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Investments - Investment Securities Continuous Unrealized Loss Position (Detail) (USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
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Investment [Line Items] |  |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | $ 150,147 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue | $ 68,985 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less Than Twelve Months, Accumulated Loss | 582 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss | 1,188 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 1,662 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue | 2,227 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Held-to-maturity Securities, Continuous Unrealized Loss Position Twelve Months Or Longer, Accumulated Loss | 82 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss | 150 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 151,809 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue | 71,212 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue
Held-to-maturity Securities, Gross Unrealized Losses | 664 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss | 1,338 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months | 110,622 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue | 138,107 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months | 487 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss | 6,191 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Available-for Sale Fair, Value of Investments with Unrealized Losses, 12 Months or Greater | 18,104 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue | 7,525 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater | 3,007 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss | 2,844 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total | 128,726 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue | 145,632 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue
Available-for Sale, Gross Unrealized Losses, Total | 3,494 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss | 9,035 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss
Fair Value of Investments with Unrealized Losses, Less Than 12 months | 260,769 amsf_ContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue | 207,092 amsf_ContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue
Gross Unrealized Loss, Less Than 12 Months | 1,069 amsf_ContinuousUnrealizedLossPositionLessThanTwelveMonthsAggregateLosses | 7,379 amsf_ContinuousUnrealizedLossPositionLessThanTwelveMonthsAggregateLosses
Fair Value of Investments with Unrealized Losses, 12 Months or Greater | 19,766 amsf_ContinuousUnrealizedLossPositionGreaterThanTwelveMonthsFairValue | 9,752 amsf_ContinuousUnrealizedLossPositionGreaterThanTwelveMonthsFairValue
Gross Unrealized Losses, 12 Months or Greater | 3,089 amsf_ContinuousUnrealizedLossPositionGreaterThanTwelveMonthsAggregateLosses | 2,994 amsf_ContinuousUnrealizedLossPositionGreaterThanTwelveMonthsAggregateLosses
Fair Value of Investments with Unrealized Losses, Total | 280,535 amsf_SecuritiesContinuousUnrealizedLossPositionFairValue | 216,844 amsf_SecuritiesContinuousUnrealizedLossPositionFairValue
Gross Unrealized Losses, Total | 4,158 amsf_SecuritiesContinuousUnrealizedLossPositionAggregateLosses | 10,373 amsf_SecuritiesContinuousUnrealizedLossPositionAggregateLosses
U.S. Treasury Securities and Obligations of U.S. Government Agencies [Member] |  |
Investment [Line Items] |  |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 3,385 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_DebtSecurityAxis = us-gaap_USTreasuryAndGovernmentMember |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less Than Twelve Months, Accumulated Loss | 2 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_DebtSecurityAxis = us-gaap_USTreasuryAndGovernmentMember |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 3,385 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_DebtSecurityAxis = us-gaap_USTreasuryAndGovernmentMember |
Held-to-maturity Securities, Gross Unrealized Losses | 2 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_DebtSecurityAxis = us-gaap_USTreasuryAndGovernmentMember |
Corporate Bonds [Member] |  |
Investment [Line Items] |  |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 129,788 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 14,090 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less Than Twelve Months, Accumulated Loss | 520 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 41 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 129,788 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 14,090 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
Held-to-maturity Securities, Gross Unrealized Losses | 520 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 41 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months | 106,185 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 29,691 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months | 470 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 361 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total | 106,185 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 29,691 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
Available-for Sale, Gross Unrealized Losses, Total | 470 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember | 361 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CorporateDebtSecuritiesMember
States and Political Subdivisions [Member] |  |
Investment [Line Items] |  |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 16,896 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 54,895 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less Than Twelve Months, Accumulated Loss | 58 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 1,147 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value |  | 311 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Continuous Unrealized Loss Position Twelve Months Or Longer, Accumulated Loss |  | 6 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 16,896 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 55,206 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Held-to-maturity Securities, Gross Unrealized Losses | 58 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 1,153 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months | 3,810 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 101,908 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months | 6 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 4,798 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for Sale Fair, Value of Investments with Unrealized Losses, 12 Months or Greater | 10,347 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 1,753 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater | 1,666 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 342 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total | 14,157 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 103,661 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Available-for Sale, Gross Unrealized Losses, Total | 1,672 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 5,140 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
U.S. Agency-Based Mortgage-Backed Securities [Member] |  |
Investment [Line Items] |  |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less than Twelve Months, Fair Value | 78 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Less Than Twelve Months, Accumulated Loss | 2 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 78 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember |
Held-to-maturity Securities, Gross Unrealized Losses | 2 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember |
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months | 627 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember | 1,303 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months | 11 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember | 465 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for Sale Fair, Value of Investments with Unrealized Losses, 12 Months or Greater | 7,757 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember | 5,772 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for Sale, Gross Unrealized Losses, 12 Months or Greater | 1,341 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember | 2,502 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total | 8,384 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember | 7,075 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Available-for Sale, Gross Unrealized Losses, Total | 1,352 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember | 2,967 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Equity Securities [Member] |  |
Investment [Line Items] |  |
Available-for Sale, Fair value of Investments with Unrealized Losses, Less Than 12 Months |  | 5,205 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThanTwelveMonthsFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Available-for Sale, Gross Unrealized Losses, Less Than 12 Months |  | 567 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Available-for Sale, Fair Value of Investments with Unrealized Losses, Total |  | 5,205 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Available-for Sale, Gross Unrealized Losses, Total |  | 567 us-gaap_AvailableForSaleSecuritiesContinuousUnrealizedLossPositionAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_EquitySecuritiesMember
Asset-Backed Securities [Member] |  |
Investment [Line Items] |  |
Held-to-maturity Securities, Continuous Unrealized Loss Position, Twelve Months or Longer, Fair Value | 1,662 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | 1,916 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionTwelveMonthsOrLongerFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Held-to-maturity Securities, Continuous Unrealized Loss Position Twelve Months Or Longer, Accumulated Loss | 82 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | 144 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Held-to-maturity Securities, Continuous Unrealized Loss Position, Fair Value | 1,662 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | 1,916 us-gaap_HeldToMaturitySecuritiesContinuousUnrealizedLossPositionFairValue / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember
Held-to-maturity Securities, Gross Unrealized Losses | $ 82 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember | $ 144 us-gaap_HeldToMaturitySecuritiesAccumulatedUnrecognizedHoldingLoss / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_AssetBackedSecuritiesMember

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- Definition Continuous unrealized loss position greater than twelve months aggregate losses. + References No definition available. + Details
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- Definition Continuous unrealized loss position greater than twelve months fair value. + References No definition available. + Details
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- Definition Continuous unrealized loss position less than twelve months aggregate losses. + References No definition available. + Details
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- Definition Continuous unrealized loss position less than twelve months fair value. + References No definition available. + Details
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- Definition Securities continuous unrealized loss position aggregate losses. + References No definition available. + Details
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- Definition Securities continuous unrealized loss position fair value. + References No definition available. + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale that have been in a continuous loss position for twelve months or longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Definition Amount of accumulated unrealized loss on investments in debt and equity securities classified as available-for-sale in a continuous loss position. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27337-111563 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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- Definition This item represents the aggregate fair value of investments in debt and equity securities in an unrealized loss position which are categorized neither as held-to-maturity nor trading securities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=27724398&loc=d3e27290-111563 + Details
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