Document and Entity Information - USD ($)
 12 Months Ended
Mar. 31, 2021
May 18, 2021
Sep. 30, 2020
Cover [Abstract]      
Entity Registrant Name ePlus inc.    
Entity Central Index Key 0001022408    
Current Fiscal Year End Date --03-31    
Document Type 10-K    
Amendment Flag false    
Document Annual Report true    
Document Period End Date Mar. 31, 2021    
Document Fiscal Year Focus 2021    
Document Fiscal Period Focus FY    
Document Transition Report false    
Entity File Number 1-34167    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 54-1817218    
Entity Address, Address Line One 13595 Dulles Technology Drive    
Entity Address, City or Town Herndon    
Entity Address, State or Province VA    
Entity Address, Postal Zip Code 20171-3413    
City Area Code 703    
Local Phone Number 984-8400    
Title of 12(b) Security Common Stock, $.01 par value    
Trading Symbol PLUS    
Security Exchange Name NASDAQ    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 967,253,381
Entity Common Stock, Shares Outstanding   13,502,767