XML 17 R1.htm IDEA: XBRL DOCUMENT v3.19.2
Document and Entity Information - USD ($)
$ in Millions
 12 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Dec. 31, 2018
Entity Information [Line Items]      
Entity Registrant Name ALPHA & OMEGA SEMICONDUCTOR Ltd    
Entity Central Index Key 0001387467    
Current Fiscal Year End Date --06-30    
Entity Filer Category Accelerated Filer    
Document Type 10-K    
Document Period End Date Jun. 30, 2019    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Amendment Flag false    
Entity Common Stock, Shares Outstanding   24,519,530  
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Shell Company false    
Entity Emerging Growth Company false    
Entity Small Business true    
Entity Public Float     $ 195