| Document and Entity Information | Apr. 18, 2021 |
| Cover [Abstract] | |
| Entity Registrant Name | MARLIN BUSINESS SERVICES CORP |
| Amendment Flag | false |
| Entity Central Index Key | 0001260968 |
| Document Type | 8-K |
| Document Period End Date | Apr. 18, 2021 |
| Entity File Number | 000-50448 |
| Entity Incorporation State Country Code | PA |
| Entity Tax Identification Number | 38-3686388 |
| Entity Address, Address Line One | 300 Fellowship Road |
| Entity Address, City or Town | Mount Laurel |
| Entity Address, State or Province | NJ |
| Entity Address, Postal Zip Code | 08054 |
| City Area Code | 888 |
| Local Phone Number | 479-9111 |
| Written Communications | false |
| Soliciting Material | true |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Shares |
| Trading Symbol | MRLN |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
