Condensed Financial Information of Parent Company (Details 3) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Operating Activities:
Net earnings attributable to shareholders	$ 129	$ 63	$ 141	$ 19	$ 127	$ 116	$ 106	$ 103	$ 352	$ 452	$ 471
Adjustments:
Net cash provided by operating activities									1,357	1,222	760
Investing Activities:
Net cash used in investing activities									(4,577)	(3,619)	(2,915)
Financing Activities:
Additional long-term borrowings									145	145	0
Reductions of long-term debt									(192)	(2)	(40)
Issuances of Common Stock									61	47	54
Repurchases of Common Stock									(126)	(191)	(70)
Cash dividends paid on Common Stock									(176)	(167)	(160)
Net cash provided by (used in) financing activities									3,097	2,101	2,089
Net Change in Cash and Cash Equivalents									(123)	(296)	(66)
Cash and cash equivalents at beginning of year				1,343				1,639	1,343	1,639	1,705
Cash and cash equivalents at end of year	1,220				1,343				1,220	1,343	1,639
AFG [Member]
Operating Activities:
Net earnings attributable to shareholders									352	452	471
Adjustments:
Equity in net earnings of subsidiaries									(451)	(545)	(579)
Dividends from subsidiaries									280	451	543
Other operating activities, net									(19)	14	(7)
Net cash provided by operating activities									162	372	428
Investing Activities:
Capital contributions to subsidiaries									(27)	(431)	(38)
Returns of capital from subsidiaries									1	0	36
Purchases of investments, property and equipment									(10)	(1)	(2)
Proceeds from sales of investments, property and equipment									3	0	0
Net cash used in investing activities									(33)	(432)	(4)
Financing Activities:
Additional long-term borrowings									145	145	0
Reductions of long-term debt									(132)	0	0
Issuances of Common Stock									57	42	50
Repurchases of Common Stock									(126)	(191)	(70)
Cash dividends paid on Common Stock									(176)	(167)	(160)
Net cash provided by (used in) financing activities									(232)	(171)	(180)
Net Change in Cash and Cash Equivalents									(103)	(231)	244
Cash and cash equivalents at beginning of year				$ 292				$ 523	292	523	279
Cash and cash equivalents at end of year	$ 189				$ 292				$ 189	$ 292	$ 523