Note 4 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Loans	$ 2,753,085,000	$ 2,558,552,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	7.60%
Commercial Portfolio Segment [Member]
Loans	$ 2,360,106,000	$ 2,203,568,000
Percent of portfolio	85.70%	86.10%
Period increase (decrease)	7.10%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 822,723,000	$ 753,764,000
Percent of portfolio	29.90%	29.40%
Period increase (decrease)	9.10%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 44,885,000	$ 29,873,000
Percent of portfolio	1.60%	1.20%
Period increase (decrease)	50.30%
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 548,619,000	$ 526,328,000
Percent of portfolio	19.90%	20.60%
Period increase (decrease)	4.20%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 816,282,000	$ 791,685,000
Percent of portfolio	29.70%	30.90%
Period increase (decrease)	3.10%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 127,597,000	$ 101,918,000
Percent of portfolio	4.60%	4.00%
Period increase (decrease)	25.20%
Retail Portfolio Segment [Member]
Loans	$ 392,979,000	$ 354,984,000
Percent of portfolio	14.30%	13.90%
Period increase (decrease)	10.70%
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 85,439,000	$ 100,425,000
Percent of portfolio	3.10%	3.90%
Period increase (decrease)	(14.90%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 307,540,000	$ 254,559,000
Percent of portfolio	11.20%	10.00%
Period increase (decrease)	20.80%
Originated Loan [Member]
Loans	$ 2,452,446,000	$ 2,169,957,000	$ 1,884,548,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	13.00%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 2,151,998,000	$ 1,934,228,000	1,728,898,000
Percent of portfolio	87.70%	89.10%
Period increase (decrease)	11.30%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 768,698,000	$ 680,805,000
Percent of portfolio	31.30%	31.30%
Period increase (decrease)	12.90%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 39,950,000	$ 23,682,000
Percent of portfolio	1.60%	1.10%
Period increase (decrease)	68.70%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 500,188,000	$ 456,065,000
Percent of portfolio	20.40%	21.00%
Period increase (decrease)	9.70%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 745,127,000	$ 708,824,000
Percent of portfolio	30.40%	32.70%
Period increase (decrease)	5.10%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 98,035,000	$ 64,852,000
Percent of portfolio	4.00%	3.00%
Period increase (decrease)	51.20%
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 300,448,000	$ 235,729,000	$ 155,650,000
Percent of portfolio	12.30%	10.90%
Period increase (decrease)	27.50%
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 65,023,000	$ 69,675,000
Percent of portfolio	2.70%	3.20%
Period increase (decrease)	(6.70%)
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 235,425,000	$ 166,054,000
Percent of portfolio	9.60%	7.70%
Period increase (decrease)	41.80%
Acquired Loan [Member]
Loans	$ 300,639,000	$ 388,595,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(22.60%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 208,108,000	$ 269,340,000
Percent of portfolio	69.20%	69.30%
Period increase (decrease)	(22.70%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 54,025,000	$ 72,959,000
Percent of portfolio	18.00%	18.80%
Period increase (decrease)	(26.00%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 4,935,000	$ 6,191,000
Percent of portfolio	1.60%	1.60%
Period increase (decrease)	(20.30%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 48,431,000	$ 70,263,000
Percent of portfolio	16.10%	18.10%
Period increase (decrease)	(31.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 71,155,000	$ 82,861,000
Percent of portfolio	23.70%	21.30%
Period increase (decrease)	(14.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 29,562,000	$ 37,066,000
Percent of portfolio	9.80%	9.50%
Period increase (decrease)	(20.20%)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 92,531,000	$ 119,255,000
Percent of portfolio	30.80%	30.70%
Period increase (decrease)	(22.40%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 20,416,000	$ 30,750,000
Percent of portfolio	6.80%	7.90%
Period increase (decrease)	(33.60%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 72,115,000	$ 88,505,000
Percent of portfolio	24.00%	22.80%
Period increase (decrease)	(18.50%)