Schedule of Unrealized Loss on Available for Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 29, 2012	Dec. 31, 2011
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	$ 4,157	$ 7,126
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	7	145
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	7,126
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	7	145
Mortgage-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value		468
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss		18
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		468
Available-for-sale investments with unrealized losses, Unrealized Loss, Total		18
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	3,387	6,067
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	6	126
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	3,387	6,067
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	6	126
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	591
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	1	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	591
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	$ 1	$ 1