v3.7.0.1
Stock-based Compensation - Summary of Changes in Stock Options Outstanding (Detail) - USD ($)
$ / shares in Units, shares in Thousands, $ in Millions
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]      
Number of Options, Beginning Balance 6,269 6,442  
Number of Options, Exercisable 2,998 3,400 1,938
Number of Options, Granted 741 438  
Number of Options, Exercised (1,333) (566)  
Number of Options, Forfeited (87) (45)  
Number of Options, Ending Balance 5,590 6,269 6,442
Weighted Average Exercise Price, Beginning Balance $ 11.58 $ 10.54  
Weighted Average Exercise Price, Options Exercisable 12.46 10.82 $ 10.60
Weighted Average Exercise Price, Granted 15.46 18.90  
Weighted Average Exercise Price, Exercised 6.97 5.50  
Weighted Average Exercise Price, Forfeited 14.58 10.12  
Weighted Average Exercise Price, Ending Balance $ 13.15 $ 11.58 $ 10.54
Remaining Contractual Term 6 years 10 months 24 days 7 years 7 months 6 days 8 years 6 months
Remaining Contractual Term, Options Exercisable 6 years 2 months 12 days 7 years 4 months 24 days 8 years 2 months 12 days
Aggregate Intrinsic Value $ 54.8 $ 45.5 $ 49.2
Aggregate Intrinsic Value, Options Exercisable 31.5 27.6 $ 15.2
Aggregate Intrinsic Value, Exercised $ 14.3 $ 8.6