Cover - USD ($)	12 Months Ended
	Dec. 31, 2020	Apr. 27, 2021	Jun. 30, 2020
Cover [Abstract]
Document Type	10-K/A
Amendment Flag	false
Document Annual Report	true
Document Transition Report	false
Document Period End Date	Dec. 31, 2020
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Current Fiscal Year End Date	--12-31
Entity File Number	000-26770
Entity Registrant Name	NOVAVAX, INC.
Entity Central Index Key	0001000694
Entity Tax Identification Number	22-2816046
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	21 Firstfield Road
Entity Address, City or Town	Gaithersburg
Entity Address, State or Province	MD
Entity Address, Postal Zip Code	20878
City Area Code	240
Local Phone Number	268-2000
Title of 12(b) Security	Common Stock, Par Value $0.01 per share
Trading Symbol	NVAX
Security Exchange Name	NASDAQ
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Public Float			$ 5,078,700,000
Entity Common Stock, Shares Outstanding		74,091,294
ICFR Auditor Attestation Flag	true