Note 8 - Loans - Accruing Troubled Debt Restructurings (Details) - Accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
Accruing TDRs	$ 62,948	$ 65,071	$ 82,785	$ 68,566
Payment Deferral [Member]
Accruing TDRs	33,610	35,510
Contractual Interest Rate Reduction [Member]
Accruing TDRs	7,715	7,747
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	21,623	21,814
Commercial Portfolio Segment [Member]
Accruing TDRs	16,660	18,135
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	16,660	18,135
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	40,413	40,860
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	13,773	14,022
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	7,391	7,420
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	19,249	19,418
Residential Portfolio Segment [Member]
Accruing TDRs	5,875	6,076
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	3,177	3,353
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	324	327
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 2,374	$ 2,396