Summary of Stock Options under Equity Plan and Non-Employee Director Plan (Detail) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 26, 2015 USD ($) $ / shares shares
Shares
Outstanding at beginning of period | shares	1,380,444
Granted | shares	24,363
Forfeited | shares	0
Expired | shares	0
Exercised | shares	(249,436)
Outstanding at end of period | shares	1,155,371
Exercisable at end of period | shares	408,752
Vested and expected to vest at end of period | shares	1,118,040
Weighted-Average Exercise Price
Outstanding at beginning of period	$ 55.37
Granted	283.22
Forfeited	0
Expired	0
Exercised	163.02
Outstanding at end of period	63.58
Exercisable at end of period	61.26
Vested and expected to vest at end of period	$ 63.54
Weighted-Average Remaining Contractual Term
Outstanding at end of period	3 years 7 months 24 days
Exercisable at end of period	3 years 4 months 6 days
Vested and expected to vest at end of period	3 years 7 months 21 days
Aggregate Intrinsic Value
Outstanding at end of period | $	$ 179,584
Exercisable at end of period | $	64,140
Vested and expected to vest at end of period | $	$ 173,812