Short-Term Investments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 25, 2012	Dec. 25, 2011
Schedule of Held-to-maturity Securities [Line Items]
Short-term investments	$ 224,878	$ 104,846
Held-to-maturity Securities, Debt Maturity, Date Range, Low	2.5 months
Held-to-maturity Securities, Debt Maturity, Date Range, High	11 months
Commercial Paper, Not Included with Cash and Cash Equivalents [Member]
Schedule of Held-to-maturity Securities [Line Items]
Carrying value of short-term investments	10,000
US Treasury Securities [Member]
Schedule of Held-to-maturity Securities [Line Items]
Carrying value of short-term investments	$ 215,000