Significant Accounting Policies - Summary of Receivables (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	$ 2,115	$ 4,562
U.S. Department of Health and Human Services [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	663	4,038
Shionogi & Co. Ltd [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	452	524
Billed [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	542	674
Billed [Member] | U.S. Department of Health and Human Services [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	90	150
Billed [Member] | Shionogi & Co. Ltd [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	452	524
Unbilled [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	1,573	3,888
Unbilled [Member] | U.S. Department of Health and Human Services [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables	1,573	3,888
Unbilled [Member] | Shionogi & Co. Ltd [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total receivables