| Document and Entity Information | Oct. 08, 2021 |
| Cover [Abstract] | |
| Amendment Flag | false |
| Entity Central Index Key | 0001519401 |
| Document Type | 8-K |
| Document Period End Date | Oct. 8, 2021 |
| Entity Registrant Name | Regional Management Corp. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-35477 |
| Entity Tax Identification Number | 57-0847115 |
| Entity Address, Address Line One | 979 Batesville Road |
| Entity Address, Address Line Two | Suite B |
| Entity Address, City or Town | Greer |
| Entity Address, State or Province | SC |
| Entity Address, Postal Zip Code | 29651 |
| City Area Code | (864) |
| Local Phone Number | 448-7000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.10 par value |
| Trading Symbol | RM |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
