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Stock-Based Compensation Plans - Summary of Transactions of the Company's Stock Option Plans (Detail) - Stock Options Plan [Member]
12 Months Ended
Dec. 31, 2018
$ / shares
shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Outstanding, Number of Options, Beginning balance | shares 357,666
Exercised, Number of Options | shares (103,562)
Forfeited, Number of Options | shares (15,671)
Outstanding, Number of Options, Ending balance | shares 545,249
Outstanding, Weighted Average Exercise Price, Beginning balance $ 13.74
Exercised, Weighted Average Exercise Price 11.00
Forfeited, Weighted Average Exercise Price 24.35
Outstanding, Weighted Average Exercise Price, Ending balance 32.46
Outstanding, Weighted Average Grant-Date Fair Value 35.69
Exercised 29.78
Forfeited, Weighted Average Grant-Date Fair Value 25.38
Outstanding, Weighted Average Grant-Date Fair Value $ 36.06
Discount [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, Number of Options | shares 287,966
Granted, Weighted Average Exercise Price $ 45.21
Granted, Weighted Average Grant-Date Fair Value $ 34.98
Market Value [Member]  
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]  
Granted, Number of Options | shares 18,850
Granted, Weighted Average Exercise Price $ 68.20
Granted, Weighted Average Grant-Date Fair Value $ 16.23