Managed Investment Entities - Selected financial information related to CLOs (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Gains (losses) on change in fair value of assets/liabilities:
Assets	[1]	$ 363	$ 0	$ (316)	$ 87
Liabilities	[1]	(368)	(2)	268	(89)
Management fees paid to AFG		4	4	8	7
CLO earnings (losses) attributable to AFG shareholders	[2]	2	5	(34)	16
Variable interest entity, primary beneficiary
Variable Interest Entity [Line Items]
Investment in CLO tranches at end of period		$ 157	$ 191	$ 157	$ 191	$ 165

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

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