Note 9 - Quantitative Information about Assets Measured at Fair Value (Details) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2019 USD ($)	Dec. 31, 2018 USD ($)
Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		$ 4,527	$ 3,060
Nonrecurring [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		4,520	3,055
Nonrecurring [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		7	5
Fair Value, Inputs, Level 3 [Member] | Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		4,527	3,060
Fair Value, Inputs, Level 3 [Member] | Nonrecurring [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		4,520	3,055
Fair Value, Inputs, Level 3 [Member] | Nonrecurring [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		$ 7	$ 5
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 liquidation inputs	[1],[2]	(10.00%)	(10.00%)
Fair Value, Inputs, Level 3 [Member] | Appraisal Valuation Technique [Member] | Measurement Input, Comparability Adjustment [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]	(0.100)	(0.200)
Fair Value, Inputs, Level 3 [Member] | Appraisal Valuation Technique [Member] | Measurement Input, Comparability Adjustment [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]	(0.400)	(0.900)
Fair Value, Inputs, Level 3 [Member] | Appraisal Valuation Technique [Member] | Nonrecurring [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements	[2]	$ 3,909	$ 1,632
Fair Value, Inputs, Level 3 [Member] | Market Approach Valuation Technique [Member] | Minimum [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[4]	(30.00%)	(25.00%)
Fair Value, Inputs, Level 3 [Member] | Market Approach Valuation Technique [Member] | Maximum [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value range of value inputs	[4]	(100.00%)	(100.00%)
Fair Value, Inputs, Level 3 [Member] | Market Approach Valuation Technique [Member] | Nonrecurring [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements	[4]	$ 611	$ 1,415
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Measurement Input, Expected Term [Member] | Minimum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value expected term		1 year	2 years
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Measurement Input, Expected Term [Member] | Maximum [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Nonrecurring fair value expected term		26 years	26 years
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Measurement Input, Discount Rate [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		12.00%	12.00%
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Measurement Input, Discount Rate [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		12.50%	12.50%
Fair Value, Inputs, Level 3 [Member] | Discounted Cash Flow Valuation Technique [Member] | Nonrecurring [Member] | Mortgage Servicing Rights [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		$ 7	$ 5
Fair Value, Inputs, Level 3 [Member] | Used Commercial Vehicle 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 range of value inputs	[5]		(10.00%)
Fair Value, Inputs, Level 3 [Member] | Used Commercial Vehicle Guides Valuation Technique [Member] | Nonrecurring [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements	[5]		$ 8

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

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