Managed Investment Entities - Selected financial information related to CLOs (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Gains (losses) on change in fair value of assets/liabilities:
Assets	[1]	$ 87	$ 14
Liabilities	[1]	(87)	(17)
Management fees paid to AFG		3	4
CLO earnings (losses) attributable to AFG shareholders	[2]	11	3
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Investment in CLO tranches at end of period		$ 193	$ 221	$ 188

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

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