Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Dec. 31, 2018
Loans	$ 2,799,639,000	$ 2,753,085,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	1.70%
Commercial Portfolio Segment [Member]
Loans	$ 2,400,198,000	$ 2,360,106,000
Percent of portfolio	85.70%	85.70%
Period increase (decrease)	1.70%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 839,207,000	$ 822,723,000
Percent of portfolio	30.00%	29.90%
Period increase (decrease)	2.00%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 45,892,000	$ 44,885,000
Percent of portfolio	1.60%	1.60%
Period increase (decrease)	2.20%
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 551,518,000	$ 548,619,000
Percent of portfolio	19.70%	19.90%
Period increase (decrease)	0.50%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 835,678,000	$ 816,282,000
Percent of portfolio	29.80%	29.70%
Period increase (decrease)	2.40%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 127,903,000	$ 127,597,000
Percent of portfolio	4.60%	4.60%
Period increase (decrease)	0.20%
Retail Portfolio Segment [Member]
Loans	$ 399,441,000	$ 392,979,000
Percent of portfolio	14.30%	14.30%
Period increase (decrease)	1.60%
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 83,127,000	$ 85,439,000
Percent of portfolio	3.00%	3.10%
Period increase (decrease)	(2.70%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 316,314,000	$ 307,540,000
Percent of portfolio	11.30%	11.20%
Period increase (decrease)	2.90%
Originated Loan [Member]
Loans	$ 2,511,036,000	$ 2,452,446,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	2.40%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 2,198,713,000	$ 2,151,998,000
Percent of portfolio	87.60%	87.70%
Period increase (decrease)	2.20%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 786,705,000	$ 768,698,000
Percent of portfolio	31.30%	31.30%
Period increase (decrease)	2.30%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 41,179,000	$ 39,950,000
Percent of portfolio	1.60%	1.60%
Period increase (decrease)	3.10%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 503,988,000	$ 500,188,000
Percent of portfolio	20.10%	20.40%
Period increase (decrease)	0.80%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 767,318,000	$ 745,127,000
Percent of portfolio	30.60%	30.40%
Period increase (decrease)	3.00%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 99,523,000	$ 98,035,000
Percent of portfolio	4.00%	4.00%
Period increase (decrease)	1.50%
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 312,323,000	$ 300,448,000
Percent of portfolio	12.40%	12.30%
Period increase (decrease)	4.00%
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 64,769,000	$ 65,023,000
Percent of portfolio	2.60%	2.70%
Period increase (decrease)	(0.40%)
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 247,554,000	$ 235,425,000
Percent of portfolio	9.80%	9.60%
Period increase (decrease)	5.20%
Acquired Loan [Member]
Loans	$ 288,603,000	$ 300,639,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(4.00%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 201,485,000	$ 208,108,000
Percent of portfolio	69.80%	69.20%
Period increase (decrease)	(3.20%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 52,502,000	$ 54,025,000
Percent of portfolio	18.20%	18.00%
Period increase (decrease)	(2.80%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 4,713,000	$ 4,935,000
Percent of portfolio	1.60%	1.60%
Period increase (decrease)	(4.50%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 47,530,000	$ 48,431,000
Percent of portfolio	16.50%	16.10%
Period increase (decrease)	(1.90%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 68,360,000	$ 71,155,000
Percent of portfolio	23.70%	23.70%
Period increase (decrease)	(3.90%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 28,380,000	$ 29,562,000
Percent of portfolio	9.80%	9.80%
Period increase (decrease)	(4.00%)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 87,118,000	$ 92,531,000
Percent of portfolio	30.20%	30.80%
Period increase (decrease)	(5.80%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 18,358,000	$ 20,416,000
Percent of portfolio	6.40%	6.80%
Period increase (decrease)	(10.10%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 68,760,000	$ 72,115,000
Percent of portfolio	23.80%	24.00%
Period increase (decrease)	(4.70%)