Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 30, 2012	Dec. 25, 2011	Dec. 26, 2010
Fair Value of Financial Instruments [Abstract]
Fair value of available for sale investments, fair value option	$ 24,091	$ 19,657
Gain on available for sale investments, fair value option	2,504	61	1,218
Reconciliation of Level 3 Assets
Balance at beginning of year	3,724	9,155
Purchases	5,000	0
Loss from change in fair value	(1,106)	(5,431)
Balance at end of year	7,618	3,724	9,155
Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	24,099	19,669
Derivatives, assets	4,254	29,500
Total assets	28,353	49,169
Derivatives, liabilities	3,461	1,908
Fair Value, Measurements, Recurring [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	8	12
Derivatives, assets	0	0
Total assets	8	12
Derivatives, liabilities	0	0
Fair Value, Measurements, Recurring [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	18,986	19,657
Derivatives, assets	1,741	25,776
Total assets	20,727	45,433
Derivatives, liabilities	3,461	1,908
Fair Value, Measurements, Recurring [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	5,105	0
Derivatives, assets	2,513	3,724
Total assets	7,618	3,724
Derivatives, liabilities	$ 0	$ 0