Other Balance Sheet Accounts - Summary of Accounts Payable and Accrued Expenses (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Payables And Accruals [Abstract]
Employee compensation	$ 1,587	$ 3,858
Clinical trial accruals	347	660
Accounts payable	395	377
Deferred rent	369	307
Post-termination benefit accrual	369
Other accrued liabilities	436	427
Total accounts payable and accrued expenses	$ 3,503	$ 5,629