Commitments and Contingencies - Additional Information (Detail) $ in Thousands										1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 16, 2023	Mar. 09, 2023 ft²	Aug. 09, 2021	Oct. 27, 2020 USD ($)	Aug. 04, 2020	May 28, 2020 USD ($) ft²	Dec. 11, 2019 USD ($)	Aug. 08, 2019 ft²	Nov. 05, 2018	Oct. 31, 2022 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)	Dec. 31, 2024 USD ($)	Oct. 31, 2024 USD ($)	May 10, 2024 USD ($)	Oct. 01, 2023 USD ($)	Sep. 01, 2023 USD ($)	Nov. 30, 2016 USD ($)
Other Commitments [Line Items]
Operating lease liabilities											$ 3,196		$ 3,196		$ 4,057
Operating lease right-of-use assets											$ 2,270		$ 2,270		$ 2,838
Weighted average remaining lease term in years											3 years 9 months 18 days		3 years 9 months 18 days		4 years 6 months
Weighted average discount rate											11.00%		11.00%		11.00%
Lease expenses											$ 100	$ 100	$ 400	$ 400
Pennsylvania [Member] \| Office [Member]
Other Commitments [Line Items]
Operating lease term								3 years 6 months
Lease extension period								3 years
Lease term commencement date		Sep. 01, 2023						Feb. 15, 2020
Operating lease liabilities																			$ 500
Operating lease right-of-use assets																			$ 500
Area of office space \| ft²		4,642						4,642
Lease term expiration date								Aug. 31, 2023
Pennsylvania [Member] \| Office and Lab [Member]
Other Commitments [Line Items]
Lease extension period									2 years
Lease term commencement date									Jan. 01, 2019
Lease term expiration date			Dec. 31, 2022		Dec. 31, 2021				Dec. 31, 2020
Pennsylvania [Member] \| Additional Office [Member]
Other Commitments [Line Items]
Lease term commencement date		Oct. 01, 2023
Operating lease liabilities																		$ 300
Operating lease right-of-use assets																		$ 300
Area of office space \| ft²		3,462
Pennsylvania [Member] \| Lab Space [Member]
Other Commitments [Line Items]
Operating lease term	4 years
Lease term commencement date	May 10, 2024
Operating lease liabilities																	$ 500
Operating lease right-of-use assets																	$ 500
Massachusetts [Member] \| Office [Member]
Other Commitments [Line Items]
Area of office space \| ft²						17,705
Lease term expiration date						Oct. 30, 2029
Massachusetts [Member] \| Office Sublease [Member]
Other Commitments [Line Items]
Lease term commencement date				Dec. 04, 2020
Lease term expiration date				Oct. 30, 2029
Massachusetts [Member] \| Letter of Credit \| Office [Member]
Other Commitments [Line Items]
Letter of credit						$ 1,300										$ 600
Massachusetts [Member] \| First Sublease Year [Member] \| Office Sublease [Member]
Other Commitments [Line Items]
Annual base rent				$ 800
Massachusetts [Member] \| First Sublease Year [Member] \| Letter of Credit \| Office Sublease [Member]
Other Commitments [Line Items]
Lease security deposits letters of credit				800
Massachusetts [Member] \| Final Sublease Year [Member] \| Office Sublease [Member]
Other Commitments [Line Items]
Annual base rent				1,000
Massachusetts [Member] \| Sixth Sublease Year \| Letter of Credit \| Office Sublease [Member]
Other Commitments [Line Items]
Lease security deposits letters of credit				$ 400
WFUHS [Member]
Other Commitments [Line Items]
License agreement consideration deduction percentage																				60.00%
WFUHS [Member] \| Maximum [Member]
Other Commitments [Line Items]
Milestone payments																				$ 2,600
IU [Member]
Other Commitments [Line Items]
License agreement consideration deduction percentage																				20.00%
IU [Member] \| Maximum [Member]
Other Commitments [Line Items]
Milestone payments																				$ 2,600
Annual royalty pay obligation																				$ 100
WFUHS and IU [Member] \| Research and Development Expenses [Member]
Other Commitments [Line Items]
Milestone expenses										$ 300
WFUHS and IU [Member] \| Maximum [Member]
Other Commitments [Line Items]
Payment for license agreements							$ 100

Larimar Therapeutics, Inc. 10-Q