Revenue from United States Government Contracts and Other Revenue (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	$ 37,329	$ 46,990	$ 29,420
July 2010 Agreement (Ebola and Marburg)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	36,557	42,875	9,822
August 2012 Agreement (Intramuscular)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	673	0	0
June 2010 Agreement (H1N1)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	0	3,490	8,809
May 2009 Agreement (H1N1)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	0	516	5,171
November 2006 Agreement (Ebola, Marburg and Junin Viruses)
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	0	0	3,204
Grants
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	0	0	1,622
Other Agreements
Accounts, Notes, Loans and Financing Receivable [Line Items]
U.S. government contract revenue	$ 99	$ 109	$ 792