Marketable Securities (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 28, 2015	Dec. 28, 2014
Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	$ 499,750	$ 636,743
Long-term marketable securities	224,950	167,820
Debt Securities | US Treasury Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	127,189	238,488
Debt Securities | Corporate Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	194,516	208,346
Long-term marketable securities	90,033	71,191
Debt Securities | US Agency Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	49,443	32,009
Long-term marketable securities	134,917	95,204
Debt Securities | Municipal Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	5,237	13,622
Long-term marketable securities	0	1,425
Debt Securities | Certificates of Deposit
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	88,393	109,293
Debt Securities | Commercial Paper
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	$ 34,972	$ 34,985
Short-term Marketable Securities | Minimum
Schedule of Held-to-maturity Securities [Line Items]
Term of investments	1 month
Short-term Marketable Securities | Maximum
Schedule of Held-to-maturity Securities [Line Items]
Term of investments	12 months
Long-term Marketable Securities | Minimum
Schedule of Held-to-maturity Securities [Line Items]
Term of investments	13 months
Long-term Marketable Securities | Maximum
Schedule of Held-to-maturity Securities [Line Items]
Term of investments	35 months