Note 8 - Loans - Non-accrual Troubled Debt Restructurings (Details) - Non-accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accruing TDRs	$ 17,889	$ 18,048	$ 23,301	$ 24,189
Payment Deferral [Member]
Accruing TDRs	17,760	17,912
Contractual Interest Rate Reduction [Member]
Accruing TDRs	0	0
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	129	136
Commercial Portfolio Segment [Member]
Accruing TDRs	16,561	16,692
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	16,561	16,692
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	1,328
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	1,199
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	0
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 129
Commercial Real Estate Portfolio Segment [Member]
Accruing TDRs		1,356
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs		1,220
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs		0
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs		$ 136