Acquisition of Isconova AB (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended		1 Months Ended	9 Months Ended
	Jul. 31, 2013	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Novavax AB [Member]	Sep. 30, 2013 Minimum [Member]	Sep. 30, 2013 Maximum [Member]
Business Acquisition [Line Items]
Novavax shares issued for Isconova AB shares acquired	15,600,000
Value of shares of Novavax Common Stock issued	$ 41,942
Cash paid to Isconova warrant holders	22
Acquired finite-lived intangible assets, weighted-average useful life							7 years	20 years
Goodwill	25,298
Revenue		4,802	5,765	12,167	17,510	400
Net loss		(15,300)	(7,217)	(37,929)	(20,472)	(1,500)
Transaction costs				1,300
Aggregate remaining rental payments due under operating lease commitments		$ 1,900		$ 1,900