Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)		3 Months Ended
		Mar. 31, 2021	Dec. 31, 2020
Loans		$ 3,364,370,000	$ 3,193,470,000
Percent of portfolio		100.00%	100.00%
Period increase (decrease)		5.40%
Commercial Portfolio Segment [Member]
Loans		$ 2,967,215,000	$ 2,793,962,000
Percent of portfolio		88.20%	87.50%
Period increase (decrease)		6.20%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	[1]	$ 1,284,507,000	$ 1,145,423,000
Percent of portfolio	[1]	38.20%	35.90%
Period increase (decrease)	[1]	12.10%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans		$ 58,738,000	$ 55,055,000
Percent of portfolio		1.70%	1.70%
Period increase (decrease)		6.70%
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans		$ 544,342,000	$ 529,953,000
Percent of portfolio		16.20%	16.60%
Period increase (decrease)		2.70%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans		$ 932,334,000	$ 917,436,000
Percent of portfolio		27.70%	28.70%
Period increase (decrease)		0.60%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans		$ 147,294,000	$ 146,095,000
Percent of portfolio		4.40%	4.60%
Period increase (decrease)		0.80%
Retail Portfolio Segment [Member]
Loans		$ 397,155,000	$ 399,508,000
Percent of portfolio		11.80%	12.50%
Period increase (decrease)		(0.60%)
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans		$ 59,311,000	$ 61,620,000
Percent of portfolio		1.80%	1.90%
Period increase (decrease)		(3.70%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans		$ 337,844,000	$ 337,888,000
Percent of portfolio		10.00%	10.60%
Period increase (decrease)		(0.10%)

[1] Includes $455 million and $365 million in loans originated under the Paycheck Protection Program for March 31, 2021 and December 31, 2020, respectively.