Managed Investment Entities - Selected financial information related to CLOs (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Gains (losses) on change in fair value of assets/liabilities:
Assets	[1]	$ (679)	$ 87
Liabilities	[1]	636	(87)
Management fees paid to AFG		4	3
CLO earnings (losses) attributable to AFG shareholders	[2]	(36)	11
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Investment in CLO tranches at end of period		$ 161	$ 193	$ 165

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

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