Managed Investment Entities (Details) (USD $) In Millions	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Gains (losses) on change in fair value of assets/liabilities (a):
Assets	$ (88)	$ 47	$ (71)	$ 97
Liabilities	89	(51)	17	(141)
Management fees paid to AFG	5	5	13	13
Collateralized loan obligations' earnings (losses) attributable to:
AFG shareholders	(2)	3	5	10
Noncontrolling interests	$ 8	$ (4)	$ (47)	$ (37)

Collateralized loan obligations' earnings (losses) attributable to.

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Earnings (losses) of variable interest entities attributable to AFG shareholders.

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Earnings (losses) of variable interest entities attributable to noncontrolling interests.

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Gain (loss) on change in fair value of assets of variable interest entities.

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Gain (loss) on change in fair value of liabilities of variable interest entities.

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Gains losses on change in fair value of assets liabilities collateralized loan obligations.

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Management fees paid by variable interest entities.

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