Goodwill and Other Intangibles	6 Months Ended
	Jun. 30, 2021
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	Goodwill and Other IntangiblesThere were no changes in the goodwill balance from AFG’s continuing operations of $176 million during the first six months of 2021.Included in other assets in AFG’s Balance Sheet is $30 million at June 30, 2021 and $34 million at December 31, 2020 in amortizable intangible assets related to property and casualty insurance acquisitions. These amounts are net of accumulated amortization of $65 million and $62 million, respectively. Amortization of intangibles was $1 million and $3 million in the second quarter of 2021 and 2020, respectively, and $4 million and $6 million in the first six months of 2021 and 2020, respectively.