Condensed Consolidating Information (Details 1) (USD $) In Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Revenues:
Property and casualty insurance premiums	$ 835	$ 736	$ 2,043	$ 1,887
Life, accident and health premiums	107	112	324	340
Realized gains (losses)	8	35	24	50
Income (loss) of managed investment entities	28	19	24	24
Investment and other income	357	353	1,052	1,040
Total revenues	1,335	1,255	3,467	3,341
Costs and Expenses:
Insurance benefits and expenses	1,059	919	2,763	2,454
Interest charges on borrowed money	21	21	63	57
Expenses of managed investment entities	17	15	53	38
Other operating and general expenses	83	92	269	279
Total costs and expenses	1,180	1,047	3,148	2,828
Operating earnings before income taxes	155	208	319	513
Provision (credit) for income taxes	48	82	126	199
Net earnings, including noncontrolling interests	107	126	193	314
Less: Net earnings (loss) attributable to noncontrolling interests	11	(6)	(41)	(32)
Net Earnings Attributable to Shareholders	96	132	234	346
AFG [Member]
Revenues:
Investment and other income	(2)	3		3
Equity in earnings of subsidiaries	169	242	447	621
Total revenues	167	245	447	624
Costs and Expenses:
Interest charges on borrowed money	16	15	48	42
Other operating and general expenses	7	16	39	37
Total costs and expenses	23	31	87	79
Operating earnings before income taxes	144	214	360	545
Provision (credit) for income taxes	48	82	126	199
Net earnings, including noncontrolling interests	96	132	234	346
Net Earnings Attributable to Shareholders	96	132	234	346
GAFRI [Member]
Revenues:
Realized gains (losses)		(2)		(2)
Investment and other income	3	3	8	8
Equity in earnings of subsidiaries	37	48	126	129
Total revenues	40	49	134	135
Costs and Expenses:
Other operating and general expenses	3	6	12	13
Total costs and expenses	3	6	12	13
Operating earnings before income taxes	37	43	122	122
Provision (credit) for income taxes	12	21	42	49
Net earnings, including noncontrolling interests	25	22	80	73
Net Earnings Attributable to Shareholders	25	22	80	73
AAG Holding [Member]
Revenues:
Equity in earnings of subsidiaries	39	76	144	172
Total revenues	39	76	144	172
Costs and Expenses:
Interest charges on borrowed money	6	6	19	19
Other operating and general expenses	2	2	4	5
Total costs and expenses	8	8	23	24
Operating earnings before income taxes	31	68	121	148
Provision (credit) for income taxes	9	22	41	50
Net earnings, including noncontrolling interests	22	46	80	98
Net Earnings Attributable to Shareholders	22	46	80	98
All Other Subs [Member]
Revenues:
Property and casualty insurance premiums	835	736	2,043	1,887
Life, accident and health premiums	107	112	324	340
Realized gains (losses)	8	37	25	52
Income (loss) of managed investment entities	28	19	24	24
Investment and other income	364	352	1,066	1,045
Total revenues	1,342	1,256	3,482	3,348
Costs and Expenses:
Insurance benefits and expenses	1,059	919	2,763	2,454
Interest charges on borrowed money	4	6	12	13
Expenses of managed investment entities	17	15	53	38
Other operating and general expenses	72	68	218	224
Total costs and expenses	1,152	1,008	3,046	2,729
Operating earnings before income taxes	190	248	436	619
Provision (credit) for income taxes	59	97	163	236
Net earnings, including noncontrolling interests	131	151	273	383
Less: Net earnings (loss) attributable to noncontrolling interests	11	(6)	(41)	(32)
Net Earnings Attributable to Shareholders	120	157	314	415
Consol. Entries [Member]
Revenues:
Realized gains (losses)			(1)
Investment and other income	(8)	(5)	(22)	(16)
Equity in earnings of subsidiaries	(245)	(366)	(717)	(922)
Total revenues	(253)	(371)	(740)	(938)
Costs and Expenses:
Interest charges on borrowed money	(5)	(6)	(16)	(17)
Other operating and general expenses	(1)		(4)
Total costs and expenses	(6)	(6)	(20)	(17)
Operating earnings before income taxes	(247)	(365)	(720)	(921)
Provision (credit) for income taxes	(80)	(140)	(246)	(335)
Net earnings, including noncontrolling interests	(167)	(225)	(474)	(586)
Net Earnings Attributable to Shareholders	$ (167)	$ (225)	$ (474)	$ (586)