Note 7 - Fair Value of Financial Instruments - Quantitative Information about Level 3 Assets (Details) $ in Thousands		Jun. 30, 2018 USD ($)	Dec. 31, 2017 USD ($)
Valuation Technique, Discounted Cash Flow [Member] | Corporate Debt Securities [Member]
Fair Value		$ 3,083	$ 3,086
Valuation Technique, Discounted Cash Flow [Member] | Corporate Debt Securities [Member] | Measurement Input, Discount Rate [Member]
Discount rate		0.0732	0.0599
Valuation Technique, Discounted Cash Flow [Member] | Collateralized Debt Obligations [Member]
Fair Value		$ 547
Valuation Technique, Discounted Cash Flow [Member] | Collateralized Debt Obligations [Member] | Measurement Input, Discount Rate [Member]
Fair Value			$ 489
Discount rate		0.0806	0.0833
Valuation Technique, Discounted Cash Flow [Member] | SBA Servicing Assets [Member]
Fair Value		$ 4,977	$ 5,243
Valuation Technique, Discounted Cash Flow [Member] | SBA Servicing Assets [Member] | Measurement Input, Discount Rate [Member]
Conditional prepayment rate		0.11	0.105
Valuation Technique, Discounted Cash Flow [Member] | SBA Servicing Assets [Member] | Measurement Input, Prepayment Rate [Member]
Conditional prepayment rate		0.0988	0.0785
Valuation, Market Approach [Member] | Impaired Loans [Member]
Fair Value	[1]	$ 7,149	$ 7,322
Valuation, Market Approach [Member] | Impaired Loans [Member] | Measurement Input, Liquidation Expenses [Member]
Discount rate	[2],[3]	0.3	0.21
Valuation, Market Approach [Member] | Impaired Loans [Member] | Measurement Input, Liquidation Expenses [Member] | Minimum [Member]
Discount rate	[2],[3]	0.1	0.1
Valuation, Market Approach [Member] | Impaired Loans [Member] | Measurement Input, Liquidation Expenses [Member] | Weighted Average [Member]
Discount rate	[2],[3]	0.13	0.14
Appraised Value of Collateral [Member] | Other Real Estate Owned [Member]
Fair Value	[1]		$ 5,727
Appraised Value of Collateral [Member] | Other Real Estate Owned [Member] | Measurement Input, Liquidation Expenses [Member] | Maximum [Member]
Liquidation expenses	[2],[3]		0.22
Sales Price Valuation Technique [Member] | Other Real Estate Owned [Member] | Measurement Input, Liquidation Expenses [Member]
Liquidation expenses	[2],[3]		0.07
Sales Price Valuation Technique [Member] | Other Real Estate Owned [Member] | Measurement Input, Liquidation Expenses [Member] | Minimum [Member]
Liquidation expenses	[2],[3]		0.04
Sales Price Valuation Technique [Member] | Other Real Estate Owned [Member] | Measurement Input, Liquidation Expenses [Member] | Weighted Average [Member]
Liquidation expenses	[2],[3]		0.07

[1] Fair value is generally determined through independent appraisals of the underlying collateral, which include Level 3 inputs that are not identifiable.

[2] Appraisals may be adjusted by management for qualitative factors such as economic conditions and estimated liquidation expenses.

[3] The range and weighted average of qualitative factors such as economic conditions and estimated liquidation expenses are presented as a percent of the appraised value.