Note 5 - Loans - Accruing Troubled Debt Restructurings (Details) - Accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accruing TDRs	$ 65,071	$ 68,565	$ 65,393	$ 81,680
Payment Deferral [Member]
Accruing TDRs	35,510	44,119
Contractual Interest Rate Reduction [Member]
Accruing TDRs	7,747	6,206
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	21,814	18,240
Commercial Portfolio Segment [Member]
Accruing TDRs	18,135	29,199
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	18,135	29,199
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	40,860	32,843
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	14,022	11,504
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	7,420	5,871
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	19,418	15,468
Residential Portfolio Segment [Member]
Accruing TDRs	6,076	6,523
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	3,353	3,416
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	327	335
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 2,396	$ 2,772