Document and Entity Information - USD ($)
$ in Millions
12 Months Ended
Mar. 31, 2019
May 21, 2019
Sep. 30, 2018
Document and Entity Information [Abstract]      
Entity Registrant Name Myovant Sciences Ltd.    
Entity Central Index Key 0001679082    
Document Type 10-K    
Document Period End Date Mar. 31, 2019    
Amendment Flag false    
Current Fiscal Year End Date --03-31    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Common Stock, Shares Outstanding   72,198,383  
Entity Small Business false    
Entity Emerging Growth Company false    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Entity Public Float     $ 755.2
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Shell Company false