Document and Entity Information - shares
3 Months Ended
Jun. 30, 2019
Jul. 31, 2019
Document And Entity Information [Abstract]    
Entity Registrant Name ORION ENERGY SYSTEMS, INC.  
Entity Central Index Key 0001409375  
Trading Symbol OESX  
Document Type 10-Q  
Document Period End Date Jun. 30, 2019  
Amendment Flag false  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q1  
Current Fiscal Year End Date --03-31  
Entity Current Reporting Status Yes  
Entity Filer Category Non-accelerated Filer  
Entity Shell Company false  
Entity Emerging Growth Company false  
Entity Small Business true  
Entity Common Stock, Shares Outstanding   30,121,487
Entity File Number 001-33887  
Entity Tax Identification Number 391847269  
Entity Address, Address Line One 2210 Woodland Drive  
Entity Address, City or Town Manitowoc  
Entity Address, State or Province Wisconsin  
Entity Address, Postal Zip Code 54220  
City Area Code 920  
Local Phone Number 892-9340