Segments of Operations (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Segment Reporting Information [Line Items]
Total premiums earned		$ 1,027	$ 985	$ 2,025	$ 1,931
Net investment income		423	404	834	792
Other income		80	92	126	142
Revenues before realized gains (losses)		1,595	1,544	3,088	2,984
Realized gains (losses) on securities		(16)	(1)	(34)	18
Realized gains (losses) on subsidiaries		2	0	2	(162)
Total revenues		1,581	1,543	3,056	2,840
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Total premiums earned		1,027	985	2,025	1,931
Net investment income		89	83	172	162
Other income	[1]	40	53	43	59
Revenues before realized gains (losses)		1,156	1,121	2,240	2,152
Annuity [Member]
Segment Reporting Information [Line Items]
Net investment income		344	306	659	598
Other income		24	24	50	51
Revenues before realized gains (losses)		368	330	709	649
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	[2]	12	49	24	95
Other [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)		59	44	115	88
Specialty Property and transportation [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Total premiums earned		365	327	704	640
Specialty casualty [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Total premiums earned		497	503	999	993
Specialty financial [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Total premiums earned		139	129	271	249
Specialty Other [Member] | Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Total premiums earned		$ 26	$ 26	$ 51	$ 49

[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.