Investments - Cost Method Investments (Details) (USD $)	3 Months Ended									12 Months Ended				1 Months Ended			3 Months Ended	0 Months Ended	1 Months Ended	3 Months Ended		1 Months Ended	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 30, 2012		Sep. 23, 2012		Jun. 24, 2012		Mar. 25, 2012		Dec. 29, 2013	Dec. 30, 2012		Dec. 25, 2011	May 31, 2012 Cost-method Investments [Member] Unit	Feb. 29, 2012 Cost-method Investments [Member] Unit	Jul. 31, 2011 Cost-method Investments [Member] Unit	Sep. 23, 2012 Cost-method Investments [Member]	Feb. 03, 2012 Fenway Sports Group [Member] Cost-method Investments [Member]	May 31, 2012 Fenway Sports Group [Member] Cost-method Investments [Member]	Jun. 30, 2013 Fenway Sports Group [Member] Cost-method Investments [Member]	Mar. 25, 2012 Fenway Sports Group [Member] Cost-method Investments [Member]	Oct. 31, 2012 Indeed.com [Member] Cost-method Investments [Member]	Mar. 25, 2012 Indeed.com [Member] Cost-method Investments [Member]	Dec. 30, 2012 Indeed.com [Member] Cost-method Investments [Member]	Dec. 30, 2012 Ongo Inc. [Member] Cost-method Investments [Member]
Schedule of Cost-method Investments [Line Items]
Gain on sale of investments, pre-tax	$ 0	$ 164,630,000	[1]	$ 0	[1]	$ 37,797,000	[1]	$ 17,848,000	[1]	$ 0	$ 220,275,000	[1]	$ 71,171,000				$ 65,273,000			$ 37,800,000	$ 17,800,000		$ 5,900,000
Units sold in Fenway Sports Group														210	100	390
Proceeds from investments – net of purchases										12,004,000	250,918,000		117,966,000			117,000,000		30,000,000	63,000,000
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	$ 0	[2]	$ 600,000	[2]	$ 0	[2]	$ 4,900,000	[2]	$ 0	$ 5,500,000	[2]	$ 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 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.