Segments of Operations - Earnings before income taxes by segment and sub-segment (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes		$ 905	$ 719	$ 766
Realized gains (losses) on securities		(266)	5	19
Realized gains on subsidiaries		0	0	2
Earnings before income taxes		639	724	787
Property and casualty insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		302	242	236
Investment and other income, net	[1]	407	349	341
Earnings before realized gains (losses) and income taxes		709	591	577
Annuity
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes		361	380	368
Other
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	[2]	(165)	(252)	(179)
Property and transportation | Property and casualty insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		120	154	166
Specialty casualty | Property and casualty insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		141	104	78
Specialty financial | Property and casualty insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		66	61	84
Other specialty | Property and casualty insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting		(5)	(2)	9
Other lines | Property and casualty insurance
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	[3]	$ (20)	$ (75)	$ (101)

[1] Includes income of $32 million (before noncontrolling interest) from the sale of an apartment property in 2016.

[2] Primarily holding company interest and expenses, including losses on retirement of debt of $51 million in 2017 and special charges to increase A&E reserves related to AFG’s former railroad and manufacturing operations ($9 million in 2018, $24 million in 2017 and $5 million in 2016).

[3] Includes special charges to increase asbestos and environmental (“A&E”) reserves of $18 million, $89 million and $36 million in 2018, 2017 and 2016, respectively. Also includes $18 million in favorable development related to the Neon exited lines recorded in connection with a reinsurance to close transaction in 2017 and a charge of $65 million related to Neon exited lines in 2016.