Shareholders' Equity (Deficit) - Narrative (Details)		1 Months Ended	12 Months Ended
	Jun. 04, 2019 USD ($) $ / shares shares	Apr. 30, 2018 USD ($) $ / shares shares	Mar. 31, 2021 $ / shares shares	Mar. 31, 2020 USD ($) $ / shares shares	Mar. 31, 2019 USD ($) $ / shares shares	Feb. 02, 2016 class
Subsidiary, Sale of Stock [Line Items]
Number of classes of stock | class						1
Common shares authorized (in shares) | shares			564,111,242	564,111,242
Common shares par value (in USD per share) | $ / shares			$ 0.000017727	$ 0.000017727
Public Offering
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares) | shares	17,424,243
Price of shares (in USD per share) | $ / shares	$ 8.25
Net proceeds from sale of shares | $	$ 134,500,000
Roivant Sciences, Ltd. | Private Placement | Majority Shareholder
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares) | shares		1,110,015
Price of shares (in USD per share) | $ / shares		$ 20.27
Net proceeds from sale of shares | $		$ 22,500,000
Cowen and Company, LLC | Private Placement
Subsidiary, Sale of Stock [Line Items]
Number of shares issued (in shares) | shares			0	106,494	3,970,129
Price of shares (in USD per share) | $ / shares				$ 24.65	$ 21.91
Net proceeds from sale of shares | $				$ 2,500,000	$ 84,100,000
Aggregate offering price | $		$ 100,000,000.0