Acquisition (Narrative) (Details) (USD $) Share data in Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Novavax shares issued for Isconova AB shares acquired		15.6
Value of shares of Novavax Common Stock issued		$ 41,900,000
Cash paid to Isconova warrant holders	171,000	0	0
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		17 years
Transaction costs		1,300,000
Other non-current liabilities	1,639,000	1,763,000
Business Acquisition Percentage of Voting Interests Acquired During Period		99.50%
Novavax AB [Member]
Cash paid to Isconova warrant holders		22,000
Other non-current liabilities	$ 1,500,000
Business Acquisition Percentage of Voting Interests Acquired During Period	0.50%
Proprietary Adjuvant Technology [Member] [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		20 years
Maximum [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		20 years
Minimum [Member]
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life		12 years