Document and Entity Information - USD ($)
12 Months Ended
Jun. 30, 2019
Aug. 22, 2019
Dec. 31, 2018
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, 2019    
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 Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Ex Transition Period false    
Entity Shell Company false    
Entity Public Float     $ 1,243,925,409
Entity Common Stock, Shares Outstanding   18,218,932  
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY