Document and Entity Information (USD $)
3 Months Ended
Jun. 30, 2011
Aug. 05, 2011
Sep. 30, 2010
Document and Entity Information [Abstract]      
Entity Registrant Name ORION ENERGY SYSTEMS, INC.    
Entity Central Index Key 0001409375    
Document Type 10-Q    
Document Period End Date Jun. 30, 2011    
Amendment Flag false    
Document Fiscal Year Focus 2012    
Document Fiscal Period Focus Q1    
Current Fiscal Year End Date --03-31    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Filer Category Accelerated Filer    
Entity Public Float     $ 72,004,102
Entity Common Stock, Shares Outstanding   22,984,286