Stockholders' Equity (Deficit) - Financial Liabilities Subject to Fair Value Measurements (Detail) - Warrants - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	$ 1,864
Basis of Fair Value Measurements, Level 3
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	1,864
March 2011 Warrants
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	38	$ 3,961
March 2011 Warrants | Basis of Fair Value Measurements, Level 3
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	38	$ 3,961
February 2015 Warrants
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	1,826
February 2015 Warrants | Basis of Fair Value Measurements, Level 3
Fair Value Inputs Liabilities Quantitative Information [Line Items]
Financial liabilities subject to fair value measurements	$ 1,826