Annual report pursuant to Section 13 and 15(d)

Equity Incentive Plans and Stock Based Compensation - Stock Options Outstanding and Exercisable by Exercise Price (Detail)

v2.4.0.6
Equity Incentive Plans and Stock Based Compensation - Stock Options Outstanding and Exercisable by Exercise Price (Detail) (USD $)
 12 Months Ended
Dec. 31, 2012
$0.42 - 1.38 [Member]
  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit $ 0.42
Range of Exercise Prices, Upper Limit $ 1.38
Options Outstanding, Number Outstanding 664,316
Options Outstanding, Weighted Average Remaining Contractual Life (Years) 5 years 3 months 22 days
Options Outstanding, Weighted Average Exercise Price $ 1.12
Options Exercisable, Number Exercisable 619,876
Options Exercisable, Weighted Average Exercise Price $ 1.10
$1.44 - 1.44 [Member]
  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit $ 1.44
Range of Exercise Prices, Upper Limit $ 1.44
Options Outstanding, Number Outstanding 1,397,189
Options Outstanding, Weighted Average Remaining Contractual Life (Years) 7 years 4 months 13 days
Options Outstanding, Weighted Average Exercise Price $ 1.44
Options Exercisable, Number Exercisable 889,657
Options Exercisable, Weighted Average Exercise Price $ 1.44
$1.49 - 1.62 [Member]
  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit $ 1.49
Range of Exercise Prices, Upper Limit $ 1.62
Options Outstanding, Number Outstanding 180,000
Options Outstanding, Weighted Average Remaining Contractual Life (Years) 8 years 2 months 23 days
Options Outstanding, Weighted Average Exercise Price $ 1.58
Options Exercisable, Number Exercisable 76,527
Options Exercisable, Weighted Average Exercise Price $ 1.61
$1.64 - 1.64 [Member]
  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit $ 1.64
Range of Exercise Prices, Upper Limit $ 1.64
Options Outstanding, Number Outstanding 962,095
Options Outstanding, Weighted Average Remaining Contractual Life (Years) 8 years 4 months 28 days
Options Outstanding, Weighted Average Exercise Price $ 1.64
Options Exercisable, Number Exercisable 378,651
Options Exercisable, Weighted Average Exercise Price $ 1.64
$1.69 - 6.85 [Member]
  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit $ 1.69
Range of Exercise Prices, Upper Limit $ 6.85
Options Outstanding, Number Outstanding 934,372
Options Outstanding, Weighted Average Remaining Contractual Life (Years) 9 years 18 days
Options Outstanding, Weighted Average Exercise Price $ 4.93
Options Exercisable, Number Exercisable 223,131
Options Exercisable, Weighted Average Exercise Price $ 4.16
$7.00 - 7.75 [Member]
  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit $ 7.00
Range of Exercise Prices, Upper Limit $ 7.75
Options Outstanding, Number Outstanding 961,000
Options Outstanding, Weighted Average Remaining Contractual Life (Years) 9 years 4 months 2 days
Options Outstanding, Weighted Average Exercise Price $ 7.28
Options Exercisable, Number Exercisable 127,496
Options Exercisable, Weighted Average Exercise Price $ 7.22
$0.42 - 7.75 [Member]
  
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit $ 0.42
Range of Exercise Prices, Upper Limit $ 7.75
Options Outstanding, Number Outstanding 5,098,972
Options Outstanding, Weighted Average Remaining Contractual Life (Years) 8 years 4 days
Options Outstanding, Weighted Average Exercise Price $ 3.18
Options Exercisable, Number Exercisable 2,315,388
Options Exercisable, Weighted Average Exercise Price $ 1.97