Funding Arrangements (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended		8 Months Ended
	Dec. 31, 2016	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Oct. 31, 2017	Dec. 31, 2018
USAMRAA grant
Funding Arrangements
Maximum reimbursable research expenditures	$ 1,100,000
Grant income recognized		$ 0	$ 200,000	$ 37,000	$ 300,000
Funds received during the period				200,000	600,000
Grants receivable		0		0			$ 200,000
CARB-X program
Funding Arrangements
Maximum reimbursable research expenditures						$ 16,400,000
Grant income recognized		400,000	$ 1,500,000	1,200,000	2,500,000
Funds received during the period				1,500,000	$ 700,000
Grants receivable		$ 1,200,000		$ 1,200,000			$ 1,500,000