Loans Receivable And Allowance For Loan Losses - Amortized Cost of Collateral Dependent Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Sep. 30, 2023
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	$ 4,009	$ 4,532
Related Allowance	123	127
Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	3,885
Related Allowance	506
Mortgage loans, one-to-four family
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	368	388
Related Allowance	0	0
Mortgage loans, one-to-four family \| Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	49
Related Allowance	0
Mortgage loans, commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	2,973	2,988
Related Allowance	0	0
Mortgage loans, commercial \| Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	1,158
Related Allowance	0
Mortgage loans, construction - custom and owner/builder \| Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	0
Related Allowance	0
Consumer loans, home equity and second mortgage
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	382	394
Related Allowance	0	0
Consumer loans, home equity and second mortgage \| Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	618
Related Allowance	0
Commercial business loans
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	286	309
Related Allowance	123	$ 127
Commercial business loans \| Collateral Pledged
Financing Receivable, Allowance for Credit Loss [Line Items]
Recorded Investment	2,060
Related Allowance	$ 506

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name Regulation S-K (SK)
-Number 229
-Section 1405
-Paragraph c
-Publisher SEC

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 13
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479319/326-20-50-13

+ Details

Name:	us-gaap_FinancingReceivableAllowanceForCreditLossesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 14A
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-14A

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of allowance for credit losses related to recorded investment.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Topic 310
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 15
-Subparagraph (a)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481962/310-10-50-15

+ Details

Name:	us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_CollateralAxis=us-gaap_CollateralPledgedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=tsbk_MortgageLoansOneToFourFamilyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=tsbk_ConstructionCustomAndOwnerbuilderMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=tsbk_ConsumerLoansHomeEquityAndSecondMortgageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_CommercialLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: