v2.4.1.9
Fair Value of Financial Instruments (Fair Value Hierarchy) (Details) (USD $)
In Thousands, unless otherwise specified
Dec. 31, 2014
Dec. 31, 2013
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value $ 91,462us-gaap_AvailableForSaleSecurities $ 105,133us-gaap_AvailableForSaleSecurities
Recurring Basis | Fair Value    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 91,462us-gaap_AvailableForSaleSecurities
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105,133us-gaap_AvailableForSaleSecurities
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Level 1 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueInputsLevel1Member
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0us-gaap_AvailableForSaleSecurities
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Level 2 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 91,462us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
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105,133us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Level 3 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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0us-gaap_AvailableForSaleSecurities
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Commercial paper    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 5,999us-gaap_AvailableForSaleSecurities
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= us-gaap_CommercialPaperMember
47,488us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperMember
Commercial paper | Recurring Basis | Fair Value    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 5,999us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperMember
47,488us-gaap_AvailableForSaleSecurities
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= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperMember
Commercial paper | Level 1 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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0us-gaap_AvailableForSaleSecurities
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperMember
Commercial paper | Level 2 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 5,999us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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47,488us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CommercialPaperMember
Commercial paper | Level 3 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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0us-gaap_AvailableForSaleSecurities
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U.S. government agencies    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 53,832us-gaap_AvailableForSaleSecurities
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18,837us-gaap_AvailableForSaleSecurities
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= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
U.S. government agencies | Recurring Basis | Fair Value    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 53,832us-gaap_AvailableForSaleSecurities
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18,837us-gaap_AvailableForSaleSecurities
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
U.S. government agencies | Level 1 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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0us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
U.S. government agencies | Level 2 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 53,832us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
18,837us-gaap_AvailableForSaleSecurities
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/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
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= us-gaap_USGovernmentAgenciesDebtSecuritiesMember
U.S. government agencies | Level 3 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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0us-gaap_AvailableForSaleSecurities
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Municipal bonds    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value   1,128us-gaap_AvailableForSaleSecurities
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= us-gaap_MunicipalBondsMember
Municipal bonds | Recurring Basis | Fair Value    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value   1,128us-gaap_AvailableForSaleSecurities
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= us-gaap_MunicipalBondsMember
Municipal bonds | Level 1 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value   0us-gaap_AvailableForSaleSecurities
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= us-gaap_MunicipalBondsMember
Municipal bonds | Level 2 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value   1,128us-gaap_AvailableForSaleSecurities
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= us-gaap_MunicipalBondsMember
Municipal bonds | Level 3 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value   0us-gaap_AvailableForSaleSecurities
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= us-gaap_MunicipalBondsMember
Corporate bonds    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 15,537us-gaap_AvailableForSaleSecurities
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= us-gaap_CorporateBondSecuritiesMember
32,179us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateBondSecuritiesMember
Corporate bonds | Recurring Basis | Fair Value    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 15,537us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByMeasurementBasisAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
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= us-gaap_CorporateBondSecuritiesMember
32,179us-gaap_AvailableForSaleSecurities
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= us-gaap_CorporateBondSecuritiesMember
Corporate bonds | Level 1 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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0us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateBondSecuritiesMember
Corporate bonds | Level 2 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 15,537us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
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= us-gaap_CorporateBondSecuritiesMember
32,179us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_CorporateBondSecuritiesMember
Corporate bonds | Level 3 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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Asset-backed securities    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 16,094us-gaap_AvailableForSaleSecurities
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= us-gaap_AssetBackedSecuritiesMember
5,501us-gaap_AvailableForSaleSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
Asset-backed securities | Recurring Basis | Fair Value    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 16,094us-gaap_AvailableForSaleSecurities
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5,501us-gaap_AvailableForSaleSecurities
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Asset-backed securities | Level 1 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 0us-gaap_AvailableForSaleSecurities
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0us-gaap_AvailableForSaleSecurities
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/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
Asset-backed securities | Level 2 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value 16,094us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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5,501us-gaap_AvailableForSaleSecurities
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/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember
Asset-backed securities | Level 3 | Recurring Basis    
Assets, Fair Value Disclosure [Abstract]    
Available-for-sale securities, fair value $ 0us-gaap_AvailableForSaleSecurities
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= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
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$ 0us-gaap_AvailableForSaleSecurities
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