| Document and Entity Information Document | Feb. 23, 2023 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Feb. 23, 2023 |
| Entity Registrant Name | Red River Bancshares, Inc. |
| Entity Central Index Key | 0001071236 |
| Amendment Flag | false |
| Entity Incorporation, State or Country Code | LA |
| Entity File Number | 001-38888 |
| Entity Tax Identification Number | 72-1412058 |
| Entity Address, Address Line One | 1412 Centre Court Drive |
| Entity Address, Address Line Two | Suite 501 |
| Entity Address, City or Town | Alexandria |
| Entity Address, State or Province | LA |
| Entity Address, Postal Zip Code | 71301 |
| City Area Code | 318 |
| Local Phone Number | 561-4000 |
| 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 | RRBI |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | true |
