Condensed Consolidating Information (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Assets:
Cash and investments	$ 26,478	$ 25,577
Recoverables from reinsurers and prepaid reinsurance premiums	3,093	3,351
Agents' balances and premiums receivable	550	565
Deferred policy acquisition costs	916	901
Assets of managed investment entities	2,952	3,058
Other assets	2,222	2,386
Total assets	36,211	35,838
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	7,613	8,004
Annuity, life, accident and health benefits and reserves	17,803	17,147
Liabilities of managed investment entities	2,672	2,787
Long-term debt	931	934
Other liabilities	2,460	2,409
Total liabilities	31,479	31,281
Total shareholders' equity	4,580	4,411
Noncontrolling interests	152	146
Total liabilities and equity	36,211	35,838
AFG [Member]
Assets:
Cash and investments	419	456
Other assets	120	105
Investment in subsidiaries and affiliates	4,931	4,732
Total assets	5,470	5,293
Liabilities and Equity:
Long-term debt	600	600
Other liabilities	290	282
Total liabilities	890	882
Total shareholders' equity	4,580	4,411
Total liabilities and equity	5,470	5,293
GAFRI [Member]
Assets:
Cash and investments	25	32
Other assets	8	5
Investment in subsidiaries and affiliates	2,169	2,015
Total assets	2,202	2,052
Liabilities and Equity:
Other liabilities	20	20
Total liabilities	20	20
Total shareholders' equity	2,182	2,032
Total liabilities and equity	2,202	2,052
AAG Holding [Member]
Assets:
Other assets	8	5
Investment in subsidiaries and affiliates	2,254	2,107
Total assets	2,262	2,112
Liabilities and Equity:
Long-term debt	219	220
Other liabilities	109	109
Total liabilities	328	329
Total shareholders' equity	1,934	1,783
Total liabilities and equity	2,262	2,112
All Other Subs [Member]
Assets:
Cash and investments	26,035	25,090
Recoverables from reinsurers and prepaid reinsurance premiums	3,093	3,351
Agents' balances and premiums receivable	550	565
Deferred policy acquisition costs	916	901
Assets of managed investment entities	2,952	3,058
Other assets	2,121	2,309
Investment in subsidiaries and affiliates	640	643
Total assets	36,307	35,917
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	7,613	8,004
Annuity, life, accident and health benefits and reserves	17,815	17,148
Liabilities of managed investment entities	2,672	2,787
Long-term debt	112	115
Other liabilities	2,247	2,196
Total liabilities	30,459	30,250
Total shareholders' equity	5,696	5,521
Noncontrolling interests	152	146
Total liabilities and equity	36,307	35,917
Consol. Entries [Member]
Assets:
Cash and investments	(1)	(1)
Other assets	(35)	(38)
Investment in subsidiaries and affiliates	(9,994)	(9,497)
Total assets	(10,030)	(9,536)
Liabilities and Equity:
Annuity, life, accident and health benefits and reserves	(12)	(1)
Long-term debt		(1)
Other liabilities	(206)	(198)
Total liabilities	(218)	(200)
Total shareholders' equity	(9,812)	(9,336)
Total liabilities and equity	$ (10,030)	$ (9,536)