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INVESTMENT SECURITIES - Investment Securities in a Continuous Unrealized Loss Position (Details) $ in Thousands | Jun. 30, 2022 USD ($) | Dec. 31, 2021 USD ($)
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Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | 1,242 | 240
12 months or longer | 109 | 66
Total | 1,351 | 306
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 4,367,516 | $ 1,395,578
12 months or longer | 902,376 | 967,788
Total | 5,269,892 | 2,363,366
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 356,573 | 17,505
12 months or longer | 311,052 | 93,774
Total | 667,625 | $ 111,279
Available-for-sale, allowance for credit losses | 0 |
Available-for-sale Securities [Member] |  |
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses [Abstract] |  |
Accrued interest receivable | $ 20,200 |
U.S. Treasury and Agency Securities |  |
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | 109 | 47
12 months or longer | 18 | 13
Total | 127 | 60
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 3,693,538 | $ 1,224,101
12 months or longer | 797,349 | 900,462
Total | 4,490,887 | 2,124,563
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 291,840 | 14,873
12 months or longer | 292,524 | 91,184
Total | $ 584,364 | $ 106,057
Obligations of State and Political Subdivisions |  |
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | 514 | 27
12 months or longer | 0 | 0
Total | 514 | 27
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 348,257 | $ 23,966
12 months or longer | 0 | 0
Total | 348,257 | 23,966
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 40,770 | 56
12 months or longer | 0 | 0
Total | $ 40,770 | $ 56
Government Agency Mortgage-Backed Securities |  |
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | 578 | 147
12 months or longer | 90 | 52
Total | 668 | 199
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 304,192 | $ 139,442
12 months or longer | 105,017 | 67,273
Total | 409,209 | 206,715
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 22,788 | 2,475
12 months or longer | 18,528 | 2,590
Total | $ 41,316 | $ 5,065
Corporate debt securities |  |
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | 2 | 1
12 months or longer | 0 | 0
Total | 2 | 1
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 7,231 | $ 4,923
12 months or longer | 0 | 0
Total | 7,231 | 4,923
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 769 | 77
12 months or longer | 0 | 0
Total | $ 769 | $ 77
Government Agency Collateralized Mortgage Obligations |  |
Available-for-Sale Securities in Unrealized Loss Positions, Number of Positions [Abstract] |  |
Less than 12 months | 39 | 18
12 months or longer | 1 | 1
Total | 40 | 19
Available-for-Sale Securities, in Unrealized Loss Position, Fair Value [Abstract] |  |
Less than 12 months | $ 14,298 | $ 3,146
12 months or longer | 10 | 53
Total | 14,308 | 3,199
Available-for-Sale Securities, in Unrealized Loss Position, Gross Unrealized Losses [Abstract] |  |
Less than 12 months | 406 | 24
12 months or longer | 0 | 0
Total | $ 406 | $ 24

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