| Document and Entity Information | Jan. 21, 2021 |
| Document and Entity Information [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Jan. 21, 2021 |
| Entity File Number | 001-37615 |
| Entity Registrant Name | Atlantic Capital Bancshares, Inc. |
| Entity Incorporation, State or Country Code | GA |
| Entity Tax Identification Number | 20-5728270 |
| Entity Address, Address Line One | 945 East Paces Ferry Rd. NE, Suite 1600 |
| Entity Address, City or Town | Atlanta |
| Entity Address, State or Province | GA |
| Entity Address, Postal Zip Code | 30326 |
| City Area Code | 404 |
| Local Phone Number | 995-60 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, no par value |
| Trading Symbol | ACBI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Central Index Key | 0001461755 |
| Amendment Flag | false |
