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SECURITIES AND OTHER INVESTMENTS (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
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Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | $ 2,942,685 | $ 2,615,536
Gross Unrealized Gains | 9,292 | 1,592
Gross Unrealized (Losses) | (343,795) | (385,867)
Total AFS securities, Estimated Fair Value | 2,608,182 | 2,231,261
US Government Agencies Debt Securities [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 65,384 | 62,367
Gross Unrealized Gains | 1,313 | 1,023
Gross Unrealized (Losses) | (26) | (34)
Total AFS securities, Estimated Fair Value | 66,671 | 63,356
US States and Political Subdivisions Debt Securities [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 600,074 | 586,865
Gross Unrealized Gains | 294 | 33
Gross Unrealized (Losses) | (111,841) | (111,451)
Total AFS securities, Estimated Fair Value | 488,527 | 475,447
Corporate Bond Securities [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 283,861 | 261,656
Gross Unrealized Gains | 631 | 7
Gross Unrealized (Losses) | (12,517) | (19,774)
Total AFS securities, Estimated Fair Value | 271,975 | 241,889
Commercial Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 364,248 | 300,518
Gross Unrealized Gains | 1,926 | 274
Gross Unrealized (Losses) | (39,357) | (43,146)
Total AFS securities, Estimated Fair Value | 326,817 | 257,646
Commercial Mortgage-Backed Securities [Member] | Agency Securities [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 287,747 | 233,775
Gross Unrealized Gains | 1,724 | 274
Gross Unrealized (Losses) | (37,721) | (41,181)
Total AFS securities, Estimated Fair Value | 251,750 | 192,868
Commercial Mortgage-Backed Securities [Member] | Non-agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 76,501 | 66,743
Gross Unrealized Gains | 202 | 0
Gross Unrealized (Losses) | (1,636) | (1,965)
Total AFS securities, Estimated Fair Value | 75,067 | 64,778
Residential Mortgage-Backed Securities [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,627,286 | 1,402,378
Gross Unrealized Gains | 5,128 | 255
Gross Unrealized (Losses) | (180,054) | (211,462)
Total AFS securities, Estimated Fair Value | 1,452,360 | 1,191,171
Residential Mortgage-Backed Securities [Member] | Agency Securities [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,522,319 | 1,312,538
Gross Unrealized Gains | 4,144 | 114
Gross Unrealized (Losses) | (176,187) | (205,635)
Total AFS securities, Estimated Fair Value | 1,350,276 | 1,107,017
Residential Mortgage-Backed Securities [Member] | Non-agency |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 104,967 | 89,840
Gross Unrealized Gains | 984 | 141
Gross Unrealized (Losses) | (3,867) | (5,827)
Total AFS securities, Estimated Fair Value | 102,084 | 84,154
Collateralized Securities, Other [Member] |  |
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract] |  |
Total AFS securities | 1,832 | 1,752
Gross Unrealized Gains | 0 | 0
Gross Unrealized (Losses) | 0 | 0
Total AFS securities, Estimated Fair Value | $ 1,832 | $ 1,752

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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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