Collaborations and Other Arrangements - Additional Information (Detail)	1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended	90 Months Ended
	Oct. 31, 2023 USD ($) Targetcap Product	Mar. 31, 2023 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2021 USD ($)
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Costs to obtain or fulfill contract capitalized			$ 0		$ 0			$ 0
Collaboration revenue			11,992,000	$ 13,266,000	38,192,000	$ 38,548,000
Deferred revenue			26,066,000	80,496,000	26,066,000	80,496,000	$ 63,771,000	26,066,000	$ 127,235,000
Collaboration agreement payment made					56,109,000
Revenue			1,000,000		6,600,000
Regeneron Pharmaceuticals Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate transaction price remaining to be recognized			12,000,000		12,000,000			12,000,000
Deferred revenue			12,000,000		12,000,000		28,800,000	12,000,000
Regeneron Pharmaceuticals Inc. [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			5,500,000		5,500,000		3,200,000	5,500,000
Regeneron Pharmaceuticals Inc. [Member] | Hemophilia Co Co Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			1,800,000	3,200,000	7,600,000	6,900,000
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			9,300,000	6,500,000	$ 23,500,000	18,600,000		196,500,000
Aggregate transaction price remaining to be recognized, period					Through September 30, 2023
Payments due			5,500,000	4,000,000	$ 14,200,000	8,700,000
Deferred revenue	$ 30,000,000
Collaboration agreement extension period	two years
Additional regeneron target cap | Targetcap	5
Number of unique ex vivo products commercialized | Product	10
Collaboration term extension period	2026-04
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member] | Research and Development Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue					46,100,000
ONK Therapeutics [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			200,000		200,000		100,000	200,000
ONK Therapeutics [Member] | Research Materials Shippmet Services [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			200,000	0	200,000	0
Kyverna Therapeutics Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue							400,000
Revenue		$ 400,000	100,000	2,300,000	100,000	4,300,000
Kyverna Therapeutics Inc [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			100,000		100,000		0	100,000
Sparing Vision [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			400,000	0	1,300,000	0
Deferred revenue			14,100,000		14,100,000		14,700,000	14,100,000
Sparing Vision [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			700,000		700,000		100,000	700,000
AvenCell [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Deferred revenue additions			1,000,000		6,600,000
Collaboration revenue			1,900,000		13,200,000
Deferred revenue			0		0		19,900,000	0
Revenue			1,900,000		13,200,000
AvenCell [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable			9,000		9,000		300,000	$ 9,000
AvenCell [Member] | AvenCell Co Co Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue			$ 0	$ 1,300,000	$ 600,000	$ 1,400,000
AvenCell [Member] | Co-Development and Co-Funding Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration agreement payment made							$ 30,000,000