INVESTMENTS - Gross Unrealized Losses (Details) - USD ($) $ in Thousands	Jun. 30, 2025	Dec. 31, 2024
Fair value
12 months or greater	$ 1,548,088	$ 2,253,146
Less than 12 months	2,052,449	4,880,934
Total	3,600,537	7,134,080
Unrealized losses
12 months or greater	(99,691)	(185,909)
Less than 12 months	(40,733)	(125,426)
Total	(140,424)	(311,335)
U.S. government and agency
Fair value
12 months or greater	191,104	262,368
Less than 12 months	284,551	1,026,139
Total	475,655	1,288,507
Unrealized losses
12 months or greater	(7,703)	(17,515)
Less than 12 months	(1,349)	(15,621)
Total	(9,052)	(33,136)
Non-U.S. government
Fair value
12 months or greater	51,913	98,846
Less than 12 months	88,634	457,889
Total	140,547	556,735
Unrealized losses
12 months or greater	(2,937)	(9,179)
Less than 12 months	(971)	(16,781)
Total	(3,908)	(25,960)
Corporate debt
Fair value
12 months or greater	612,795	934,975
Less than 12 months	653,866	2,032,254
Total	1,266,661	2,967,229
Unrealized losses
12 months or greater	(40,511)	(78,979)
Less than 12 months	(15,019)	(47,245)
Total	(55,530)	(126,224)
Agency RMBS
Fair value
12 months or greater	211,459	280,550
Less than 12 months	608,114	749,040
Total	819,573	1,029,590
Unrealized losses
12 months or greater	(21,542)	(35,333)
Less than 12 months	(15,227)	(26,657)
Total	(36,769)	(61,990)
CMBS
Fair value
12 months or greater	295,077	410,213
Less than 12 months	207,460	260,411
Total	502,537	670,624
Unrealized losses
12 months or greater	(14,764)	(22,334)
Less than 12 months	(7,469)	(11,836)
Total	(22,233)	(34,170)
Non-agency RMBS
Fair value
12 months or greater	46,613	69,418
Less than 12 months	17,089	8,302
Total	63,702	77,720
Unrealized losses
12 months or greater	(5,277)	(9,900)
Less than 12 months	(19)	(82)
Total	(5,296)	(9,982)
ABS
Fair value
12 months or greater	108,310	147,281
Less than 12 months	184,532	295,897
Total	292,842	443,178
Unrealized losses
12 months or greater	(5,221)	(8,471)
Less than 12 months	(508)	(4,806)
Total	(5,729)	(13,277)
Municipals
Fair value
12 months or greater	30,817	49,495
Less than 12 months	8,203	51,002
Total	39,020	100,497
Unrealized losses
12 months or greater	(1,736)	(4,198)
Less than 12 months	(171)	(2,398)
Total	$ (1,907)	$ (6,596)