Acquisitions - Additional Information (Details)	1 Months Ended			9 Months Ended
	Oct. 31, 2020 USD ($)	Jun. 30, 2020 USD ($)	May 31, 2020 Milestone	Sep. 30, 2020 USD ($) Milestone $ / shares	Dec. 31, 2019 USD ($)	Jan. 31, 2018 USD ($)	Aug. 31, 2017 USD ($)	Sep. 30, 2016 USD ($)
TomegaVax | TomegaVax Letter Agreement
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum								$ 30,000,000.0
Minimum common stock conversion price for milestone payments consideration | $ / shares				$ 45
Milestone payments related terms				the Company will be required to pay to the former stockholders of TomegaVax milestone payments of up to an aggregate of $30.0 million if the per-share price of the Company’s publicly traded common stock, or implied price per share of the Company’s Series A-1 convertible preferred stock (or common stock upon conversion) upon a certain asset sale, merger or stock sale, is at least $45 (as adjusted in the case of any stock dividend, stock split or other similar recapitalization), with the amount of such payments determined by the share price and the stage of the Company’s clinical development at the time of the relevant event triggering the payment.
Estimated fair value of embedded derivative				$ 9,500,000
Humabs
Business Acquisition [Line Items]
Specified clinical development milestones payment		$ 10,000,000.0
Contingent consideration recognized				42,500,000	$ 14,900,000
Humabs | HBV Product
Business Acquisition [Line Items]
Additional consideration payable upon achievement of specified milestone events							$ 135,000,000.0
Number of specified clinical milestones achieved | Milestone			1
Specified clinical development milestones payment		$ 10,000,000.0
Contingent consideration recognized				42,500,000
Humabs | SARS-CoV-2 Product
Business Acquisition [Line Items]
Additional consideration payable upon achievement of specified milestone events							$ 105,000,000.0
Humabs | SARS-CoV-2 Product | Subsequent Event
Business Acquisition [Line Items]
Specified clinical development milestones payment	$ 10,000,000.0
Agenovir
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum						$ 180,000,000.0
Contingent consideration recognized				$ 0
Sales milestone payments for achievement of specified levels of annual net sales of each program maximum						90,000,000.0
Number of milestones achieved | Milestone				0
Agenovir | HPV Program
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum						45,000,000.0
Agenovir | HBV Product
Business Acquisition [Line Items]
Milestone payments aggregate amount payable, maximum						$ 45,000,000.0