Managed Investment Entities - Selected financial information related to CLOs (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Gains (losses) on change in fair value of assets/liabilities:
Assets	[1]	$ (9)	$ 48	$ (4)	$ 47
Liabilities	[1]	20	(37)	15	(49)
Management fees paid to AFG		5	4	9	8
CLO earnings (losses) attributable to AFG shareholders	[2]	5	19	11	12
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Investment in CLO tranches at end of period		$ 188	$ 218	$ 188	$ 218	$ 216

[1] Included in revenues in AFG’s Statement of Earnings.

[2] Included in earnings before income taxes in AFG’s Statement of Earnings.