Material Agreements - Additional Information (Detail) - USD ($)			1 Months Ended	3 Months Ended				6 Months Ended
	Dec. 07, 2018	Dec. 19, 2017	May 31, 2019	Sep. 30, 2020		Sep. 30, 2019		Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront, non-refundable payment		$ 30,000,000.0
Research and development and out-of-pocket		50.00%
Costs incurred and reported to the company				$ 11,976,000	[1]	$ 10,331,000	[1]	$ 28,898,000	$ 28,807,000
Purchase price	$ 37,800,000
Swiss value-added tax receivable										$ 3,000,000.0
HanAll Biopharma Co., Ltd
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Costs incurred and reported to the company				$ 0		$ 0		$ 0	$ 0
Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Consideration paid		$ 20,000,000.0
Maximum | Upon Achievement Of Development Regulatory And Sales Milestones
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Contingent milestone payments		$ 452,500,000
Achievement of Development and Regulatory
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone Payments			$ 10,000,000.0

[1] Includes $68 and $176 of costs allocated from Roivant Sciences Ltd. for the three and six months ended September 30, 2020, respectively, and $1 and $152 of costs allocated from Roivant Sciences Ltd. for the three and six months ended September 30, 2019, respectively.