Commitments and Contingencies (Details) $ in Thousands	12 Months Ended
Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Reserve for unfunded loan commitments	$ 241	$ 207
Employee severance compensation plan, employee minimum service requirement (in years)	2 years
Employee severance compensation plan, period following effective date of a change in company control (in months)	12 months
Employee severance compensation plan, eligible payment, maximum compensation term (in months)	18 months
Employee severance compensation plan, annual compensation multiplier	2.99
Employee severance compensation plan, period following effective date of change in control for eligible severance benefits (in years)	5 years

Employee Severance Compensation Plan, Annual Compensation Multiplier

No definition available.

Name:	tsbk_EmployeeSeveranceCompensationPlanAnnualCompensationMultiplier
Namespace Prefix:	tsbk_
Data Type:	xbrli:pureItemType
Balance Type:	na
Period Type:	duration

Employee Severance Compensation Plan, Eligible Payment, Maximum Compensation Term

No definition available.

Name:	tsbk_EmployeeSeveranceCompensationPlanEligiblePaymentMaximumCompensationTerm
Namespace Prefix:	tsbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Employee Severance Compensation Plan, Employee Service Requirement

No definition available.

Name:	tsbk_EmployeeSeveranceCompensationPlanEmployeeServiceRequirement
Namespace Prefix:	tsbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Employee Severance Compensation Plan, Period Following Effective Date Of A Change In Company Control

No definition available.

Name:	tsbk_EmployeeSeveranceCompensationPlanPeriodFollowingEffectiveDateOfAChangeInCompanyControl
Namespace Prefix:	tsbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

Employee Severance Compensation Plan, Period Following Effective Date Of Change In Control For Eligible Severance Benefits

No definition available.

Name:	tsbk_EmployeeSeveranceCompensationPlanPeriodFollowingEffectiveDateOfChangeInControlForEligibleSeveranceBenefits
Namespace Prefix:	tsbk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

No definition available.

Name:	tsbk_ReserveForUnfundedLoanCommitments
Namespace Prefix:	tsbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

No definition available.

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