Options Outstanding and Exercisable (Detail) (USD $)
6 Months Ended
Jun. 30, 2012
Dec. 31, 2011
Jul. 01, 2010
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Outstanding Number of Stock Options 7,809,270 7,542,459  
Outstanding Weighted Average Remaining Life (Years) 5 years 9 months 22 days    
Outstanding Weighted Average Exercise Price $ 0.39 $ 0.41  
Exercisable Number of Stock Options 6,177,948    
Exercisable Weighted Average Exercise Price $ 0.44   $ 0.27
Range 1
     
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Price range, lower limit $ 0.07    
Price range, upper limit $ 0.20    
Outstanding Number of Stock Options 2,038,760    
Outstanding Weighted Average Remaining Life (Years) 7 years 9 months 18 days    
Outstanding Weighted Average Exercise Price $ 0.12    
Exercisable Number of Stock Options 1,279,659    
Exercisable Weighted Average Exercise Price $ 0.11    
Range 2
     
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Price range, lower limit $ 0.21    
Price range, upper limit $ 0.30    
Outstanding Number of Stock Options 2,180,032    
Outstanding Weighted Average Remaining Life (Years) 8 years 1 month 6 days    
Outstanding Weighted Average Exercise Price $ 0.28    
Exercisable Number of Stock Options 1,380,036    
Exercisable Weighted Average Exercise Price $ 0.28    
Range 3
     
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Price range, lower limit $ 0.31    
Price range, upper limit $ 0.50    
Outstanding Number of Stock Options 1,794,070    
Outstanding Weighted Average Remaining Life (Years) 4 years 6 months    
Outstanding Weighted Average Exercise Price $ 0.41    
Exercisable Number of Stock Options 1,721,845    
Exercisable Weighted Average Exercise Price $ 0.41    
Range 4
     
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Price range, lower limit $ 0.51    
Price range, upper limit $ 1.00    
Outstanding Number of Stock Options 1,763,408    
Outstanding Weighted Average Remaining Life (Years) 2 years 1 month 6 days    
Outstanding Weighted Average Exercise Price $ 0.81    
Exercisable Number of Stock Options 1,763,408    
Exercisable Weighted Average Exercise Price $ 0.81    
Range 5
     
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]      
Price range, lower limit $ 1.01    
Price range, upper limit $ 1.33    
Outstanding Number of Stock Options 33,000    
Outstanding Weighted Average Remaining Life (Years) 1 year 6 months    
Outstanding Weighted Average Exercise Price $ 1.13    
Exercisable Number of Stock Options 33,000    
Exercisable Weighted Average Exercise Price $ 1.13