DEBT SECURITIES - Debt securities in an unrealized loss position (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Fair Value
Less than 12 months	$ 1,070,674	$ 2,676,734
12 months or more	1,368,859	106,443
Total	2,439,533	2,783,177
Unrealized Losses
Less than 12 months	(81,841)	(49,847)
12 months or more	(229,363)	(4,807)
Total	(311,204)	(54,654)
Fair Value
Less than 12 months	58,065
12 months or more	727,230
Total	785,295	0
Unrealized Losses
Less than 12 months	(8,009)
12 months or more	(125,008)
Total	(133,017)	0
U.S. Treasury securities
Fair Value
Less than 12 months	74	163,653
12 months or more	113,987	0
Total	114,061	163,653
Unrealized Losses
Less than 12 months	0	(1,047)
12 months or more	(3,744)	0
Total	(3,744)	(1,047)
Obligations of U.S. government corporations and agencies
Fair Value
Less than 12 months	19,603
12 months or more	0
Total	19,603
Unrealized Losses
Less than 12 months	(321)
12 months or more	0
Total	(321)
Obligations of states and political subdivisions
Fair Value
Less than 12 months	166,147	92,680
12 months or more	75,217	0
Total	241,364	92,680
Unrealized Losses
Less than 12 months	(10,059)	(1,493)
12 months or more	(16,016)	0
Total	(26,075)	(1,493)
Asset-backed securities
Fair Value
Less than 12 months	390,164	89,983
12 months or more	79,711	0
Total	469,875	89,983
Unrealized Losses
Less than 12 months	(15,648)	(164)
12 months or more	(4,035)	0
Total	(19,683)	(164)
Commercial mortgage-backed securities
Fair Value
Less than 12 months	89,428	389,078
12 months or more	18,966	85,905
Total	108,394	474,983
Unrealized Losses
Less than 12 months	(12,623)	(10,186)
12 months or more	(3,406)	(3,580)
Total	(16,029)	(13,766)
Fair Value
Less than 12 months	58,065
12 months or more	353,017
Total	411,082
Unrealized Losses
Less than 12 months	(8,009)
12 months or more	(55,729)
Total	(63,738)
Residential mortgage-backed securities
Fair Value
Less than 12 months	366,221	1,700,187
12 months or more	876,668	20,538
Total	1,242,889	1,720,725
Unrealized Losses
Less than 12 months	(38,111)	(33,453)
12 months or more	(182,606)	(1,227)
Total	(220,717)	(34,680)
Fair Value
Less than 12 months	0
12 months or more	374,213
Total	374,213
Unrealized Losses
Less than 12 months	0
12 months or more	(69,279)
Total	(69,279)
Corporate debt securities
Fair Value
Less than 12 months	39,037	241,153
12 months or more	204,310	0
Total	243,347	241,153
Unrealized Losses
Less than 12 months	(5,079)	(3,504)
12 months or more	(19,556)	0
Total	$ (24,635)	$ (3,504)