Note 8 - Loans (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Impaired Financing Receivable, Recorded Investment, Total	$ 88,097	$ 75,859
Percentage Of Charge Off To Contractual Balances For Impaired Loans	0.30%	2.10%
Financing Receivables, Impaired, Troubled Debt Restructuring, Specific Reserve	$ 0		$ 0
Financing Receivable, Troubled Debt Restructuring, Subsequent Default	$ 0
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend		$ 0
Minimum [Member]
Period Loan Is In Payment Default (Day)	60 days
Maximum [Member]
Period Loan Is In Payment Default (Day)	90 days
Nonaccrual Loans [Member]
Impaired Financing Receivable, Recorded Investment, Total	$ 53,700	40,500
Accruing Troubled Debt Restructuring [Member]
Impaired Financing Receivable, Recorded Investment, Total	34,400	35,400
Financing Receivable, Troubled Debt Restructuring	34,400	35,300
Troubled Debt Restructuring, Specific Reserves	1,000
Financing Receivables, Impaired, Troubled Debt Restructuring, Specific Reserve	822
Non-accruing Troubled Debt Restructuring [Member]
Financing Receivable, Troubled Debt Restructuring	17,900	18,000
Troubled Debt Restructuring, Specific Reserves	$ 2,200
Financing Receivables, Impaired, Troubled Debt Restructuring, Specific Reserve		$ 2,200