Acquisition of Isconova AB (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended
	Jul. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Novavax shares issued for Isconova AB shares acquired	15,600,000
Value of shares of Novavax Common Stock issued	$ 41,900
Cash paid to Isconova warrant holders	22,000
Goodwill		58,621	33,141	58,707	33,141
Currency translation adjustment		(86)
Novavax AB [Member]
Business Acquisition [Line Items]
Goodwill	$ 26,200	$ 25,400