| Cover | Aug. 06, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Aug. 6, 2020 |
| 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 |
