Fair Value of Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jul. 01, 2012	Jun. 26, 2011	Jul. 01, 2012	Jun. 26, 2011	Dec. 25, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	$ 19,871	$ 20,144	$ 19,871	$ 20,144	$ 19,669
Derivatives, assets	33,045	26,156	33,045	26,156	29,500
Total assets, fair value hierarchy	52,916	46,300	52,916	46,300	49,169
Derivatives, liabilities	765	28,230	765	28,230	1,908
Fair Value of Available for Sale Investments, Fair Value Option	19,859	20,119	19,859	20,119	19,657
Gain (Loss) on Available for Sale Investments, Fair Value Option	(331)	366	765	523
Reconciliation of fair value measurements of the Company's warrants
Balance at beginning of year			3,724	9,155
Loss from change in fair value			(398)	(2,686)
Balance at end of period	3,326	6,469	3,326	6,469
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	12	25	12	25	12
Derivatives, assets	0	0	0	0	0
Total assets, fair value hierarchy	12	25	12	25	12
Derivatives, liabilities	0	0	0	0	0
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	19,859	20,119	19,859	20,119	19,657
Derivatives, assets	29,719	19,687	29,719	19,687	25,776
Total assets, fair value hierarchy	49,578	39,806	49,578	39,806	45,433
Derivatives, liabilities	765	28,230	765	28,230	1,908
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, assets	0	0	0	0	0
Derivatives, assets	3,326	6,469	3,326	6,469	3,724
Total assets, fair value hierarchy	3,326	6,469	3,326	6,469	3,724
Derivatives, liabilities	$ 0	$ 0	$ 0	$ 0	$ 0