License, Collaboration and Service Agreements - Additional Information (Detail) £ in Millions			1 Months Ended					3 Months Ended				12 Months Ended
	Jan. 15, 2021	Jan. 04, 2019 USD ($)	Nov. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2016 GBP (£)	May 31, 2016 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2020 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($)	Oct. 31, 2017 USD ($)
Cantab Related Agreements [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payment upon achievement of specified clinical and regulatory milestones					$ 5,800,000
Potential milestone payment upon achievement of specified commercial milestone						£ 5.0		$ 6,900,000				$ 6,800,000
License agreement research and development expense related to achievement of regulatory milestones								0	$ 0
Contract termination period					10 years	10 years
Vertex License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
License agreement research and development expense related to achievement of regulatory milestones								$ 0
Contract termination period								10 years
Nonrefundable upfront payments							$ 500,000
Potential milestone payment upon achievement of specified clinical, regulatory and commercial milestones							$ 80,200,000
Contract termination period if no material development or commercialization occurs								1 year
Meiji License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Nonrefundable upfront payments				$ 600,000
Potential milestone payments upon achievement of specified condition													$ 1,000,000.0
License agreement fixed assets related payments											$ 1,600,000
Meiji License Agreement [Member] | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Potential milestone payment upon achievement of specified clinical and regulatory milestones								$ 2,000,000.0
Sublicense fee payable to counter party				$ 7,500,000
Everest License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Period of option granted on an agreement								12 months
Upfront payment received										$ 3,000,000.0
Potential milestone payments upon completion and delivery of results of a clinical study		$ 2,000,000.0
Receivable amount upon achievement of certain milestone		59,500,000
Everest License Agreement [Member] | SPR 206 [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received										2,000,000.0
Everest License Agreement [Member] | SPR 741 [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment received										$ 1,000,000.0
Everest License Agreement [Member] | Maximum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Future milestone payments		$ 1,500,000
Agreement termination period upon written notice	180 days
Everest License Agreement [Member] | Minimum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Agreement termination period upon written notice	90 days
Gates MRI [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Reduction to research and development expense								$ 600,000
Savior Service Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Supervision fee amortization service period			34 months
Savior Service Agreement [Member] | Prepaid Asset [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Non-refundable supervision fee related to commercial manufacturing facility			$ 2,000,000.0
Savior Service Agreement [Member] | Long-term Asset [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Service agreement additional payment related to facility build out costs								$ 5,100,000