Condensed Financial Information of Parent Company (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Operating Activities:
Net earnings attributable to shareholders	$ 127	$ 116	$ 106	$ 103	$ 158	$ 83	$ 110	$ 120	$ 452	$ 471	$ 488
Adjustments:
Net cash provided by operating activities									1,222	760	817
Investing Activities:
Net cash used in investing activities									(3,619)	(2,915)	(1,425)
Financing Activities:
Additional long-term borrowings									145	0	372
Reductions of long-term debt									(2)	(40)	(365)
Issuances of Common Stock									47	54	46
Repurchases of Common Stock									(191)	(70)	(415)
Cash dividends paid on Common Stock									(167)	(160)	(90)
Net cash provided by (used in) financing activities									2,101	2,089	989
Net Change in Cash and Cash Equivalents									(296)	(66)	381
Cash and cash equivalents at beginning of year				1,639				1,705	1,639	1,705	1,324
Cash and cash equivalents at end of year	1,343				1,639				1,343	1,639	1,705
AFG [Member]
Operating Activities:
Net earnings attributable to shareholders									452	471	488
Adjustments:
Equity in net earnings of subsidiaries									(545)	(579)	(515)
Dividends from subsidiaries									451	543	417
Other operating activities, net									14	(7)	(10)
Net cash provided by operating activities									372	428	380
Investing Activities:
Capital contributions to subsidiaries									(431)	(38)	(274)
Returns of capital from subsidiaries									0	36	1
Purchases of investments, property and equipment									(1)	(2)	(11)
Net cash used in investing activities									(432)	(4)	(284)
Financing Activities:
Additional long-term borrowings									145	0	344
Reductions of long-term debt									0	0	(115)
Issuances of Common Stock									42	50	44
Repurchases of Common Stock									(191)	(70)	(415)
Cash dividends paid on Common Stock									(167)	(160)	(90)
Net cash provided by (used in) financing activities									(171)	(180)	(232)
Net Change in Cash and Cash Equivalents									(231)	244	(136)
Cash and cash equivalents at beginning of year				523				279	523	279	415
Cash and cash equivalents at end of year	$ 292				$ 523				$ 292	$ 523	$ 279