Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)	9 Months Ended
	Sep. 30, 2019	Dec. 31, 2018
Loans	$ 2,933,013,000	$ 2,753,085,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	6.50%
Commercial Portfolio Segment [Member]
Loans	$ 2,508,367,000	$ 2,360,106,000
Percent of portfolio	85.50%	85.70%
Period increase (decrease)	6.30%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 882,748,000	$ 822,723,000
Percent of portfolio	30.10%	29.90%
Period increase (decrease)	7.30%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 48,417,000	$ 44,885,000
Percent of portfolio	1.70%	1.60%
Period increase (decrease)	7.90%
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 567,267,000	$ 548,619,000
Percent of portfolio	19.30%	19.90%
Period increase (decrease)	3.40%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 883,080,000	$ 816,282,000
Percent of portfolio	30.10%	29.70%
Period increase (decrease)	8.20%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 126,855,000	$ 127,597,000
Percent of portfolio	4.30%	4.60%
Period increase (decrease)	(0.60%)
Retail Portfolio Segment [Member]
Loans	$ 424,646,000	$ 392,979,000
Percent of portfolio	14.50%	14.30%
Period increase (decrease)	8.10%
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 78,552,000	$ 85,439,000
Percent of portfolio	2.70%	3.10%
Period increase (decrease)	(8.10%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 346,094,000	$ 307,540,000
Percent of portfolio	11.80%	11.20%
Period increase (decrease)	12.50%
Originated Loan [Member]
Loans	$ 2,690,177,000	$ 2,452,446,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	9.70%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 2,341,797,000	$ 2,151,998,000
Percent of portfolio	87.00%	87.70%
Period increase (decrease)	8.80%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 848,659,000	$ 768,698,000
Percent of portfolio	31.50%	31.30%
Period increase (decrease)	10.40%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 44,016,000	$ 39,950,000
Percent of portfolio	1.60%	1.60%
Period increase (decrease)	10.20%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 527,580,000	$ 500,188,000
Percent of portfolio	19.60%	20.40%
Period increase (decrease)	5.50%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 819,743,000	$ 745,127,000
Percent of portfolio	30.50%	30.40%
Period increase (decrease)	10.00%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 101,799,000	$ 98,035,000
Percent of portfolio	3.80%	4.00%
Period increase (decrease)	3.80%
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 348,380,000	$ 300,448,000
Percent of portfolio	13.00%	12.30%
Period increase (decrease)	16.00%
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 63,026,000	$ 65,023,000
Percent of portfolio	2.40%	2.70%
Period increase (decrease)	(3.10%)
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 285,354,000	$ 235,425,000
Percent of portfolio	10.60%	9.60%
Period increase (decrease)	21.20%
Acquired Loan [Member]
Loans	$ 242,836,000	$ 300,639,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(19.20%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 166,570,000	$ 208,108,000
Percent of portfolio	68.60%	69.20%
Period increase (decrease)	(20.00%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 34,089,000	$ 54,025,000
Percent of portfolio	14.10%	18.00%
Period increase (decrease)	(36.90%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 4,401,000	$ 4,935,000
Percent of portfolio	1.80%	1.60%
Period increase (decrease)	(10.80%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 39,687,000	$ 48,431,000
Percent of portfolio	16.30%	16.10%
Period increase (decrease)	(18.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 63,337,000	$ 71,155,000
Percent of portfolio	26.10%	23.70%
Period increase (decrease)	(11.00%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 25,056,000	$ 29,562,000
Percent of portfolio	10.30%	9.80%
Period increase (decrease)	(15.20%)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 76,266,000	$ 92,531,000
Percent of portfolio	31.40%	30.80%
Period increase (decrease)	(17.60%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 15,526,000	$ 20,416,000
Percent of portfolio	6.40%	6.80%
Period increase (decrease)	(24.00%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 60,740,000	$ 72,115,000
Percent of portfolio	25.00%	24.00%
Period increase (decrease)	(15.80%)