Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Accrued Liabilities [Line Items]
Accrued clinical and research services	$ 4,428	$ 2,492
Accrued compensation and benefits	495	679
Other	302	333
Total	$ 5,225	$ 3,504	[1]

[1] The condensed consolidated balance sheet at December 31, 2011 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by accounting principles generally accepted in the United States for complete financial statements.