Note 8 - Loans - Accruing Troubled Debt Restructurings (Details) - Accruing Troubled Debt Restructuring [Member] - USD ($) $ in Thousands	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Accruing TDRs	$ 41,647	$ 64,898	$ 65,071	$ 74,598	$ 84,487	$ 68,566
Payment Deferral [Member]
Accruing TDRs	14,469		35,510
Contractual Interest Rate Reduction [Member]
Accruing TDRs	6,076		7,747
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	21,102		21,814
Commercial Portfolio Segment [Member]
Accruing TDRs	10,756		18,135
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	10,756		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	25,475		40,860
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	782		14,022
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	5,757		7,420
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	18,936		19,418
Residential Portfolio Segment [Member]
Accruing TDRs	5,416		6,076
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	2,931		3,353
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	319		327
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 2,166		$ 2,396