Property and Equipment - Tabular Disclosure of Major Components of Property and Equipment and Related Accumulated Depreciation (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Property Plant And Equipment [Abstract]
Leasehold improvements	$ 525	$ 525
Laboratory equipment and other	3,238	2,854
Total property and equipment, at cost	3,763	3,379
Less: accumulated depreciation	3,077	3,289
Property and equipment, net	$ 686	$ 90