| Cover | Apr. 19, 2021 |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Apr. 19, 2021 |
| Entity File Number | 001-36452 |
| Entity Registrant Name | ServisFirst Bancshares, Inc. |
| Entity Central Index Key | 0001430723 |
| Entity Tax Identification Number | 26-0734029 |
| Entity Incorporation, State or Country Code | DE |
| Entity Address, Address Line One | 2500 Woodcrest Place |
| Entity Address, City or Town | Birmingham |
| Entity Address, State or Province | AL |
| Entity Address, Postal Zip Code | 35209 |
| City Area Code | 205 |
| Local Phone Number | 949-0302 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common |
| Trading Symbol | SFBS |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
