Commitments and Contingencies - Additional Information (Detail) - USD ($)	1 Months Ended
	Apr. 30, 2016	Sep. 30, 2017	Dec. 31, 2016
Product Liability Contingency [Line Items]
Accounts payable and accrued liabilities			$ 100,000
Operating Leases, Future Minimum Payments Due		$ 48,000
Other Inventory, Gross		700,000	$ 400,000
Other Commitment, Due in Next Twelve Months		1,800,000
Drug Supplier Project Plan [Member]
Product Liability Contingency [Line Items]
Other Commitment		2,200,000
Manufacturer of Prexigebersen [Member]
Product Liability Contingency [Line Items]
Other Commitment		1,400,000
Manufacture of Drug Substance [Member]
Product Liability Contingency [Line Items]
Other Commitment		600,000
Manufacturing Development [Member]
Product Liability Contingency [Line Items]
Other Commitment		200,000
Office Space
Product Liability Contingency [Line Items]
Operating Leases, Future Minimum Payments Due		$ 200,000
Lab Space
Product Liability Contingency [Line Items]
Operating Lease Monthly Rental Payments	$ 2,500