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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, 2023 | Dec. 31, 2022
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Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | $ 2,608,028 | $ 3,204,361
Gross Unrealized Gains | 308 | 293
Gross Unrealized (Losses) | (523,408) | (462,838)
Total AFS securities, Estimated Fair Value | 2,084,928 | 2,741,816
U.S. government and agency securities |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 62,221 | 70,196
Gross Unrealized Gains | 0 | 0
Gross Unrealized (Losses) | (383) | (8,253)
Total AFS securities, Estimated Fair Value | 61,838 | 61,943
Obligations of states and political subdivisions |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 587,340 | 959,999
Gross Unrealized Gains | 0 | 137
Gross Unrealized (Losses) | (169,880) | (152,701)
Total AFS securities, Estimated Fair Value | 417,460 | 807,435
Corporate and other bonds |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 267,816 | 243,979
Gross Unrealized Gains | 0 | 0
Gross Unrealized (Losses) | (24,998) | (17,599)
Total AFS securities, Estimated Fair Value | 242,818 | 226,380
Commercial |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 287,260 | 349,598
Gross Unrealized Gains | 307 | 75
Gross Unrealized (Losses) | (52,864) | (43,512)
Total AFS securities, Estimated Fair Value | 234,703 | 306,161
Commercial | Agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 215,203 | 250,186
Gross Unrealized Gains | 307 | 75
Gross Unrealized (Losses) | (50,289) | (39,268)
Total AFS securities, Estimated Fair Value | 165,221 | 210,993
Commercial | Non-agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 72,057 | 99,412
Gross Unrealized Gains | 0 | 0
Gross Unrealized (Losses) | (2,575) | (4,244)
Total AFS securities, Estimated Fair Value | 69,482 | 95,168
Residential |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,401,664 | 1,578,925
Gross Unrealized Gains | 1 | 81
Gross Unrealized (Losses) | (275,283) | (240,773)
Total AFS securities, Estimated Fair Value | 1,126,382 | 1,338,233
Residential | Agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,319,987 | 1,510,110
Gross Unrealized Gains | 1 | 81
Gross Unrealized (Losses) | (268,152) | (233,961)
Total AFS securities, Estimated Fair Value | 1,051,836 | 1,276,230
Residential | Non-agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 81,677 | 68,815
Gross Unrealized Gains | 0 | 0
Gross Unrealized (Losses) | (7,131) | (6,812)
Total AFS securities, Estimated Fair Value | 74,546 | 62,003
Other securities |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,727 | 1,664
Gross Unrealized Gains | 0 | 0
Gross Unrealized (Losses) | 0 | 0
Total AFS securities, Estimated Fair Value | $ 1,727 | $ 1,664

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- Definition Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481800/320-10-50-2 + Details
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