Fair Value Measurements and Other-Than-Temporary Impairments - Investments at Fair Value (Details) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2013	Dec. 29, 2012
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	$ 281,140	$ 117,741
Gross Unrealized Gains	52	193
Gross Unrealized Losses	(100)	(11)
Fair Value	281,092	117,923
Money Market Funds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	72,386	25,560
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	72,386	25,560
Certificates of Deposit [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	2,640	2,160
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	2,640	2,160
Commercial Paper [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	88,713	14,848
Gross Unrealized Gains	13	0
Gross Unrealized Losses	(6)	(5)
Fair Value	88,720	14,843
Corporate Bonds [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	109,598	57,451
Gross Unrealized Gains	36	22
Gross Unrealized Losses	(94)	(6)
Fair Value	109,540	57,467
U.S. Treasuries [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost	7,803	15,015
Gross Unrealized Gains	3	5
Gross Unrealized Losses	0	0
Fair Value	7,806	15,020
ARS [Member]
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Adjusted Amortized Cost		2,707	[1]
Gross Unrealized Gains		166
Gross Unrealized Losses		0
Fair Value		$ 2,873

[1] (1) Amount represents the par value less $0.4 million of credit-related OTTI recognized through earnings in prior years.