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Note 4 - Investment Securities - Summary of Investment Securities with Unrealized Losses (Details) - USD ($) $ in Thousands | Dec. 31, 2023 | Dec. 31, 2022
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Less than Twelve Months Estimated Fair Value, available for sale | $ 83,611 |  | $ 121,563 |
Less than Twelve Months Unrealized Losses, available for sale | (213) |  | (5,116) |
Twelve Months or More Estimated Fair Value, available for sale | 176,221 |  | 118,611 |
Twelve Months or More Unrealized Losses | (28,516) |  | (26,145) |
Total Estimated Fair Value, available for sale | 259,832 |  | 240,174 |
Total Unrealized Losses, available for sale | (28,729) |  | (31,261) |
Less than Twelve Months Estimated Fair Value, held to maturity | 1,397 |  | 5,054 |
Less than Twelve Months Unrealized Losses, held to maturity | (19) |  | (173) |
Twelve Months or More Estimated Fair Value, held to maturity | 3,196 |  | 0 |
Twelve Months or More Unrealized Losses, held to maturity | (96) |  | 0 |
Total Estimated Fair Value, held to maturity | 4,593 |  | 5,054 |
Total Unrealized Losses, held to maturity | (115) |  | (173) |
US Government Agencies Debt Securities [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 4,238 |  | 354 |
Less than Twelve Months Unrealized Losses, available for sale | (72) |  | (24) |
Twelve Months or More Estimated Fair Value, available for sale | 3,923 |  | 4,141 |
Twelve Months or More Unrealized Losses | (472) |  | (493) |
Total Estimated Fair Value, available for sale | 8,161 |  | 4,495 |
Total Unrealized Losses, available for sale | (544) |  | (517) |
SBA Securities [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 5,102 |  | 2,411 |
Less than Twelve Months Unrealized Losses, available for sale | (18) |  | (223) |
Twelve Months or More Estimated Fair Value, available for sale | 2,094 |  | 0 |
Twelve Months or More Unrealized Losses | (198) |  | 0 |
Total Estimated Fair Value, available for sale | 7,196 |  | 2,411 |
Total Unrealized Losses, available for sale | (216) |  | (223) |
Residential Mortgage-Backed Securities [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 0 |  | 5,535 |
Less than Twelve Months Unrealized Losses, available for sale | 0 |  | (362) |
Twelve Months or More Estimated Fair Value, available for sale | 34,652 |  | 32,522 |
Twelve Months or More Unrealized Losses | (5,855) |  | (6,390) |
Total Estimated Fair Value, available for sale | 34,652 |  | 38,057 |
Total Unrealized Losses, available for sale | (5,855) |  | (6,752) |
Residential Collateralized Mortgage Obligations [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 2,597 |  | 27,050 |
Less than Twelve Months Unrealized Losses, available for sale | (37) |  | (1,842) |
Twelve Months or More Estimated Fair Value, available for sale | 60,275 |  | 39,815 |
Twelve Months or More Unrealized Losses | (12,161) |  | (11,014) |
Total Estimated Fair Value, available for sale | 62,872 |  | 66,865 |
Total Unrealized Losses, available for sale | (12,198) |  | (12,856) |
Commercial Mortgage-Backed Securities [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale |  |  | 4,871 |
Less than Twelve Months Unrealized Losses, available for sale |  |  | (16) |
Twelve Months or More Estimated Fair Value, available for sale |  |  | 0 |
Twelve Months or More Unrealized Losses |  |  | 0 |
Total Estimated Fair Value, available for sale |  |  | 4,871 |
Total Unrealized Losses, available for sale |  |  | (16) |
Commercial Collateralized Mortgage Obligations [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 18,463 |  | 18,741 |
Less than Twelve Months Unrealized Losses, available for sale | (70) |  | (790) |
Twelve Months or More Estimated Fair Value, available for sale | 35,077 |  | 22,949 |
Twelve Months or More Unrealized Losses | (2,594) |  | (2,111) |
Total Estimated Fair Value, available for sale | 53,540 |  | 41,690 |
Total Unrealized Losses, available for sale | (2,664) |  | (2,901) |
Commercial Paper [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 53,211 | [1] | 39,624 | [2]
Less than Twelve Months Unrealized Losses, available for sale | (16) | [1] | (16) | [2]
Twelve Months or More Estimated Fair Value, available for sale | 0 |  | 0 |
Twelve Months or More Unrealized Losses | 0 |  | 0 |
Total Estimated Fair Value, available for sale | 53,211 | [1] | 39,624 | [2]
Total Unrealized Losses, available for sale | (16) | [1] | (16) | [2]
Corporate Debt Securities [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 0 |  | 22,977 |
Less than Twelve Months Unrealized Losses, available for sale | 0 |  | (1,843) |
Twelve Months or More Estimated Fair Value, available for sale | 30,691 |  | 10,330 |
Twelve Months or More Unrealized Losses | (4,109) |  | (2,322) |
Total Estimated Fair Value, available for sale | 30,691 |  | 33,307 |
Total Unrealized Losses, available for sale | (4,109) |  | (4,165) |
Municipal Bonds [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, available for sale | 0 |  | 0 |
Less than Twelve Months Unrealized Losses, available for sale | 0 |  | 0 |
Twelve Months or More Estimated Fair Value, available for sale | 9,509 |  | 8,854 |
Twelve Months or More Unrealized Losses | (3,127) |  | (3,815) |
Total Estimated Fair Value, available for sale | 9,509 |  | 8,854 |
Total Unrealized Losses, available for sale | (3,127) |  | (3,815) |
Less than Twelve Months Estimated Fair Value, held to maturity | 1,397 |  | 4,556 |
Less than Twelve Months Unrealized Losses, held to maturity | (19) |  | (170) |
Twelve Months or More Estimated Fair Value, held to maturity | 3,196 |  | 0 |
Twelve Months or More Unrealized Losses, held to maturity | (96) |  | 0 |
Total Estimated Fair Value, held to maturity | 4,593 |  | 4,556 |
Total Unrealized Losses, held to maturity | $ (115) |  | (170) |
Taxable Municipal Bonds [Member] |  |  |  |
Less than Twelve Months Estimated Fair Value, held to maturity |  |  | 498 |
Less than Twelve Months Unrealized Losses, held to maturity |  |  | (3) |
Twelve Months or More Estimated Fair Value, held to maturity |  |  | 0 |
Twelve Months or More Unrealized Losses, held to maturity |  |  | 0 |
Total Estimated Fair Value, held to maturity |  |  | 498 |
Total Unrealized Losses, held to maturity |  |  | $ (3) |
[1] | The Company held $19.9 million of commercial paper where the recorded value and fair value are equal as of December 31, 2023.
[2] | The Company held $9.9 million of commercial paper where the recorded value and fair value are equal as of December 31, 2022.

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