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Summary of Restricted Stock Unit Activity (Detail) - Restricted stock units - $ / shares
12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward]      
Restricted stock units outstanding at December 31, 2015 1,029,949    
Granted 199,148    
Released (181,684)    
Forfeited (21,420)    
Restricted stock units outstanding at December 31, 2016 1,025,993 1,029,949  
Weighted average grant date fair value      
Restricted stock units outstanding at December 31, 2015 $ 46.97    
Granted 51.55 $ 56.48 $ 48.56
Released 44.58    
Forfeited 48.92    
Restricted stock units outstanding at December 31, 2016 $ 48.24 $ 46.97