Activity Related to Product Warranty (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 29, 2012		Sep. 24, 2011		Sep. 29, 2012		Sep. 24, 2011
Product Warranty Disclosure [Line Items]
Beginning balance	$ 13,702		$ 10,694		$ 12,865		$ 11,422
Charges to operations	4,241		2,547		10,065		6,278
Utilization	(1,684)		(1,738)		(5,488)		(5,033)
Change in estimate	(960)	[1]	(399)	[1]	(2,143)	[1]	(1,563)	[1]
Balance at the end of the period	$ 15,299		$ 11,104		$ 15,299		$ 11,104

[1] The Company records hardware warranty liabilities based on the latest quality and cost information available as of that date. The favorable changes in estimate shown here are due to continued improvements in overall actual failure rates and the impact of these improvements on the Company's estimate of expected future returns and changes in the estimated cost of replacing failed units using either repaired or new units