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INVESTMENT SECURITIES - Investment securities in a continuous unrealized loss position (Details) $ in Thousands | Dec. 31, 2023 USD ($) position | Dec. 31, 2022 USD ($)
--- | --- | ---
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value |  |
Less than 12 months | $ 72,127 | $ 1,955,294
12 months or longer | 2,720,541 | 2,106,692
Total | 2,792,668 | 4,061,986
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses |  |
Less than 12 months | 933 | 188,107
12 months or longer | 382,227 | 336,081
Total | 383,160 | 524,188
Fair Value |  |
Less than 12 Months | 555,836 | 1,034,795
12 Months or Longer | 522,743 | 0
Total | 1,078,579 | 1,034,795
Gross Unrealized Losses |  |
Less than 12 Months | 16,111 | 44,900
12 Months or Longer | 34,935 | 0
Total | 51,046 | 44,900
Available-for-sale, allowance for credit losses | 0 | 0
Accrued interest receivable on available-for-sale debt securities | $ 14,400 | $ 19,300
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration] | Interest Receivable | Interest Receivable
U.S. Treasury and agency securities |  |
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value |  |
Less than 12 months | $ 0 | $ 1,384,075
12 months or longer | 2,080,783 | 1,859,462
Total | 2,080,783 | 3,243,537
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses |  |
Less than 12 months | 0 | 132,511
12 months or longer | 300,385 | 284,498
Total | 300,385 | 417,009
Fair Value |  |
Less than 12 Months | 536,885 | 1,034,795
12 Months or Longer | 521,350 | 0
Total | 1,058,235 | 1,034,795
Gross Unrealized Losses |  |
Less than 12 Months | 15,953 | 44,900
12 Months or Longer | 34,913 | 0
Total | 50,866 | 44,900
Obligations of state and political subdivisions |  |
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value |  |
Less than 12 months | 63,541 | 370,524
12 months or longer | 287,191 | 47,923
Total | 350,732 | 418,447
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses |  |
Less than 12 months | 878 | 35,488
12 months or longer | 29,107 | 9,839
Total | 29,985 | 45,327
Government agency mortgage-backed securities |  |
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value |  |
Less than 12 months | 8,586 | 190,727
12 months or longer | 336,266 | 189,919
Total | 344,852 | 380,646
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses |  |
Less than 12 months | 55 | 19,508
12 months or longer | 51,557 | 40,606
Total | 51,612 | 60,114
Fair Value |  |
Less than 12 Months | 18,951 |
12 Months or Longer | 1,393 |
Total | 20,344 |
Gross Unrealized Losses |  |
Less than 12 Months | 158 |
12 Months or Longer | 22 |
Total | $ 180 |
Corporate debt securities |  |
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions |  |
Total | position | 2 |
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value |  |
Less than 12 months | $ 0 | 0
12 months or longer | 7,394 | 7,114
Total | 7,394 | 7,114
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses |  |
Less than 12 months | 0 | 0
12 months or longer | 606 | 886
Total | 606 | 886
Government agency collateralized mortgage obligations |  |
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value |  |
Less than 12 months | 0 | 9,968
12 months or longer | 8,907 | 2,274
Total | 8,907 | 12,242
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses |  |
Less than 12 months | 0 | 600
12 months or longer | 572 | 252
Total | $ 572 | $ 852

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