Investments - Cost Method Investments (Details) (USD $)	1 Months Ended			3 Months Ended																	12 Months Ended					1 Months Ended	3 Months Ended		0 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended
	May 31, 2012 Unit	Feb. 29, 2012 Unit	Jul. 31, 2011 Unit	Dec. 30, 2012		Sep. 23, 2012		Jun. 24, 2012		Mar. 25, 2012 Unit		Dec. 25, 2011		Sep. 25, 2011		Jun. 26, 2011		Mar. 27, 2011		Jun. 27, 2010 Unit	Dec. 30, 2012		Dec. 25, 2011		Dec. 26, 2010	Oct. 31, 2012 Indeed.com [Member] Cost-method Investments [Member]	Dec. 30, 2012 Indeed.com [Member] Cost-method Investments [Member]	Mar. 27, 2011 Indeed.com [Member] Cost-method Investments [Member]	Feb. 03, 2012 Fenway Sports Group [Member]	May 31, 2012 Fenway Sports Group [Member]	Jun. 24, 2012 Fenway Sports Group [Member]	Dec. 30, 2012 Ongo Inc. [Member] Cost-method Investments [Member]
Schedule of Cost-method Investments [Line Items]
Proceeds from investments – net of purchases			$ 117,000,000																		$ 250,918,000		$ 117,966,000		$ 9,254,000				$ 30,000,000	$ 63,000,000
Gain on sale of investments, pre-tax				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			5,900,000	17,800,000		37,800,000
Units sold in Fenway Sports Group	210	100	390							100										50
Gain (Loss) on Sale of Investments																										164,600,000	164,600,000
Proceeds from Sale of Cost Method Investments																										167,000,000
Impairment of assets				$ 0	[3]	$ 600,000	[3]	$ 0	[3]	$ 4,900,000	[3]										$ 5,500,000	[3]	$ 0		$ 0							$ 5,500,000

[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.

[3] In the first and third quarters of 2012, we recorded a $4.9 million and $0.6 million non-cash charge, respectively, for the impairment of certain investments.