Document and Entity Information - shares
6 Months Ended
Mar. 31, 2017
May 02, 2017
Document and Entity Information    
Entity Registrant Name LIQUIDITY SERVICES INC  
Entity Central Index Key 0001235468  
Document Type 10-Q  
Document Period End Date Mar. 31, 2017  
Amendment Flag false  
Current Fiscal Year End Date --09-30  
Entity Current Reporting Status Yes  
Entity Filer Category Accelerated Filer  
Entity Common Stock, Shares Outstanding   31,485,857
Document Fiscal Year Focus 2017  
Document Fiscal Period Focus Q2