Amortized Cost and Fair Value of Available for Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 28, 2013	Dec. 29, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 102,159	$ 90,995
Gross Unrealized Gains	833	1,414
Gross Unrealized Losses	455	7
Fair Value	102,537	92,402
Money market investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	2,499	2,865
Fair Value	2,499	2,865
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,350	2,175
Gross Unrealized Gains	19	73
Gross Unrealized Losses	72
Fair Value	4,297	2,248
Corporate bonds and direct obligations of government agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	76,786	69,173
Gross Unrealized Gains	783	1,294
Gross Unrealized Losses	370	6
Fair Value	77,199	70,461
U.S. Treasury Obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,524	16,782
Gross Unrealized Gains	31	47
Gross Unrealized Losses	13	1
Fair Value	$ 18,542	$ 16,828