Summary of Stock Option Activity (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended
	Sep. 29, 2012
Options Outstanding
Outstanding, beginning balance	865,445
Granted	242,866
Forfeited	(18,724)
Exercised	(256,331)
Outstanding, ending balance	833,256
Options exercisable at end of period	364,397
Weighted-Average Exercise Price
Outstanding, beginning balance	$ 26.72
Granted	$ 56.86
Forfeited	$ 30.95
Exercised	$ 23.82
Outstanding, ending balance	$ 36.31
Options exercisable at end of period	$ 24.85
Weighted-Average Remaining Contractual Term
Outstanding at end of period	4 years 9 months 18 days
Options exercisable at end of period	3 years 6 months
Aggregate Intrinsic Value
Outstanding at end of period	$ 7,936
Options exercisable at end of period	$ 6,001