REINSURANCE - Schedule of Premiums Written And Earned And Incurred Losses (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Written premiums:
Direct	$ 3,785	$ 3,701	$ 3,300
Assumed	7,332	5,975	6,031
Ceded	(1,905)	(1,645)	(1,612)
Net written premiums	9,212	8,032	7,719
Premiums earned:
Direct	3,709	3,544	2,982
Assumed	6,705	5,945	5,741
Ceded	(1,878)	(1,613)	(1,544)
Net premiums earned	8,536	7,876	7,179
Incurred losses and LAE:
Direct	2,594	2,423	2,043
Assumed	3,449	4,107	3,872
Ceded	(465)	(708)	(528)
Net incurred losses and LAE	$ 5,578	$ 5,823	$ 5,387