Employee Benefit Plans - Summary of Average Remaining Life of the Stock Options (Detail)	12 Months Ended
	Dec. 31, 2016 $ / shares shares
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	228,272
Exercise Price Range Per Share Minimum	$ 19.27
Exercise Price Range Per Share Maximum	$ 32.37
Options Outstanding | shares	276,122
Weighted Average Exercise Price	$ 29.71
Weighted Avg. Remaining Contractual Life in Years	5 years 22 days
2010 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	3,234
Exercise Price Range Per Share Minimum	$ 19.27
Options Outstanding | shares	3,234
Weighted Average Exercise Price	$ 19.27
Weighted Avg. Remaining Contractual Life in Years	4 months 17 days
2011 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	6,250
Exercise Price Range Per Share Minimum	$ 19.76
Options Outstanding | shares	6,250
Weighted Average Exercise Price	$ 19.76
Weighted Avg. Remaining Contractual Life in Years	1 year 4 months 17 days
2012 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	12,000
Exercise Price Range Per Share Minimum	$ 20.02
Options Outstanding | shares	12,000
Weighted Average Exercise Price	$ 20.02
Weighted Avg. Remaining Contractual Life in Years	2 years 4 months 13 days
2013 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	30,750
Exercise Price Range Per Share Minimum	$ 25.00
Options Outstanding | shares	30,750
Weighted Average Exercise Price	$ 25.00
Weighted Avg. Remaining Contractual Life in Years	3 years 4 months 13 days
2014 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	49,550
Exercise Price Range Per Share Minimum	$ 28.79
Options Outstanding | shares	49,550
Weighted Average Exercise Price	$ 28.79
Weighted Avg. Remaining Contractual Life in Years	4 years 4 months 21 days
2015 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	78,638
Exercise Price Range Per Share Minimum	$ 31.58
Options Outstanding | shares	78,638
Weighted Average Exercise Price	$ 31.58
Weighted Avg. Remaining Contractual Life in Years	5 years 5 months 1 day
2016 [Member]
Share-based Compensation, Shares Authorized under Stock Option Plans, Exercise Price Range [Line Items]
Exercisable at Year End | shares	47,850
Exercise Price Range Per Share Minimum	$ 32.37
Options Outstanding | shares	95,700
Weighted Average Exercise Price	$ 32.37
Weighted Avg. Remaining Contractual Life in Years	6 years 4 months 24 days