Commitments and Contingencies - Additional Information (Detail) $ in Thousands				1 Months Ended		12 Months Ended
	Oct. 31, 2020 USD ($)	Aug. 31, 2019 USD ($)	Jul. 31, 2019	Jun. 30, 2020 item	Jul. 31, 2019 agreement	Dec. 31, 2021 USD ($) item	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2016	May 31, 2016 USD ($)
Other Commitments [Line Items]
Research and development expense						$ 82,701	$ 107,851	$ 113,820
Operating lease liabilities						3,673
Operating lease right-of-use assets						$ 2,973	$ 4,279
New Stamford Lease [Member]
Other Commitments [Line Items]
Operating lease liabilities	$ 1,934
Operating lease right-of-use assets	1,934
Lease incentives	$ 0
Stamford Operating Lease [Member]
Other Commitments [Line Items]
Number of renewable terms | item						1
Lease term									7 years
Operating Lease, renewable term						5 years
Operating lease, expiration date						Dec. 31, 2023
Tenant improvement expenses										$ 1,094
Operating lease cost								937
Stamford Operating Lease [Member] | Research and Development [Member]
Other Commitments [Line Items]
Operating lease cost								656
Stamford Operating Lease [Member] | General and Administrative [Member]
Other Commitments [Line Items]
Operating lease cost								281
Stamford Operating Lease [Member] | ASC 842 [Member]
Other Commitments [Line Items]
Number of renewable terms | item						1
Operating Lease, renewable term						5 years
Stamford Operating Lease [Member] | Standby Letter of Credit [Member]
Other Commitments [Line Items]
Letter of credit, renewal term						automatically renewed annually through November 2023.
New Stamford Lease [Member]
Other Commitments [Line Items]
Number of renewable terms | item				1
Operating Lease, renewable term				5 years
Operating lease, expiration date				Dec. 31, 2023
New Stamford Lease [Member] | ASC 842 [Member]
Other Commitments [Line Items]
Number of renewable terms | item						1
Operating Lease, renewable term						5 years
Stamford Operating Lease and New Stamford Lease [Member]
Other Commitments [Line Items]
Lease term						2 years	3 years
Operating lease cost						$ 1,624	$ 1,116
Stamford Operating Lease and New Stamford Lease [Member] | Research and Development [Member]
Other Commitments [Line Items]
Operating lease cost						1,137	781
Stamford Operating Lease and New Stamford Lease [Member] | General and Administrative [Member]
Other Commitments [Line Items]
Operating lease cost						487	335
Non-Exclusive License Agreement
Other Commitments [Line Items]
Research and development expense						15,000	5,000	$ 8,000
Non-Exclusive License Agreement | Enteris Biopharma, Inc. [Member]
Other Commitments [Line Items]
Upfront fee		$ 8,000
Upfront fee payment, cash		4,000
Upfront fee payment, stock		$ 4,000
Payment of milestone payment						$ 15,000	$ 5,000
License agreement expiration period, first commercial sale		10 years
Agreement termination period for material breach		60 days
Agreement termination period for material breach of a payment obligation		30 days
Agreement termination period for challenged patent rights		30 days
Agreement termination period prior to first regulatory approval		30 days
Agreement termination period after first regulatory approval		60 days
MSA [Member]
Other Commitments [Line Items]
Agreement initial term, expiration date			Dec. 31, 2023
Agreement renewal term			2 years
MSA [Member] | Minimum [Member]
Other Commitments [Line Items]
Termination notice effective period			18 months
MSA [Member] | Patheon and Patheon Manufacturing Services LLC [Member]
Other Commitments [Line Items]
Number of related product agreements | agreement					2
MSA or Product Agreement [Member]
Other Commitments [Line Items]
Agreement Termination Notice Description			Either party may terminate the MSA or a Product Agreement upon written notice if the other party (1) has failed to remedy a material breach within a specified time or (2) is declared insolvent or bankrupt, voluntarily files a petition of bankruptcy or assigns such agreement for the benefit of creditors. The Company may terminate a Product Agreement (a) upon 90 days’ prior written notice if any governmental agency takes any action that prevents the Company from selling the relevant product in the relevant territory, (b) upon six months’ prior written notice if it does not intend to order manufacturing services due to a product’s discontinuance in the market, or (c) upon 90 days’ prior written notice if it determines that the manufacture or supply of a product likely infringes third-party rights. Patheon may terminate the MSA or a Product Agreement (i) upon six months’ prior written notice if the Company assigns such agreement to an assignee that is unacceptable to Patheon for certain reasons, or (ii) upon 30 days’ prior written notice if, after the first year of commercial sales, the Company forecasts zero volume for 12 months.
Termination notice effective period upon government agency restrictions			90 days
Termination notice effective period upon discontinuance in the market			6 months
Termination notice period if likely infringes on third-party rights			90 days
Termination notice period if assignee is unacceptable			6 months
Termination notice period if zero volume is forecasted after first year of commercial sales			30 days