Amortized Cost and Fair Value of Available for Sale Investments (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 29, 2013	Dec. 29, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 101,548	$ 90,995
Gross Unrealized Gains	812	1,414
Gross Unrealized Losses	643	7
Fair Value	101,717	92,402
Money market investments
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	860	2,865
Fair Value	860	2,865
Asset-backed securities
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,609	2,175
Gross Unrealized Gains	35	73
Gross Unrealized Losses	112
Fair Value	5,532	2,248
Corporate bonds and direct obligations of government agencies
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	76,297	69,173
Gross Unrealized Gains	740	1,294
Gross Unrealized Losses	517	6
Fair Value	76,520	70,461
U.S. Treasury Obligations
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	18,782	16,782
Gross Unrealized Gains	37	47
Gross Unrealized Losses	14	1
Fair Value	$ 18,805	$ 16,828