Note 8 - Loans - Impaired Loans and Related Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Loans with no related allowance, unpaid principal balance	$ 57,066	$ 41,315
Loans with no related allowance, recorded investment	52,720	35,540
Loans with related allowance, unpaid principal balance	36,754	41,626
Loans with related allowance, recorded investment	35,377	40,319
Allowance	3,451	3,236
Total impaired loans, unpaid principal balance	93,820	82,941
Total impaired loans, recorded investment	88,097	75,859
Commercial Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	28,685	20,134
Loans with no related allowance, recorded investment	25,991	15,857
Loans with related allowance, unpaid principal balance	9,223	8,769
Loans with related allowance, recorded investment	9,152	8,739
Allowance	2,827	2,543
Real Estate Construction Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	5,776	5,776
Loans with no related allowance, recorded investment	4,482	4,580
Commercial Real Estate Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	16,559	9,234
Loans with no related allowance, recorded investment	16,223	9,030
Loans with related allowance, unpaid principal balance	20,513	26,117
Loans with related allowance, recorded investment	20,420	26,040
Allowance	405	473
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	6,046	6,171
Loans with no related allowance, recorded investment	6,024	6,073
Loans with related allowance, unpaid principal balance	7,018	6,740
Loans with related allowance, recorded investment	5,805	5,540
Allowance	$ 219	$ 220