Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2013
Options Outstanding
Outstanding, beginning balance	831,504
Granted	268,019
Forfeited	(88,180)
Exercised	(197,052)
Outstanding, ending balance	814,291
Options exercisable at end of period	365,477
Weighted-Average Exercise Price
Outstanding, beginning balance	$ 36.31
Granted	$ 43.15
Forfeited	$ 46.08
Exercised	$ 27.83
Outstanding, ending balance	$ 39.56
Options exercisable at end of period	$ 31.46
Weighted-Average Remaining Contractual Term
Outstanding at end of period	4 years 6 months
Options exercisable at end of period	3 years 2 months 12 days
Aggregate Intrinsic Value
Outstanding at end of period	$ 15,262
Options exercisable at end of period	$ 9,808