| Cover | May 06, 2021 | Aug. 06, 2020 |
| Cover [Abstract] | ||
| Document Type | 8-K | |
| Document Period End Date | May 6, 2021 | |
| Entity Registrant Name | LIQUIDITY SERVICES, INC. | |
| Entity Incorporation, State or Country Code | DE | |
| Entity File Number | 0-51813 | |
| Entity Tax Identification Number | 52-2209244 | |
| Entity Address, Address Line One | 6931 Arlington Road, Suite 200 | |
| Entity Address, City or Town | Bethesda | |
| Entity Address, State or Province | MD | |
| Entity Address, Postal Zip Code | 20814 | |
| City Area Code | (202) | |
| Local Phone Number | 467-6868 | |
| 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 | 0001235468 | |
| Amendment Flag | false | |
| Title of 12(b) Security | Common Stock, $0.001 par value | |
| Trading Symbol | LQDT | |
| Security Exchange Name | NASDAQ |
