Investment Securities: Schedule of significant inputs utilized to measure management's estimate of the credit loss component on OTTI securities (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recoveries (other than temporary impairment OTTI) on investment securities	$ (19)	$ 0	$ (60)	$ 0
Net recoveries on investment securities	(19)	0	(55)	0
Held-to-maturity Securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Recoveries (other than temporary impairment OTTI) on investment securities	19	0	60	0
Held to Maturity - adjustment for portion of OTTI recorded as OCI before income taxes	0	0	(5)	0
Net recoveries on investment securities	19	0	55	0
Available-for-sale Securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
AFS - OTTI	0	0	0	0
AFS - - adjustment for portion of OTTI recorded as OCI before income taxes	0	0	0	0
AFS - Net OTTI recognized in earnings	$ 0	$ 0	$ 0	$ 0
Minimum
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
OTTI significant inputs - Constant prepayment rate	6.00%	6.00%	6.00%	6.00%
OTTI significant inputs - Collateral default rate	0.00%	0.09%	0.00%	0.09%
OTTI significant inputs - Loss severity rate	0.00%	6.00%	0.00%	6.00%
Maximum
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
OTTI significant inputs - Constant prepayment rate	15.00%	15.00%	15.00%	15.00%
OTTI significant inputs - Collateral default rate	12.31%	9.88%	12.31%	9.88%
OTTI significant inputs - Loss severity rate	74.00%	62.00%	74.00%	62.00%
Weighted Average
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
OTTI significant inputs - Constant prepayment rate	11.58%	11.54%	11.58%	11.54%
OTTI significant inputs - Collateral default rate	5.51%	4.66%	5.51%	4.66%
OTTI significant inputs - Loss severity rate	42.49%	41.93%	42.49%	41.93%

Marketable Securities, Realized Losses (Recoveries), Other than Temporary Impairments, Amount

No definition available.

Name:	tsbk_MarketableSecuritiesRealizedLossesRecoveriesOtherthanTemporaryImpairmentsAmount
Namespace Prefix:	tsbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	tsbk_OTTISignificantInputsCollateralDefaultRate
Namespace Prefix:	tsbk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	tsbk_OTTISignificantInputsConstantPrepaymentRate
Namespace Prefix:	tsbk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	tsbk_OTTISignificantInputsLossSeverityRate
Namespace Prefix:	tsbk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Other than Temporary Impairment Losses (Recoveries), Investments, Portion Recognized in Earnings, Net

+ References

No definition available.

+ Details

Name:	tsbk_OtherthanTemporaryImpairmentLossesRecoveriesInvestmentsPortionRecognizedinEarningsNet
Namespace Prefix:	tsbk_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

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.

+ References

No definition available.

+ Details

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

- Definition

The amount by which the fair value of an investment in debt and equity securities categorized as Available-for-sale is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=82896770&loc=SL6284422-111562

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsAvailableforsaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount before tax of other than temporary impairment (OTTI) on investment in available-for-sale debt security, recognized in other comprehensive loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 35
-URI http://asc.fasb.org/extlink&oid=82895926&loc=d3e25362-111560

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterestAvailableforsaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount before tax of other than temporary impairment (OTTI) on investment in held-to-maturity debt security, recognized in other comprehensive loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 14A
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669686-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 10A
-Subparagraph (g)
-URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669646-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 8A
-URI http://asc.fasb.org/extlink&oid=82896770&loc=SL6284422-111562

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section 45
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=84228862&loc=d3e637-108580

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionInOtherComprehensiveIncomeLossBeforeTaxIncludingPortionAttributableToNoncontrollingInterestHeldtomaturitySecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis.

+ References

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNetAvailableforsaleSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_InformationByCategoryOfDebtSecurityAxis=us-gaap_HeldtomaturitySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_InformationByCategoryOfDebtSecurityAxis=us-gaap_AvailableforsaleSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: