Investments and Fair Value Measurements-Fixed Income Maturities (Details 7) - Fixed Income Securities [Member] - USD ($) $ in Thousands	Sep. 27, 2015	Dec. 28, 2014
Available-for-sale Securities, Amortized Cost Basis [Abstract]
Due in one year or less	$ 571,603
After one year through five years	1,999,230
After five years through ten years	94,761
After ten years	530,714
Total, Amortized Cost	3,196,308	$ 4,233,395
Available-for-sale Securities, Debt Maturities, Fair Value, Fiscal Year Maturity [Abstract]
Due in one year or less	572,651
After one year through five years	2,003,399
After five years through ten years	94,860
After ten years	531,672
Total, Fair Value	$ 3,202,582	$ 4,238,761