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DEBT SECURITIES - Debt securities in an unrealized loss position (Details) - USD ($) $ in Thousands | Mar. 31, 2024 | Dec. 31, 2023
--- | --- | ---
Fair Value |  |
Less than 12 months | $ 13,002 | $ 13,033
12 months or more | 1,661,232 | 2,049,784
Total | 1,674,234 | 2,062,817
Unrealized Losses |  |
Less than 12 months | (171) | (65)
Unrealized Losses | (248,141) | (247,180)
Total | (248,312) | (247,245)
Fair Value |  |
12 months or more | 713,031 | 730,397
Total | 713,031 | 730,397
Unrealized Losses |  |
12 months or more | (149,187) | (142,231)
Total | (149,187) | (142,231)
U.S. Treasury securities |  |
Fair Value |  |
Less than 12 months | 0 | 0
12 months or more | 742 | 15,946
Total | 742 | 15,946
Unrealized Losses |  |
Less than 12 months | 0 | 0
Unrealized Losses | (7) | (85)
Total | (7) | (85)
Obligations of U.S. government corporations and agencies |  |
Fair Value |  |
Less than 12 months | 0 | 0
12 months or more | 5,629 | 5,709
Total | 5,629 | 5,709
Unrealized Losses |  |
Less than 12 months | 0 | 0
Unrealized Losses | (35) | (58)
Total | (35) | (58)
Obligations of states and political subdivisions |  |
Fair Value |  |
Less than 12 months | 8,524 | 11,442
12 months or more | 134,945 | 146,797
Total | 143,469 | 158,239
Unrealized Losses |  |
Less than 12 months | (68) | (54)
Unrealized Losses | (18,023) | (17,972)
Total | (18,091) | (18,026)
Asset-backed securities |  |
Fair Value |  |
Less than 12 months | 0 | 0
12 months or more | 253,231 | 468,223
Total | 253,231 | 468,223
Unrealized Losses |  |
Less than 12 months | 0 | 0
Unrealized Losses | (384) | (1,823)
Total | (384) | (1,823)
Commercial mortgage-backed securities |  |
Fair Value |  |
Less than 12 months | 0 | 0
12 months or more | 92,563 | 103,509
Total | 92,563 | 103,509
Unrealized Losses |  |
Less than 12 months | 0 | 0
Unrealized Losses | (15,443) | (15,535)
Total | (15,443) | (15,535)
Fair Value |  |
12 months or more | 350,356 | 357,526
Total | 350,356 | 357,526
Unrealized Losses |  |
12 months or more | (74,590) | (71,000)
Total | (74,590) | (71,000)
Residential mortgage-backed securities |  |
Fair Value |  |
Less than 12 months | 165 | 141
12 months or more | 1,021,383 | 1,110,906
Total | 1,021,548 | 1,111,047
Unrealized Losses |  |
Less than 12 months | (1) | (1)
Unrealized Losses | (201,721) | (195,546)
Total | (201,722) | (195,547)
Fair Value |  |
12 months or more | 362,675 | 372,871
Total | 362,675 | 372,871
Unrealized Losses |  |
12 months or more | (74,597) | (71,231)
Total | (74,597) | (71,231)
Corporate debt securities |  |
Fair Value |  |
Less than 12 months | 4,313 | 1,450
12 months or more | 152,739 | 198,694
Total | 157,052 | 200,144
Unrealized Losses |  |
Less than 12 months | (102) | (10)
Unrealized Losses | (12,528) | (16,161)
Total | $ (12,630) | $ (16,171)

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