Note 15 - Fair Value Measurements and Fair Values of Financial Instruments - Quantitative Information about Level 3 Assets (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2017	Dec. 31, 2016
Income Approach Valuation Technique [Member] | Corporate Debt Securities [Member]
Fair Value		$ 3,086	$ 2,971
Valuation Technique		Discounted Cash Flows	Discounted Cash Flows
Unobservable Input		Discount Rate	Discount Rate
Income Approach Valuation Technique [Member] | Corporate Debt Securities [Member] | Weighted Average [Member]
Discount Rate		5.99%	4.68%
Income Approach Valuation Technique [Member] | Collateralized Debt Obligations [Member]
Fair Value		$ 489	$ 1,820
Valuation Technique		Discounted Cash Flows	Discounted Cash Flows
Unobservable Input		Discount Rate	Discount Rate
Income Approach Valuation Technique [Member] | Collateralized Debt Obligations [Member] | Weighted Average [Member]
Discount Rate		8.33%	9.08%
Income Approach Valuation Technique [Member] | Collateralized Debt Obligations [Member] | Minimum [Member]
Discount Rate			8.85%
Income Approach Valuation Technique [Member] | Collateralized Debt Obligations [Member] | Maximum [Member]
Discount Rate			9.35%
Income Approach Valuation Technique [Member] | SBA Servicing Assets [Member]
Fair Value		$ 5,243	$ 5,352
Valuation Technique		Discounted Cash Flows	Discounted Cash Flows
Unobservable Input		Conditional Prepayment Rate	Conditional Prepayment Rate
Unobservable Input		Discount Rate	Discount Rate	[1]
Income Approach Valuation Technique [Member] | SBA Servicing Assets [Member] | Weighted Average [Member]
Discount Rate		10.50%	10.00%
Conditional prepayment rate		7.85%	6.12%
Market Approach Valuation Technique [Member] | Impaired Loans [Member]
Fair Value		$ 7,322	$ 9,110
Valuation Technique	[2]	Appraised Value of Collateral	Appraised Value of Collateral
Unobservable Input	[1]	Liquidation expenses	Liquidation expenses
Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Weighted Average [Member]
Liquidation expenses	[3]	14.00%	11.00%
Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Minimum [Member]
Liquidation expenses	[3]	10.00%	7.00%
Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Maximum [Member]
Liquidation expenses	[3]	21.00%	20.00%
Market Approach Valuation Technique [Member] | Other Real Estate Owned [Member]
Fair Value		$ 5,727	$ 8,563
Valuation Technique	[2]	Appraised Value of Collateral	Appraised Value of Collateral
Unobservable Input	[1]	Liquidation expenses	Liquidation expenses
Market Approach Valuation Technique [Member] | Other Real Estate Owned [Member] | Weighted Average [Member]
Liquidation expenses	[3]	22.00%	17.00%
Market Approach Valuation Technique [Member] | Other Real Estate Owned [Member] | Minimum [Member]
Liquidation expenses	[3]		5.00%
Market Approach Valuation Technique [Member] | Other Real Estate Owned [Member] | Maximum [Member]
Liquidation expenses	[3]		76.00%
Sales Price Valuation Technique [Member] | Impaired Loans [Member]
Valuation Technique			Sales Price
Unobservable Input			Liquidation expenses
Sales Price Valuation Technique [Member] | Impaired Loans [Member] | Weighted Average [Member]
Discount Rate	[3]		7.00%
Sales Price Valuation Technique [Member] | Other Real Estate Owned [Member]
Valuation Technique		Sales Price	Sales Price
Unobservable Input	[1]	Liquidation expenses	Liquidation expenses
Sales Price Valuation Technique [Member] | Other Real Estate Owned [Member] | Weighted Average [Member]
Liquidation expenses	[3]	7.00%	7.00%
Sales Price Valuation Technique [Member] | Other Real Estate Owned [Member] | Minimum [Member]
Liquidation expenses	[3]	4.00%	7.00%
Sales Price Valuation Technique [Member] | Other Real Estate Owned [Member] | Maximum [Member]
Liquidation expenses	[3]	7.00%	8.00%

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

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

[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.