Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)		9 Months Ended
		Sep. 30, 2020	Dec. 31, 2019
Loans		$ 3,350,544,000	$ 2,856,667,000
Percent of portfolio		100.00%	100.00%
Period increase (decrease)		17.30%
Commercial Portfolio Segment [Member]
Loans		$ 2,938,361,000	$ 2,441,544,000
Percent of portfolio		87.70%	85.50%
Period increase (decrease)		20.30%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	[1]	$ 1,321,419,000	$ 846,551,000
Percent of portfolio	[1]	39.50%	29.60%
Period increase (decrease)	[1]	56.10%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans		$ 50,941,000	$ 56,119,000
Percent of portfolio		1.50%	2.00%
Period increase (decrease)		(0.90%)
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans		$ 549,364,000	$ 579,003,000
Percent of portfolio		16.40%	20.30%
Period increase (decrease)		(5.10%)
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans		$ 878,897,000	$ 835,346,000
Percent of portfolio		26.20%	29.20%
Period increase (decrease)		5.20%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans		$ 137,740,000	$ 124,525,000
Percent of portfolio		4.10%	4.40%
Period increase (decrease)		10.60%
Retail Portfolio Segment [Member]
Loans		$ 412,183,000	$ 415,123,000
Percent of portfolio		12.30%	14.50%
Period increase (decrease)		(0.70%)
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans		$ 63,723,000	$ 75,374,000
Percent of portfolio		1.90%	2.60%
Period increase (decrease)		(15.50%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans		$ 348,460,000	$ 339,749,000
Percent of portfolio		10.40%	11.90%
Period increase (decrease)		2.60%

[1] For September 30, 2020, includes $555 million in loans originated under the Paycheck Protection Program.