Segments of Operations (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Total premiums earned		$ 998	$ 946
Net investment income		411	388
Other income		46	50
Revenues before realized gains (losses)		1,493	1,440
Realized gains (losses) on securities		(18)	19
Realized losses on subsidiaries		0	(162)
Total revenues		1,475	1,297
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Net investment income		83	79
Other income		3	6
Revenues before realized gains (losses)		1,084	1,031
Annuity [Member]
Segment Reporting Information [Line Items]
Net investment income		315	292
Other income		26	27
Revenues before realized gains (losses)		341	319
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	[1]	12	46
Other [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)		56	44
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Total premiums earned		339	313
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Total premiums earned		502	490
Specialty financial [Member]
Segment Reporting Information [Line Items]
Total premiums earned		132	120
Specialty Other [Member]
Segment Reporting Information [Line Items]
Total premiums earned		$ 25	$ 23

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