Note 7 - Fair Value Measurements - Fair Value of Financial Instruments Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	$ 407,224	$ 421,145
Fair Value, Recurring [Member] \| Reported Value Measurement [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	407,224	421,145
Mortgage loans held for sale	22,183	18,179
Derivative, fair value	503	328
Bank owned life insurance	31,945	31,762
Total assets	461,855	471,414
Mortgage banking derivatives	385	23
Total liabilities	385	23
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
Mortgage loans held for sale	0	0
Derivative, fair value	0	0
Bank owned life insurance	0	0
Total assets	0	0
Mortgage banking derivatives	0	0
Total liabilities	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	407,224	421,145
Mortgage loans held for sale	22,183	18,179
Derivative, fair value	503	328
Bank owned life insurance	0	0
Total assets	429,910	439,652
Mortgage banking derivatives	385	23
Total liabilities	385	23
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
Mortgage loans held for sale	0	0
Derivative, fair value	0	0
Bank owned life insurance	31,945	31,762
Total assets	31,945	31,762
Mortgage banking derivatives	0	0
Total liabilities	0	0
US Government-sponsored Enterprises Debt Securities [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	52,938	59,579
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member] \| Reported Value Measurement [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	52,938	59,579
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	52,938	59,579
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
Collateralized Mortgage Backed Securities [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	254,216	267,313
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member] \| Reported Value Measurement [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	254,216	267,313
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	254,216	267,313
Collateralized Mortgage Backed Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
Asset-backed Securities [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	26,330	27,229
Asset-backed Securities [Member] \| Fair Value, Recurring [Member] \| Reported Value Measurement [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	26,330	27,229
Asset-backed Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
Asset-backed Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	26,330	27,229
Asset-backed Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	73,740	67,024
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Reported Value Measurement [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	73,740	67,024
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	0	0
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	73,740	67,024
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Available-for-sale, at market (amortized cost $400,731 and $420,207, respectively)	$ 0	$ 0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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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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Fair value portion of the amount that could be realized under a life insurance contract or contracts owned by the entity, commonly known as corporate-owned life insurance (COLI) or bank-owned life insurance (BOLI).

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Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

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Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

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Fair value of financial obligations, including, but not limited to, debt instruments, derivative liabilities, federal funds purchased and sold under agreements to repurchase, securities loaned or sold under agreements to repurchase, financial instruments sold not yet purchased, guarantees, line of credit, loans and notes payable, servicing liability, and trading liabilities.

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Fair value portion of loans held-for-sale including, but not limited to, mortgage loans and finance receivables.

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