Note 7 - Fair Value Measurements - Fair Value of Financial Instruments Measured on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	$ 613,932	$ 580,543
US Government-sponsored Enterprises Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	124,025	125,905
Collateralized Mortgage Backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	288,662	263,790
Asset-backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	40,130	36,957
Corporate Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	2,544	2,600
US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	158,571	151,291
Fair Value, Recurring [Member] \| Reported Value Measurement [Member]
Hedged Loans	26,494	29,417
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	613,932	580,543
Mortgage loans held for sale	28,635	19,474
Derivative, fair value	2,685	714
Bank owned life insurance	35,401	35,197
Total assets	707,147	665,345
Derivative Liability, Fair Value, Gross Liability, Total	0	208
Total liabilities	0	208
Fair Value, Recurring [Member] \| Reported Value Measurement [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	124,025	125,905
Fair Value, Recurring [Member] \| Reported Value Measurement [Member] \| Collateralized Mortgage Backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	288,662	263,790
Fair Value, Recurring [Member] \| Reported Value Measurement [Member] \| Asset-backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	40,130	36,957
Fair Value, Recurring [Member] \| Reported Value Measurement [Member] \| Corporate Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	2,544	2,600
Fair Value, Recurring [Member] \| Reported Value Measurement [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	158,571	151,291
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Hedged Loans	0	0
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Mortgage loans held for sale	0	0
Derivative, fair value	0	0
Bank owned life insurance	0	0
Total assets		0
Derivative Liability, Fair Value, Gross Liability, Total	0	0
Total liabilities	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Collateralized Mortgage Backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Asset-backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| Corporate Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member]
Hedged Loans	26,494	29,417
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	613,932	580,543
Mortgage loans held for sale	28,635	19,474
Derivative, fair value	2,685	714
Bank owned life insurance	0	0
Total assets	671,746	630,148
Derivative Liability, Fair Value, Gross Liability, Total	0	208
Total liabilities	0	208
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	124,025	125,905
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Collateralized Mortgage Backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	288,662	263,790
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Asset-backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	40,130	36,957
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| Corporate Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	2,544	2,600
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 2 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	158,571	151,291
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member]
Hedged Loans	0	0
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Mortgage loans held for sale	0	0
Derivative, fair value	0	0
Bank owned life insurance	35,401	35,197
Total assets	35,401	35,197
Derivative Liability, Fair Value, Gross Liability, Total	0	0
Total liabilities	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| US Government-sponsored Enterprises Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Collateralized Mortgage Backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Asset-backed Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| Corporate Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, respectively)	0	0
Fair Value, Recurring [Member] \| Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 3 [Member] \| US States and Political Subdivisions Debt Securities [Member]
Available-for-sale, at market (amortized cost $616,063 and $570,842, 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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Fair value portion of hedged loans.

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