Note 2 - Securities - Debt Securities by Maturity (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Due in 2020, weighted average yield	2.15%
Due in 2020, amortized cost	$ 13,522,000
Due in 2020, fair value	$ 13,531,000
Due in 2021 through 2025, weighted average yield	2.02%
Due in 2021 through 2025, amortized cost	$ 68,273,000
Due in 2021 through 2025, fair value	$ 68,995,000
Due in 2026 through 2030, weighted average yield	2.43%
Due in 2026 through 2030, amortized cost	$ 114,339,000
Due in 2026 through 2030, fair value	$ 116,535,000
Due in 2031 and beyond, weighted average yield	3.05%
Due in 2031 and beyond, amortized cost	$ 70,932,000
Due in 2031 and beyond, fair value	$ 72,817,000
Weighted average yield	2.51%
Debt Securities, Available-for-sale, Amortized Cost, Total	$ 306,080,000	$ 329,979,000
Debt Securities, Available-for-sale, Total	$ 312,147,000	334,655,000
Collateralized Mortgage Backed Securities [Member]
No single maturity, weighted average yield	2.69%
No single maturity, amortized cost	$ 38,514,000
No single maturity, fair value	39,769,000
Debt Securities, Available-for-sale, Amortized Cost, Total	38,514,000	41,998,000
Debt Securities, Available-for-sale, Total	$ 39,769,000	42,470,000
Other Debt and Equity Securities [Member]
No single maturity, weighted average yield	5.25%
No single maturity, amortized cost	$ 500,000
No single maturity, fair value	500,000
Debt Securities, Available-for-sale, Amortized Cost, Total	500,000	500,000
Debt Securities, Available-for-sale, Total	$ 500,000	$ 500,000

The aggregate weighted average yield of a securities portfolio.

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The weighted average yield of a securities portfolio with due dates after 10 years.

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The weighted average yield of a securities portfolio with due dates before 5 years and before 10 years.

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The weighted average yield of a securities portfolio with due dates after 1 year and before 5 years.

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The weighted average yield of securities portfolio with due dates in less than 1 year.

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The weighted average yield of a securities portfolio with no single maturity date defined.

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in second through fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing after tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in remainder of current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), with single maturity date and allocated without single maturity date, maturing in remainder of current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Amortized cost of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping.

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Fair value of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), without single maturity date and not allocated over maturity grouping.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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