Commitments and Contingencies - Additional Information (Details) $ in Millions	Sep. 30, 2020 USD ($)
Product Liability Contingency [Line Items]
Other Commitment, Due in Next Twelve Months	$ 1.4
Drug Supplier Project Plan [Member]
Product Liability Contingency [Line Items]
Other Commitment	1.5
Manufacturer of prexigebersen and BP1002 drug products
Product Liability Contingency [Line Items]
Other Commitment	1.0
Manufacture Of Drug Substance [Member]
Product Liability Contingency [Line Items]
Other Commitment	0.4
Manufacturing Development [Member]
Product Liability Contingency [Line Items]
Other Commitment	$ 0.1