Grant Agreements - Additional Information (Details) - USD ($)	1 Months Ended	3 Months Ended		9 Months Ended
	Aug. 31, 2017	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Mar. 31, 2020	Feb. 29, 2020	Mar. 16, 2018	Jan. 26, 2018
Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		$ 1,740,000	$ 1,166,000	$ 7,690,000	$ 6,771,000
Bill & Melinda Gates Foundation | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		0	0	0	900,000
National Institutes of Health
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount		5,100,000		5,100,000
National Institutes of Health | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		100,000	200,000	500,000	700,000
2017 Grant | Bill & Melinda Gates Foundation
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant agreement expiration date	May 31, 2019
2017 Grant | Bill & Melinda Gates Foundation | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount	$ 4,700,000
Human Immunodeficiency Virus ("HIV") Grant
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount							$ 8,600,000
Human Immunodeficiency Virus ("HIV") Grant | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount									$ 12,200,000
Human Immunodeficiency Virus ("HIV") Grant | Bill & Melinda Gates Foundation | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		800,000	500,000	6,200,000	3,400,000
Tuberculosis ("TB") Grant
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Funds received in advance						$ 3,800,000
Tuberculosis ("TB") Grant | Grant Revenue [Member]
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Revenue from grants		$ 900,000	$ 400,000	$ 1,000,000.0	$ 1,800,000
Tuberculosis ("TB") Grant | Maximum
Collaborative Arrangements And Noncollaborative Arrangement Transactions [Line Items]
Grant awarded amount								$ 14,900,000