INVESTMENTS - Schedule of Contractual Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2024	Dec. 31, 2023
Amortized cost
Due in one year or less	$ 895,177	$ 474,557
Due after one year through five years	5,637,336	5,902,571
Due after five years through ten years	1,895,116	2,064,619
Due after ten years	214,595	157,653
Total fixed maturities with a single maturity date (amortized cost)	8,642,224	8,599,400
Amortized cost	12,419,905	12,634,254
Fair value
Due in one year or less	885,866	463,789
Due after one year through five years	5,567,905	5,790,493
Due after five years through ten years	1,826,564	1,954,449
Due after ten years	205,597	155,287
Total fixed maturities with a single maturity date (fair value)	8,485,932	8,364,018
Fair value	$ 12,152,753	$ 12,234,742
% of Total fair value
Due in one year or less	7.40%	3.60%
Due after one year through five years	45.80%	47.30%
Due after five years through ten years	15.00%	16.00%
Due after ten years	1.70%	1.30%
Fixed maturities with a single maturity date (% of total fair value)	69.90%	68.20%
Total	100.00%	100.00%
Agency RMBS
Amortized cost
Fixed maturities without a single maturity date	$ 1,245,681	$ 1,706,204
Amortized cost	1,245,681	1,706,204
Fair value
Fixed maturities without a single maturity date (fair value)	1,184,845	1,634,661
Fair value	$ 1,184,845	$ 1,634,661
% of Total fair value
Fixed maturities without a single maturity date (% of total fair value)	9.70%	13.40%
CMBS
Amortized cost
Fixed maturities without a single maturity date	$ 852,534	$ 897,553
Amortized cost	852,534	897,553
Fair value
Fixed maturities without a single maturity date (fair value)	819,608	839,696
Fair value	$ 819,608	$ 839,696
% of Total fair value
Fixed maturities without a single maturity date (% of total fair value)	6.70%	6.90%
Non-agency RMBS
Amortized cost
Fixed maturities without a single maturity date	$ 132,116	$ 165,910
Amortized cost	132,116	165,910
Fair value
Fixed maturities without a single maturity date (fair value)	122,536	153,396
Fair value	$ 122,536	$ 153,396
% of Total fair value
Fixed maturities without a single maturity date (% of total fair value)	1.00%	1.30%
ABS
Amortized cost
Fixed maturities without a single maturity date	$ 1,547,350	$ 1,265,187
Amortized cost	1,547,350	1,265,187
Fair value
Fixed maturities without a single maturity date (fair value)	1,539,832	1,242,971
Fair value	$ 1,539,832	$ 1,242,971
% of Total fair value
Fixed maturities without a single maturity date (% of total fair value)	12.70%	10.20%