Grant Revenue (Details) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended			6 Months Ended
	Apr. 30, 2020	Sep. 30, 2016	Jun. 30, 2020	Jun. 30, 2019		Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Disaggregation of Revenue [Line Items]
Total grant revenue			$ 66,351	$ 13,083	[1]	$ 74,740	$ 29,108
Contract with customer, liability			253,722			253,722		$ 202,305
Grant revenue
Disaggregation of Revenue [Line Items]
Total grant revenue			37,909	3,053	[1]	41,841	4,963
Contract with customer, liability			5,758			5,758		$ 1,496
BARDA
Disaggregation of Revenue [Line Items]
Amount committed for funding			449,300			449,300
Award amount	$ 483,300	$ 125,800
BARDA | Grant revenue
Disaggregation of Revenue [Line Items]
Total grant revenue			37,048	1,876		39,816	3,365
BARDA | Contract options
Disaggregation of Revenue [Line Items]
Award amount			76,000
Available funding			8,400			8,400
The Bill & Melinda Gates Foundation | Initial project
Disaggregation of Revenue [Line Items]
Available funding			12,700			12,700
Contract with customer, liability			80,000			80,000
Other grant revenue | Grant revenue
Disaggregation of Revenue [Line Items]
Total grant revenue			$ 861	$ 1,177		$ 2,025	$ 1,598

[1] Restated to conform to ASC 842. See accompanying Note 2.