Marketable Securities (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 25, 2016	Dec. 27, 2015
Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	$ 589,065	$ 507,639
Long-term marketable securities	198,861	291,136
Debt Securities | US Treasury Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	220,194	184,278
Long-term marketable securities	14,790	20,769
Debt Securities | Corporate Debt Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	159,846	185,561
Long-term marketable securities	72,817	119,784
Debt Securities | U.S. governmental agency securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	88,722	65,222
Long-term marketable securities	111,254	150,583
Debt Securities | Municipal Securities
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	0	1,363
Debt Securities | Certificates of Deposit
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	21,301	60,244
Debt Securities | Commercial Paper
Schedule of Held-to-maturity Securities [Line Items]
Short-term marketable securities	$ 99,002	$ 10,971
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