Schedule of Unrealized Loss on Available for Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 30, 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		$ 4,157
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss		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		4,157
Available-for-sale investments with unrealized losses, Unrealized Loss, Total		7
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	4,184	3,387
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	4	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	4,184	3,387
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	4	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		770
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss		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		770
Available-for-sale investments with unrealized losses, Unrealized Loss, Total		$ 1