v3.26.1
Cover Page - USD ($)
$ in Billions
 12 Months Ended
Mar. 31, 2026
May 07, 2026
Sep. 30, 2025
Cover [Abstract]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Mar. 31, 2026    
Current Fiscal Year End Date --03-31    
Document Transition Report false    
Entity File Number 1-33026    
Entity Registrant Name Commvault Systems, Inc    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 22-3447504    
Entity Address, Address Line One 1 Commvault Way    
Entity Address, City or Town Tinton Falls    
Entity Address, State or Province NJ    
Entity Address, Postal Zip Code 07724    
City Area Code 732    
Local Phone Number 870-4000    
Title of 12(b) Security Common Stock, $0.01 par value    
Trading Symbol CVLT    
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    
ICFR Auditor Attestation Flag true    
Document Financial Statement Error Correction false    
Entity Shell Company false    
Entity Public Float     $ 8.2
Entity Common Stock, Shares Outstanding   41,250,627  
Documents Incorporated by Reference Information required by Part III of Form 10-K (Items 10, 11, 12, 13 and 14) is incorporated by reference to portions of the registrant’s definitive Proxy Statement for its 2026 Annual Meeting of Stockholders (the "Proxy Statement"), which is expected to be filed not later than 120 days after the registrant’s fiscal year ended March 31, 2026. Except as expressly incorporated by reference, the Proxy Statement shall not be deemed to be part of this Annual Report on Form 10-K.    
Central Index Key 0001169561    
Document Fiscal Year Focus 2026    
Document Fiscal Period Focus FY    
Amendment Flag false