INVESTMENTS - Schedule of Contractual Maturities of Fixed Maturity Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Amortized  Cost
Due in less than one year	$ 392,098	$ 364,501
Due after one through five years	8,891,383	8,117,971
Due after five through ten years	4,896,604	4,072,142
Due after ten years	309,877	356,268
Amortized  Cost	16,754,568	15,038,551
Fair Value
Due in less than one year	384,293	356,770
Due after one through five years	8,682,922	7,875,771
Due after five through ten years	4,606,488	3,805,287
Due after ten years	261,019	311,856
Fixed maturity investments trading	16,083,046	14,351,402
Mortgage-backed
Amortized  Cost
Amortized  Cost	1,119,512	1,009,205
Fair Value
Fixed maturity investments trading	1,017,062	924,416
Asset-backed
Amortized  Cost
Amortized  Cost	1,145,094	1,118,464
Fair Value
Fixed maturity investments trading	$ 1,131,262	$ 1,077,302