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SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands | Sep. 30, 2022 | Dec. 31, 2021
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Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | $ 3,225,031 | $ 3,448,784
Gross Unrealized Gains | 159 | 65,198
Gross Unrealized (Losses) | (507,867) | (32,332)
Total AFS securities, Estimated Fair Value | 2,717,323 | 3,481,650
U.S. government and agency securities |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 70,399 | 73,830
Gross Unrealized Gains | 0 | 179
Gross Unrealized (Losses) | (8,763) | (160)
Total AFS securities, Estimated Fair Value | 61,636 | 73,849
Obligations of states and political subdivisions |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 961,722 | 971,126
Gross Unrealized Gains | 7 | 39,343
Gross Unrealized (Losses) | (197,186) | (2,073)
Total AFS securities, Estimated Fair Value | 764,543 | 1,008,396
Corporate and other bonds |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 246,411 | 150,201
Gross Unrealized Gains | 0 | 3,353
Gross Unrealized (Losses) | (15,323) | (178)
Total AFS securities, Estimated Fair Value | 231,088 | 153,376
Commercial |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 349,314 | 468,893
Gross Unrealized Gains | 84 | 6,900
Gross Unrealized (Losses) | (40,824) | (4,636)
Total AFS securities, Estimated Fair Value | 308,574 | 471,157
Commercial | Agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 247,854 | 361,806
Gross Unrealized Gains | 84 | 6,761
Gross Unrealized (Losses) | (36,739) | (4,215)
Total AFS securities, Estimated Fair Value | 211,199 | 364,352
Commercial | Non-agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 101,460 | 107,087
Gross Unrealized Gains | 0 | 139
Gross Unrealized (Losses) | (4,085) | (421)
Total AFS securities, Estimated Fair Value | 97,375 | 106,805
Residential |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,595,531 | 1,783,094
Gross Unrealized Gains | 68 | 15,423
Gross Unrealized (Losses) | (245,771) | (25,285)
Total AFS securities, Estimated Fair Value | 1,349,828 | 1,773,232
Residential | Agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,520,401 | 1,691,651
Gross Unrealized Gains | 68 | 15,180
Gross Unrealized (Losses) | (238,966) | (24,337)
Total AFS securities, Estimated Fair Value | 1,281,503 | 1,682,494
Residential | Non-agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 75,130 | 91,443
Gross Unrealized Gains | 0 | 243
Gross Unrealized (Losses) | (6,805) | (948)
Total AFS securities, Estimated Fair Value | 68,325 | 90,738
Other securities |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,654 | 1,640
Gross Unrealized Gains | 0 | 0
Gross Unrealized (Losses) | 0 | 0
Total AFS securities, Estimated Fair Value | $ 1,654 | $ 1,640

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