Schedule IV (SUPPLEMENTAL INFORMATION CONCERNING REINSURANCE) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 41,138	$ 37,037	$ 35,876
Ceded To Other Companies	8,433	7,243	7,693
Assumed From Other Companies	3,650	3,323	3,107
Net Amount	$ 36,355	$ 33,117	$ 31,290
Percentage of Amount Assumed to Net	10.00%	10.00%	10.00%
Property and Casualty [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 35,767	$ 31,546	$ 30,339
Ceded To Other Companies	7,982	6,782	7,236
Assumed From Other Companies	3,441	3,044	2,797
Net Amount	$ 31,226	$ 27,808	$ 25,900
Percentage of Amount Assumed to Net	11.00%	11.00%	11.00%
Accident and Health [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 4,062	$ 4,249	$ 4,546
Ceded To Other Companies	362	368	376
Assumed From Other Companies	109	111	119
Net Amount	$ 3,809	$ 3,992	$ 4,289
Percentage of Amount Assumed to Net	3.00%	3.00%	3.00%
Life [Member]
SEC Schedule, 12-17, Insurance Companies, Reinsurance [Line Items]
Direct Amount	$ 1,309	$ 1,242	$ 991
Ceded To Other Companies	89	93	81
Assumed From Other Companies	100	168	191
Net Amount	$ 1,320	$ 1,317	$ 1,101
Percentage of Amount Assumed to Net	8.00%	13.00%	17.00%