Income Taxes - Narrative (Details) £ in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2021 GBP (£)
Income Tax Reconciliation [Line Items]
Statutory rate of income taxes	21.00%	21.00%	21.00%
Income tax expense (benefit)	$ 254	$ 25	$ 143
Effective income tax rate reconciliation, percent, excluding the impact of the sale of subsidiaries		28.00%
Income (losses) subject to tax in foreign jurisdictions	33	$ (131)	(109)
Operating loss carryforwards, valuation allowance	9
Interest on income taxes accrued		0
Amount of expense for penalties related to a tax position	0
Cash payments for income taxes	$ 212	179	278
Limitation on the use of tax credit carryforwards	A SRLY NOL can be used only by the entity that created it and only in years that both it and the consolidated group have taxable income. Approximately $27 million of AFG’s SRLY NOLs expired unutilized at December 31, 2021.
Amount unutilized
Income Tax Reconciliation [Line Items]
Operating loss carryforwards	$ 27
Neon Capital Limited
Income Tax Reconciliation [Line Items]
Income tax expense (benefit)		(72)
Income tax benefit, portion attributable to current taxes payable		(65)
AFG
Income Tax Reconciliation [Line Items]
Income tax expense (benefit)	360	127	239
Unrecognized tax benefits that would impact the effective tax rate		0
Interest included in tax provision		0	0
Income tax penalties accrued	0	0
Maximum | AFG
Income Tax Reconciliation [Line Items]
Unrecognized tax benefits that would impact the effective tax rate	1
Interest included in tax provision	1
Interest on income taxes accrued	1
Amount of expense for penalties related to a tax position		$ 0	$ 1
United Kingdom
Income Tax Reconciliation [Line Items]
Operating loss carryforwards	$ 37			£ 28