Income Taxes - Summary of Income Tax Benefit (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012
Income Tax Examination [Line Items]
Gross tax assets	$ 32,095,000	$ 45,066,000
Valuation allowance	(32,095,000)	(45,066,000)
Net deferred tax assets
Net Operating Losses and Capitalized Research and Development Expenditures [Member]
Income Tax Examination [Line Items]
Gross tax assets	4,391,000	(3,382,000)
Valuation allowance	(4,391,000)	3,382,000
Net deferred tax assets
Net Operating Losses and Capitalized Research and Development Expenditures [Member] | Federal [Member]
Income Tax Examination [Line Items]
Gross tax assets	3,574,000	(2,737,000)
Net Operating Losses and Capitalized Research and Development Expenditures [Member] | State [Member]
Income Tax Examination [Line Items]
Gross tax assets	$ 817,000	$ (645,000)