Note 8 - Loans - Non-accrual Troubled Debt Restructurings (Details) - Non-accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accruing TDRs	$ 23,301	$ 24,189	$ 31,195	$ 33,415
Payment Deferral [Member]
Accruing TDRs	18,498	19,194
Contractual Interest Rate Reduction [Member]
Accruing TDRs
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	4,803	4,995
Commercial Portfolio Segment [Member]
Accruing TDRs	13,148	13,771
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	13,148	13,771
Commercial Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs
Commercial Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs
Commercial Real Estate Portfolio Segment [Member]
Accruing TDRs	8,331	8,566
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	3,636	3,682
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	4,695	4,884
Residential Portfolio Segment [Member]
Accruing TDRs	1,822	1,852
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	1,714	1,741
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 108	$ 111