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Accounting for Stock Based Compensation - Summarizes Stock Option Activity (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]        
Stock Options Outstanding, beginning balance, Shares 1,653,000 2,652,142 2,103,470  
Granted, Shares 0 0 808,500  
Exercised, Shares (428,250) (615,358) (202,328)  
Forfeited, Shares (355,750) (383,784) (57,500)  
Stock Options Outstanding, ending balance, Shares 869,000 1,653,000 2,652,142 2,103,470
Stock Options Exercisable, Shares 665,000 788,125 984,374  
Stock Options Outstanding, beginning balance, Weighted-Average Exercise Price $ 38.53 $ 35.34 $ 32.72  
Granted, Weighted-Average Exercise Price     37.23  
Exercised, Weighted-Average Exercise Price 38.66 24.01 13.62  
Forfeited, Weighted-Average Exercise Price 39.99 39.59 42.54  
Stock Options Outstanding, ending balance, Weighted-Average Exercise Price 37.87 38.53 35.34 $ 32.72
Exercisable, Weighted-Average Exercise Price $ 38.10 $ 38.15 $ 29.84  
Stock Options Outstanding, Weighted-Average Remaining Contractual Term 3 years 6 months 3 days 4 years 3 months 10 days 4 years 9 months 3 days 4 years 10 months 9 days
Exercisable, Weighted-Average Remaining Contractual Term 3 years 2 months 23 days 3 years 8 months 15 days 3 years 5 months 8 days  
Stock Options Outstanding, Aggregate Intrinsic Value $ 5,172 $ 3,610 $ 6,964 $ 12,265
Exercisable, Aggregate Intrinsic Value $ 3,725 $ 2,200 $ 6,534