v3.25.4

Loans And Allowance For Credit Losses (Schedule Of Loans Modified During The Period) (Details) - Real Estate Loans - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Dec. 31, 2025 | Dec. 31, 2024
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 1,372 | $ 1,810
Modified Loans, to Total Financing Receivables, Percentage | 0.01% | 0.01%
Construction/Permanent Loans |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 0 | $ 0
Residential Non Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 1,085 | $ 1,420
Modified Loans, to Total Financing Receivables, Percentage | 0.01% | 0.01%
Residential Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 112 | $ 166
Modified Loans, to Total Financing Receivables, Percentage | 0.33% | 0.42%
Home Equity Line of Credit |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 80 | $ 224
Modified Loans, to Total Financing Receivables, Percentage | 0.00% | 0.01%
Home Equity Loan |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 95 | $ 0
Modified Loans, to Total Financing Receivables, Percentage | 0.01% | 0.00%
Interest Rate Reduction |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 0 | $ 0
Interest Rate Reduction | Residential Non Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Interest Rate Reduction | Residential Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Interest Rate Reduction | Home Equity Line of Credit |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Interest Rate Reduction | Home Equity Loan |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Term Extension |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 702 | 286
Term Extension | Residential Non Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 621 | 213
Term Extension | Residential Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 81 | 27
Term Extension | Home Equity Line of Credit |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 46
Term Extension | Home Equity Loan |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Significant Payment Delay |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 416 | 1,199
Significant Payment Delay | Residential Non Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 293 | 1,030
Significant Payment Delay | Residential Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 28 | 138
Significant Payment Delay | Home Equity Line of Credit |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 31
Significant Payment Delay | Home Equity Loan |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 95 | 0
Rate Reduction & Term Extension |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 251 | 325
Rate Reduction & Term Extension | Residential Non Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 171 | 177
Rate Reduction & Term Extension | Residential Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 1
Rate Reduction & Term Extension | Home Equity Line of Credit |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 80 | 147
Rate Reduction & Term Extension | Home Equity Loan |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Other Loan Modification |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 3 | 0
Other Loan Modification | Residential Non Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Other Loan Modification | Residential Home Today |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 3 | 0
Other Loan Modification | Home Equity Line of Credit |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | 0 | 0
Other Loan Modification | Home Equity Loan |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |
Modified Loans | $ 0 | $ 0

X
- Definition Amortized cost excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-42 + Details
Name: | us-gaap_FinancingReceivableExcludingAccruedInterestModifiedPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Percentage, excluding accrued interest, of financing receivable modified during period for debtor experiencing financial difficulty to total financing receivables. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-42 + Details
Name: | us-gaap_FinancingReceivableModificationToTotalFinancingReceivablesExcludingAccruedInterestPercent
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- 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 Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 55 -Paragraph 12A -Publisher FASB -URI https://asc.fasb.org/1943274/2147481933/310-10-55-12A Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 34 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-34 Reference 3: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 33 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-33 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(2) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-42 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Topic 310 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 42 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org/1943274/2147481962/310-10-50-42 + Details
Name: | us-gaap_FinancingReceivableModificationsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_CollateralAxis=us-gaap_ResidentialRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=tfsl_ConstructionPermanentLoansMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=tfsl_ResidentialNonHomeTodayMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=tfsl_ResidentialHomeTodayMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityLoanMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_ContractualInterestRateReductionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_PaymentDeferralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=us-gaap_ExtendedMaturityAndInterestRateReductionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_LoanRestructuringModificationAxis=tfsl_OtherLoanModificationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |