Quarterly report pursuant to Section 13 or 15(d)

Stock-Based Compensation - Stock Option Activity (Detail)

v2.4.0.8
Stock-Based Compensation - Stock Option Activity (Detail) (USD $)
In Millions, except Share data in Thousands, unless otherwise specified
 9 Months Ended 12 Months Ended
Sep. 30, 2013
Dec. 31, 2012
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]    
Number of Shares Underlying Options, Outstanding at beginning of period 4,065  
Number of Shares Underlying Options, Granted 1,236  
Number of Shares Underlying Options, Exercised (173)  
Number of Shares Underlying Options, Forfeited (1)  
Number of Shares Underlying Options, Outstanding at end of period 5,127 4,065
Number of Shares Underlying Options, Exercisable at end of period 4,245  
Weighted Average Exercise Price Per Share, Outstanding at beginning of period $ 6.12  
Weighted Average Exercise Price Per Share, Granted $ 7.59  
Weighted Average Exercise Price Per Share, Exercised $ 4.24  
Weighted Average Exercise Price Per Share, Forfeited $ 7.75  
Weighted Average Exercise Price Per Share, Outstanding at end of period $ 6.53 $ 6.12
Weighted Average Exercise Price Per Share, Exercisable at end of period $ 6.21  
Weighted Average Remaining Contractual Term, Outstanding balance 2 years 6 months 29 days 2 years 7 months 24 days
Weighted Average Remaining Contractual Term, Granted 4 years 5 months 16 days  
Weighted Average Remaining Contractual Term, Exercised 11 days  
Weighted Average Remaining Contractual Term, Forfeited 4 years 5 months 5 days  
Weighted Average Remaining Contractual Term, Exercisable at end of period 2 years 3 months 7 days  
Aggregate Intrinsic Value, Outstanding at end of period $ 4.82  
Aggregate Intrinsic Value, Exercisable at end of period $ 4.82