Note 7 - Fair Value of Financial Instruments (Details Textual) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Servicing Asset, Total	$ 207,300,000		$ 207,300,000		$ 204,900,000
Loans Held-for-sale, Write-down	0				0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member]
Mortgages Held-for-sale, Fair Value Disclosure	0		0		$ 0
Interest and Fees [Member]
Interest and Fee Income, Loans Held-for-sale, Mortgages	231,000	$ 171,000	525,000	$ 300,000
SBA Servicing Assets [Member]
Contractually Specified Servicing Fees, Amount	$ 493,000	$ 485,000	$ 986,000	$ 918,000
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 10 Percent Adverse Change in Key Assumptions, Percent	10.00%		10.00%		10.00%
Sensitivity Analysis of Fair Value, Transferor's Interests in Transferred Financial Assets, Impact of 20 Percent Adverse Change in Key Assumptions					20.00%

The amount of write-down on loans held-for-sale during the period.

No definition available.

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- Definition

The measurement of the hypothetical financial impact of a 10 percent adverse changes in key assumptions on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

No definition available.

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- Definition

The measurement of the hypothetical financial impact of a 20 percent adverse changes in key assumptions on the fair value of transferor's interests in transferred financial assets (including any servicing assets or servicing liabilities) as of the balance sheet date.

+ References

No definition available.

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- Definition

All amounts that, per contract, are due to the servicer in exchange for servicing the financial asset and would no longer be received by a servicer if the beneficial owners of the serviced assets (or their trustees or agents) were to exercise their actual or potential authority under the contract to shift the servicing to another servicer. Depending on the servicing contract, those fees may include some or all of the difference between the interest rate collected on the asset being serviced and the rate to be paid to the beneficial owners of the asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122596-111746

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- Definition

Interest and fee income from mortgage loans considered to be held-for-sale.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.1)
-URI http://asc.fasb.org/extlink&oid=114873765&loc=SL114874048-224260

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- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

No definition available.

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- Definition

Aggregate amount of servicing assets that are subsequently measured at fair value and servicing assets that are subsequently measured using the amortization method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=6469459&loc=d3e122501-111745

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