for financial oversight. The primary measure of performance is consolidated net income. Financial performance is reviewed monthly by the CODMs. The presentation of financial performance is consistent with amounts and financial statement line items shown in the Company's consolidated balance sheets and consolidated statements of income. All of the Company's operations are considered by management to be aggregated in one reportable operating segment.

(d) The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, and the disclosure of contingent assets and liabilities, as of the date of the consolidated balance sheets, and the reported amounts of income and expenses during the reporting period. Actual results could differ from those estimates.