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Investment Securities - Amortized cost and fair value for available for sale securities (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Investment securities held-to-maturity |  |
Amortized cost | $ 2,301,307 | $ 2,487,440
Gross Unrealized Losses | (337,561) | (402,704)
Fair Value | 1,963,746 | 2,084,736
Investment securities available for sale |  |
Amortized cost | 5,204,198 | 5,561,006
Gross Unrealized Gains | 3,206 | 1,898
Gross Unrealized Losses | (643,041) | (778,516)
Fair Value | 4,564,363 | 4,784,388
U.S. Treasuries |  |
Investment securities available for sale |  |
Amortized cost | 2,684 | 74,720
Gross Unrealized Gains | 1 |
Gross Unrealized Losses |  | (830)
Fair Value | 2,685 | 73,890
U.S. Government agencies |  |
Investment securities held-to-maturity |  |
Amortized cost | 147,271 | 197,267
Gross Unrealized Losses | (19,271) | (24,607)
Fair Value | 128,000 | 172,660
Investment securities available for sale |  |
Amortized cost | 191,177 | 246,089
Gross Unrealized Losses | (15,453) | (21,383)
Fair Value | 175,724 | 224,706
Residential mortgage-backed securities issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 1,333,263 | 1,438,102
Gross Unrealized Losses | (188,925) | (227,312)
Fair Value | 1,144,338 | 1,210,790
Investment securities available for sale |  |
Amortized cost | 1,702,457 | 1,822,104
Gross Unrealized Gains | 491 | 294
Gross Unrealized Losses | (216,862) | (264,092)
Fair Value | 1,486,086 | 1,558,306
Residential collateralized mortgage-obligations issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 419,838 | 444,883
Gross Unrealized Losses | (58,371) | (68,139)
Fair Value | 361,467 | 376,744
Investment securities available for sale |  |
Amortized cost | 574,447 | 626,735
Gross Unrealized Gains | 49 |
Gross Unrealized Losses | (82,254) | (99,313)
Fair Value | 492,242 | 527,422
Commercial mortgage-backed securities issued by U.S. government agencies or sponsored enterprises |  |
Investment securities held-to-maturity |  |
Amortized cost | 349,860 | 354,055
Gross Unrealized Losses | (61,691) | (71,327)
Fair Value | 288,169 | 282,728
Investment securities available for sale |  |
Amortized cost | 1,215,415 | 1,217,125
Gross Unrealized Gains | 2,545 | 1,516
Gross Unrealized Losses | (157,131) | (194,471)
Fair Value | 1,060,829 | 1,024,170
State and municipal obligations |  |
Investment securities available for sale |  |
Amortized cost | 1,123,634 | 1,129,750
Gross Unrealized Gains | 63 | 2
Gross Unrealized Losses | (134,394) | (152,291)
Fair Value | 989,303 | 977,461
Small Business Administration loan-backed securities |  |
Investment securities held-to-maturity |  |
Amortized cost | 51,075 | 53,133
Gross Unrealized Losses | (9,303) | (11,319)
Fair Value | 41,772 | 41,814
Investment securities available for sale |  |
Amortized cost | 363,885 | 413,950
Gross Unrealized Gains | 57 | 86
Gross Unrealized Losses | (34,432) | (42,350)
Fair Value | 329,510 | 371,686
Corporate securities |  |
Investment securities available for sale |  |
Amortized cost | 30,499 | 30,533
Gross Unrealized Losses | (2,515) | (3,786)
Fair Value | $ 27,984 | $ 26,747

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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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