Income Taxes - Components of Deferred Tax Assets (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Income Tax Disclosure [Abstract]
Net operating loss carryforwards	$ 8,970,000	$ 24,318,000
Net operating loss carryforwards - Section 382 Limited NOL	11,737,000	2,277,000
Research and development credit carryforwards	1,473,000	4,176,000
Compensation expense	3,353,000	2,948,000
Other	509,000	503,000
Total deferred tax assets	26,042,000	34,222,000
Valuation allowance for deferred tax assets	(26,042,000)	(34,222,000)
Net deferred tax assets