Income Taxes (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended			3 Months Ended		12 Months Ended
	Sep. 30, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 Tax litigation settlement [Member]	Sep. 30, 2012 Tax litigation settlement [Member]	Dec. 31, 2013 AFG [Member]	Dec. 31, 2012 AFG [Member]	Dec. 31, 2011 AFG [Member]	Dec. 31, 2011 Charge for valuation allowance [Member]	Dec. 31, 2011 Charge for valuation allowance related to prior year losses [Member]
Income Tax Reconciliation [Line Items]
Statutory rate of income taxes		35.00%	35.00%	35.00%
Tax benefit related to settlement of litigation					$ 39	$ 28
Expected refund of tax and interest paid related to tax settlements						17
Income (losses) subject to tax in foreign jurisdictions		12	(3)	(26)
Charge for valuation allowance against deferred tax assets										44	34
Operating loss carryforwards, valuation allowance				50
Change in AFG's liability for uncertain tax positions of current year, uncertainty as to timing of tax return inclusion of income related to certain securities		1	3	7
Change in AFG's liability for uncertain tax positions of current year related to deductibility of certain expenses			2
Change in AFG's liability for uncertain tax positions of prior year related to resolution of tax case			36
Change in AFG's related liability for interest for uncertain tax positions			14
Change in AFG's liability for uncertain tax positions of prior year	10	0	46	0
Potential decrease in the liability for uncertain tax positions		19
Unrecognized tax benefits that would impact effective tax rate		4
Interest included in tax provision							1	(14)	3
Decrease in related accrued interest		1	1
Cash payments for income taxes		$ 204	$ 277	$ 157