Collaboration Agreements - Additional Information (Detail)			1 Months Ended		3 Months Ended		50 Months Ended
	Oct. 15, 2021 USD ($)	Apr. 02, 2018	Apr. 30, 2018 USD ($) Target $ / shares shares	Feb. 28, 2018 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2021 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration revenue recognized					$ 1,750,000
Collaboration and license agreement, deferred revenue current					36,426,000		$ 36,426,000	$ 37,098,000
Takeda [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Fund receivable for research and preclinical activities			$ 60,000,000.0
Up-front consideration received			$ 110,000,000.0
Collaboration And License Agreement [Member] | Category One Programs [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of global costs and potential profits sharing ratio			50.00%
Collaboration And License Agreement [Member] | Takeda [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront payment under collaboration agreement			$ 110,000,000.0
Collaboration and license agreement month and year			2018-02
Fund receivable for research and preclinical activities			$ 60,000,000.0
Research term under collaboration and license agreement			4 years
Collaboration agreement commencement date		Apr. 02, 2018
Collaboration agreement termination period		180 days
Collaboration revenue recognized						$ 0
Collaboration And License Agreement [Member] | Takeda [Member] | Minimum [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration agreement, committed cash				$ 230,000,000.0
Collaboration And License Agreement [Member] | Takeda [Member] | Category One Programs [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Percentage of global costs and potential profits sharing ratio			50.00%
Collaboration and License Agreement Date	Oct. 15, 2021
Collaboration revenue recognized					1,600,000		79,500,000
Collaboration and license agreement, deferred revenue					113,000,000.0		113,000,000.0	114,600,000
Collaboration and license agreement, deferred revenue current					$ 36,400,000		$ 36,400,000	$ 37,100,000
Collaboration And License Agreement [Member] | Takeda [Member] | Category Two Programs [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Fund receivable for research and preclinical activities			$ 60,000,000.0
Research term under collaboration and license agreement			4 years
Maximum targets for preclinical programs | Target			6
Option to reach maximum targets for preclinical programs					any one time
Collaboration-budgeted research and preclinical expenses	$ 22,500,000
Collaboration and Share Purchase Agreements [Member] | Takeda [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Shares issued under equity agreement | shares			1,096,892
Purchase price per share | $ / shares			$ 54.70
Proceeds from issuance of ordinary shares, net of offering costs			$ 60,000,000.0
Equity investment agreement official closure month and year			2018-04