Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands			12 Months Ended
	Aug. 20, 2019	Jul. 08, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	May 31, 2016
Other Commitments [Line Items]
Research and development			$ 113,820	$ 75,531	$ 48,524
Deferred lease obligation				1,562
Operating lease liability			4,319
Operating lease cost			937
Research and Development [Member]
Other Commitments [Line Items]
Operating lease cost			656
General and Administrative [Member]
Other Commitments [Line Items]
Operating lease cost			$ 281
Stamford Operating Lease [Member]
Other Commitments [Line Items]
Operating Lease, renewable term			5 years
Operating lease, expiration date			Nov. 01, 2023
Operating Lease, description			The Stamford Lease requires monthly lease payments, including rent escalations and rent holidays, during the initial lease term. The Company began to make rental payments from the Commencement Date. Prior to January 1, 2019, the Company recorded monthly rent expense on a straight-line basis from March 2016, upon taking possession of the Premises, through December 31, 2018. As of December 31, 2018, the balance of deferred lease obligation, representing the difference between cash rent paid and straight-line rent expense, was $864.
Tenant improvement expenses							$ 1,094
Deferred lease obligation				864
Lease, rent expense				974	$ 935
Tenant improvement incentives				698
Stamford Operating Lease [Member] | ASC 842 [Member]
Other Commitments [Line Items]
Operating Lease, renewable term			5 years
Operating lease liability						$ 5,198
Stamford Operating Lease [Member] | Standby Letter of Credit [Member]
Other Commitments [Line Items]
Operating lease, renewable term description			Automatically renewed annually through November 2023
Stamford Operating Lease [Member] | Standby Letter of Credit [Member] | Maximum [Member]
Other Commitments [Line Items]
Letter of credit, renewal date			Nov. 30, 2023
Stamford Operating Lease [Member] | Leasehold Improvements [Member]
Other Commitments [Line Items]
Deferred lease obligation				$ 698
Non-Exclusive License Agreement
Other Commitments [Line Items]
Upfront fee	$ 8,000
Upfront fee payable, cash	4,000
Upfront fee payable, stock	$ 4,000
Research and development			$ 8,000
Percentage of payment, stock	50.00%
Payment of milestone payment			0
Payments for Royalties			$ 0
License agreement expiration period, first commercial sale	10 years
Agreement Termination Notice Description	Either party may terminate the Enteris License Agreement upon written notice if the other party has failed to remedy a material breach within 60 days (or 30 days in the case of a material breach of a payment obligation). Enteris may terminate the Enteris License Agreement upon 30 days' written notice to the Company if the Company or any of its affiliates formally challenge the validity of any licensed patent rights or assists a third party in doing so. The Company may terminate the Enteris License Agreement for any reason or no reason (a) prior to receipt of first regulatory approval for a licensed product in the United States for any indication upon 30 days' prior written notice to Enteris or (b) on or after receipt of first regulatory approval for a licensed product in the United States for any indication upon 60 days' prior written notice to Enteris.
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
Other Commitments [Line Items]
Agreement initial term, expiration date		Dec. 31, 2023
Agreement renewal term		2 years
MSA | Minimum [Member]
Other Commitments [Line Items]
Termination notice effective period		18 months
MSA or Product Agreement
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