| Document And Entity Information | Jul. 06, 2023 |
| Document Information [Line Items] | |
| Entity, Registrant Name | MALVERN BANCORP, INC. |
| Document, Type | 8-K |
| Document, Period End Date | Jul. 06, 2023 |
| Entity, Incorporation, State or Country Code | PA |
| Entity, File Number | 000-54835 |
| Entity, Tax Identification Number | 45-5307782 |
| Entity, Address, Address Line One | 42 East Lancaster Avenue |
| Entity, Address, City or Town | Paoli |
| Entity, Address, State or Province | PA |
| Entity, Address, Postal Zip Code | 19301 |
| City Area Code | 610 |
| Local Phone Number | 644-9400 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock |
| Trading Symbol | MLVF |
| Security Exchange Name | NASDAQ |
| Entity, Emerging Growth Company | false |
| Amendment Flag | false |
| Entity, Central Index Key | 0001550603 |
