Collaboration Revenue - Additional Information (Detail) - USD ($)				3 Months Ended		6 Months Ended		12 Months Ended
	Jul. 21, 2021	Jul. 01, 2021	Jan. 31, 2016	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Nov. 30, 2018	Feb. 29, 2016
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration (profit) loss sharing - related party				$ (271,000)	$ 0	$ 705,000	$ 0
Change in collaboration revenue-related party				1,216,000	5,263,000	2,709,000	9,911,000
Upfront collaboration/license fee			$ 120,000,000
Collaboration revenue - related party				1,216,000	5,263,000	2,709,000	9,911,000
2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration product, percentage of commercial profit		50.00%
Collaborative arrangement, sharing of pre-launch costs, percentage		50.00%
Nestle Health Science [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront cash payment				97,200,000		97,200,000		$ 97,728,000						$ 120,000,000
Maximum development milestone payments to be received				285,000,000		285,000,000
Maximum regulatory payments to be received				375,000,000		375,000,000
Maximum amount to be received on achievement of certain commercial milestones				1,125,000,000		1,125,000,000
Proceeds on achievement of development milestone									$ 10,000,000	$ 40,000,000	$ 20,000,000	$ 10,000,000
Transaction price allocated to remaining performance obligations				200,000,000		200,000,000
Collaboration revenue - related party				(197,000)	$ 5,263,000	528,000	$ 9,911,000
Deferred revenue				101,108,000		101,108,000		103,817,000
Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration product, percentage of commercial profit		50.00%
Upfront payment received	$ 175,000,000
Maximum Amount To Be Received On Achievement Of Regulatory and Sales Milestones		$ 360,000,000
Maximum amount to be received on achievement of sales milestones		225,000,000
Collaboration (profit) loss sharing - related party				271,000		705,000
Maximum regulatory payments to be received		$ 135,000,000
Transaction price allocated to remaining performance obligations	$ 139,500,000
Termination notice period	60 days
Nestle Health Science [Member] | Phase 2 [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront collaboration milestone payments receivable			20,000,000
Nestle Health Science [Member] | Phase 3 [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront collaboration milestone payments receivable			$ 20,000,000
Nestle Health Science [Member] | Phase 2b [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Upfront collaboration milestone payments receivable													$ 40,000,000
Proceeds on achievement of development milestone										$ 40,000,000
License [Member] | Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration revenue - related party								$ 131,343,000
Service [Member] | Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Collaboration revenue - related party				1,413,000		2,181,000
Topic 808 [Member] | Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated under collaborative arrangement	$ 35,500,000
Topic 808 [Member] | Total Liabilities [Member] | Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated under collaborative arrangement	$ 35,500,000
Topic 808 [Member] | Accrued Expenses and Other Current Liabilities [Member] | Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Transaction price allocated under collaborative arrangement				33,062,000		33,062,000
Research and Development Expense [Member] | Topic 808 [Member] | Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Cost associated with pre-launch activities				1,538,000		3,173,000
General and Administrative Expense [Member] | Topic 808 [Member] | Nestle Health Science [Member] | 2021 License Agreement [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Cost associated with pre-launch activities				$ 2,176,000		$ 4,614,000