Managed Investment Entities (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 collateralizedloanobligations	Dec. 31, 2011
Managed Investment Entities (Textual) [Abstract]
Percentage of investment of most subordinate debt tranche, Minimum	7.50%
Percentage of investment of most subordinate debt tranche, Maximum	51.20%
Number of collateralized loan obligation entities	9
Difference between aggregate unpaid principal balance and fair value of CLOs' fixed maturity investments	$ 29	$ 120
Difference between aggregate unpaid principal balance and fair value of CLOs' debt	123	306
Carrying amount of CLO loans in default	5	2
Aggregate unpaid principal balance of CLO loans in default	12	7
Variable Interest Entity, Primary Beneficiary [Member]
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations	257	98
Aggregate fair value of investment in collateralized loan obligations, most subordinate debt tranches	89
New CLOs Formed in 2012 [Member]
Variable Interest Entity [Line Items]
Face amount of liabilities	860
Face amount of liabilities purchased by subsidiaries of AFG	74
Senior Debt Obligations [Member]
Variable Interest Entity [Line Items]
Purchased CLO senior debt, face amount	74
Purchased CLO senior debt, purchase price	$ 69