Summary Of Significant Accounting Policies: Basis of Presentation (Policies)	9 Months Ended
	Jun. 30, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation: The accompanying unaudited consolidated financial statements for Timberland Bancorp, Inc. (“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 year ended September 30, 2015 (“2015 Form 10-K”). The unaudited consolidated results of operations for the nine months ended June 30, 2016 are not necessarily indicative of the results that may be expected for the entire fiscal year ending September 30, 2016.
Principles of Consolidation	Principles of Consolidation: The unaudited consolidated financial statements include the accounts of the Company and its wholly-owned subsidiary, Timberland Bank (“Bank”), and the Bank’s wholly-owned subsidiary, Timberland Service Corporation. All significant intercompany transactions and balances have been eliminated in consolidation.
Operating Segment	Operating Segment: The Company has one reportable operating segment which is defined as community banking in western Washington under the operating name, “Timberland Bank.”
Use of Estimates	The preparation of consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from those estimates.
Reclassification	Certain prior period amounts have been reclassified to conform to the June 30, 2016 presentation with no change to net income or total shareholders’ equity as previously reported.
Recent Accounting Pronouncements	RECENT ACCOUNTING PRONOUNCEMENTS In May 2014, the Financial Accounting Standards Board ("FASB") issued Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers (Topic 606), with an effective date for annual reporting periods beginning after December 15, 2016. The core principle of this ASU is that an entity recognizes revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In general, the ASU requires companies to use more judgment and make more estimates than under current guidance, including identifying performance obligations in the contract and estimating the amount of variable consideration to include in the transaction price related to each separate performance obligation. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606), which deferred the effective date of ASU No. 2014-09 to annual periods beginning after December 15, 2017, including interim periods within that reporting period. The adoption of ASU No. 2014-09 is not expected to have a material impact on the Company's consolidated financial statements. In January 2015, the FASB issued ASU No. 2015-01, Income Statement - Extraordinary and Unusual Items (Subtopic 225-20). The ASU eliminates the need to separately classify, present and disclose extraordinary events. The disclosure of events or transactions that are unusual or infrequent in nature will be included in other guidance. The amendments in this ASU are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. The adoption of ASU No. 2015-01 is not expected to have a material impact on the Company's consolidated financial statements. In September 2015, the FASB issued ASU No. 2015-16, Business Combinations (Topic 805): Simplifying the Accounting for Measurement-Period Adjustments. This ASU requires that an acquirer recognize adjustments to provisional amounts that are identified during the measurement period in the reporting period in which the adjustment amounts are determined. The amendments in this ASU require that the acquirer record, in the same period's financial statements, the effect on earnings of changes in depreciation, amortization, or other income effects, if any, as a result of the change to the provisional amounts, calculated as if the accounting had been completed at the acquisition date. The amendments in this ASU require an entity to present separately on the face of the income statement or disclose in the notes the portion of the amount recorded in the current-period earnings by line item that would have been recorded in previous reporting periods if the adjustment to the provisional amounts had been recognized as of the acquisition date. The amendments in this ASU are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2015. The adoption of ASU No. 2015-16 is not expected to have a material impact on the Company's consolidated financial statements. In January 2016, the FASB issued ASU No. 2016-01, Financial Instruments - Overall (Subtopic 825-10): Recognition and Measurement of Financial Assets and Financial Liabilities. The main provisions of this ASU address the valuation and impairment of certain equity investments along with simplified disclosures about those investments. Equity securities with readily determinable fair values will be treated in the same manner as other financial instruments. The amendments in this ASU are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. The adoption of ASU No. 2016-01 is not expected to have a material impact on the Company's consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). This ASU is intended to increase transparency and comparability among organizations by requiring the recognition of lease assets and lease liabilities on the balance sheet and disclosure of key information about leasing arrangements. The principal change required by this ASU relates to lessee accounting, and is that for operating leases, a lessee is required to (1) recognize a right-of-use asset and a lease liability, initially measured at the present value of the lease payments, in the statement of financial position, (2) recognize a single lease cost, calculated so that the cost of the lease is allocated over the lease term on a generally straight-line basis, and (3) classify all cash payments within operating activities in the statement of cash flows. For leases with a term of 12 months or less, a lessee is permitted to make an accounting policy election by class of underlying asset not to recognize lease assets and lease liabilities. If a lessee makes this election, it should recognize lease expense for such leases generally on a straight-line basis over the lease term. This ASU also changes disclosure requirements related to leasing activities, and requires certain qualitative disclosures along with specific quantitative disclosures. The amendments in this ASU are effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2018. Early application of the amendments in this ASU is permitted. The adoption of ASU No. 2016-02 is being reviewed for any material impact there may be on the Company's future consolidated financial statements. In March 2016, the FASB issued ASU No. 2016-09, Improvements to Employee Share-Based Payment Accounting, which amends ASC Topic 718, Compensation - Stock Compensation. This ASU includes provisions intended to simplify various aspects related to how share-based payments are accounted for and presented in the financial statements. This ASU is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2016. The adoption of ASU No. 2016-09 is being reviewed for any material impact there may be on the Company's future consolidated financial statements. In June 2016, the FASB issued ASU No. 2016-13, Financial Instruments - Credit Losses. This ASU replaces the existing incurred losses methodology for estimating allowances with a current expected credit losses methodology. ASU No. 2016-13 will apply to most financial assets measured at amortized cost and certain other instruments, including trade and other receivables, loans, held to maturity investment securities and off-balance sheet commitments. This ASU is effective for fiscal years beginning after December 15, 2019, including interim periods within those fiscal years. The Company is currently evaluating the impact that the adoption of ASU 2016-13 will have on the Company’s future consolidated financial statements.