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Note 4 - Investment and Equity Securities - Amortized Cost and Fair Values of Securities Available for Sale (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019
--- | --- | ---
Amortized cost | $ 108,937 | $ 103,401
Gross unrealized gains | 5,435 | 2,466
Gross unrealized losses | (12) | (134)
Investment securities available for sale, at fair value | 114,360 | 105,733
Subordinated Debt Securities [Member] |  |
Amortized cost | 21,050 | 4,000
Gross unrealized gains | 254 | 126
Gross unrealized losses | (7) | 0
Investment securities available for sale, at fair value | 21,297 | 4,126
Taxable Municipal Bonds [Member] |  |
Amortized cost | 500 | 500
Gross unrealized gains | 2 | 1
Gross unrealized losses | 0 | 0
Investment securities available for sale, at fair value | 502 | 501
Nontaxable Municipal Bonds [Member] |  |
Amortized cost | 73,157 | 80,436
Gross unrealized gains | 4,643 | 2,065
Gross unrealized losses | 0 | (25)
Investment securities available for sale, at fair value | 77,800 | 82,476
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] |  |
Amortized cost | 14,230 | 18,465
Gross unrealized gains | 536 | 274
Gross unrealized losses | (5) | (109)
Investment securities available for sale, at fair value | $ 14,761 | $ 18,630

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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://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121645371&loc=d3e27161-111563 + Details
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