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Investment Securities - Amortized cost and fair value for available for sale securities (Details) - USD ($) $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
--- | --- | ---
Investment securities held-to-maturity |  |
Amortized cost | $ 2,096,727 | $ 2,254,670
Gross Unrealized Losses | (331,240) | (420,143)
Fair Value | 1,765,487 | 1,834,527
Investment securities available for sale |  |
Amortized cost | 6,468,315 | 5,129,216
Gross Unrealized Gains | 30,641 | 701
Gross Unrealized Losses | (456,156) | (809,324)
Fair Value | 6,042,800 | 4,320,593
U.S. Treasuries |  |
Investment securities available for sale |  |
Amortized cost |  | 10,654
Gross Unrealized Gains |  | 2
Fair Value |  | 10,656
U.S. Government agencies |  |
Investment securities held-to-maturity |  |
Amortized cost | 132,911 | 147,272
Gross Unrealized Losses | (16,729) | (23,498)
Fair Value | 116,182 | 123,774
Investment securities available for sale |  |
Amortized cost |  | 169,207
Gross Unrealized Losses |  | (18,789)
Fair Value |  | 150,418
Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 1,187,818 | 1,297,543
Gross Unrealized Losses | (186,684) | (241,204)
Fair Value | 1,001,134 | 1,056,339
Investment securities available for sale |  |
Amortized cost | 1,689,961 | 1,659,851
Gross Unrealized Gains | 7,641 | 97
Gross Unrealized Losses | (147,237) | (282,423)
Fair Value | 1,550,365 | 1,377,525
Residential collateralized mortgage-obligations issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 386,777 | 411,721
Gross Unrealized Losses | (58,177) | (72,057)
Fair Value | 328,600 | 339,664
Investment securities available for sale |  |
Amortized cost | 2,268,056 | 557,288
Gross Unrealized Gains | 18,908 | 19
Gross Unrealized Losses | (49,790) | (98,212)
Fair Value | 2,237,174 | 459,095
Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 342,054 | 348,338
Gross Unrealized Losses | (60,516) | (72,391)
Fair Value | 281,538 | 275,947
Investment securities available for sale |  |
Amortized cost | 749,857 | 1,234,573
Gross Unrealized Gains | 2,809 | 562
Gross Unrealized Losses | (77,054) | (194,580)
Fair Value | 675,612 | 1,040,555
State and municipal obligations |  |
Investment securities available for sale |  |
Amortized cost | 1,112,505 | 1,117,330
Gross Unrealized Gains | 754 | 2
Gross Unrealized Losses | (152,147) | (171,609)
Fair Value | 961,112 | 945,723
Small Business Administration loan-backed securities |  |
Investment securities held-to-maturity |  |
Amortized cost | 47,167 | 49,796
Gross Unrealized Losses | (9,134) | (10,993)
Fair Value | 38,033 | 38,803
Investment securities available for sale |  |
Amortized cost | 619,437 | 351,814
Gross Unrealized Gains | 528 | 19
Gross Unrealized Losses | (28,405) | (41,721)
Fair Value | 591,560 | 310,112
Corporate securities |  |
Investment securities available for sale |  |
Amortized cost | 28,499 | 28,499
Gross Unrealized Gains | 1 |
Gross Unrealized Losses | (1,523) | (1,990)
Fair Value | $ 26,977 | $ 26,509

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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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