v3.7.0.1
Document and Entity Information - shares
3 Months Ended
Jul. 30, 2017
Sep. 01, 2017
Document and Entity Information [Abstract]    
Entity Registrant Name FINISAR CORP  
Entity Central Index Key 0001094739  
Current Fiscal Year End Date --04-29  
Entity Filer Category Large Accelerated Filer  
Document Type 10-Q  
Document Period End Date Jul. 30, 2017  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q1  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   113,887,565