XML 70 R58.htm IDEA: XBRL DOCUMENT
v3.19.1

Derivatives - Gain (loss) included in the Statement of Earnings for changes in the fair value of derivatives that do not qualify for hedge accounting (Details) - Not Designated as Hedging Instrument - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2019 | Mar. 31, 2018
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |
Derivative | $ (90) | $ 21
MBS with embedded derivatives | Realized gains (losses) on securities |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |
Derivative | 6 | (4)
Public company warrants | Realized gains (losses) on securities |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |
Derivative | 0 | (1)
Fixed-indexed and variable-indexed annuities (embedded derivative) | Annuity benefits |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |
Derivative | (462) | 63
Equity index call options | Annuity benefits |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |
Derivative | 366 | (38)
Equity index put options | Annuity benefits |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |
Derivative | 1 | 0
Reinsurance contracts (embedded derivative) | Net investment income |  |
Derivative, Gain (Loss) on Derivative, Net [Abstract] |  |
Derivative | $ (1) | $ 1

X
- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
Name: | us-gaap_DerivativeGainLossOnDerivativeNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- References No definition available. + Details
Name: | us-gaap_DerivativeGainLossOnDerivativeNetAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_HedgingDesignationAxis=us-gaap_NondesignatedMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=afg_MortgageBackedSecuritiesWithEmbeddedDerivativesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=afg_RealizedGainsLossesOnSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_WarrantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=afg_FixedIndexedandVariableIndexedAnnuitiesEmbeddedDerivativesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=afg_AnnuitybenefitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CallOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_PutOptionMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_OtherContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeStatementLocationAxis=us-gaap_InvestmentIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |