Long-Term Debt - Narrative (Details) - USD ($)	1 Months Ended	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2022	Jun. 30, 2021	Jun. 03, 2022	Dec. 31, 2021
Long-term Debt, Fiscal Year Maturity [Abstract]
Scheduled principal payments on debt remainder of fiscal year	$ 0	$ 0
Scheduled principal payments on debt in year one	0	0
Scheduled principal payments on debt in year two	0	0
Scheduled principal payments on debt in year three	0	0
Scheduled principal payments on debt in year four	0	0
Scheduled principal payments on debt in year five	0	0
Scheduled principal payments on debt thereafter	1,570,000,000	1,570,000,000
Reductions of long-term debt		433,000,000	$ 0
3.50% Senior Notes due August 2026 | Senior Notes
Long-term Debt, Fiscal Year Maturity [Abstract]
Loss on retirement of debt, including make-whole call premium	(6,000,000)
AFG
Long-term Debt, Fiscal Year Maturity [Abstract]
Revolving credit line	500,000,000	500,000,000
Amount borrowed under revolving credit facility	0	0			$ 0
AFG | 3.50% Senior Notes due August 2026 | Senior Notes
Long-term Debt, Fiscal Year Maturity [Abstract]
Face amount of debt repurchased	$ 49,000,000	$ 49,000,000		$ 376,000,000
Interest rate on debt instruments	3.50%	3.50%		3.50%
Reductions of long-term debt	$ 382,000,000
Amount of debt repurchased	$ 51,000,000	$ 51,000,000
LIBOR | AFG
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate on revolving debt facility		1.375%
LIBOR | AFG | Minimum
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate on revolving debt facility		1.00%
LIBOR | AFG | Maximum
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate on revolving debt facility		1.875%