Condensed Consolidating Information (Details 1) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Revenues:
Property and casualty insurance premiums	$ 609	$ 572	$ 1,208	$ 1,151
Life, accident and health premiums	107	113	217	228
Realized gains (losses)	19	11	16	15
Income (loss) of managed investment entities	4	8	(4)	5
Investment and other income	354	348	695	687
Total revenues	1,093	1,052	2,132	2,086
Costs and Expenses:
Insurance benefits and expenses	886	774	1,704	1,535
Interest charges on borrowed money	21	18	42	36
Expenses of managed investment entities	18	14	36	23
Other operating and general expenses	99	88	186	187
Total costs and expenses	1,024	894	1,968	1,781
Operating earnings before income taxes	69	158	164	305
Provision (credit) for income taxes	32	58	78	117
Net earnings, including noncontrolling interests	37	100	86	188
Less: Net earnings (loss) attributable to noncontrolling interests	(18)	(8)	(52)	(26)
Net Earnings Attributable to Shareholders	55	108	138	214
AFG [Member]
Revenues:
Investment and other income		(1)	2
Equity in earnings of subsidiaries	118	187	278	379
Total revenues	118	186	280	379
Costs and Expenses:
Interest charges on borrowed money	16	13	32	27
Other operating and general expenses	15	7	32	21
Total costs and expenses	31	20	64	48
Operating earnings before income taxes	87	166	216	331
Provision (credit) for income taxes	32	58	78	117
Net earnings, including noncontrolling interests	55	108	138	214
Net Earnings Attributable to Shareholders	55	108	138	214
GAFRI [Member]
Revenues:
Investment and other income	2	3	5	5
Equity in earnings of subsidiaries	40	41	89	81
Total revenues	42	44	94	86
Costs and Expenses:
Other operating and general expenses	6	3	9	7
Total costs and expenses	6	3	9	7
Operating earnings before income taxes	36	41	85	79
Provision (credit) for income taxes	12	15	30	28
Net earnings, including noncontrolling interests	24	26	55	51
Net Earnings Attributable to Shareholders	24	26	55	51
AAG Holding [Member]
Revenues:
Equity in earnings of subsidiaries	48	47	105	96
Total revenues	48	47	105	96
Costs and Expenses:
Interest charges on borrowed money	7	7	13	13
Other operating and general expenses	1	1	2	3
Total costs and expenses	8	8	15	16
Operating earnings before income taxes	40	39	90	80
Provision (credit) for income taxes	14	14	32	28
Net earnings, including noncontrolling interests	26	25	58	52
Net Earnings Attributable to Shareholders	26	25	58	52
All Other Subs [Member]
Revenues:
Property and casualty insurance premiums	609	572	1,208	1,151
Life, accident and health premiums	107	113	217	228
Realized gains (losses)	20	11	17	15
Income (loss) of managed investment entities	4	8	(4)	5
Investment and other income	359	352	702	693
Total revenues	1,099	1,056	2,140	2,092
Costs and Expenses:
Insurance benefits and expenses	886	774	1,704	1,535
Interest charges on borrowed money	4	4	8	7
Expenses of managed investment entities	18	14	36	23
Other operating and general expenses	79	74	146	156
Total costs and expenses	987	866	1,894	1,721
Operating earnings before income taxes	112	190	246	371
Provision (credit) for income taxes	46	67	104	139
Net earnings, including noncontrolling interests	66	123	142	232
Less: Net earnings (loss) attributable to noncontrolling interests	(18)	(8)	(52)	(26)
Net Earnings Attributable to Shareholders	84	131	194	258
Consol. Entries [Member]
Revenues:
Realized gains (losses)	(1)		(1)
Investment and other income	(7)	(6)	(14)	(11)
Equity in earnings of subsidiaries	(206)	(275)	(472)	(556)
Total revenues	(214)	(281)	(487)	(567)
Costs and Expenses:
Interest charges on borrowed money	(6)	(6)	(11)	(11)
Other operating and general expenses	(2)	3	(3)
Total costs and expenses	(8)	(3)	(14)	(11)
Operating earnings before income taxes	(206)	(278)	(473)	(556)
Provision (credit) for income taxes	(72)	(96)	(166)	(195)
Net earnings, including noncontrolling interests	(134)	(182)	(307)	(361)
Net Earnings Attributable to Shareholders	$ (134)	$ (182)	$ (307)	$ (361)