Deferred Revenue - Additional Information (Details) - USD ($)							3 Months Ended		6 Months Ended		14 Months Ended
	Sep. 30, 2018	Sep. 19, 2018	Sep. 22, 2015	Jul. 20, 2015	Sep. 17, 2014	Dec. 17, 2013	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Apr. 17, 2018
Deferred Revenue Arrangement [Line Items]
Proceeds from funding agreement				$ 250,000	$ 500,000	$ 250,000
Interest in asset				0.50%	1.00%	0.50%
Number of shares issuable term					60 days	60 days
Number of shares issuable (in shares)					62,500	31,250
Number of shares per dollar exchange rate (in shares)			0.1
Grants receivable												$ 7,400,000
Revenue from contract with customer							$ 6,129,000	$ 3,053,000	$ 9,875,000	$ 4,702,000
BARDA
Deferred Revenue Arrangement [Line Items]
Proceeds from funding agreement	$ 600,000
Period of funding for remaining balance		2 years
Plan | BARDA
Deferred Revenue Arrangement [Line Items]
Proceeds from funding agreement		$ 4,600,000
Grant
Deferred Revenue Arrangement [Line Items]
Revenue from contract with customer									1,600,000		$ 5,600,000
Research and Development Arrangement December 17, 2013
Deferred Revenue Arrangement [Line Items]
Recognized as revenue									115,900	29,000
Research and Development Arrangement September 17, 2014
Deferred Revenue Arrangement [Line Items]
Recognized as revenue									313,700	78,400.0
Research and Development Arrangement July 20, 2015
Deferred Revenue Arrangement [Line Items]
Recognized as revenue									214,300	$ 0
Research And Development Arrangement September 19, 2018
Deferred Revenue Arrangement [Line Items]
Recognized as revenue									$ 96,823