| Document and Entity Information | Feb. 04, 2021 |
| Document and Entity Information | |
| Document Type | 8-K |
| Document Period End Date | Feb. 4, 2021 |
| Entity Registrant Name | USA TRUCK INC. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 1-35740 |
| Entity Tax Identification Number | 71-0556971 |
| Entity Address, Address Line One | 3200 Industrial Park Road |
| Entity Address, City or Town | Van Buren |
| Entity Address, State or Province | AR |
| Entity Address, Postal Zip Code | 72956 |
| City Area Code | 479 |
| Local Phone Number | 471-2500 |
| Title of 12(b) Security | Common Stock, $0.01 Par Value |
| Trading Symbol | USAK |
| Security Exchange Name | NASDAQ |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0000883945 |
| Amendment Flag | false |
