Investments and Fair Value Measurements-Fin Assets and Liabilities 1 (Details 2) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 30, 2012
Financial assets measured at fair value on a recurring basis
Total financial assets	$ 5,120,439	$ 5,548,126
Financial Liabilities measured at fair value on a recurring basis
Total financial liabilities	10,351	13,584
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets measured at fair value on a recurring basis
Total financial assets	742,523	610,129
Financial Liabilities measured at fair value on a recurring basis
Total financial liabilities	0	0
Significant Other Observable Inputs (Level 2) [Member]
Financial assets measured at fair value on a recurring basis
Total financial assets	4,377,916	4,937,997
Financial Liabilities measured at fair value on a recurring basis
Total financial liabilities	10,351	13,584
Significant Unobservable Inputs (Level 3) [Member]
Financial assets measured at fair value on a recurring basis
Total financial assets	0	0
Financial Liabilities measured at fair value on a recurring basis
Total financial liabilities	0	0
Derivative Liabilities [Member]
Financial Liabilities measured at fair value on a recurring basis
Derivative liabilities	10,351	13,584
Derivative Liabilities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial Liabilities measured at fair value on a recurring basis
Derivative liabilities	0	0
Derivative Liabilities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial Liabilities measured at fair value on a recurring basis
Derivative liabilities	10,351	13,584
Derivative Liabilities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial Liabilities measured at fair value on a recurring basis
Derivative liabilities	0	0
Money Market Funds [Member]
Financial assets measured at fair value on a recurring basis
Money market funds	613,718	582,743
Money Market Funds [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets measured at fair value on a recurring basis
Money market funds	613,718	582,743
Money Market Funds [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets measured at fair value on a recurring basis
Money market funds	0	0
Money Market Funds [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets measured at fair value on a recurring basis
Money market funds	0	0
Fixed Income Securities [Member]
Financial assets measured at fair value on a recurring basis
Fixed income securities	4,498,967	4,945,325
Fixed Income Securities [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets measured at fair value on a recurring basis
Fixed income securities	128,805	27,386
Fixed Income Securities [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets measured at fair value on a recurring basis
Fixed income securities	4,370,162	4,917,939
Fixed Income Securities [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets measured at fair value on a recurring basis
Fixed income securities	0	0
Derivative Assets [Member]
Financial assets measured at fair value on a recurring basis
Derivative assets	7,754	20,058
Derivative Assets [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Financial assets measured at fair value on a recurring basis
Derivative assets	0	0
Derivative Assets [Member] | Significant Other Observable Inputs (Level 2) [Member]
Financial assets measured at fair value on a recurring basis
Derivative assets	7,754	20,058
Derivative Assets [Member] | Significant Unobservable Inputs (Level 3) [Member]
Financial assets measured at fair value on a recurring basis
Derivative assets	$ 0	$ 0