Schedule IV (SUPPLEMENTAL INFORMATION CONCERNING REINSURANCE) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 46,154	$ 41,138	$ 37,037
Ceded To Other Companies	10,195	8,433	7,243
Assumed From Other Companies	4,430	3,650	3,323
Net Amount	$ 40,389	$ 36,355	$ 33,117
Percentage of Amount Assumed to Net	11.00%	10.00%	10.00%
Property and Casualty [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 39,449	$ 35,767	$ 31,546
Ceded To Other Companies	9,678	7,982	6,782
Assumed From Other Companies	4,242	3,441	3,044
Net Amount	$ 34,013	$ 31,226	$ 27,808
Percentage of Amount Assumed to Net	12.00%	11.00%	11.00%
Accident and Health [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 5,206	$ 4,062	$ 4,249
Ceded To Other Companies	411	362	368
Assumed From Other Companies	97	109	111
Net Amount	$ 4,892	$ 3,809	$ 3,992
Percentage of Amount Assumed to Net	2.00%	3.00%	3.00%
Life [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 1,499	$ 1,309	$ 1,242
Ceded To Other Companies	106	89	93
Assumed From Other Companies	91	100	168
Net Amount	$ 1,484	$ 1,320	$ 1,317
Percentage of Amount Assumed to Net	6.00%	8.00%	13.00%