Annual report pursuant to Section 13 and 15(d)

Outstanding Stock Options, Vested and Expected to Vest, Non-Vested and Stock Options Currently Exercisable (Detail)

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Outstanding Stock Options, Vested and Expected to Vest, Non-Vested and Stock Options Currently Exercisable (Detail) (USD $)
12 Months Ended
Dec. 31, 2013
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Fully vested and expected to vest number of shares outstanding 5,864,340 5,821,461    
Fully vested and expected to vest Weighted average remaining contractual life 7 years 11 months 9 days 7 years 5 months 19 days    
Fully vested and expected to vest Weighted average price per share $ 18.53 $ 13.93    
Number of shares outstanding 5,914,802 5,858,613 7,292,031 9,131,494
Weighted average price per share $ 18.56 $ 13.97 $ 9.95 $ 6.05
Number of shares outstanding, exercisable 1,984,472 2,367,409    
Weighted average remaining contractual life, exercisable 6 years 6 months 29 days 6 years 2 months 1 day    
Weighted average price per share, exercisable $ 14.42 $ 9.52    
Non Vested Stock Options
       
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]        
Number of shares outstanding 3,930,330 3,491,204    
Weighted average remaining contractual life 8 years 7 months 28 days 8 years 4 months 24 days    
Weighted average price per share $ 20.66 $ 16.98