Condensed Financial Information of Parent Company - Condensed Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Operating Activities:
Net earnings (loss) attributable to shareholders	$ 1,995	$ 732	$ 897
Adjustments:
Net cash provided by operating activities	1,714	2,183	2,456
Investing Activities:
Payments to acquire subsidiaries	(123)	(3)	0
Net cash used in investing activities	(436)	(1,564)	(3,065)
Financing Activities:
Additional long-term borrowings	0	634	315
Reductions of long-term debt	0	(150)	(150)
Issuances of Common Stock	66	22	36
Repurchases of Common Stock	(319)	(313)	0
Cash dividends paid on Common Stock	(2,374)	(334)	(444)
Net cash provided by (used in) financing activities	(1,957)	(123)	1,408
Cash and cash equivalents at beginning of year	1,665
Cash and cash equivalents at end of year	2,131	1,665
AFG
Operating Activities:
Net earnings (loss) attributable to shareholders	1,995	732	897
Adjustments:
Equity in net earnings of subsidiaries	(2,144)	(780)	(1,032)
Dividends from subsidiaries	830	543	408
Other operating activities, net	152	(12)	33
Net cash provided by operating activities	833	483	306
Investing Activities:
Capital contributions to subsidiaries	(107)	(297)	(60)
Returns of capital from subsidiaries	3	0	4
Investments, property and equipment	(1,478)	(2)	(3)
Payments to acquire subsidiaries	(120)	0	0
Proceeds from maturities and redemptions of investments	277	2	3
Sales of investments, property and equipment	11	0	0
Proceeds from sales of businesses	3,581	3	0
Net cash used in investing activities	2,167	(294)	(56)
Financing Activities:
Additional long-term borrowings	0	634	315
Reductions of long-term debt	0	(150)	(150)
Issuances of Common Stock	67	23	37
Repurchases of Common Stock	(319)	(313)	0
Cash dividends paid on Common Stock	(2,374)	(334)	(444)
Net cash provided by (used in) financing activities	(2,626)	(140)	(242)
Cash and cash equivalents, period increase (decrease)	374	49	8
Cash and cash equivalents at beginning of year	215	166	158
Cash and cash equivalents at end of year	$ 589	$ 215	$ 166