Document and Entity Information (USD $)
12 Months Ended
Jun. 30, 2012
Aug. 16, 2012
Dec. 31, 2011
Document and Entity Information [Abstract]      
Entity Registrant Name QUINSTREET, INC    
Entity Central Index Key 0001117297    
Document Type 10-K    
Document Period End Date Jun. 30, 2012    
Amendment Flag false    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus FY    
Current Fiscal Year End Date --06-30    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Public Float     $ 270,210,124
Entity Common Stock, Shares Outstanding   42,760,305