Note 8 - Loans - Impaired Loans and Related Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Loans with no related allowance, unpaid principal balance	$ 52,903	$ 41,315
Loans with no related allowance, recorded investment	47,974	35,540
Loans with related allowance, unpaid principal balance	65,829	41,626
Loans with related allowance, recorded investment	57,804	40,319
Allowance	8,495	3,236
Total impaired loans, unpaid principal balance	118,732	82,941
Total impaired loans, recorded investment	105,778	75,859
Commercial Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	16,210	20,134
Loans with no related allowance, recorded investment	13,293	15,857
Loans with related allowance, unpaid principal balance	28,059	8,769
Loans with related allowance, recorded investment	20,871	8,739
Allowance	7,704	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	4,335	4,580
Commercial Real Estate Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	22,996	9,234
Loans with no related allowance, recorded investment	22,532	9,030
Loans with related allowance, unpaid principal balance	31,138	26,117
Loans with related allowance, recorded investment	31,019	26,040
Allowance	582	473
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	7,921	6,171
Loans with no related allowance, recorded investment	7,814	6,073
Loans with related allowance, unpaid principal balance	6,632	6,740
Loans with related allowance, recorded investment	5,914	5,540
Allowance	$ 209	$ 220