Investments Cost-method Investments (Details) (USD $)	3 Months Ended						6 Months Ended		12 Months Ended		3 Months Ended	1 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	Mar. 25, 2012 Cost-method Investments [Member]	May 31, 2012 Cost-method Investments [Member] Fenway Sports Group [Member] Unit	Feb. 29, 2012 Cost-method Investments [Member] Fenway Sports Group [Member] Unit	Dec. 30, 2012 Cost-method Investments [Member] Fenway Sports Group [Member]
Cost-method Investments
Units sold in Fenway Sports Group												210	100
Proceeds from sale of investments												$ 63,000,000	$ 30,000,000
Gain on sale of investment, pre-tax	0	0	164,630,000	0	37,797,000	17,848,000	0	55,645,000	220,275,000	71,171,000		37,800,000	17,800,000	55,600,000
Impairment of investments	$ 0	$ 0	$ 0	$ 600,000	$ 0	$ 4,900,000	$ 0	$ 4,900,000	$ 5,500,000	$ 0	$ 4,900,000