Schedule of Unrealized Loss on Available for Sale for sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 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 Market Value	$ 3,112	$ 7,126
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	3	145
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Market Value	496
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss	4
Available-for-sale investments with unrealized losses, Fair Market Value, Total	3,608	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 Market Value	131	468
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	1	18
Available-for-sale investments with unrealized losses, Fair Market Value, Total	131	468
Available-for-sale investments with unrealized losses, Unrealized Loss, Total	1	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 Market Value	2,981	6,067
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss	2	126
Available-for-sale investments with unrealized losses, 12 months or longer, Fair Market Value	496
Available-for-sale investments with unrealized losses, 12 months or longer, Unrealized Loss	4
Available-for-sale investments with unrealized losses, Fair Market Value, Total	3,477	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 Market Value		591
Available-for-sale investments with unrealized losses, Less than 12 months, Unrealized Loss		1
Available-for-sale investments with unrealized losses, Fair Market Value, Total		591
Available-for-sale investments with unrealized losses, Unrealized Loss, Total		$ 1