Schedule of Unrealized Loss on Available for Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2013	Dec. 29, 2012
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	$ 29,007	$ 4,157
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	415	7
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Value, Total	29,007	4,157
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	415	7
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	3,456
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	73
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Value, Total	3,456
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	73
Corporate bonds and direct obligations of government agencies
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	24,792	3,387
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	332	6
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Value, Total	24,792	3,387
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	332	6
U.S. Treasury Obligations
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	759	770
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	10	1
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Value
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss
Available-for-sale investments with unrealized losses, Fair Value, Total	759	770
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	$ 10	$ 1