Note 8 - Loans - Accruing Troubled Debt Restructurings (Details) - Accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
Accruing TDRs	$ 64,898	$ 62,948	$ 65,071	$ 84,487	$ 82,785	$ 68,566
Payment Deferral [Member]
Accruing TDRs	37,524		35,510
Contractual Interest Rate Reduction [Member]
Accruing TDRs	6,096		7,747
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	21,278		21,814
Commercial Portfolio Segment [Member]
Accruing TDRs	24,753		18,135
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	24,753		18,135
Commercial Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	0		0
Commercial Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	0		0
Commercial Real Estate Portfolio Segment [Member]
Accruing TDRs	34,626		40,860
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	9,761		14,022
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	5,775		7,420
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	19,090		19,418
Residential Portfolio Segment [Member]
Accruing TDRs	5,519		6,076
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	3,010		3,353
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	321		327
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 2,188		$ 2,396