Note 8 - Loans - Non-accrual Troubled Debt Restructurings (Details) - Non-accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accruing TDRs	$ 8,661	$ 8,985	$ 17,889	$ 18,048
Payment Deferral [Member]
Accruing TDRs	8,661	8,985
Contractual Interest Rate Reduction [Member]
Accruing TDRs	0	0
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	0	0
Commercial Portfolio Segment [Member]
Accruing TDRs	8,150	8,462
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	8,150	8,462
Commercial Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	0	0
Commercial Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	0	0
Residential Portfolio Segment [Member]
Accruing TDRs	511	523
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	511	523
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	0	0
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 0	$ 0