v3.25.4

Commitments And Contingent Liabilities (Narrative) (Details) - USD ($) $ in Thousands | 3 Months Ended |
--- | --- | ---
Dec. 31, 2025 | Sep. 30, 2025
Minimum |  |
Unfunded And Commitments To Originate [Line Items] |  |
Fixed expiration of commitments to extend credit (in days) | 60 days |
Maximum |  |
Unfunded And Commitments To Originate [Line Items] |  |
Fixed expiration of commitments to extend credit (in days) | 360 days |
Unfunded Commitments, Equity Lines of Credit Including Suspended Accounts |  |
Unfunded And Commitments To Originate [Line Items] |  |
Unfunded commitments on home equity lines of credit (including commitments for suspended accounts) | $ 5,629,816 |
Loan Sale Commitments | Residential Mortgage |  |
Unfunded And Commitments To Originate [Line Items] |  |
Contractual Obligation | 11,298 | $ 59,340
Unfunded Loan Commitment |  |
Unfunded And Commitments To Originate [Line Items] |  |
Unfunded commitments on home equity lines of credit (including commitments for suspended accounts) | 5,582,424 |
Unfunded Loan Commitment | Home Equity Line of Credit |  |
Unfunded And Commitments To Originate [Line Items] |  |
Unfunded commitments on home equity lines of credit (including commitments for suspended accounts) | $ 5,574,340 |
Unfunded Loan Commitment | Home Equity Line of Credit | Maximum |  |
Unfunded And Commitments To Originate [Line Items] |  |
Home equity unfunded commitments expiration period, years | 10 years |
Loan Purchase Commitments | Residential Mortgage |  |
Unfunded And Commitments To Originate [Line Items] |  |
Contractual Obligation | $ 38,457 | $ 28,460

X
- Definition Fixed Expiration Of Commitments To Extend Credit, Days + References No definition available. + Details
Name: | tfsl_FixedExpirationOfCommitmentsToExtendCreditDays
Namespace Prefix: | tfsl_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of contractual obligation, including, but not limited to, long-term debt, lease obligation, purchase obligation, and other commitments. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 942 -SubTopic 235 -Name Accounting Standards Codification -Section S99 -Paragraph 2 -Publisher FASB -URI https://asc.fasb.org/1943274/2147477314/942-235-S99-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S50 -Paragraph 4 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480738/235-10-S50-4 Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 235 -SubTopic 10 -Name Accounting Standards Codification -Section S99 -Paragraph 3 -Subparagraph (SX 210.12-04(a)) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480678/235-10-S99-3 + Details
Name: | us-gaap_ContractualObligation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The face amount of financial liabilities, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 825 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 11 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482907/825-10-50-11 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 942 -SubTopic 825 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147478898/942-825-50-1 + Details
Name: | us-gaap_FairValueDisclosureOffbalanceSheetRisksFaceAmountLiability
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Period remaining on line of credit facility before it terminates, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityExpirationPeriod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:durationItemType
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 No definition available. + Details
Name: | us-gaap_OtherCommitmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=tfsl_UnfundedCommitmentsEquityLinesOfCreditIncludingSuspendedAccountsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=tfsl_LoanSaleCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_UnfundedLoanCommitmentMember
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_FinancialInstrumentAxis=us-gaap_LoanPurchaseCommitmentsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |