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Securities - Amortized cost and fair value for held to maturity and available for sale securities (Details) - USD ($) $ in Thousands | Mar. 31, 2026 | Dec. 31, 2025
--- | --- | ---
Investment securities held-to-maturity |  |
Amortized cost | $ 2,007,249 | $ 2,048,030
Gross Unrealized Losses | (323,111) | (315,180)
Fair Value | 1,684,138 | 1,732,850
Investment securities available for sale |  |
Amortized cost | 6,969,183 | 6,696,576
Gross Unrealized Gains | 17,074 | 39,169
Gross Unrealized Losses | (455,909) | (421,989)
Fair Value | 6,530,348 | 6,313,756
U.S. Government agencies |  |
Investment securities held-to-maturity |  |
Amortized cost | 132,914 | 132,913
Gross Unrealized Losses | (16,892) | (15,767)
Fair Value | 116,022 | 117,146
Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 1,123,852 | 1,153,024
Gross Unrealized Losses | (181,274) | (177,101)
Fair Value | 942,578 | 975,923
Investment securities available for sale |  |
Amortized cost | 1,991,530 | 1,826,307
Gross Unrealized Gains | 5,089 | 10,108
Gross Unrealized Losses | (147,521) | (138,307)
Fair Value | 1,849,098 | 1,698,108
Residential collateralized mortgage-obligations issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 372,106 | 379,107
Gross Unrealized Losses | (58,553) | (55,232)
Fair Value | 313,553 | 323,875
Investment securities available for sale |  |
Amortized cost | 2,148,049 | 2,208,710
Gross Unrealized Gains | 9,383 | 23,979
Gross Unrealized Losses | (52,877) | (47,105)
Fair Value | 2,104,555 | 2,185,584
Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 332,619 | 336,910
Gross Unrealized Losses | (58,228) | (58,332)
Fair Value | 274,391 | 278,578
Investment securities available for sale |  |
Amortized cost | 1,047,410 | 903,209
Gross Unrealized Gains | 1,545 | 3,282
Gross Unrealized Losses | (78,644) | (74,042)
Fair Value | 970,311 | 832,449
State and municipal obligations |  |
Investment securities available for sale |  |
Amortized cost | 1,191,625 | 1,141,377
Gross Unrealized Gains | 593 | 1,252
Gross Unrealized Losses | (151,023) | (135,217)
Fair Value | 1,041,195 | 1,007,412
Small Business Administration loan-backed securities |  |
Investment securities held-to-maturity |  |
Amortized cost | 45,758 | 46,076
Gross Unrealized Losses | (8,164) | (8,748)
Fair Value | 37,594 | 37,328
Investment securities available for sale |  |
Amortized cost | 567,569 | 593,973
Gross Unrealized Gains | 464 | 548
Gross Unrealized Losses | (24,548) | (26,088)
Fair Value | 543,485 | 568,433
Corporate securities |  |
Investment securities available for sale |  |
Amortized cost | 23,000 | 23,000
Gross Unrealized Losses | (1,296) | (1,230)
Fair Value | $ 21,704 | $ 21,770

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