Managed Investment Entities - Selected financial information related to CLOs (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Gains (losses) on change in fair value of assets/liabilities:
Assets	[1]	$ (189)	$ (8)	$ 131
Liabilities	[1]	168	20	(116)
Management fees paid to AFG		16	18	17
CLO earnings (losses) attributable to AFG Shareholders	[2]	7	23	37
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Investment in CLO tranches		$ 188	$ 215	$ 216

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

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