Marketable Securities - Narrative (Details) (USD $)	3 Months Ended						6 Months Ended		12 Months Ended
	Jun. 30, 2013	Mar. 31, 2013	Dec. 30, 2012	Sep. 23, 2012	Jun. 24, 2012	Mar. 25, 2012	Jun. 30, 2013	Jun. 24, 2012	Dec. 30, 2012	Dec. 25, 2011
Investment [Line Items]
Unrealized gain/(loss) on available-for-sale security	$ 1,260,000	$ (1,374,000)	$ (1,980,000)	$ (2,338,000)	$ (3,425,000)	$ 7,014,000	$ (114,000)	$ 3,589,000	$ (729,000)	$ 0
Marketable debt securities [Member] | Minimum [Member]
Investment [Line Items]
Term of securities	1 month
Marketable debt securities [Member] | Maximum [Member]
Investment [Line Items]
Term of securities	36 months
Brightcove, Inc. [Member] | Available-for-sale Securities [Member]
Investment [Line Items]
Unrealized gain/(loss) on available-for-sale security	1,300,000
Unrealized loss on available-for-sale security, net of tax	$ 700,000