Quarterly report [Sections 13 or 15(d)]

SECURITIES AND OTHER INVESTMENTS (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details)

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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, 2026
Dec. 31, 2025
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities $ 4,223,973 $ 4,489,998
Gross Unrealized Gains 1,786 19,804
Gross Unrealized (Losses) (476,794) (315,501)
Total AFS securities, Estimated Fair Value 3,748,965 4,194,301
US Government Agencies Debt Securities [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 99,959 103,335
Gross Unrealized Gains 57 681
Gross Unrealized (Losses) (225) (14)
Total AFS securities, Estimated Fair Value 99,791 104,002
US States and Political Subdivisions Debt Securities [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 595,755 589,194
Gross Unrealized Gains 2 178
Gross Unrealized (Losses) (156,541) (101,487)
Total AFS securities, Estimated Fair Value 439,216 487,885
Corporate Bond Securities [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 206,525 221,432
Gross Unrealized Gains 531 709
Gross Unrealized (Losses) (2,511) (4,207)
Total AFS securities, Estimated Fair Value 204,545 217,934
Commercial Mortgage-Backed Securities [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 450,074 469,414
Gross Unrealized Gains 295 1,463
Gross Unrealized (Losses) (54,555) (41,711)
Total AFS securities, Estimated Fair Value 395,814 429,166
Commercial Mortgage-Backed Securities [Member] | Agency Securities [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 332,716 354,405
Gross Unrealized Gains 295 1,276
Gross Unrealized (Losses) (50,588) (39,806)
Total AFS securities, Estimated Fair Value 282,423 315,875
Commercial Mortgage-Backed Securities [Member] | Non-agency    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 117,358 115,009
Gross Unrealized Gains 0 187
Gross Unrealized (Losses) (3,967) (1,905)
Total AFS securities, Estimated Fair Value 113,391 113,291
Residential Mortgage-Backed Securities [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 2,869,639 3,104,667
Gross Unrealized Gains 901 16,773
Gross Unrealized (Losses) (262,962) (168,082)
Total AFS securities, Estimated Fair Value 2,607,578 2,953,358
Residential Mortgage-Backed Securities [Member] | Agency Securities [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 2,732,428 2,942,900
Gross Unrealized Gains 901 15,838
Gross Unrealized (Losses) (256,404) (165,524)
Total AFS securities, Estimated Fair Value 2,476,925 2,793,214
Residential Mortgage-Backed Securities [Member] | Non-agency    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 137,211 161,767
Gross Unrealized Gains 0 935
Gross Unrealized (Losses) (6,558) (2,558)
Total AFS securities, Estimated Fair Value 130,653 160,144
Collateralized Securities, Other [Member]    
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]    
Total AFS securities 2,021 1,956
Gross Unrealized Gains 0 0
Gross Unrealized (Losses) 0 0
Total AFS securities, Estimated Fair Value $ 2,021 $ 1,956