Investments - Available-for-Sale Security (Details) (USD $)	3 Months Ended																	12 Months Ended
	Dec. 30, 2012		Sep. 23, 2012		Jun. 24, 2012		Mar. 25, 2012		Dec. 25, 2011		Sep. 25, 2011		Jun. 26, 2011		Mar. 27, 2011		Jun. 27, 2010	Dec. 30, 2012		Dec. 25, 2011		Dec. 26, 2010
Schedule of Available-for-sale Securities [Line Items]
Unrealized loss on available-for-sale security																		$ (729,000)		$ 0		$ 0
Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, after Tax																		(400,000)
Gain on sale of investments	164,630,000	[1]	0	[1]	37,797,000	[1]	17,848,000	[1]	0	[2]	65,273,000	[2]	0	[2]	5,898,000	[2]	9,128,000	220,275,000	[1]	71,171,000	[2]	9,128,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Proceeds from sale of availabe-for-sale security																		2,200,000
Equity Securities [Member] | Categories of Investments, Marketable Securities, Available-for-sale Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Gain on sale of investments																		$ 400,000

[1] In the first quarter of 2012, we recorded a $17.8 million gain on the sale of 100 of our units in Fenway Sports Group. In the second quarter of 2012, we recorded a $37.8 million gain on the sale of our remaining 210 units in Fenway Sports Group. In the fourth quarter of 2012, we recorded a $164.6 million gain on the sale of our ownership interest in Indeed.com.

[2] In the first quarter of 2011, we recorded a $5.9 million gain from the sale of a portion of our interest in Indeed.com. In the third quarter of 2011, we recorded a $65.3 million gain from the sale of 390 units in Fenway Sports Group.