XML 62 R50.htm IDEA: XBRL DOCUMENT
v3.20.2

Investments - Narrative (Details) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2020 USD ($) | Mar. 31, 2020 USD ($) | Sep. 30, 2019 USD ($) | Sep. 30, 2020 USD ($) security | Sep. 30, 2019 USD ($) | Dec. 31, 2019 USD ($)
Schedule of Investments [Line Items] |  |  |  |  |  |
Percentage (based on amount of unrealized loss) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade |  |  |  | 77.00% |  |
Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade |  |  |  | 84.00% |  |
Net investment income | $ 572 |  | $ 588 | $ 1,584 | $ 1,710 |
Fixed maturities |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Gross unrealized losses on fixed maturities | 254 |  |  | $ 254 |  | $ 88
Number of available for sale securities in an unrealized loss position | security |  |  |  | 759 |  |
Residential MBS |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Gross unrealized losses on fixed maturities | 6 |  |  | $ 6 |  | $ 5
Number of securities purchased with credit deterioration | security |  |  |  | 2 |  |
Aggregate par value of securities purchased with credit deterioration, at time of purchase |  |  |  | $ 8 |  |
Aggregate purchase price of securities purchased with credit deterioration, at time of purchase |  |  |  | 6 |  |
Initial allowance for purchased securities with credit deterioration |  |  |  | 1 |  |
Initial discount for purchased securities with credit deterioration |  |  |  | 1 |  |
Neon Capital Limited |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Net investment income | $ 1 |  |  | $ (5) |  |
Accounting Standards Update 2016-01 | Equity securities | Neon Capital Limited |  |  |  |  |  |
Schedule of Investments [Line Items] |  |  |  |  |  |
Net investment income |  | $ (7) |  |  |  |

X
- Definition Debt securities, available-for-sale, purchased with credit deterioration, number of securities + References No definition available. + Details
Name: | afg_DebtSecuritiesAvailableForSalePurchasedWithCreditDeteriorationNumberOfSecurities
Namespace Prefix: | afg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Number of available-for-sale securities in an unrealized loss position. + References No definition available. + Details
Name: | afg_NumberOfAvailableForSaleSecuritiesInUnrealizedLossPosition
Namespace Prefix: | afg_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade. + References No definition available. + Details
Name: | afg_PercentageBasedOnFairValueOfAvailableForSaleFixedMaturitiesThatAreInUnrealizedLossPositionAndRatedInvestmentGrade
Namespace Prefix: | afg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage based on unrealized loss of available for sale fixed maturities that are in an unrealized loss position and rated investment grade. + References No definition available. + Details
Name: | afg_PercentageBasedOnUnrealizedLossOfAvailableForSaleFixedMaturitiesThatAreInUnrealizedLossPositionAndRatedInvestmentGrade
Namespace Prefix: | afg_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit loss at acquisition date of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 10 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922903-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSalePurchasedWithCreditDeteriorationAllowanceForCreditLossAtAcquisitionDate
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount at par value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 10 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922903-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSalePurchasedWithCreditDeteriorationAmountAtParValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount at purchase price of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922903-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSalePurchasedWithCreditDeteriorationAmountAtPurchasePrice
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of discount (premium) attributable to other factors on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), purchased with credit deterioration. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 326 -SubTopic 30 -Section 50 -Paragraph 10 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121582814&loc=SL82922903-210455 + Details
Name: | us-gaap_DebtSecuritiesAvailableForSalePurchasedWithCreditDeteriorationDiscountPremium
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount, after investment expense, of income earned from investments in securities and real estate. Includes, but is not limited to, real estate investment, policy loans, dividends, and interest. Excludes realized gain (loss) on investments. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04(2)) -URI http://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 + Details
Name: | us-gaap_NetInvestmentIncome
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_ScheduleOfInvestmentsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_FixedMaturitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_ConsolidatedEntitiesAxis=afg_NeonCapitalLimitedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201601Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_InvestmentTypeAxis=us-gaap_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |