Note 8 - Loans - Accruing Troubled Debt Restructurings (Details) - Accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018
Accruing TDRs	$ 34,364	$ 35,336	$ 62,948	$ 65,071
Payment Deferral [Member]
Accruing TDRs	7,612	8,355
Contractual Interest Rate Reduction [Member]
Accruing TDRs	6,013	6,059
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	20,739	20,922
Commercial Portfolio Segment [Member]
Accruing TDRs	4,700	5,215
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	4,700	5,215
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
Commercial Real Estate Portfolio Segment [Member]
Accruing TDRs	24,784	25,142
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	459	615
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	5,707	5,748
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	18,618	18,779
Residential Portfolio Segment [Member]
Accruing TDRs	4,880	4,979
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	2,453	2,525
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	306	311
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 2,121	$ 2,143