Annual report pursuant to Section 13 and 15(d)


Cover - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2020
Jun. 29, 2020
Sep. 30, 2019
Document Information [Line Items]      
Entity Registrant Name IMMUNOVANT, INC.    
Entity Central Index Key 0001764013    
Amendment Flag false    
Current Fiscal Year End Date --03-31    
Document Type 10-K    
Document Period End Date Mar. 31, 2020    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2019    
Entity Current Reporting Status Yes    
Entity Filer Category Non-accelerated Filer    
Entity Emerging Growth Company true    
Entity Small Business true    
Entity Shell Company false    
Entity Ex Transition Period true    
Entity Common Stock, Shares Outstanding   81,811,727  
Entity File Number 001-38906    
Document Annual Report true    
Document Transition Report false    
Entity Interactive Data Current Yes    
Entity Tax Identification Number 83-2771572    
Entity Incorporation, State or Country Code DE    
Entity Address, State or Province NY    
Entity Address, Postal Zip Code 10018    
Entity Address, Address Line One 320 West 37th Street    
Entity Address, City or Town NY    
Entity Well-known Seasoned Issuer No    
Entity Voluntary Filers No    
Entity Public Float     $ 115.3
Common Stock [Member]      
Document Information [Line Items]      
Trading Symbol IMVT    
Security Exchange Name NASDAQ    
Title of 12(b) Security Common Stock