Condensed Financial Information of Parent Company (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Revenues:
Total revenues	$ 1,236	$ 1,563	$ 1,150	$ 1,113	$ 1,283	$ 1,335	$ 1,093	$ 1,039	$ 5,062	$ 4,750	$ 4,497
Costs and Expenses:
Other operating and general expenses									404	376	395
Total costs and expenses									4,525	4,192	3,803
Operating earnings before income taxes									537	558	694
Provision for income taxes									135	239	268
Net Earnings Attributable to Shareholders	50	226	99	113	109	97	48	88	488	342	482
AFG [Member]
Revenues:
Dividends from subsidiaries									433	544	554
Equity in undistributed earnings of subsidiaries									325	164	301
Investment and other income									5	2	4
Total revenues									763	710	859
Costs and Expenses:
Interest charges on intercompany borrowings									11	11	12
Interest charges on other borrowings									61	53	46
Other operating and general expenses									68	65	51
Total costs and expenses									140	129	109
Operating earnings before income taxes									623	581	750
Provision for income taxes									135	239	268
Net Earnings Attributable to Shareholders									$ 488	$ 342	$ 482