Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 20, 2019	Jul. 08, 2019	Oct. 31, 2020	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	May 31, 2020	Jan. 01, 2019	May 31, 2016
Other Commitments [Line Items]
Research and development				$ 21,067	$ 35,992	$ 80,711	$ 83,956
Operating lease liability				3,721		3,721
Lessee Operating Lease Liability Payments Due				$ 4,175		$ 4,175
New Stamford Lease [Member]
Other Commitments [Line Items]
Operating Lease, renewable term								5 years
Lessee Operating Lease Liability Payments Due								$ 2,000
Lessee Operating Lease Discount Rate								7.00%
Stamford Operating Lease [Member]
Other Commitments [Line Items]
Operating Lease, renewable term				5 years		5 years
Operating lease, expiration date						Dec. 31, 2023
Tenant improvement expenses										$ 1,094
Deferred lease obligation									$ 864
Operating lease cost				$ 239	$ 234	$ 709	$ 702
Lessee Operating Lease Discount Rate				7.00%	7.00%	7.00%	7.00%
Stamford Operating Lease [Member] | Research and Development [Member]
Other Commitments [Line Items]
Operating lease cost				$ 167	$ 164	$ 496	$ 492
Stamford Operating Lease [Member] | General and Administrative [Member]
Other Commitments [Line Items]
Operating lease cost				$ 72	$ 70	$ 213	$ 210
Stamford Operating Lease [Member] | ASC 842 [Member]
Other Commitments [Line Items]
Operating lease liability									5,198
Stamford Operating Lease [Member] | Standby Letter of Credit [Member]
Other Commitments [Line Items]
Letter of credit, renewal term						automatically renewed annually through November 2023.
Letter of credit, expiration date						Nov. 30, 2023
Stamford Operating Lease [Member] | Leasehold Improvements [Member]
Other Commitments [Line Items]
Tenant improvement expenses									$ 698
Non-Exclusive License Agreement
Other Commitments [Line Items]
Upfront fee	$ 8,000
Upfront fee payment, cash	4,000
Upfront fee payment, stock	$ 4,000
Percentage of payment, stock	50.00%
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.
Non-Exclusive License Agreement | Subsequent Event [Member]
Other Commitments [Line Items]
Payment of milestone payment			$ 2,500
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.