Financial Instruments Measured at Amortized Costs, Gross Unrealized Gain, Gross Unrealized Loss and Fair Value by Significant Investment Categories (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 28, 2013
Cash and Cash Equivalents
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	$ 65,058
Gross Unrealized Losses	(1)
Fair Value	65,057
Cash and Cash Equivalents | Cash
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	501
Fair Value	501
Cash and Cash Equivalents | Money Market Funds
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	63,553
Fair Value	63,553
Cash and Cash Equivalents | Corporate Debt Securities
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	1,004
Gross Unrealized Losses	(1)
Fair Value	1,003
Short-term Investments
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	40,341
Gross Unrealized Gains	25
Gross Unrealized Losses	(19)
Fair Value	40,347
Short-term Investments | Corporate Debt Securities
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	32,339
Gross Unrealized Gains	16
Gross Unrealized Losses	(19)
Fair Value	32,336
Short-term Investments | U.S. Agency Debt Securities
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	5,007
Gross Unrealized Gains	3
Fair Value	5,010
Short-term Investments | U.S. Government Securities
Cash And Cash Equivalents And Short Term Investments [Line Items]
Amortized Costs	2,995
Gross Unrealized Gains	6
Fair Value	$ 3,001