XML 82 R41.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified | 3 Months Ended
--- | ---
Mar. 31, 2015 | Mar. 31, 2014
US Treasury and Government [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | $ 15 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | $ 15 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember |
Total realized/unrealized gains (losses) included in Net income | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
Purchases and issuances | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
Sales and settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
Transfer into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
Transfer out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
Financial assets, Ending Balance | 15 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember | 15 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USTreasuryAndGovernmentMember
States, municipalities and political subdivisions [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | 100 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 61 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember |
Total realized/unrealized gains (losses) included in Net income | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Purchases and issuances | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Sales and settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Transfer into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Transfer out of Level 3 | (39)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Financial assets, Ending Balance | 61 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember | 61 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_USStatesAndPoliticalSubdivisionsMember
Residential Mortgage Backed Securities [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | 300 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 316 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember |
Total realized/unrealized gains (losses) included in Net income | (1)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 1 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | 3 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 4 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Purchases and issuances | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Sales and settlements | (7)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (8)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Transfer into Level 3 | 41 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 32 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Transfer out of Level 3 | (30)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | (73)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Financial assets, Ending Balance | 306 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember | 272 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember
Commercial Mortgage Backed Securities [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | 44 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 28 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember |
Total realized/unrealized gains (losses) included in Net income | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Purchases and issuances | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Sales and settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Transfer into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Transfer out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Financial assets, Ending Balance | 44 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember | 28 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CommercialMortgageBackedSecuritiesMember
Asset-backed Securities [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | 226 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | 75 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember |
Total realized/unrealized gains (losses) included in Net income | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | 1 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
Purchases and issuances | 5 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | 50 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
Sales and settlements | (41)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | (1)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
Transfer into Level 3 | 21 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | 81 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
Transfer out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
Financial assets, Ending Balance | 211 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember | 206 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_AssetBackedSecuritiesMember
All other corporate [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | 546 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | 335 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember |
Total realized/unrealized gains (losses) included in Net income | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | 1 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | 6 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | 3 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Purchases and issuances | 44 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | 1 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Sales and settlements | (13)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | (16)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Transfer into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Transfer out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | (2)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Financial assets, Ending Balance | 583 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember | 322 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_CorporateDebtSecuritiesMember
Equity securities [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | 93 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | 31 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember |
Total realized/unrealized gains (losses) included in Net income | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | 1 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | (2)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | 2 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Purchases and issuances | 10 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | 30 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Sales and settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | (9)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Transfer into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Transfer out of Level 3 | (17)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | (14)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Financial assets, Ending Balance | 84 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember | 41 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = us-gaap_EquitySecuritiesMember
Assets of Managed Investment Entities [Member] |  |
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward] |  |
Financial assets, Beginning Balance | 31 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | 30 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember
Impact of accounting change | 0 afg_FairValueMeasurementwithUnobservableInputsReconciliationRecurringBasisAssetImpactofAccountingChange / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember |
Total realized/unrealized gains (losses) included in Net income | (2)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | (1)us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInEarnings1 / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember
Total realized/unrealized gains (losses) included in other comprehensive income (loss) | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetGainLossIncludedInOtherComprehensiveIncomeLoss / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember
Purchases and issuances | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember
Sales and settlements | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSales / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember
Transfer into Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersIntoLevel3 / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember
Transfer out of Level 3 | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | 0 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetTransfersOutOfLevel3 / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember
Financial assets, Ending Balance | $ 29 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember | $ 29 us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetValue / us-gaap_FairValueByAssetClassAxis = afg_AssetsOfManagedInvestmentEntitiesMember

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- Definition Amount of gain (loss) recognized in the income statement for financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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- Definition Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=36462937&loc=d3e19207-110258 + Details
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