Note 8 - Loans - Accruing Troubled Debt Restructurings (Details) - Accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Accruing TDRs	$ 82,785	$ 68,565	$ 80,419	$ 65,393
Payment Deferral [Member]
Accruing TDRs	52,348	44,119
Contractual Interest Rate Reduction [Member]
Accruing TDRs	7,832	6,206
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	22,605	18,240
Commercial Portfolio Segment [Member]
Accruing TDRs	28,995	29,199
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	28,995	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	46,967	32,843
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	19,609	11,504
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	7,499	5,871
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	19,859	15,468
Residential Portfolio Segment [Member]
Accruing TDRs	6,823	6,523
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	3,744	3,416
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	333	335
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 2,746	$ 2,772