Note 1 - Summary of Significant Accounting Policies (Details Textual)	Sep. 30, 2020 USD ($)	Jan. 01, 2020	Dec. 31, 2019
Financing Receivable, Nonaccural, Not Impaired, Number of Positions	0		0
Financing Receivable, Threshold for Individually Evaluated for Impairment	$ 500,000
Financing Receivable, Maximum for Measurement Using Allocation Rate	$ 500,000
Minimum [Member] | Pro Forma [Member] | COVID 19 [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease), Percentage	4.00%
Minimum [Member] | Accounting Standards Update 2016-13 [Member] | Pro Forma [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease), Percentage	4.00%	4.00%
Maximum [Member] | Pro Forma [Member] | COVID 19 [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease), Percentage	6.00%
Maximum [Member] | Accounting Standards Update 2016-13 [Member] | Pro Forma [Member]
Allowance for Loan and Lease Losses, Period Increase (Decrease), Percentage	6.00%	6.00%