Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plans and Stock Based Compensation - Assumptions of Equity-Based Payments to Non-Employees (Detail)

v3.3.1.900
Equity Incentive Plans and Stock Based Compensation - Assumptions of Equity-Based Payments to Non-Employees (Detail) - Non-employee Stock-based Compensation Expense
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]      
Risk-free interest rate 2.14% 2.52% 2.51%
Expected life (in years) 10 years 10 years 10 years
Expected volatility 103.00% 97.00% 100.00%