Segments of Operations (Details 1) - 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
Segment Reporting Information [Line Items]
Total premiums earned										$ 4,224	$ 3,878	$ 3,204
Net investment income										1,633	1,501	1,346
Other income										243	122	108
Revenues before realized gains (losses)										6,325	5,681	4,886
Realized gains (losses) on securities										(19)	52	221
Realized losses on subsidiaries										(161)	0	(4)
Total revenues		$ 1,626	$ 1,684	$ 1,541	$ 1,294	$ 1,549	$ 1,581	$ 1,392	$ 1,211	6,145	5,733	5,103
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Net investment income										319	294	263
Other income	[1]									78	9	15
Revenues before realized gains (losses)										4,621	4,181	3,482
Annuity [Member]
Segment Reporting Information [Line Items]
Net investment income										1,224	1,136	1,034
Other income										98	97	77
Revenues before realized gains (losses)										1,322	1,233	1,111
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	[2]									188	195	195
Other [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)										194	72	98
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Total premiums earned										1,599	1,544	1,521
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Total premiums earned										2,011	1,765	1,135
Specialty financial [Member]
Segment Reporting Information [Line Items]
Total premiums earned										517	469	469
Specialty Other [Member]
Segment Reporting Information [Line Items]
Total premiums earned										$ 97	$ 100	$ 79

[1] Includes pretax income of $51 million (before noncontrolling interest) from the sale of the Le Pavillon Hotel in the second quarter of 2015 and $15 million from the sale of an apartment property in the fourth quarter of 2015.

[2] AFG sold substantially all of its run-off long-term care insurance business in December 2015.