Document And Entity Information - USD ($)	12 Months Ended
	Sep. 30, 2025	Nov. 21, 2025	Mar. 31, 2025
Cover [Abstract]
Document Type	10-K
Document Annual Report	true
Document Period End Date	Sep. 30, 2025
Document Transition Report	false
Entity File Number	001-33390
Entity Registrant Name	TFS FINANCIAL CORPORATION
Entity Incorporation, State or Country Code	X1
Entity Tax Identification Number	52-2054948
Entity Address, Address Line One	7007 Broadway Avenue
Entity Address, City or Town	Cleveland,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	44105
City Area Code	216
Local Phone Number	441-6000
Title of 12(b) Security	Common Stock, par value $0.01 per share
Trading Symbol	TFSL
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 647,700,000
Entity Common Stock, Shares Outstanding		280,513,055
Entity Central Index Key	0001381668
Current Fiscal Year End Date	--09-30
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Amendment Flag	false
ICFR Auditor Attestation Flag	true
Auditor Name	Deloitte & Touche LLP
Auditor Location	Cleveland, Ohio
Auditor Firm ID	34
Document Financial Statement Error Correction [Flag]	false