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Fair Value Measurements (Details Textual) (USD $) In Millions, unless otherwise specified | 3 Months Ended
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Mar. 31, 2014 professional stock | Mar. 31, 2013 stock
Fair Value Measurements (Textual) [Abstract] |  |
AFG's internal investment professionals | 20 |
Number of stocks transferred from Level 2 to Level 1 | 0 | 0
Level 3 assets as a percentage of total assets measured at fair value | 3.00% |
Percentage of level 3 assets that were priced using non-binding broker quotes | 85.00% |
Level 3 assets that were priced using non-binding broker quotes | $ 833 |
Percentage of internally developed Level 3 assets to total assets (are less than) | 0.50% |
Percentage of internally developed Level 3 assets to Shareholders' equity (are less than) | 3.00% |
Total realized/unrealized losses included in net income on liabilities still outstanding | 4 | (18)
Fixed-indexed annuities (embedded derivative) [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Fair value of derivatives in annuity benefits accumulated measured using a discounted cash flow approach | 904 |
Fixed-indexed annuities (embedded derivative) [Member] | Minimum [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Unobservable input surrenders used in Level 3 fair value determination | 4.00% |
Fixed-indexed annuities (embedded derivative) [Member] | Maximum [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Unobservable input surrenders used in Level 3 fair value determination | 16.00% |
Fixed-indexed annuties (embedded derivative), majority of future years [Member] | Minimum [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Unobservable input surrenders used in Level 3 fair value determination | 6.00% |
Fixed-indexed annuties (embedded derivative), majority of future years [Member] | Maximum [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Unobservable input surrenders used in Level 3 fair value determination | 12.00% |
Perpetual preferred stocks [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Number of stocks transferred from Level 1 to Level 2 | 8 |
Fair value of assets transferred from Level 1 to Level 2 | 55 |
Number of stocks transferred from Level 2 to Level 1 |  |
Fair value of assets transferred from Level 2 to Level 1 |  |
Common stocks [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Number of stocks transferred from Level 1 to Level 2 |  |
Fair value of assets transferred from Level 1 to Level 2 |  |
Number of stocks transferred from Level 2 to Level 1 |  |
Fair value of assets transferred from Level 2 to Level 1 |  |
Redeemable preferred stocks [Member] |  |
Fair Value Measurements (Textual) [Abstract] |  |
Number of stocks transferred from Level 1 to Level 2 |  |
Fair value of assets transferred from Level 1 to Level 2 |  |
Number of stocks transferred from Level 2 to Level 1 |  |
Fair value of assets transferred from Level 2 to Level 1 |  |

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- Definition Fair value measurement with unobservable inputs reconciliation recurring basis liability gain (loss) included in earnings on liabilities still outstanding. + References No definition available. + Details
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- Definition Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and not elected to be offset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 10 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13433-108611 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41228-113958 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 825 -SubTopic 10 -Section 50 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=28364263&loc=d3e13495-108611 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 45 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6945355&loc=d3e41271-113958 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 10 -URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226008-175313 + Details
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