Document and Entity Information (USD $)
12 Months Ended
Sep. 30, 2015
Nov. 16, 2015
Mar. 31, 2015
Document and Entity Information      
Entity Registrant Name LIQUIDITY SERVICES INC    
Entity Central Index Key 0001235468    
Document Type 10-K    
Document Period End Date Sep. 30, 2015    
Amendment Flag false    
Current Fiscal Year End Date --09-30    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 237,886,000
Entity Common Stock, Shares Outstanding   30,551,081  
Document Fiscal Year Focus 2015    
Document Fiscal Period Focus FY