Fair Value Measurements and Other-Than-Temporary Impairments - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) (Fair Value, Measurements, Recurring [Member], USD $) In Thousands, unless otherwise specified	Sep. 27, 2014	Dec. 28, 2013
Assets
Total Assets	$ 314,304	$ 296,877
Money Market Funds [Member]
Assets
Total Assets	15,369	51,749
Certificates of Deposit [Member]
Assets
Total Assets	3,460	3,840
Commercial Paper [Member]
Assets
Total Assets	83,838	85,860
Corporate Bonds [Member]
Assets
Total Assets	202,804	150,595
U.S. Treasuries [Member]
Assets
Total Assets	8,833	4,804
Foreign Currency Exchange Forward Contracts [Member]
Assets
Total Assets	0	29
Liabilities
Total Liabilities	32	26
Level 1 [Member]
Assets
Total Assets	24,202	56,553
Level 1 [Member] | Money Market Funds [Member]
Assets
Total Assets	15,369	51,749
Level 1 [Member] | Certificates of Deposit [Member]
Assets
Total Assets	0	0
Level 1 [Member] | Commercial Paper [Member]
Assets
Total Assets	0	0
Level 1 [Member] | Corporate Bonds [Member]
Assets
Total Assets	0	0
Level 1 [Member] | U.S. Treasuries [Member]
Assets
Total Assets	8,833	4,804
Level 1 [Member] | Foreign Currency Exchange Forward Contracts [Member]
Assets
Total Assets	0	0
Liabilities
Total Liabilities	0	0
Level 2 [Member]
Assets
Total Assets	290,102	240,324
Level 2 [Member] | Money Market Funds [Member]
Assets
Total Assets	0	0
Level 2 [Member] | Certificates of Deposit [Member]
Assets
Total Assets	3,460	3,840
Level 2 [Member] | Commercial Paper [Member]
Assets
Total Assets	83,838	85,860
Level 2 [Member] | Corporate Bonds [Member]
Assets
Total Assets	202,804	150,595
Level 2 [Member] | U.S. Treasuries [Member]
Assets
Total Assets	0	0
Level 2 [Member] | Foreign Currency Exchange Forward Contracts [Member]
Assets
Total Assets	0	29
Liabilities
Total Liabilities	32	26
Level 3 [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Money Market Funds [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Certificates of Deposit [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Commercial Paper [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Corporate Bonds [Member]
Assets
Total Assets	0	0
Level 3 [Member] | U.S. Treasuries [Member]
Assets
Total Assets	0	0
Level 3 [Member] | Foreign Currency Exchange Forward Contracts [Member]
Assets
Total Assets	0	0
Liabilities
Total Liabilities	$ 0	$ 0