XML 64 R51.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Investments - Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2018 | Sep. 30, 2017 | Sep. 30, 2018 | Sep. 30, 2017
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments |  | $ 36 | $ 26 | $ (25) | $ 52
Realized — impairments |  | (2) | (38) | (3) | (53)
Realized gains (losses) on securities |  | 34 | (12) | (28) | (1)
Net of tax |  |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments |  | 28 | 17 | (20) | 34
Realized — impairments |  | (1) | (25) | (2) | (35)
Realized gains (losses) on securities |  | 27 | (8) | (22) | (1)
Change in unrealized |  | (98) | 67 | (526) | 302
Total pretax |  |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments |  | 36 | 26 | (25) | 52
Realized — impairments |  | (2) | (38) | (3) | (53)
Realized gains (losses) on securities |  | 34 | (12) | (28) | (1)
Change in unrealized |  | (124) | 104 | (666) | 465
Fixed maturities |  |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments |  | 0 | 9 | 3 | 25
Realized — impairments |  | (2) | (15) | (3) | (16)
Realized gains (losses) on securities |  | (2) | (6) | 0 | 9
Change in unrealized |  | (213) | 133 | (1,150) | 597
Equity securities |  |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments |  | 33 | 19 | (39) | 29
Realized — impairments |  | 0 | (29) | 0 | (49)
Realized gains (losses) on securities |  | 33 | (10) | (39) | (20)
Change in unrealized |  | 0 | 24 | 0 | 116
Mortgage loans and other investments |  |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments |  | 0 | 0 | 0 | 3
Realized — impairments |  | 0 | 0 | 0 | 0
Realized gains (losses) on securities |  | 0 | 0 | 0 | 3
Change in unrealized |  | 0 | 0 | 0 | 0
Other, Including DPAC and reserves related to the annuity business |  |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments | [1] | 3 | (2) | 11 | (5)
Realized — impairments | [1] | 0 | 6 | 0 | 12
Realized gains (losses) on securities | [1] | 3 | 4 | 11 | 7
Change in unrealized | [1] | 89 | (53) | 484 | (248)
Tax effects |  |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |  |
Realized before impairments |  | (8) | (9) | 5 | (18)
Realized — impairments |  | 1 | 13 | 1 | 18
Realized gains (losses) on securities |  | (7) | 4 | 6 | 0
Change in unrealized |  | $ 26 | $ (37) | $ 140 | $ (163)
[1] | Primarily adjustments to deferred policy acquisition costs and reserves related to the annuity business.

X
- Definition Change in unrealized appreciation depreciation. + References No definition available. + Details
Name: | afg_ChangeInUnrealizedAppreciationDepreciation
Namespace Prefix: | afg_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments. + References No definition available. + Details
Name: | afg_RealizedGainsLossesAndChangesInUnrealizedAppreciationDepreciationRelatedToFixedMaturityAndEquitySecurityInvestmentsAbstract
Namespace Prefix: | afg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI). + References No definition available. + Details
Name: | us-gaap_MarketableSecuritiesRealizedGainLoss
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of realized gain (loss) on investment in marketable security, excluding other-than-temporary impairment (OTTI). + References No definition available. + Details
Name: | us-gaap_MarketableSecuritiesRealizedGainLossExcludingOtherThanTemporaryImpairments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition The amount of other than temporary impairment losses on investments in debt and equity securities categorized as Available-for-sale which have been recognized in earnings during the period. Such impairment losses consist of other than temporary impairments (OTTI) on equity securities, credit losses on investments in debt securities, and when the entity intends to sell an impaired debt security or it is more likely than not that the entity will be required to sell the impaired debt security before recovery of its amortized cost basis. + References No definition available. + Details
Name: | us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNetAvailableforsaleSecurities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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

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

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_EquitySecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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