Annual report pursuant to Section 13 and 15(d)

Subsequent Event - Additional Information (Detail)

v3.20.2
Subsequent Event - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Thousands
1 Months Ended 12 Months Ended
Jun. 30, 2020
Jun. 15, 2020
May 12, 2020
May 31, 2020
Apr. 30, 2020
Mar. 31, 2019
May 14, 2020
Mar. 31, 2020
Subsequent Event [Line Items]                
Proceeds from issuance of common stock           $ 14,910    
Class of Warrant or Right, Outstanding               11,500,000
Subsequent Event [Member]                
Subsequent Event [Line Items]                
Proceeds from value added tax refunds         $ 2,900      
Repayment of notes receivable from RSL       $ 2,900        
Restricted Share For Each Milestone     900,000          
Class of Warrant or Right, Outstanding   11,438,290         11,500,000  
Number Of Exercisable Options   5,719,145         5,750,000  
Class of Warrant or Right, Exercise Price of Warrants or Rights   $ 11.50         $ 11.50  
Proceeds from Warrant Exercises   $ 65,800            
Subsequent Event [Member] | Sublease 6th Floor Of Building [Member]                
Subsequent Event [Line Items]                
Lease expiration date       Feb. 27, 2024        
Subsequent Event [Member] | Sublease 9th Floor Of Building [Member]                
Subsequent Event [Line Items]                
Lease expiration date       Apr. 29, 2024        
Subsequent Event [Member] | Sublease Agreement 1 [Member] | Roivant Science LTD [Member]                
Subsequent Event [Line Items]                
Operating Lease Payments $ 4,300              
Lease Period 4 years              
Subsequent Event [Member] | Sublease Agreement 2 [Member] | Roivant Science LTD [Member]                
Subsequent Event [Line Items]                
Operating Lease Payments $ 4,300              
Lease Period 4 years              
Subsequent Event [Member] | Warrant [Member]                
Subsequent Event [Line Items]                
Price per share       $ 16.50        
Warrants redemption price per warrant $ 0.01              
Subsequent Event [Member] | Common stock [Member] | Immunovant Sciences Ltd [Member]                
Subsequent Event [Line Items]                
Earnout Shares For Issuance     10,000,000          
Subsequent Event [Member] | Common stock [Member] | Roivant Science LTD [Member]                
Subsequent Event [Line Items]                
Earnout Shares For Issuance     8,773,969          
Subsequent Event [Member] | Underwritten Public Offering [Member]                
Subsequent Event [Line Items]                
Sale of stock, number of shares         9,613,365      
Price per share         $ 14.50      
Proceeds from issuance of common stock         $ 131,000      
Subsequent Event [Member] | Underwritten Public Offering [Member] | Roivant Sciences Ltd. (RSL) [Member]                
Subsequent Event [Line Items]                
Sale of stock, number of shares         1,034,483      
Subsequent Event [Member] | Over-Allotment Option [Member]                
Subsequent Event [Line Items]                
Sale of stock, number of shares         1,253,917