Stock-Based Compensation - Summary of Activity Under Stock Option Plan (Detail) (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Outstanding at beginning period - Options	1,216,981	1,298,431
Options granted	115,000	49,000
Options exercised	(153,664)	(130,450)
Options cancelled, forfeited, or expired - Options	(20,000)
Outstanding at ending period - Options	1,158,317	1,216,981
Exercisable at ending period - Options	561,167	620,281
Outstanding at beginning period - Wgtd. Avg. Exercise Price	$ 31.98	$ 30.14
Options granted - Wgtd. Avg. Exercise Price	$ 49.13	$ 40.93
Options exercised - Wgtd. Avg. Exercise Price	$ 25.03	$ 17.07
Options cancelled, forfeited, or expired - Wgtd. Avg. Exercise Price	$ 40.83
Outstanding at ending period - Wgtd. Avg. Exercise Price	$ 34.45	$ 31.98
Exercisable at ending period - Wgtd. Avg. Exercise Price	$ 27.95	$ 25.72
Outstanding at ending period - Wgtd. Avg. Remaining Contractual Term, years	8 years 10 months 2 days	8 years 7 months 17 days
Exercisable at ending period - Wgtd. Avg. Remaining Contractual Term, years	6 years 8 months 12 days	5 years 2 months 19 days
Outstanding at ending period - Aggregate Intrinsic Value	$ 25,034	$ 12,637
Exercisable at ending period - Aggregate Intrinsic Value	$ 15,774	$ 10,324