Notes Payable (Aggregate Future Minimum Principal Payments on Equipment Loan) (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013
Notes Payable [Abstract]
2013 (remainder)	$ 143
2014	571
2015	571
2016	396
Total	$ 1,681

Amount of minimum loan payments maturing in the remainder of the fiscal year following the latest fiscal year ended.

No definition available.

Name:	nvax_LoanAgreementFutureMinimumPaymentsRemainderOfFiscalYear
Namespace Prefix:	nvax_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant