XML 12 R1.htm IDEA: XBRL DOCUMENT v3.20.2
Document and Entity Information - shares
 6 Months Ended
Oct. 31, 2020
Dec. 04, 2020
Document And Entity Information    
Entity Registrant Name Ocean Power Technologies, Inc.  
Entity Central Index Key 0001378140  
Document Type 10-Q  
Document Period End Date Oct. 31, 2020  
Amendment Flag false  
Current Fiscal Year End Date --04-30  
Entity's Reporting Status Current Yes  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business Flag true  
Entity Emerging Growth Company false  
Entity Shell Company false  
Entity Common Stock, Shares Outstanding   30,798,438
Document Fiscal Period Focus Q2  
Document Fiscal Year Focus 2021