Note 2 - Securities - Debt Securities by Maturity (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Due in 2019, weighted average yield	2.05%
Due in 2019, amortized cost	$ 24,718,000
Due in 2019, fair value	$ 24,702,000
Due in 2020 through 2024, weighted average yield	2.29%
Due in 2020 through 2024, amortized cost	$ 67,504,000
Due in 2020 through 2024, fair value	$ 67,148,000
Due in 2025 through 2029, weighted average yield	2.73%
Due in 2025 through 2029, amortized cost	$ 112,356,000
Due in 2025 through 2029, fair value	$ 110,312,000
Due in 2030 and beyond, weighted average yield	3.18%
Due in 2030 and beyond, amortized cost	$ 96,452,000
Due in 2030 and beyond, fair value	$ 93,204,000
Weighted average yield	2.73%
Amortized cost	$ 343,856,000	$ 347,795,000
Securities available for sale, fair value	$ 337,876,000	337,366,000
Collateralized Mortgage Backed Securities [Member]
No single maturity, weighted average yield	2.81%
No single maturity, amortized cost	$ 42,326,000
No single maturity, fair value	42,010,000
Amortized cost	42,326,000	44,263,000
Securities available for sale, fair value	$ 42,010,000	43,658,000
Other Debt and Equity Securities [Member]
No single maturity, weighted average yield	6.50%
No single maturity, amortized cost	$ 500,000
No single maturity, fair value	500,000
Amortized cost	500,000	500,000
Securities available for sale, fair value	$ 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 fiscal year through tenth fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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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 latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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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 latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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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 latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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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 latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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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 fiscal year following latest fiscal year. Excludes interim and annual periods when interim period is reported on rolling approach, from latest statement of financial position date.

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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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