Note 8 - Loans - Accruing Troubled Debt Restructurings (Details) - Accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018
Accruing TDRs	$ 31,671	$ 34,364	$ 35,336	$ 64,898	$ 62,948	$ 65,071
Payment Deferral [Member]
Accruing TDRs	5,127		8,355
Contractual Interest Rate Reduction [Member]
Accruing TDRs	5,988		6,059
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	20,556		20,922
Commercial Portfolio Segment [Member]
Accruing TDRs	2,129		5,215
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	2,129		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	24,733		25,142
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	585		615
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	5,689		5,748
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	18,459		18,779
Residential Portfolio Segment [Member]
Accruing TDRs	4,809		4,979
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	2,413		2,525
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	299		311
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 2,097		$ 2,143