Subsequent Events (Details) - Subsequent Event shares in Millions	1 Months Ended			2 Months Ended	12 Months Ended
	Feb. 28, 2021 dose	Feb. 24, 2021 USD ($) shares	Jan. 31, 2021 USD ($)	Feb. 28, 2021 dose	Dec. 31, 2021 dose
Common Stock | January 2021 Sales Agreement
Subsequent Event [Line Items]
Allowable gross proceeds of common stock | $			$ 500,000,000
Number of shares issued in transaction (in shares) | shares		1.7
Consideration received on transaction, net of issuance costs | $		$ 452,000,000.0
Remaining unissued capital | $		$ 42,200,000
Government contracts
Subsequent Event [Line Items]
Additional purchase option, number of doses | dose				75,000,000
SK Sars Cov2 Vaccine Supply Agreement Member
Subsequent Event [Line Items]
Additional purchase option, number of doses | dose					40,000,000
Gavi Vaccine Alliance
Subsequent Event [Line Items]
Additional purchase option, number of doses | dose	1,100,000,000