Document and Entity Information - USD ($)
12 Months Ended
Jun. 30, 2018
Aug. 24, 2018
Dec. 31, 2017
Document and Entity Information      
Entity Registrant Name OSI SYSTEMS INC    
Entity Central Index Key 0001039065    
Document Type 10-K    
Document Period End Date Jun. 30, 2018    
Amendment Flag false    
Current Fiscal Year End Date --06-30    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Public Float     $ 1,163,504,202
Entity Common Stock, Shares Outstanding   18,093,373  
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY