INVESTMENTS - Schedule of Fair Value of Fixed Maturity Investments Trading (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Schedule of Investments [Line Items]
Total fixed maturity investments trading	$ 16,083,046	$ 14,351,402
U.S. treasuries
Schedule of Investments [Line Items]
Total fixed maturity investments trading	8,587,946	7,180,129
Corporate
Schedule of Investments [Line Items]
Total fixed maturity investments trading	4,482,082	4,390,568
Agencies
Schedule of Investments [Line Items]
Total fixed maturity investments trading	460,936	395,149
Non-U.S. government
Schedule of Investments [Line Items]
Total fixed maturity investments trading	403,758	383,838
Residential mortgage-backed
Schedule of Investments [Line Items]
Total fixed maturity investments trading	806,120	710,429
Commercial mortgage-backed
Schedule of Investments [Line Items]
Total fixed maturity investments trading	210,942	213,987
Asset-backed
Schedule of Investments [Line Items]
Total fixed maturity investments trading	$ 1,131,262	$ 1,077,302