Goodwill and Other Intangibles	9 Months Ended
	Sep. 30, 2020
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	Goodwill and Other IntangiblesThere were no changes in the goodwill balance of $207 million during the first nine months of 2020. Included in other assets in AFG’s Balance Sheet is $34 million at September 30, 2020 and $43 million at December 31, 2019 in amortizable intangible assets related to property and casualty insurance acquisitions. These amounts are net of accumulated amortization of $59 million and $50 million, respectively. Amortization of intangibles was $3 million in both the third quarters of 2020 and 2019, and $9 million in both the first nine months of 2020 and 2019.