v2.4.1.9
Marketable Securities (Schedule of Available-for-sale-securities Unrealized Loss on Investments) (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended
Mar. 28, 2015
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months $ (3,344)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
Gross Unrealized Losses 12 Consecutive Months or Longer (6,741)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
Fair Value  
Fair Value Less than 12 Consecutive Months 548,256us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Fair Value 12 Consecutive Months or Longer 404,108us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Mortgage-backed securities  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (1,476)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Gross Unrealized Losses 12 Consecutive Months or Longer (1,618)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Fair Value  
Fair Value Less than 12 Consecutive Months 175,026us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Fair Value 12 Consecutive Months or Longer 85,274us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MortgageBackedSecuritiesMember
Corporate securities  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (1,253)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Gross Unrealized Losses 12 Consecutive Months or Longer (1,793)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Fair Value  
Fair Value Less than 12 Consecutive Months 264,951us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Fair Value 12 Consecutive Months or Longer 91,093us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Other  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (10)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
Gross Unrealized Losses 12 Consecutive Months or Longer (42)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
Fair Value  
Fair Value Less than 12 Consecutive Months 14,866us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
Fair Value 12 Consecutive Months or Longer 13,527us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_OtherDebtSecuritiesMember
US Treasury Securities  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (2)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
Gross Unrealized Losses 12 Consecutive Months or Longer 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
Fair Value  
Fair Value Less than 12 Consecutive Months 4,777us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
Fair Value 12 Consecutive Months or Longer 0us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasurySecuritiesMember
Agency Securities  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (221)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
Gross Unrealized Losses 12 Consecutive Months or Longer (3,259)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
Fair Value  
Fair Value Less than 12 Consecutive Months 36,997us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
Fair Value 12 Consecutive Months or Longer 204,858us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_AgencySecuritiesMember
Municipal securities  
Gross Unrealized Losses  
Gross Unrealized Losses Less than 12 Consecutive Months (382)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalBondsMember
Gross Unrealized Losses 12 Consecutive Months or Longer (29)us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAggregateLosses
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalBondsMember
Fair Value  
Fair Value Less than 12 Consecutive Months 51,639us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalBondsMember
Fair Value 12 Consecutive Months or Longer $ 9,356us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
/ us-gaap_InvestmentTypeAxis
= us-gaap_MunicipalBondsMember