| Document and Entity Information | Oct. 31, 2021 |
| Cover [Abstract] | |
| Document Type | 8-K/A |
| Amendment Flag | false |
| Document Period End Date | Oct. 21, 2021 |
| Entity Registrant Name | South Plains Financial, Inc. |
| Entity Incorporation, State or Country Code | TX |
| Entity File Number | 001-38895 |
| Entity Tax Identification Number | 75-2453320 |
| Entity Address, Address Line One | 5219 City Bank Parkway |
| Entity Address, City or Town | Lubbock |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 79407 |
| City Area Code | 806 |
| Local Phone Number | 792-7101 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | true |
| Entity Ex Transition Period | false |
| Entity Central Index Key | 0001163668 |
| Title of 12(b) Security | Common Stock, par value $1.00 per share |
| Trading Symbol | SPFI |
| Security Exchange Name | NASDAQ |
