Schedule of Unrealized Loss on Available for Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Mar. 29, 2014	Dec. 28, 2013
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	$ 26,395	$ 26,355
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	308	455
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	26,395	26,355
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	308	455
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Available-for-sale investments with unrealized losses, Less than 12 months, Fair Value	4,501	3,429
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	56	72
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	4,501	3,429
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	56	72
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	19,132	22,169
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	240	370
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	19,132	22,169
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	240	370
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	2,762	757
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	12	13
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	2,762	757
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	$ 12	$ 13