v3.19.3.a.u2
Document and Entity Information - shares
9 Months Ended
Dec. 31, 2019
Jan. 31, 2020
Document and Entity Information [Line Items]    
Entity Registrant Name ORION ENERGY SYSTEMS, INC.  
Entity Central Index Key 0001409375  
Document Type 10-Q  
Document Period End Date Dec. 31, 2019  
Amendment Flag false  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q3  
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   30,255,062
Entity File Number 001-33887  
Entity Tax Identification Number 39-1847269  
Entity Address, Address Line One 2210 Woodland Drive  
Entity Address, City or Town Manitowoc  
Entity Address, State or Province WI  
Entity Address, Postal Zip Code 54220  
City Area Code 920  
Local Phone Number 892-9340  
Entity Interactive Data Current Yes  
Entity Incorporation, State or Country Code WI  
Document Quarterly Report true  
Document Transition Report false  
Common stock, no par value    
Document and Entity Information [Line Items]    
Title of 12(b) Security Common stock, no par value  
Trading Symbol OESX  
Security Exchange Name NASDAQ  
Common stock purchase rights    
Document and Entity Information [Line Items]    
Title of 12(b) Security Common stock purchase rights  
Security Exchange Name NASDAQ  
No Trading Symbol Flag true