Marketable Debt Securities (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 29, 2012		Dec. 31, 2011
Investments of marketable debt securities [Abstract]
Amortized cost	$ 89,873		$ 30,021
Unrealized Gains	57		41
Unrealized Losses	(24)		0
Marketable debt securities	89,906	[1]	30,062
Amortized Cost [Abstract]
Marketable debt securities - current (due in less than one year)	51,238		20,004
Marketable debt securities - non-current (due in one to two years)	38,635		10,017
Marketable debt securities	89,873		30,021
Fair Value [Abstract]
Marketable debt securities - current (due in less than one year)	51,264	[1]	20,020	[1]
Marketable debt securities - non-current (due in one to two years)	38,642	[1]	10,042	[1]
Marketable debt securities	89,906	[1]	30,062	[1]
U.S. Treasury securities [Member]
Schedule of Available-for-sale Securities [Line Items]
ProceedsFromSaleAndMaturityOfAvailableForSaleSecuritesNet	26,000
Investments of marketable debt securities [Abstract]
Amortized cost	32,518		30,021
Unrealized Gains	24		41
Unrealized Losses	0		0
Marketable debt securities	32,542	[1]	30,062	[1]
Corporate bonds [Member]
Investments of marketable debt securities [Abstract]
Amortized cost	31,929
Unrealized Gains	2
Unrealized Losses	(23)
Marketable debt securities	31,908	[1]
Agency Securities [Member]
Investments of marketable debt securities [Abstract]
Amortized cost	17,632
Unrealized Gains	11
Unrealized Losses	(1)
Marketable debt securities	17,642	[1]
Municipal bonds [Member]
Investments of marketable debt securities [Abstract]
Amortized cost	7,794
Unrealized Gains	20
Unrealized Losses	0
Marketable debt securities	$ 7,814	[1]

[1] See Note 2 for discussion of fair value measurements.