Managed Investment Entities (Details) (USD $) In Millions	3 Months Ended	6 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Gains (losses) on change in fair value of assets/liabilities (a):
Assets	$ (12)	$ (31)	$ 17	$ 50
Liabilities	(10)	16	(72)	(90)
Management fees paid to AFG	5	4	8	8
Collateralized loan obligations' earnings (losses) attributable to:
AFG shareholders	1	3	7	7
Noncontrolling interests	$ (20)	$ (13)	$ (55)	$ (33)

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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