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Stock-Based Compensation Plans - Summary of Transactions of the Company's Stock Option Plans (Detail) - Stock Options Plan [Member]
3 Months Ended
Mar. 31, 2017
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Outstanding, Number of Options, Beginning balance | shares 570,994
Exercised, Number of Options | shares (72,994)
Forfeited, Number of Options | shares (2,281)
Outstanding, Number of Options, Ending balance | shares 591,226
Outstanding, Weighted Average Exercise Price, Beginning balance $ 20.38
Exercised, Weighted Average Exercise Price 12.92
Forfeited, Weighted Average Exercise Price 9.62
Outstanding, Weighted Average Exercise Price, Ending balance 20.30
Outstanding, Weighted Average Grant-Date Fair Value 21.68
Exercised 24.77
Forfeited, Weighted Average Grant-Date Fair Value 24.60
Outstanding, Weighted Average Grant-Date Fair Value $ 26.43
Discount [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, Number of Options | shares 76,664
Granted, Weighted Average Exercise Price $ 0.00
Granted, Weighted Average Grant-Date Fair Value $ 62.22
Market Value [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, Number of Options | shares 18,843
Granted, Weighted Average Exercise Price $ 70.60
Granted, Weighted Average Grant-Date Fair Value $ 16.84