XML 29 R43.htm IDEA: XBRL DOCUMENT v2.4.1.9
Fair Value Measurements (Quantitative Disclosures of Fair Value Assets) (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Available-for-sale Securities, Debt Securities $ 4,174,242us-gaap_AvailableForSaleSecuritiesDebtSecurities $ 4,066,122us-gaap_AvailableForSaleSecuritiesDebtSecurities
Equity securities, AFS 211,571us-gaap_AvailableForSaleSecuritiesEquitySecurities 191,400us-gaap_AvailableForSaleSecuritiesEquitySecurities
Total AFS securities 4,385,813us-gaap_AvailableForSaleSecurities 4,257,522us-gaap_AvailableForSaleSecurities
Short-term investments 124,376us-gaap_OtherShortTermInvestments 131,972us-gaap_OtherShortTermInvestments
Fair Value [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 4,174,242us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 4,066,122us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Equity securities, AFS 211,571us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 191,400us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total AFS securities 4,385,813us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 4,257,522us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Short-term investments 124,376us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 131,972us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total assets measured at fair value 4,510,189us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 4,389,494us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Fair Value [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 119,486us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember		 124,130us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember
Fair Value [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 27,915us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember		 27,831us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember
Fair Value [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 1,294,375us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember		 1,246,264us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Fair Value [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 1,824,265us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember		 1,799,806us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Fair Value [Member] | Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 185,387us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember		 177,224us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
Fair Value [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 200,511us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember		 179,593us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember
Fair Value [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 522,303us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember		 511,274us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_EstimateOfFairValueFairValueDisclosureMember
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 52,977us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 53,199us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Equity securities, AFS 208,671us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 188,500us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Total AFS securities 261,648us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 241,699us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Short-term investments 124,376us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 131,972us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Total assets measured at fair value 386,024us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 373,671us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 52,977us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember		 [1] 53,199us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember		 [1]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember		 [1] 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember		 [1]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember		 [1] 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember		 [1]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember		 [1] 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember		 [1]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember		 [1] 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember		 [1]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember		 [1] 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember		 [1]
Quoted Prices in Active Markets for Identical Assets/Liabilities (Level 1) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember		 [1] 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 4,121,265us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 4,012,923us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Equity securities, AFS 0us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 0us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Total AFS securities 4,121,265us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 4,012,923us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Short-term investments 0us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 0us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Total assets measured at fair value 4,121,265us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1] 4,012,923us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 66,509us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember		 [1] 70,931us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 27,915us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember		 [1] 27,831us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 1,294,375us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember		 [1] 1,246,264us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 1,824,265us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember		 [1] 1,799,806us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 185,387us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember		 [1] 177,224us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 200,511us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember		 [1] 179,593us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember		 [1]
Significant Other Observable Inputs (Level 2) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 522,303us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember		 [1] 511,274us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember		 [1]
Significant Unobservable Inputs (Level 3) [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Equity securities, AFS 2,900us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 2,900us-gaap_AvailableForSaleSecuritiesEquitySecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total AFS securities 2,900us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 2,900us-gaap_AvailableForSaleSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Short-term investments 0us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 0us-gaap_OtherShortTermInvestments
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Total assets measured at fair value 2,900us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember		 2,900us-gaap_AssetsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
Significant Unobservable Inputs (Level 3) [Member] | U.S. Government and Government Agencies [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember		 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USTreasuryAndGovernmentMember
Significant Unobservable Inputs (Level 3) [Member] | Foreign Government [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember		 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ForeignGovernmentDebtSecuritiesMember
Significant Unobservable Inputs (Level 3) [Member] | Obligations of States and Political Subdivisions [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember		 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_USStatesAndPoliticalSubdivisionsMember
Significant Unobservable Inputs (Level 3) [Member] | Corporate Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember		 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CorporateDebtSecuritiesMember
Significant Unobservable Inputs (Level 3) [Member] | Asset-Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember		 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_AssetBackedSecuritiesMember
Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember		 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_CommercialMortgageBackedSecuritiesMember
Significant Unobservable Inputs (Level 3) [Member] | Residential Mortgage Backed Securities [Member] | Fair Value, Measurements, Recurring [Member]    
Available-for-sale Securities, Debt Securities $ 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember		 $ 0us-gaap_AvailableForSaleSecuritiesDebtSecurities
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel3Member
/ us-gaap_FairValueByMeasurementFrequencyAxis
= us-gaap_FairValueMeasurementsRecurringMember
/ us-gaap_InvestmentTypeAxis
= us-gaap_ResidentialMortgageBackedSecuritiesMember
[1] 1 There were no transfers of securities between Level 1 and Level 2.