Note 8 - Quantitative Information about Assets Measured at Fair Value (Details) - USD ($) $ in Thousands		3 Months Ended	12 Months Ended
		Mar. 31, 2017	Dec. 31, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements		$ 3,046	$ 2,957
Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements		3,003	2,899
Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements		43	58
Fair Value, Inputs, Level 3 [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements		3,046	2,957
Fair Value, Inputs, Level 3 [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements		$ 3,003	2,899
Nonrecurring fair value liquidation inputs	[1]	(10.00%)
Fair Value, Inputs, Level 3 [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements		$ 43	58
Fair Value, Inputs, Level 3 [Member] | Appraisal Valuation Technique [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements	[2]	$ 1,281	$ 938
Nonrecurring fair value liquidation inputs	[1],[2]		(10.00%)
Fair Value, Inputs, Level 3 [Member] | Appraisal Valuation Technique [Member] | Impaired Loans [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[2],[3]	10.00%	10.00%
Fair Value, Inputs, Level 3 [Member] | Appraisal Valuation Technique [Member] | Impaired Loans [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[2],[3]	80.00%	80.00%
Fair Value, Inputs, Level 3 [Member] | Commercial Vehicle and Equipment Guides Valuation Technique [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements	[4]	$ 24	$ 76
Fair Value, Inputs, Level 3 [Member] | Commercial Vehicle and Equipment Guides Valuation Technique [Member] | Impaired Loans [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[4]	0.00%	0.00%
Fair Value, Inputs, Level 3 [Member] | Commercial Vehicle and Equipment Guides Valuation Technique [Member] | Impaired Loans [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[4]	25.00%	25.00%
Fair Value, Inputs, Level 3 [Member] | Market Approach Valuation Technique [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements	[5]	$ 1,698	$ 1,880
Fair Value, Inputs, Level 3 [Member] | Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[5]	20.00%	20.00%
Fair Value, Inputs, Level 3 [Member] | Market Approach Valuation Technique [Member] | Impaired Loans [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[5]	50.00%	50.00%
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements		$ 43	$ 58
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Mortgage Servicing Rights [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs		14.00%	14.00%
Nonrecurring fair value expected term		2 years	2 years
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Mortgage Servicing Rights [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs		16.00%	16.00%
Nonrecurring fair value expected term		27 years	27 years
Fair Value, Inputs, Level 3 [Member] | Agreement of Sale [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value measurements	[6]		$ 5

[1] Appraisals and pending agreements of sale are adjusted by management for estimated liquidation expenses. The range is presented as a percent of the initial appraised value.

[2] Fair value is primarily determined through appraisals of the underlying collateral by independent parties, which generally includes various level 3 inputs which are not always identifiable.

[3] Appraisals may be adjusted by management for qualitative factors such as economic conditions and the age of the appraisal. The range is presented as a percent of the initial appraised value.

[4] If lendable value (lower than wholesale) is utilized then no additional discounts are taken. If lendable value is not provided, additional discounts are applied.

[5] Values obtained from financial statements for UCC collateral (fixed assets and inventory) are discounted to estimated realizable liquidation value.

[6] Fair value is determined by the net amount due.