Segments of Operations (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Segment Reporting Information [Line Items]
Operating earnings before realized gains (losses) and income taxes	$ 166		$ 485		$ 606
Realized gains (losses) on securities	210		76		101
Realized gains (losses) on subsidiaries	161		(3)		(13)
Operating earnings before income taxes	537		558		694
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	87		180		306
Investment and other income, net	237		263		299
Operating earnings before realized gains (losses) and income taxes	324		443		605
Annuity [Member]
Segment Reporting Information [Line Items]
Operating earnings before realized gains (losses) and income taxes	256		188		159
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Operating earnings before realized gains (losses) and income taxes	(157)	[1]	0		7
Medicare Supplement and Critical Illness [Member]
Segment Reporting Information [Line Items]
Operating earnings before realized gains (losses) and income taxes	28	[2]	34		31
Other [Member]
Segment Reporting Information [Line Items]
Operating earnings before realized gains (losses) and income taxes	(285)	[3]	(180)	[3]	(196)	[3]
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	19		113		141
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	53		35		45
Specialty financial [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	44		65		123
Specialty Other [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	15		18		8
Other Lines [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	$ (44)	[4]	$ (51)	[4]	$ (11)

[1] Includes a loss recognition charge of $153 million in the fourth quarter of 2012.

[2] Sold in August 2012.

[3] Includes holding company expenses, a second quarter 2011 special charge of $9 million to increase asbestos and environmental reserves and $98 million, $24 million and $64 million in losses of managed investment entities attributable to noncontrolling interests for the years ended December 31, 2012, 2011 and 2010, respectively. Holding company expenses in 2012 also include an $8 million loss on retirement of debt and a $15 million charge for a labor matter related to AFG’s former railroad operations.

[4] Includes third quarter 2012 and second quarter 2011 special charges of $31 million and $50 million, respectively, to increase asbestos and environmental reserves.