Annual report pursuant to Section 13 and 15(d)

Options Outstanding and Exercisable (Detail)

v3.7.0.1
Options Outstanding and Exercisable (Detail) - 2002 Stock Incentive Plan
 12 Months Ended
Dec. 31, 2016
$ / shares
shares
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Options Outstanding Number of Shares | shares 6,611,563
Options Outstanding Weighted Average Exercise Price $ 2.06
Options Outstanding Weighted Average Remaining Life (Years) 7 years 8 months 12 days
Options Exercisable Number of Shares | shares 3,352,355
Options Exercisable Weighted Average Exercise Price $ 2.50
Range One  
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit 0.82
Range of Exercise Prices, Upper Limit $ 1.43
Options Outstanding Number of Shares | shares 1,207,757
Options Outstanding Weighted Average Exercise Price $ 1.26
Options Outstanding Weighted Average Remaining Life (Years) 8 years 9 months 7 days
Options Exercisable Number of Shares | shares 504,736
Options Exercisable Weighted Average Exercise Price $ 1.28
Range Two  
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 $ 1.55
Options Outstanding Number of Shares | shares 1,410,000
Options Outstanding Weighted Average Exercise Price $ 1.45
Options Outstanding Weighted Average Remaining Life (Years) 9 years 9 months 18 days
Options Exercisable Number of Shares | shares 33,332
Options Exercisable Weighted Average Exercise Price $ 1.44
Range Three  
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit 1.56
Range of Exercise Prices, Upper Limit $ 2.10
Options Outstanding Number of Shares | shares 1,470,510
Options Outstanding Weighted Average Exercise Price $ 1.87
Options Outstanding Weighted Average Remaining Life (Years) 8 years 5 months 19 days
Options Exercisable Number of Shares | shares 547,171
Options Exercisable Weighted Average Exercise Price $ 1.94
Range Four  
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit 2.11
Range of Exercise Prices, Upper Limit $ 2.50
Options Outstanding Number of Shares | shares 976,947
Options Outstanding Weighted Average Exercise Price $ 2.28
Options Outstanding Weighted Average Remaining Life (Years) 7 years 2 months 19 days
Options Exercisable Number of Shares | shares 975,155
Options Exercisable Weighted Average Exercise Price $ 2.28
Range Five  
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit 2.51
Range of Exercise Prices, Upper Limit $ 3.50
Options Outstanding Number of Shares | shares 1,054,499
Options Outstanding Weighted Average Exercise Price $ 2.70
Options Outstanding Weighted Average Remaining Life (Years) 5 years 11 months 5 days
Options Exercisable Number of Shares | shares 805,528
Options Exercisable Weighted Average Exercise Price $ 2.70
Range Six  
Share Based Compensation Shares Authorized Under Stock Option Plans Exercise Price Range [Line Items]  
Range of Exercise Prices, Lower Limit 3.51
Range of Exercise Prices, Upper Limit $ 8.75
Options Outstanding Number of Shares | shares 491,850
Options Outstanding Weighted Average Exercise Price $ 4.59
Options Outstanding Weighted Average Remaining Life (Years) 1 year 6 months 11 days
Options Exercisable Number of Shares | shares 486,433
Options Exercisable Weighted Average Exercise Price $ 4.59