Note 8 - Loans - Non-accrual Troubled Debt Restructurings (Details) - Non-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	$ 22,457	$ 23,301	$ 24,189	$ 30,347	$ 31,195	$ 33,415
Payment Deferral [Member]
Accruing TDRs	17,936		19,194
Contractual Interest Rate Reduction [Member]
Accruing TDRs	0		0
Rate Reduction and Payment Deferral [Member]
Accruing TDRs	4,521		4,995
Commercial Portfolio Segment [Member]
Accruing TDRs	16,278		13,771
Commercial Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	16,278		13,771
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	4,417		8,566
Commercial Real Estate Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	0		3,682
Commercial Real Estate Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	0		0
Commercial Real Estate Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	4,417		4,884
Residential Portfolio Segment [Member]
Accruing TDRs	1,762		1,852
Residential Portfolio Segment [Member] | Payment Deferral [Member]
Accruing TDRs	1,658		1,741
Residential Portfolio Segment [Member] | Contractual Interest Rate Reduction [Member]
Accruing TDRs	0		0
Residential Portfolio Segment [Member] | Rate Reduction and Payment Deferral [Member]
Accruing TDRs	$ 104		$ 111