Marketable Securities (Schedule of Available-for-sale-securities Unrealized Loss on Investments) (Details) (USD $) In Thousands, unless otherwise specified
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3 Months Ended |
Mar. 28, 2015
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Gross Unrealized Losses |
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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 |
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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 |
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Gross Unrealized Losses |
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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 |
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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 |
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Gross Unrealized Losses |
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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 |
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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 |
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Gross Unrealized Losses |
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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 |
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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 |
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Gross Unrealized Losses |
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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 |
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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 |
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Gross Unrealized Losses |
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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 |
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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 |
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Gross Unrealized Losses |
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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 |
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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 |