Marketable Securities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 27, 2015	Dec. 28, 2014
Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	$ 499,486	$ 636,743
Long-term marketable securities	228,586	167,820
Debt Securities | US Treasury Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	170,815	238,488
Debt Securities | Corporate Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	184,579	208,346
Long-term marketable securities	96,454	71,191
Debt Securities | US Agency Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	56,274	32,009
Long-term marketable securities	132,132	95,204
Debt Securities | Municipal Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	3,242	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	63,583	109,293
Debt Securities | Commercial Paper
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	$ 20,993	$ 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	36 months