Note 4 - Loans - Impaired Loans and Related Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Loans with no related allowance, unpaid principal balance	$ 41,315	$ 77,605
Loans with no related allowance, recorded investment	35,540	65,315
Loans with related allowance, unpaid principal balance	41,626	42,686
Loans with related allowance, recorded investment	40,319	41,571
Allowance	3,236	3,802
Total impaired loans, unpaid principal balance	82,941	120,291
Total impaired loans, recorded investment	75,859	106,886
Commercial Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	20,134	32,015
Loans with no related allowance, recorded investment	15,857	30,368
Loans with related allowance, unpaid principal balance	8,769	6,653
Loans with related allowance, recorded investment	8,739	6,570
Allowance	2,543	1,837
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	4,580	4,873
Commercial Real Estate Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	9,234	34,129
Loans with no related allowance, recorded investment	9,030	24,409
Loans with related allowance, unpaid principal balance	26,117	27,099
Loans with related allowance, recorded investment	26,040	27,063
Allowance	473	877
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	6,171	5,685
Loans with no related allowance, recorded investment	6,073	5,665
Loans with related allowance, unpaid principal balance	6,740	8,934
Loans with related allowance, recorded investment	5,540	7,938
Allowance	$ 220	$ 1,088