Note 8 - Loans - Impaired Loans and Related Allowance for Credit Losses (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Loans with no related allowance, unpaid principal balance	$ 48,958	$ 77,605
Loans with no related allowance, recorded investment	43,408	65,315
Loans with related allowance, unpaid principal balance	46,618	42,686
Loans with related allowance, recorded investment	45,439	41,571
Allowance	1,501	3,802
Total impaired loans, unpaid principal balance	95,576	120,291
Total impaired loans, recorded investment	88,847	106,886
Commercial Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	24,711	32,015
Loans with no related allowance, recorded investment	20,492	30,368
Loans with related allowance, unpaid principal balance	13,251	6,653
Loans with related allowance, recorded investment	13,234	6,570
Allowance	744	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	4,629	4,873
Commercial Real Estate Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	11,663	34,129
Loans with no related allowance, recorded investment	11,517	24,409
Loans with related allowance, unpaid principal balance	26,356	27,099
Loans with related allowance, recorded investment	26,288	27,063
Allowance	536	877
Residential Mortgage and Equity Lines Portfolio Segment [Member]
Loans with no related allowance, unpaid principal balance	6,808	5,685
Loans with no related allowance, recorded investment	6,770	5,665
Loans with related allowance, unpaid principal balance	7,011	8,934
Loans with related allowance, recorded investment	5,917	7,938
Allowance	$ 221	$ 1,088