Segments of Operations (Details Textual) $ in Millions		3 Months Ended				12 Months Ended
		Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2013 USD ($)	Dec. 31, 2015 USD ($) segment	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Segment Reporting Information [Line Items]
Number of segments | segment						4
Revenue derived from sales of property and casualty insurance outside of the United States						4.00%	5.00%	5.00%
Other income						$ 243	$ 122	$ 108
Earnings (losses) of managed investment entities attributable to noncontrolling interests	[1]					0	(51)	(26)
Other Lines [Member]
Segment Reporting Information [Line Items]
Special charges to increase asbestos and environmental reserves						67	24	54
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Other income	[2]					78	9	15
Property and Casualty Insurance [Member] | Real Estate Investment [Member]
Segment Reporting Information [Line Items]
Other income		$ 15		$ 51
Annuity [Member]
Segment Reporting Information [Line Items]
Other income						98	97	77
Annuity [Member] | Insurance-related Assessments [Member]
Segment Reporting Information [Line Items]
Charge for guaranty fund assessments for the insolvency and liquidation of an unaffiliated life insurance company					$ 5
Other [Member]
Segment Reporting Information [Line Items]
Special charges to increase asbestos and environmental reserves						$ 12	6	22
Write off of deferred debt issuance cost due to the retirement of debt			$ 4
Earnings (losses) of managed investment entities attributable to noncontrolling interests							$ (51)	$ (26)

[1] Included in Earnings before income taxes in AFG’s Statement of Earnings.

[2] Includes pretax income of $51 million (before noncontrolling interest) from the sale of the Le Pavillon Hotel in the second quarter of 2015 and $15 million from the sale of an apartment property in the fourth quarter of 2015.