| Document And Entity Information - shares | 3 Months Ended | |
| Dec. 31, 2023 | Feb. 05, 2024 | |
| Cover [Abstract] | ||
| Document Type | 10-Q/A | |
| Document Quarterly Report | true | |
| Document Period End Date | Dec. 31, 2023 | |
| 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 | |
| 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 | |
| Title of 12(b) Security | Common Stock, par value $0.01 per share | |
| Trading Symbol | TFSL | |
| Security Exchange Name | NASDAQ | |
| Entity Common Stock, Shares Outstanding | 280,710,854 | |
| Entity Central Index Key | 0001381668 | |
| Current Fiscal Year End Date | --09-30 | |
| Document Fiscal Year Focus | 2024 | |
| Document Fiscal Period Focus | Q1 | |
| Amendment Flag | false |
