Significant Agreements and Contracts - Additional Information (Detail) - USD ($)	1 Months Ended							3 Months Ended				12 Months Ended
	Jun. 30, 2018	Feb. 28, 2018	Oct. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Jan. 31, 2012	Sep. 30, 2011	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2019	Mar. 03, 2019	Oct. 31, 2011
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contract expiration date												Dec. 31, 2019
Contracts revenue								$ 1,755,000		$ 1,273,000
Everest Medicines [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront payment receivable								2,000,000
Everest Medicines [Member] | Everest Medicines License Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Number of years considered after first commercial sale of product for royalty payment		10 years
Everest Medicines [Member] | Everest Medicines License Agreement [Member] | Phase Three Clinical Trial [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront cash payment received								7,000,000			$ 7,000,000
Cash payment received									$ 3,000,000
Milestone payments receivable								3,000,000
Everest Medicines [Member] | Everest Medicines License Agreement [Member] | National Medical Products Administration [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront cash payment received	$ 2,500,000
Everest Medicines [Member] | Everest Medicines License Agreement [Member] | Chinese Food and Drug Administration [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments receivable								2,500,000
Patheon [Member] | Patheon UK Limited Master Manufacturing Services Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Agreement expiration date				Dec. 31, 2022
Agreement renewal period				2 years
Notice period for termination of agreement				30 days
Patheon [Member] | Minimum [Member] | Patheon UK Limited Master Manufacturing Services Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Notice period for intention for termination agreement				18 months
Finorga SAS [Member] | Finorga SAS Commercial Supply Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Agreement expiration date			Oct. 16, 2022
Notice period for termination of agreement			30 days
Finorga SAS [Member] | Minimum [Member] | Finorga SAS Commercial Supply Agreement [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Notice period for intention for termination agreement			18 months
Biomedical Advanced Research and Development Authority (BARDA) [Member] | BARDA Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Awarded contract for development, contract period						5 years
Government contract for research and development, amount						$ 67,300,000
CUBRC Inc [Member] | NIAID Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Committed funding for subcontracts								$ 16,300,000
Contract expiration date								Mar. 31, 2019
CUBRC Inc [Member] | Maximum [Member] | NIAID Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Committed funding for subcontracts														$ 16,900,000
National Institutes of Health's (NIH) National Institute of Allergy and Infectious Diseases (NIAID) Division [Member] | NIAID Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contract expiration date							Mar. 31, 2019
National Institutes of Health's (NIH) National Institute of Allergy and Infectious Diseases (NIAID) Division [Member] | Subcontract with CUBRC [Member] | NIAID Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Proceed from awarded contract for development								$ 16,200,000		100,000
Contracts revenue								0
National Institutes of Health's (NIH) National Institute of Allergy and Infectious Diseases (NIAID) Division [Member] | Maximum [Member] | NIAID Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Government contract for research and development, amount							$ 35,800,000
Combating Antibiotic Resistant Bacteria Biopharmaceutical Accelerator (CARB-X) [Member] | CARB-X Award [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Research funding period					18 months
Combating Antibiotic Resistant Bacteria Biopharmaceutical Accelerator (CARB-X) [Member] | Sub-Award Agreement with Trustees of Boston University [Member] | CARB-X Award [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contracts revenue								0		300,000
Combating Antibiotic Resistant Bacteria Biopharmaceutical Accelerator (CARB-X) [Member] | Maximum [Member] | CARB-X Award [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Government contract for research and development, amount					$ 4,000,000
License Agreements [Member] | Harvard [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Upfront and milestone payments, paid								$ 17,000,000
Common stock, shares issued								1,568
Upfront and milestone payments, payable								$ 15,100,000
Regulatory milestone payment								0		25,000
Future Clinical Development and Regulatory Milestone [Member] | Everest Medicines [Member] | Maximum [Member] | Everest Medicines License Agreement [Member] | Phase Three Clinical Trial [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments receivable		$ 11,000,000
Sales Milestone [Member] | Everest Medicines [Member] | Maximum [Member] | Everest Medicines License Agreement [Member] | Phase Three Clinical Trial [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Milestone payments receivable		$ 20,000,000
Additional Funding Agreement Terms [Member] | CUBRC Inc [Member] | BARDA Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Contract maturity date												Dec. 31, 2019
Proceed from awarded contract for development												$ 40,700,000
Contracts revenue								$ 0		$ 600,000
Additional Funding Agreement Terms [Member] | CUBRC Inc [Member] | Maximum [Member] | BARDA Contract [Member]
Research and Development Arrangement, Contract to Perform for Others [Line Items]
Committed funding for subcontracts													$ 41,300,000