RESERVES FOR LOSSES AND LAE - Schedule of Activity in the Reserve for Losses and Loss Adjustment Expenses (“LAE”) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Gross reserve beginning of period	$ 15,796	$ 14,977
Less reinsurance recoverables on unpaid losses	(3,098)	(3,586)	$ (3,182)	$ (3,684)
Net reserves beginning of period	12,851	11,729	12,614	11,294
Incurred related to:
Current year	1,399	1,403
Prior years	(24)	(9)
Total incurred losses and LAE	1,375	1,394
Paid related to:
Current year	199	585
Prior years	910	379
Total paid losses and LAE	1,109	964
Foreign exchange/translation adjustment	(29)	5
Net reserves end of period	12,851	11,729
Plus (less) reinsurance recoverables on unpaid losses	3,098	3,586	$ 3,182	$ 3,684
Gross reserves end of period	$ 15,949	$ 15,315