Collaboration Agreements - Additional Information (Detail) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended	12 Months Ended
	Jan. 31, 2020 shares	Aug. 31, 2017 USD ($) employee	Mar. 31, 2019 USD ($)	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration				$ 117,316	$ 125,568	$ 106,732
Exercise Price Of Common Stock Warrants | $ / shares				$ 24.70
Celgene Corporation | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from Collaborators			$ 1,100			600
Collaboration					4,400	2,600
Merck Sharp & Dohme Corp. | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration						1,600
Merck Sharp & Dohme Corp. | Collaborative Arrangement | Development Funding
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from Collaborators						1,100
Lam Research Corporation | Collaborative Arrangement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Proceeds from Collaborators					14,900	21,700
Collaboration				$ 4,800	$ 16,300	$ 18,600
Maximum Amount Of Royalties Payable, Ratio To License And Service Revenue		3
Reimbursement Of Counterparty Costs, Maximum Number Of Employees | employee		10
Class Of Warrant Or Right, Number Of Warrants Or Rights Exercised | shares	1,000,000.0
Lam Research Corporation | Collaborative Arrangement | Maximum
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Collaboration		$ 50,000
Class of Warrant or Right, Outstanding | shares	407,247