Condensed Consolidating Information (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets:
Cash and investments	$ 25,577	$ 22,670
Recoverables from reinsurers and prepaid reinsurance premiums	3,351	3,386
Agents' balances and premiums receivable	565	535
Deferred policy acquisition costs	1,105	1,244
Assets of managed investment entities	3,058	2,537
Other assets	2,386	2,082
Investment in subsidiaries and affiliates	0	0
Total assets	36,042	32,454	27,683
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	8,004	7,947
Annuity, life, accident and health benefits and reserves	17,147	14,555
Liabilities of managed investment entities	2,787	2,323
Long-term debt	934	952
Other liabilities	2,479	2,057
Total liabilities	31,351	27,834
Total shareholders' equity	4,545	4,470
Noncontrolling interests	146	150
Total liabilities and equity	36,042	32,454
AFG [Member]
Assets:
Cash and investments	456	412
Recoverables from reinsurers and prepaid reinsurance premiums	0	0
Agents' balances and premiums receivable	0	0
Deferred policy acquisition costs	0	0
Assets of managed investment entities	0	0
Other assets	105	36
Investment in subsidiaries and affiliates	4,866	4,816
Total assets	5,427	5,264
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	0	0
Annuity, life, accident and health benefits and reserves	0	0
Liabilities of managed investment entities	0	0
Long-term debt	600	600
Other liabilities	282	194
Total liabilities	882	794
Total shareholders' equity	4,545	4,470
Noncontrolling interests	0	0
Total liabilities and equity	5,427	5,264
GAFRI [Member]
Assets:
Cash and investments	32	33
Recoverables from reinsurers and prepaid reinsurance premiums	0	0
Agents' balances and premiums receivable	0	0
Deferred policy acquisition costs	0	0
Assets of managed investment entities	0	0
Other assets	5	6
Investment in subsidiaries and affiliates	2,055	1,899
Total assets	2,092	1,938
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	0	0
Annuity, life, accident and health benefits and reserves	0	0
Liabilities of managed investment entities	0	0
Long-term debt	0	1
Other liabilities	20	19
Total liabilities	20	20
Total shareholders' equity	2,072	1,918
Noncontrolling interests	0	0
Total liabilities and equity	2,092	1,938
AAG Holding [Member]
Assets:
Cash and investments	0	0
Recoverables from reinsurers and prepaid reinsurance premiums	0	0
Agents' balances and premiums receivable	0	0
Deferred policy acquisition costs	0	0
Assets of managed investment entities	0	0
Other assets	5	5
Investment in subsidiaries and affiliates	2,146	1,996
Total assets	2,151	2,001
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	0	0
Annuity, life, accident and health benefits and reserves	0	0
Liabilities of managed investment entities	0	0
Long-term debt	220	219
Other liabilities	109	110
Total liabilities	329	329
Total shareholders' equity	1,822	1,672
Noncontrolling interests	0	0
Total liabilities and equity	2,151	2,001
All Other Subs [Member]
Assets:
Cash and investments	25,090	22,228
Recoverables from reinsurers and prepaid reinsurance premiums	3,351	3,386
Agents' balances and premiums receivable	565	535
Deferred policy acquisition costs	1,105	1,244
Assets of managed investment entities	3,058	2,537
Other assets	2,309	2,050
Investment in subsidiaries and affiliates	643	671
Total assets	36,121	32,651
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	8,004	7,947
Annuity, life, accident and health benefits and reserves	17,148	14,556
Liabilities of managed investment entities	2,787	2,323
Long-term debt	115	133
Other liabilities	2,266	1,888
Total liabilities	30,320	26,847
Total shareholders' equity	5,655	5,654
Noncontrolling interests	146	150
Total liabilities and equity	36,121	32,651
Consol. Entries [Member]
Assets:
Cash and investments	(1)	(3)
Recoverables from reinsurers and prepaid reinsurance premiums	0	0
Agents' balances and premiums receivable	0	0
Deferred policy acquisition costs	0	0
Assets of managed investment entities	0	0
Other assets	(38)	(15)
Investment in subsidiaries and affiliates	(9,710)	(9,382)
Total assets	(9,749)	(9,400)
Liabilities and Equity:
Unpaid losses and loss adjustment expenses and unearned premiums	0	0
Annuity, life, accident and health benefits and reserves	(1)	(1)
Liabilities of managed investment entities	0	0
Long-term debt	(1)	(1)
Other liabilities	(198)	(154)
Total liabilities	(200)	(156)
Total shareholders' equity	(9,549)	(9,244)
Noncontrolling interests	0	0
Total liabilities and equity	$ (9,749)	$ (9,400)