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Note 2 - Securities - Fair Value of Securities Available for Sale and The Related Unrealized Gains and Losses Recognized in Accumulated Comprehensive Income (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Amortized Cost | $ 560,828 | $ 337,865
Gross Unrealized Gains | 14,856 | 3,340
Gross Unrealized Losses | (897) | (1,626)
Securities available for sale | 574,787 | 339,579
US Treasury and Government [Member] |  |
Amortized Cost | 2,007 | 17,231
Gross Unrealized Gains | 44 | 23
Gross Unrealized Losses | 0 | (39)
Securities available for sale | 2,051 | 17,215
US Treasury Securities [Member] |  |
Amortized Cost | 1,996 | 1,994
Gross Unrealized Gains | 60 | 14
Gross Unrealized Losses | 0 | 0
Securities available for sale | 2,056 | 2,008
US States and Political Subdivisions Debt Securities [Member] |  |
Amortized Cost | 307,201 | 172,487
Gross Unrealized Gains | 13,191 | 2,694
Gross Unrealized Losses | (24) | (1,257)
Securities available for sale | 320,368 | 173,924
Collateralized Mortgage Backed Securities [Member] |  |
Amortized Cost | 246,085 | 142,504
Gross Unrealized Gains | 1,510 | 585
Gross Unrealized Losses | (872) | (329)
Securities available for sale | 246,723 | 142,760
Corporate Debt Securities [Member] |  |
Amortized Cost | 2,539 | 2,649
Gross Unrealized Gains | 51 | 24
Gross Unrealized Losses | (1) | (1)
Securities available for sale | 2,589 | 2,672
Trust Preferred Securities [Member] |  |
Amortized Cost | 1,000 | 1,000
Gross Unrealized Gains | 0 | 0
Gross Unrealized Losses | 0 | 0
Securities available for sale | $ 1,000 | $ 1,000

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