Subsequent Events - Additional Information (Detail) $ in Millions		1 Months Ended	3 Months Ended
	Feb. 18, 2025 USD ($) ft² $ / ft²	Feb. 28, 2022 ft²	Mar. 31, 2025 USD ($)	Dec. 31, 2024
840 Winter Street Lease [Member]
Subsequent Event [Line Items]
Operating lease, description		In February 2022 and subsequently amended in June 2023, the Company entered into an agreement to lease approximately 140,000 square feet of office, general laboratory and manufacturing space at 840 Winter Street in Waltham
Area of space leased | ft²		140,000
Operating lease, term of contract				12 years
Subsequent Event [Member] | Tech Square Lease [Member]
Subsequent Event [Line Items]
Operating lease, description	On February 18, 2025, the Company entered into a Lease Agreement (the “Tech Square Lease”) with ARE-Tech Square, LLC, an affiliate of Alexandria Real Estate Equities, Inc. (the “Tech Square Landlord”) for office and laboratory space located at 400 Technology Square, Cambridge, Massachusetts (“400 Tech Square”). Under the terms of the Tech Square Lease, the Company will initially lease approximately 101,000 square feet at 400 Tech Square (the “Initial Tech Square Premises”), which will supplement, and eventually replace certain parts of, the Company’s current leased premises in Cambridge, Massachusetts. In addition, the Tech Square Lease will expand, in two tranches, to include approximately 46,000 square feet of additional office and laboratory space at 400 Tech Square (the “Additional Tech Square Premises”) when each such space becomes available. The Tech Square Lease is expected to commence on July 1, 2025 (the “Commencement Date”) with respect to the Initial Tech Square Premises, and the Company’s obligation to pay rent will start on the date that is approximately 14 months after the Commencement Date (the “Rent Commencement Date”).
Area of space leased | ft²	101,000
Area of space leased expandable | ft²	46,000
Operating lease, option to extend	In addition, the Tech Square Lease will expand, in two tranches, to include approximately 46,000 square feet of additional office and laboratory space at 400 Tech Square (the “Additional Tech Square Premises”) when each such space becomes available.
Operating lease, renewal term	5 years
Operating lease commencement date	Jul. 01, 2025
Operating lease rent per square foot | $ / ft²	108
Operating lease percentage of annual increase	3.00%
Landlord contribution towards cost of construction and tenant improvements | $	$ 41.5
Subsequent Event [Member] | Additional Tech Square Premises [Member]
Subsequent Event [Line Items]
Operating lease, description	In addition, the lease of the Additional Tech Square Premises will commence when the Tech Square Landlord delivers such space to the Company, which is anticipated to occur in December 2027 and January 2028 (in each case, an “Additional Premises Commencement Date”), and the Company’s obligation to pay rent for such Additional Tech Square Premises will start on the date that is approximately 14 months after each Additional Premises Commencement Date (in each case, an “Additional Premises Rent Commencement Date”).
Subsequent Event [Member] | 840 Winter Street Lease [Member]
Subsequent Event [Line Items]
Operating lease, option to terminate	June 30, 2028
Operating lease, modification payments | $	$ 78.0
Minimum [Member] | Subsequent Event [Member] | Tech Square Lease [Member]
Subsequent Event [Line Items]
Operating lease, term of contract	3 months
Maximum [Member] | Subsequent Event [Member] | Tech Square Lease [Member]
Subsequent Event [Line Items]
Operating lease, term of contract	12 years
Forecast [Member]
Subsequent Event [Line Items]
Net reduction of employee headcount			27.00%
Severance and other employee termination-related costs | $			$ 8.0