v3.19.3
Cover Page - shares
6 Months Ended
Sep. 30, 2019
Oct. 25, 2019
Cover page.    
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2020  
Document Fiscal Period Focus Q2  
Entity Registrant Name Commvault Systems, Inc.  
Entity Central Index Key 0001169561  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Current Fiscal Year End Date --03-31  
Entity Filer Category Large Accelerated Filer  
Entity Common Stock, Shares Outstanding   45,711,386
Entity Shell Company false  
Entity Small Business false  
Entity Emerging Growth Company false  
Title of 12(b) Security Common Stock  
Trading Symbol CVLT  
Security Exchange Name NASDAQ  
Entity File Number 1-33026  
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  
Document Quarterly Report true  
Document Transition Report false