INVESTMENTS - Gross Unrealized Losses (Details) $ in Thousands	Jun. 30, 2023 USD ($) security	Dec. 31, 2022 USD ($) security
Fixed maturities, available for sale
Fair value
12 months or greater	$ 6,061,831	$ 3,615,234
Less than 12 months	4,453,564	6,269,478
Total	10,515,395	9,884,712
Unrealized losses
12 months or greater	(599,211)	(497,762)
Less than 12 months	(115,496)	(358,826)
Total	$ (714,707)	$ (856,588)
Number of securities in unrealized loss position | security	4,491	4,525
Number of securities in a continuous unrealized loss position | security	3,089	1,842
Fixed maturities, available for sale | Below Investment Grade or Not Rated
Unrealized losses
Total	$ (33,000)	$ (64,000)
U.S. government and agency
Fair value
12 months or greater	875,378	467,032
Less than 12 months	1,776,604	1,414,181
Total	2,651,982	1,881,213
Unrealized losses
12 months or greater	(62,863)	(41,365)
Less than 12 months	(34,730)	(56,424)
Total	(97,593)	(97,789)
Non-U.S. government
Fair value
12 months or greater	232,887	207,637
Less than 12 months	288,238	298,048
Total	521,125	505,685
Unrealized losses
12 months or greater	(30,092)	(33,027)
Less than 12 months	(7,541)	(19,885)
Total	(37,633)	(52,912)
Corporate debt
Fair value
12 months or greater	2,448,366	1,562,355
Less than 12 months	1,359,957	2,350,504
Total	3,808,323	3,912,859
Unrealized losses
12 months or greater	(288,978)	(268,289)
Less than 12 months	(38,104)	(150,701)
Total	(327,082)	(418,990)
Agency RMBS
Fair value
12 months or greater	512,098	220,595
Less than 12 months	693,467	771,191
Total	1,205,565	991,786
Unrealized losses
12 months or greater	(72,058)	(40,469)
Less than 12 months	(24,562)	(58,832)
Total	(96,620)	(99,301)
CMBS
Fair value
12 months or greater	750,801	343,494
Less than 12 months	105,984	599,877
Total	856,785	943,371
Unrealized losses
12 months or greater	(72,713)	(40,888)
Less than 12 months	(6,558)	(41,257)
Total	(79,271)	(82,145)
Non-agency RMBS
Fair value
12 months or greater	95,695	75,137
Less than 12 months	28,298	53,484
Total	123,993	128,621
Unrealized losses
12 months or greater	(15,256)	(14,691)
Less than 12 months	(644)	(3,834)
Total	(15,900)	(18,525)
ABS
Fair value
12 months or greater	1,038,046	685,990
Less than 12 months	172,761	686,190
Total	1,210,807	1,372,180
Unrealized losses
12 months or greater	(44,731)	(48,913)
Less than 12 months	(2,297)	(21,808)
Total	(47,028)	(70,721)
Municipals
Fair value
12 months or greater	108,560	52,994
Less than 12 months	28,255	96,003
Total	136,815	148,997
Unrealized losses
12 months or greater	(12,520)	(10,120)
Less than 12 months	(1,060)	(6,085)
Total	$ (13,580)	$ (16,205)