XML 31 R89.htm IDEA: XBRL DOCUMENT
v3.19.3.a.u2

Shareholders' Equity - Progression of the components of accumulated other comprehensive income (Details) - USD ($) $ in Millions |  | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2017 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017 | Jan. 01, 2018
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
AOCI beginning balance |  |  | $ 48 |  |  |  |  |  |
Other comprehensive income (loss), net of tax |  |  | 815 |  | $ (544) |  | $ 296 |  |
Cumulative effect of accounting change |  |  |  |  |  |  |  | $ 4 |
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect |  |  |  |  |  |  | 0 |  |
AOCI ending balance |  |  | 863 |  | 48 |  |  |  |
Accumulated net investment gain (loss) including portion attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), unrealized holding gains on securities arising during the period, Pretax |  |  | 997 |  | (689) |  | 456 |  |
Other comprehensive income (loss), unrealized holding gains on securities arising during the period, tax |  |  | (209) |  | 145 |  | (159) |  |
Other comprehensive income (loss), unrealized holding gains on securities arising during the period, net of tax |  |  | 788 |  | (544) |  | 297 |  |
Reclassification from accumulated other comprehensive income, pretax | [1] |  | (11) |  | 10 |  | (15) |  |
Reclassification from accumulated other comprehensive income, tax | [1] |  | 2 |  | (2) |  | 5 |  |
Reclassification from accumulated other comprehensive income, net of tax |  |  | (9) |  | 8 |  | (10) |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), pretax |  |  | 986 |  | (679) |  | 441 |  |
Other comprehensive income (loss), tax |  |  | (207) |  | 143 |  | (154) |  |
Other comprehensive income (loss), net of tax |  |  | 779 |  | (536) |  | 287 |  |
Accumulated net investment gain (loss) attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), unrealized holding gains on securities arising during the period, net of tax |  |  | 0 |  | 0 |  | 0 |  |
Reclassification from accumulated other comprehensive income, net of tax | [1] |  | 0 |  | 0 |  | 0 |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), net of tax |  |  | 0 |  | 0 |  | 0 |  |
Accumulated net investment gain (loss) attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income (Loss) [Line Items] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), unrealized holding gains on securities arising during the period, net of tax |  |  | 788 |  | (544) |  | 297 |  |
Reclassification from accumulated other comprehensive income, net of tax |  |  | (9) |  | 8 |  | (10) |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
AOCI beginning balance |  |  | 83 | [2] | 840 | [2] | 404 |  |
Other comprehensive income (loss), net of tax |  |  | 779 |  | (536) |  | 287 |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  | (221) | [3]
AOCI ending balance | [2] | $ 840 | 862 |  | 83 |  | 840 |  |
Accumulated net gain (loss) from cash flow hedges including portion attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), pretax |  |  | 36 |  | 2 |  | (6) |  |
Other comprehensive income (loss), tax |  |  | (8) |  | 0 |  | 2 |  |
Other comprehensive income (loss), net of tax |  |  | 28 |  | 2 |  | (4) |  |
Accumulated net gain (loss) from cash flow hedges attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), net of tax |  |  | 0 |  | 0 |  | 0 |  |
Accumulated net gain (loss) from cash flow hedges attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
AOCI beginning balance |  |  | (11) |  | (13) |  | (7) |  |
Other comprehensive income (loss), net of tax |  |  | 28 |  | 2 |  | (4) |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  | 0 | [3]
AOCI ending balance |  | (13) | 17 |  | (11) |  | (13) |  |
Accumulated foreign currency adjustment including portion attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), pretax |  |  | 7 |  | (9) |  | 9 |  |
Other comprehensive income (loss), tax |  |  | 0 |  | (1) |  | 3 |  |
Other comprehensive income (loss), net of tax |  |  | 7 |  | (10) |  | 12 |  |
Accumulated foreign currency adjustment attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), net of tax |  |  | 0 |  | 0 |  | 0 |  |
Accumulated foreign currency adjustment attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
AOCI beginning balance |  |  | (16) |  | (6) |  | (15) |  |
Other comprehensive income (loss), net of tax |  |  | 7 |  | (10) |  | 12 |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  | 0 | [3]
AOCI ending balance |  | (6) | (9) |  | (16) |  | (6) |  |
Accumulated defined benefit plans adjustment including portion attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), pretax |  |  | 1 |  | 0 |  | 1 |  |
Other comprehensive income (loss), tax |  |  | 0 |  | 0 |  | 0 |  |
Other comprehensive income (loss), net of tax |  |  | 1 |  | 0 |  | 1 |  |
Accumulated defined benefit plans adjustment attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), net of tax |  |  | 0 |  | 0 |  | 0 |  |
Accumulated defined benefit plans adjustment attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
AOCI beginning balance |  |  | (8) |  | (8) |  | (7) |  |
Other comprehensive income (loss), net of tax |  |  | 1 |  | 0 |  | 1 |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  | 0 | [3]
AOCI ending balance |  | (8) | (7) |  | (8) |  | (8) |  |
AOCI including portion attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), pretax |  |  | 1,030 |  | (686) |  | 445 |  |
Other comprehensive income (loss), tax |  |  | (215) |  | 142 |  | (149) |  |
Other comprehensive income (loss), net of tax |  |  | 815 |  | (544) |  | 296 |  |
AOCI attributable to noncontrolling interest |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Other comprehensive income (loss), net of tax |  |  | 0 |  | 0 |  | 0 |  |
AOCI attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
AOCI beginning balance |  |  | 48 |  | 813 |  | 375 |  |
Other comprehensive income (loss), net of tax |  |  | 815 |  | (544) |  | 296 |  |
Cumulative effect of accounting change |  |  | 0 |  |  |  |  | $ (221) | [3]
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect |  |  |  |  |  |  | 145 |  |
AOCI ending balance |  | 813 | $ 863 |  | $ 48 |  | $ 813 |  |
Tax Cuts and Jobs Act of 2017 | Accumulated net investment gain (loss) attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect | [3] | 149 |  |  |  |  |  |  |
Tax Cuts and Jobs Act of 2017 | Accumulated net gain (loss) from cash flow hedges attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect | [3] | (2) |  |  |  |  |  |  |
Tax Cuts and Jobs Act of 2017 | Accumulated defined benefit plans adjustment attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect | [3] | (2) |  |  |  |  |  |  |
Tax Cuts and Jobs Act of 2017 | AOCI attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect | [3] | 142 |  |  |  |  |  |  |
Redeemable noncontrolling interests | Tax Cuts and Jobs Act of 2017 | Accumulated foreign currency adjustment attributable to parent |  |  |  |  |  |  |  |  |
Accumulated Other Comprehensive Income [Roll Forward] |  |  |  |  |  |  |  |  |
Tax Cuts and Jobs Act, reclassification from AOCI to retained earnings, tax effect | [3] | $ (3) |  |  |  |  |  |  |
[1] | The reclassification adjustment out of net unrealized gains (losses) on securities affected the following lines in AFG’s Statement of Earnings:
| OCI component |  | Affected line in the statement of earnings |
| Pretax |  | Realized gains (losses) on securities |
| Tax |  | Provision for income taxes |
[2] | Includes net unrealized gains of $55 million at December 31, 2019 compared to $58 million and $68 million at December 31, 2018 and 2017, related to securities for which only the credit portion of an other-than-temporary impairment has been recorded in earnings.
[3] | On January 1, 2018, AFG adopted new guidance that requires all equity securities other than those accounted for under the equity method to be reported at fair value with holding gains and losses recognized in net earnings. At the date of adoption, the $221 million net unrealized gain on equity securities classified as available for sale (with unrealized holding gains and losses reported in AOCI) under the prior guidance was reclassified from AOCI to retained earnings as the cumulative effect of an accounting change. Other also includes the December 2017 reclassification of $145 million stranded in AOCI from accounting for the Tax Cuts and Jobs Act of 2017 to retained earnings (see Note A — “Accounting Policies — Income Taxes”) and the impact on AOCI of the December 2017 sale of redeemable noncontrolling interests in Neon.

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_AOCIAttributableToParentNetOfTaxRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
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_AccumulatedOtherComprehensiveIncomeLossLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e637-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e681-108580 + Details
Name: | us-gaap_AccumulatedOtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption. + References No definition available. + Details
Name: | us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax and reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax, before reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=118951672&loc=d3e1436-108581 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) allocated to other comprehensive income (loss) before reclassification adjustment from accumulated other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 11 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e39076-109324 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeReclassificationsTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount before tax, after reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33775-111570 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount after tax and reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669619-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21463-112644 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=118951672&loc=d3e1436-108581 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669625-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) allocated to other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 11 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e39076-109324 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e38679-109324 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount before tax of reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 17B -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL34724394-108580 + Details
Name: | us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount after tax of reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 17B -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL34724394-108580 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 14A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL7669686-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=118951672&loc=d3e1436-108581 + Details
Name: | us-gaap_ReclassificationFromAccumulatedOtherComprehensiveIncomeCurrentPeriodNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of tax expense (benefit) of reclassification adjustment from accumulated other comprehensive income (loss). + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12 -URI http://asc.fasb.org/extlink&oid=118930883&loc=d3e640-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 17A -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL34724391-108580 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 20 -Section 45 -Paragraph 11 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109238882&loc=d3e39076-109324 + Details
Name: | us-gaap_ReclassificationFromAociCurrentPeriodTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 12A -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=118930883&loc=SL116659650-108580 + Details
Name: | us-gaap_TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetInvestmentGainLossIncludingPortionAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetInvestmentGainLossAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetGainLossFromCashFlowHedgesIncludingPortionAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetGainLossFromCashFlowHedgesAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetGainLossFromDesignatedOrQualifyingCashFlowHedgesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedForeignCurrencyAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedForeignCurrencyAdjustmentAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedTranslationAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentIncludingPortionAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedDefinedBenefitPlansAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AociIncludingPortionAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AociAttributableToNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedOtherComprehensiveIncomeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_IncomeTaxAuthorityAxis=afg_TaxCutsandJobsActof2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_SubsidiarySaleOfStockAxis=afg_RedeemableNoncontrollingInterestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |