Segments of Operations - Earnings before income taxes by segment and sub-segment (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes		$ 176	$ 110	$ 500	$ 510
Realized gains (losses) on securities		2	(16)	(32)	2
Realized gains (losses) on subsidiaries		0	5	2	(157)
Earnings before income taxes		178	99	470	355
Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		42	15	126	125
Investment and other income, net	[1]	79	75	269	272
Earnings before realized gains (losses) and income taxes		121	90	395	397
Annuity
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes		107	67	236	230
Run-off Long-term Care and Life
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	[2]	1	6	0	14
Other
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	[3]	(53)	(53)	(131)	(131)
Specialty Property and transportation | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		44	20	91	14
Specialty casualty | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		13	31	65	96
Specialty financial | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		19	26	64	72
Other specialty | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		2	7	7	13
Other Lines | Property and Casualty Insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	[4]	$ (36)	$ (69)	$ (101)	$ (70)

[1] Includes pretax income of $32 million (before noncontrolling interest) from the sale of an apartment property in the second quarter of 2016 and $51 million (before noncontrolling interest) from the sale of the Le Pavillon Hotel in the second quarter of 2015.

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

[3] Includes holding company interest and expenses, including a $4 million loss on retirement of debt in the third quarter of 2015, and special charges of $5 million and $12 million in the third quarter of 2016 and 2015, respectively, to increase A&E reserves related to AFG’s former railroad and manufacturing operations.

[4] Includes a special charge of $65 million related to the exit of certain lines of business within AFG’s Lloyd’s-based insurer, Neon, in the second quarter of 2016 and special charges of $36 million and $67 million in the third quarter of 2016 and 2015, respectively, to increase asbestos and environmental (“A&E”) reserves.