v3.8.0.1
Document and Entity Information - shares
9 Months Ended
Jan. 28, 2018
Mar. 02, 2018
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 Jan. 28, 2018  
Document Fiscal Year Focus 2018  
Document Fiscal Period Focus Q3  
Amendment Flag false  
Entity Common Stock, Shares Outstanding   114,694,866