Income Taxes - Effect of Temporary Differences and Carryforwards (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 31,989	$ 21,569
Research and development tax credit carryforwards	1,654	761
Other	2,369	2,717
Total deferred tax assets	36,012	25,047
Less: Valuation allowance	(36,012)	(25,047)
Net deferred tax assets