Note 9 - Quantitative Information about Assets Measured at Fair Value (Details) $ in Thousands		9 Months Ended	12 Months Ended
		Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Nonrecurring [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		$ 4,996	$ 5,219
Nonrecurring [Member] | Impaired Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis Valuation Techniques [Line Items]
Asset fair value measurements		4,670	5,212
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		326	7
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		4,996	5,219
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		4,670	5,212
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		$ 326	$ 7
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]	(0.10)	(0.05)
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]	(0.30)	(0.40)
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]	$ 3,712	$ 4,655
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]	(20.00%)	(30.00%)
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]	$ 922	$ 521
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]	(30.00%)	(30.00%)
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]	$ 36	$ 36
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		2 years	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		30 years	27 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		$ 326	$ 7

[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.