Condensed Financial Information of Parent Company - Condensed Statement of Earnings (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
Total revenues	$ 1,737	$ 1,705	$ 1,581	$ 1,475	$ 1,618	$ 1,687	$ 1,543	$ 1,297	$ 6,498	$ 6,145	$ 5,733
Costs and Expenses:
Other expenses									353	336	280
Total costs and expenses									5,711	5,580	5,107
Earnings before income taxes									787	565	626
Provision for income taxes									119	195	220
Net Earnings Attributable to Shareholders	385	$ 109	$ 54	$ 101	$ 129	$ 63	$ 141	$ 19	649	352	452
AFG
Revenues:
Dividends from subsidiaries									643	311	480
Equity in undistributed earnings of subsidiaries									286	386	332
Investment and other income									7	4	5
Total revenues									936	701	817
Costs and Expenses:
Interest charges on intercompany borrowings									9	9	10
Interest charges on other borrowings									77	73	70
Other expenses									82	72	65
Total costs and expenses									168	154	145
Earnings before income taxes									768	547	672
Provision for income taxes	$ (177)								119	195	220
Net Earnings Attributable to Shareholders									$ 649	$ 352	$ 452