| Document and Entity Information | Feb. 24, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 24, 2021 |
| Entity File Number | 0-49731 |
| Entity Registrant Name | Severn Bancorp, Inc. |
| Entity Incorporation, State or Country Code | MD |
| Entity Tax Identification Number | 52-1726127 |
| Entity Address State Or Province | MD |
| Entity Address, Address Line One | 200 Westgate Circle, Suite 200 |
| Entity Address, City or Town | Annapolis |
| Entity Address, Postal Zip Code | 21401 |
| City Area Code | 410 |
| Local Phone Number | 260-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.01 par value |
| Trading Symbol | SVBI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000868271 |
| Amendment Flag | false |
