Collaborations and Other Arrangements - Additional Information (Detail) - USD ($)		1 Months Ended				12 Months Ended			69 Months Ended
		Oct. 31, 2021	Sep. 30, 2021	Jul. 31, 2021	Mar. 31, 2020	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2021	Jul. 30, 2021
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Expenses incurred to obtain collaboration agreements and costs to fulfill contracts						$ 0
Costs to obtain or fulfill contract capitalized						$ 0			$ 0
Common stock, par value						$ 0.0001	$ 0.0001		$ 0.0001
Collaboration revenue	[1]					$ 33,053,000	$ 57,994,000	$ 43,103,000
Deferred revenue						$ 127,235,000	73,931,000	28,810,000	$ 127,235,000
Development costs and pay royalties						50.00%
Shares of Series A2 Preferred Stock						83,316			83,316
Equity Ownership						11.00%			11.00%
Maximum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
opt-in fee						$ 20,000.0
Minimum [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
opt-in fee						10,000.0
Second CoDevelopment and CoPromotion Agreement [Member] | New CAR T-Cell Therapy [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration Payment				$ 30,000,000.0
AvenCell Member
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions						2,900,000
Collaboration revenue						5,900,000
Deferred revenue						$ 54,100,000			$ 54,100,000
Equity Method Investment, Ownership Percentage						33.33%			33.33%
AvenCell Member | New CAR T-Cell Therapy [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Equity Method Investment, Ownership Percentage										33.33%
AvenCell Member | NewCo Co/Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration transaction price						$ 62,900,000
AvenCell Member | AvenCell Co/Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						200,000
Deferred revenue						2,900,000			$ 2,900,000
Regeneron Pharmaceuticals Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate transaction price remaining to be recognized						51,400,000			51,400,000
Accounts receivable						2,000,000.0	2,100,000		2,000,000.0
Deferred revenue						51,400,000	73,900,000		51,400,000
Regeneron Pharmaceuticals Inc. [Member] | Hemophilia Co Co Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue						2,700,000	0	0
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions									145,000,000.0
Collaboration revenue						$ 25,700,000	53,000,000.0	24,600,000	149,000,000.0
Aggregate transaction price remaining to be recognized, period						Through December 31, 2021
Payments due						$ 5,900,000	10,700,000	12,000,000.0
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member] | Research and Development Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue									37,900,000
Novartis [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Strategic collaboration agreement amended date						2018-12
One Time Payment To Novartis						$ 10,000,000.0
Novartis [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			$ 300,000		$ 5,000.0	62,400,000		$ 18,500,000
Deferred revenue						0	$ 0		0
Sparing Vision [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue						14,800,000			14,800,000
Collaboration transaction price		$ 14,800,000
Collaboration description		For product candidates the Company chooses to option, it will pay an opt-in fee between $10.0 million and $20.0 million depending on the stage of development of the target, reimburse certain costs, share in 50% of development costs and pay royalties to SparingVision on U.S. sales.
Development and commercial milestone payment to be received		$ 200,000,000
Kyverna [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration Payment						5,000,000.0
Deferred revenue						7,000,000.0			$ 7,000,000.0
Collaboration transaction price						7,000,000.0
Development Costs and Future Net Profit						$ 50,000

[1]   (1) Including the following revenue from related party (see Notes 9 and 15):   $ 6,072     $ -     $ -