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Note 3 - Debt Securities Available for Sale and Held to Maturity - Gross Unrealized Losses, Investment Securities Portfolio (Details) $ in Thousands | Sep. 30, 2025 USD ($) | Dec. 31, 2024 USD ($)
--- | --- | ---
Available for sale securities, less than 12 months, number of investment positions | 42 | 22
Held to Maturity securities, less than 12 months, number of investment positions | 3 | 47
Available for sale securities, less than 12 months, fair value | $ 278,653 | $ 66,670
Held to Maturity securities, less than 12 months, fair value | 5,070 | 267,612
Available for sale securities, less than 12 months, unrealized loss | (2,627) | (692)
Held to Maturity securities, less than 12 months, unrealized loss | $ (9) | $ (4,308)
Available for sale securities, 12 months or longer, number of investment positions | 291 | 332
Held to Maturity securities, 12 months or longer, number of investment positions | 110 | 141
Available for sale securities, 12 months or longer, fair value | $ 2,383,031 | $ 2,653,765
Held to Maturity securities, 12 months or longer, fair value | 434,944 | 530,005
Available for sale securities, 12 months or longer, unrealized loss | (140,591) | (238,759)
Held to Maturity securities, 12 months or longer, unrealized loss | $ (11,926) | $ (32,524)
Available for sale securities, total, number of investment positions | 333 | 354
Held to Maturity securities, total, number of investment positions | 113 | 188
Available for sale securities, total, fair value | $ 2,661,684 | $ 2,720,435
Held to Maturity securities, total, fair value | 440,014 | 797,617
Available for sale securities, total, unrealized loss | (143,218) | (239,451)
Held to Maturity securities, total, unrealized loss | $ (11,935) | $ (36,832)
Agency Residential MBS [Member] |  |
Available for sale securities, less than 12 months, number of investment positions | 5 | 12
Held to Maturity securities, less than 12 months, number of investment positions | 0 | 0
Available for sale securities, less than 12 months, fair value | $ 18,550 | $ 18,030
Held to Maturity securities, less than 12 months, fair value | 0 | 0
Available for sale securities, less than 12 months, unrealized loss | (337) | (471)
Held to Maturity securities, less than 12 months, unrealized loss | $ 0 | $ 0
Available for sale securities, 12 months or longer, number of investment positions | 104 | 103
Held to Maturity securities, 12 months or longer, number of investment positions | 63 | 80
Available for sale securities, 12 months or longer, fair value | $ 173,381 | $ 192,963
Held to Maturity securities, 12 months or longer, fair value | 42,819 | 52,771
Available for sale securities, 12 months or longer, unrealized loss | (11,108) | (17,520)
Held to Maturity securities, 12 months or longer, unrealized loss | $ (2,566) | $ (4,218)
Available for sale securities, total, number of investment positions | 109 | 115
Held to Maturity securities, total, number of investment positions | 63 | 80
Available for sale securities, total, fair value | $ 191,931 | $ 210,993
Held to Maturity securities, total, fair value | 42,819 | 52,771
Available for sale securities, total, unrealized loss | (11,445) | (17,991)
Held to Maturity securities, total, unrealized loss | $ (2,566) | $ (4,218)
US States and Political Subdivisions Debt Securities [Member] |  |
Available for sale securities, less than 12 months, number of investment positions | 1 | 2
Held to Maturity securities, less than 12 months, number of investment positions | 1 | 24
Available for sale securities, less than 12 months, fair value | $ 1,311 | $ 2,764
Held to Maturity securities, less than 12 months, fair value | 365 | 15,822
Available for sale securities, less than 12 months, unrealized loss | (2) | (21)
Held to Maturity securities, less than 12 months, unrealized loss | $ 0 | $ (78)
Available for sale securities, 12 months or longer, number of investment positions | 30 | 40
Held to Maturity securities, 12 months or longer, number of investment positions | 20 | 26
Available for sale securities, 12 months or longer, fair value | $ 40,371 | $ 51,759
Held to Maturity securities, 12 months or longer, fair value | 18,465 | 25,814
Available for sale securities, 12 months or longer, unrealized loss | (571) | (1,680)
Held to Maturity securities, 12 months or longer, unrealized loss | $ (45) | $ (299)
Available for sale securities, total, number of investment positions | 31 | 42
Held to Maturity securities, total, number of investment positions | 21 | 50
Available for sale securities, total, fair value | $ 41,682 | $ 54,523
Held to Maturity securities, total, fair value | 18,830 | 41,636
Available for sale securities, total, unrealized loss | (573) | (1,701)
Held to Maturity securities, total, unrealized loss | $ (45) | $ (377)
Agency Commercial MBS [Member] |  |
Available for sale securities, less than 12 months, number of investment positions | 33 | 2
Available for sale securities, less than 12 months, fair value | $ 233,147 | $ 6,966
Available for sale securities, less than 12 months, unrealized loss | $ (2,210) | $ (132)
Available for sale securities, 12 months or longer, number of investment positions | 0 | 0
Available for sale securities, 12 months or longer, fair value | $ 0 | $ 0
Available for sale securities, 12 months or longer, unrealized loss | $ 0 | $ 0
Available for sale securities, total, number of investment positions | 33 | 2
Available for sale securities, total, fair value | $ 233,147 | $ 6,966
Available for sale securities, total, unrealized loss | $ (2,210) | $ (132)
Corporate Debt Securities [Member] |  |
Available for sale securities, less than 12 months, number of investment positions | 0 | 0
Held to Maturity securities, less than 12 months, number of investment positions | 2 | 23
Available for sale securities, less than 12 months, fair value | $ 0 | $ 0
Held to Maturity securities, less than 12 months, fair value | 4,705 | 251,790
Available for sale securities, less than 12 months, unrealized loss | 0 | 0
Held to Maturity securities, less than 12 months, unrealized loss | $ (9) | $ (4,230)
Available for sale securities, 12 months or longer, number of investment positions | 129 | 138
Held to Maturity securities, 12 months or longer, number of investment positions | 27 | 35
Available for sale securities, 12 months or longer, fair value | $ 1,796,562 | $ 1,824,327
Held to Maturity securities, 12 months or longer, fair value | 373,660 | 451,420
Available for sale securities, 12 months or longer, unrealized loss | (119,619) | (195,334)
Held to Maturity securities, 12 months or longer, unrealized loss | $ (9,315) | $ (28,007)
Available for sale securities, total, number of investment positions | 129 | 138
Held to Maturity securities, total, number of investment positions | 29 | 58
Available for sale securities, total, fair value | $ 1,796,562 | $ 1,824,327
Held to Maturity securities, total, fair value | 378,365 | 703,210
Available for sale securities, total, unrealized loss | (119,619) | (195,334)
Held to Maturity securities, total, unrealized loss | $ (9,324) | $ (32,237)
US Government Agencies Debt Securities [Member] |  |
Available for sale securities, less than 12 months, number of investment positions | 0 | 3
Available for sale securities, less than 12 months, fair value | $ 0 | $ 12,085
Available for sale securities, less than 12 months, unrealized loss | $ 0 | $ (53)
Available for sale securities, 12 months or longer, number of investment positions | 19 | 19
Available for sale securities, 12 months or longer, fair value | $ 288,409 | $ 275,467
Available for sale securities, 12 months or longer, unrealized loss | $ (7,888) | $ (19,032)
Available for sale securities, total, number of investment positions | 19 | 22
Available for sale securities, total, fair value | $ 288,409 | $ 287,552
Available for sale securities, total, unrealized loss | $ (7,888) | $ (19,085)
Collateralized Debt Obligations [Member] |  |
Available for sale securities, less than 12 months, number of investment positions | 3 | 3
Available for sale securities, less than 12 months, fair value | $ 25,645 | $ 26,825
Available for sale securities, less than 12 months, unrealized loss | $ (78) | $ (15)
Available for sale securities, 12 months or longer, number of investment positions | 9 | 32
Available for sale securities, 12 months or longer, fair value | $ 84,308 | $ 309,249
Available for sale securities, 12 months or longer, unrealized loss | $ (1,405) | $ (5,193)
Available for sale securities, total, number of investment positions | 12 | 35
Available for sale securities, total, fair value | $ 109,953 | $ 336,074
Available for sale securities, total, unrealized loss | $ (1,483) | $ (5,208)

X
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 55 -Paragraph 8 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479081/326-30-55-8 Reference 2: http://fasb.org/us-gaap/role/ref/otherTransitionRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 7 -Publisher FASB -URI https://asc.fasb.org/1943274/2147481800/320-10-50-7 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Topic 326 -SubTopic 30 -Name Accounting Standards Codification -Section 50 -Paragraph 5 -Publisher FASB -URI https://asc.fasb.org/1943274/2147479106/326-30-50-5 + Details
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