SCHEDULE IV - SUPPLEMENTARY REINSURANCE INFORMATION (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Supplementary Insurance Information [Line Items]
GROSS AMOUNT	$ 5,102,958	$ 4,405,452	$ 3,610,201
CEDED TO OTHER COMPANIES	2,951,539	2,759,360	2,490,529
ASSUMED FROM OTHER COMPANIES	3,111,637	3,280,532	3,216,737
Net	$ 5,263,056	$ 4,926,624	$ 4,336,409
PERCENTAGE OF AMOUNT ASSUMED TO NET	59.10%	66.60%	74.20%
Property and Casualty
Supplementary Insurance Information [Line Items]
GROSS AMOUNT	$ 4,858,629	$ 4,233,758	$ 3,455,690
CEDED TO OTHER COMPANIES	2,900,300	2,700,693	2,446,890
ASSUMED FROM OTHER COMPANIES	2,685,677	2,874,687	2,840,834
Net	$ 4,644,006	$ 4,407,752	$ 3,849,634
PERCENTAGE OF AMOUNT ASSUMED TO NET	57.80%	65.20%	73.80%
Accident and health
Supplementary Insurance Information [Line Items]
GROSS AMOUNT	$ 244,329	$ 171,694	$ 154,511
CEDED TO OTHER COMPANIES	51,239	58,667	43,639
ASSUMED FROM OTHER COMPANIES	425,960	405,845	375,903
Net	$ 619,050	$ 518,872	$ 486,775
PERCENTAGE OF AMOUNT ASSUMED TO NET	68.80%	78.20%	77.20%