Commitments and Contingencies - Additional Information (Detail) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended
	Aug. 20, 2019	Jul. 08, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019	Dec. 31, 2018	May 31, 2016
Other Commitments [Line Items]
Research and development			$ 35,992	$ 22,303	$ 83,956	$ 52,732
Deferred lease obligation								$ 1,562
Operating lease liability			$ 4,547		$ 4,547
Stamford Operating Lease [Member]
Other Commitments [Line Items]
Operating Lease, renewable term			5 years		5 years
Operating lease, expiration date					Nov. 30, 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				$ 246		$ 737
Tenant improvement incentives								698
Operating lease cost			$ 234		$ 702
Stamford Operating Lease [Member] | Research and Development [Member]
Other Commitments [Line Items]
Operating lease cost			164		492
Stamford Operating Lease [Member] | General and Administrative [Member]
Other Commitments [Line Items]
Operating lease cost			$ 70		$ 210
Stamford Operating Lease [Member] | ASC 842 [Member]
Other Commitments [Line Items]
Operating Lease, renewable term			5 years		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		$ 8,000
Percentage of payment, stock	50.00%
Payment of milestone payment			0		0
Payments for Royalties			$ 0		$ 0
License agreement expiration period, first commercial sale					10 years
Agreement Termination Notice Description					Either party may terminate the 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 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 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 initial term, expiration date					Either party may terminate the 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 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 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.
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.
Agreement initial term, expiration date					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.