v3.25.4

Earnings Per Share (Narrative) (Details) - shares	Dec. 31, 2025	Dec. 31, 2024
Earnings Per Share [Abstract]
Shares Held By Parent Holding Company	227,119,132
Employee Stock Ownership Plan (ESOP), neither allocated nor committed to be released to participants (in shares)	1,733,356	2,166,696

X

- Definition

Shares held by the parent holding company

+ References

No definition available.

+ Details

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Namespace Prefix:	tfsl_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

X

- References

No definition available.

+ Details

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

X

- Definition

Shares contributed to the ESOP that have not yet been released, committed to be released, or allocated to participant accounts. Suspense shares generally collateralize ESOP debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 718
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480459/718-40-55-20

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 718
-SubTopic 40
-Name Accounting Standards Codification
-Section 55
-Paragraph 9
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480459/718-40-55-9

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 718
-SubTopic 40
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480489/718-40-50-1

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
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Period Type:	instant