Note 16 - Assets and Liabilities Measured and Reported at Fair Value - Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Securities available for sale	$ 507,131	$ 436,995
Fair Value, Recurring [Member]
Securities available for sale	507,131	436,995
Interest rate swaps	524	1,035
Total assets	507,655	438,030
Interest rate swaps	240	543
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available for sale
Interest rate swaps
Total assets
Interest rate swaps
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available for sale	507,131	436,995
Interest rate swaps	524	1,035
Total assets	507,655	438,030
Interest rate swaps	240	543
Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Securities available for sale
Interest rate swaps
Total assets	0	0
Interest rate swaps
US Government-sponsored Enterprises Debt Securities [Member]
Securities available for sale	342,866	261,039
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member]
Securities available for sale	342,866	261,039
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available for sale
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available for sale	342,866	261,039
US Government-sponsored Enterprises Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Securities available for sale
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale	137,131	146,277
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Recurring [Member]
Securities available for sale	137,131	146,277
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available for sale
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available for sale	137,131	146,277
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Securities available for sale
US States and Political Subdivisions Debt Securities [Member]
Securities available for sale	27,134	29,679
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member]
Securities available for sale	27,134	29,679
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 1 [Member]
Securities available for sale
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 2 [Member]
Securities available for sale	27,134	29,679
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Recurring [Member] \| Fair Value, Inputs, Level 3 [Member]
Securities available for sale

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
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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).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26610-111562

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aa)
-URI http://asc.fasb.org/extlink&oid=118939692&loc=d3e27161-111563

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Fair value as of the balance sheet date of interest rate derivative assets, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as assets.

+ References

No definition available.

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+ References

No definition available.

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