Condensed Financial Information of Parent Company (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Operating Activities:
Net earnings attributable to shareholders	$ 158	$ 83	$ 110	$ 120	$ 50	$ 226	$ 99	$ 113	$ 471	$ 488	$ 342
Adjustments:
Net cash provided by operating activities									760	817	667
Investing Activities:
Net cash used in investing activities									(2,915)	(1,425)	(2,439)
Financing Activities:
Additional long-term borrowings									0	372	2
Reductions of long-term debt									(40)	(365)	(20)
Issuances of Common Stock									54	46	39
Repurchases of Common Stock									(70)	(415)	(315)
Cash dividends paid on Common Stock									(160)	(90)	(67)
Net cash provided by (used in) financing activities									2,089	989	1,997
Net Change in Cash and Cash Equivalents									(66)	381	225
Cash and cash equivalents at beginning of year				1,705				1,324	1,705	1,324	1,099
Cash and cash equivalents at end of year	1,639				1,705				1,639	1,705	1,324
AFG [Member]
Operating Activities:
Net earnings attributable to shareholders									471	488	342
Adjustments:
Equity in net earnings of subsidiaries									(579)	(515)	(439)
Dividends from subsidiaries									543	417	542
Other operating activities, net									(7)	(10)	17
Net cash provided by operating activities									428	380	462
Investing Activities:
Capital contributions to subsidiaries									(38)	(274)	(29)
Returns of capital from subsidiaries									36	1	2
Purchases of investments, property and equipment									(2)	(11)	(54)
Proceeds from maturities and redemptions of investments									0	0	4
Proceeds from sales of investments, property and equipment									0	0	5
Net cash used in investing activities									(4)	(284)	(72)
Financing Activities:
Additional long-term borrowings									0	344	0
Reductions of long-term debt									0	(115)	0
Issuances of Common Stock									50	44	37
Repurchases of Common Stock									(70)	(415)	(315)
Cash dividends paid on Common Stock									(160)	(90)	(67)
Net cash provided by (used in) financing activities									(180)	(232)	(345)
Net Change in Cash and Cash Equivalents									244	(136)	45
Cash and cash equivalents at beginning of year				279				415	279	415	370
Cash and cash equivalents at end of year	$ 523				$ 279				$ 523	$ 279	$ 415