Amortized Cost and Fair Value of 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]
Amortized Cost	$ 102,483	$ 102,159
Gross Unrealized Gains	856	833
Gross Unrealized Losses	308	455
Fair Value	103,031	102,537
Money market investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,821	2,499
Fair Value	2,821	2,499
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,332	4,350
Gross Unrealized Gains	13	19
Gross Unrealized Losses	56	72
Fair Value	5,289	4,297
Corporate bonds and direct obligations of government agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	75,816	76,786
Gross Unrealized Gains	814	783
Gross Unrealized Losses	240	370
Fair Value	76,390	77,199
U.S. Treasury Obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,514	18,524
Gross Unrealized Gains	29	31
Gross Unrealized Losses	12	13
Fair Value	$ 18,531	$ 18,542