Collaborations and Other Arrangements - Additional Information (Detail) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2023	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Costs to obtain or fulfill contract capitalized		$ 0		$ 0
Collaboration revenue		9,111,000	$ 11,992,000	45,003,000	$ 38,192,000
Deferred revenue		44,762,000	26,066,000	44,762,000	26,066,000	$ 60,993,000	$ 63,771,000
Regeneron Pharmaceuticals Inc. [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Aggregate transaction price remaining to be recognized		31,600,000		31,600,000
Deferred revenue		31,600,000		31,600,000		47,100,000
Development and commercial milestone payments				320,000,000
Regeneron Pharmaceuticals Inc. [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable		8,100,000		8,100,000		35,700,000
Regeneron Pharmaceuticals Inc. [Member] | Hemophilia Co Co Agreements
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue		4,000,000	1,800,000	11,600,000	7,600,000
Regeneron Pharmaceuticals Inc. [Member] | Regeneron Agreement [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue		8,300,000	9,300,000	22,100,000	23,500,000
Payments due		6,400,000	5,500,000	16,100,000	14,200,000
Deferred revenue	$ 30,000,000
Collaboration agreement extension period	two years
Collaboration term extension period	2026-04
Sparing Vision [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue		600,000	400,000	1,700,000	1,300,000
Deferred revenue		13,200,000		13,200,000		13,900,000
Sparing Vision [Member] | Related Party [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Accounts receivable		300,000		300,000		500,000
ReCode Therapeutics, Inc.
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Development and commercial milestone payments				262,000,000
AvenCell [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue		200,000	1,900,000	21,000,000	12,700,000
Accounts receivable		400,000		400,000		$ 200,000
Revenue			1,900,000		12,700,000
Kyverna Therapeutics Inc [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue		0		0
Revenue			100,000		500,000
ONK Therapeutics [Member]
Collaborative Arrangements and Non-collaborative Arrangement Transactions [Line Items]
Collaboration revenue		$ 0		$ 0
Revenue			$ 200,000		$ 200,000