Marketable Securities Composition (Details) (USD $) In Thousands, unless otherwise specified	Jun. 29, 2013	Dec. 29, 2012
Schedule of Available-for-sale Securities [Line Items]
Maturities of less than five years	$ 74,948	$ 64,865
Maturities of more than ten years	4,717	4,717
Total marketable securities	79,665	69,582
Short-term marketable securities \| Corporate and government bonds and notes and commercial paper
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities	74,948	64,865
Long-term marketable securities \| Federally-insured or FFELP guaranteed student loan auction rate securities
Schedule of Available-for-sale Securities [Line Items]
Total marketable securities	$ 4,717	$ 4,717

Amount of investment in debt and equity securities categorized neither as held-to-maturity nor trading.

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+ Details