Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Loans	$ 2,551,204,000	$ 2,558,552,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(0.30%)
Commercial Portfolio Segment [Member]
Loans	$ 2,193,029,000	$ 2,203,568,000
Percent of portfolio	86.00%	86.10%
Period increase (decrease)	(0.50%)
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 739,805,000	$ 753,764,000
Percent of portfolio	29.00%	29.40%
Period increase (decrease)	(1.90%)
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 31,438,000	$ 29,873,000
Percent of portfolio	1.20%	1.20%
Period increase (decrease)	5.20%
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 531,152,000	$ 526,328,000
Percent of portfolio	20.80%	20.60%
Period increase (decrease)	0.90%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 794,206,000	$ 791,685,000
Percent of portfolio	31.20%	30.90%
Period increase (decrease)	0.30%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 96,428,000	$ 101,918,000
Percent of portfolio	3.80%	4.00%
Period increase (decrease)	(5.40%)
Retail Portfolio Segment [Member]
Loans	$ 358,175,000	$ 354,984,000
Percent of portfolio	14.00%	13.90%
Period increase (decrease)	0.90%
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 93,179,000	$ 100,425,000
Percent of portfolio	3.60%	3.90%
Period increase (decrease)	(7.20%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 264,996,000	$ 254,559,000
Percent of portfolio	10.40%	10.00%
Period increase (decrease)	4.10%
Originated Loan [Member]
Loans	$ 2,191,851,000	$ 2,169,957,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	1.00%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 1,946,966,000	$ 1,934,228,000
Percent of portfolio	88.80%	89.10%
Period increase (decrease)	0.70%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 675,188,000	$ 680,805,000
Percent of portfolio	30.80%	31.30%
Period increase (decrease)	(0.80%)
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 25,514,000	$ 23,682,000
Percent of portfolio	1.20%	1.10%
Period increase (decrease)	7.70%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 468,777,000	$ 456,065,000
Percent of portfolio	21.40%	21.00%
Period increase (decrease)	2.80%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 715,725,000	$ 708,824,000
Percent of portfolio	32.60%	32.70%
Period increase (decrease)	1.00%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 61,762,000	$ 64,852,000
Percent of portfolio	2.80%	3.00%
Period increase (decrease)	(4.80%)
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 244,885,000	$ 235,729,000
Percent of portfolio	11.20%	10.90%
Period increase (decrease)	3.90%
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 65,604,000	$ 69,675,000
Percent of portfolio	3.00%	3.20%
Period increase (decrease)	(5.80%)
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 179,281,000	$ 166,054,000
Percent of portfolio	8.20%	7.70%
Period increase (decrease)	8.00%
Acquired Loan [Member]
Loans	$ 359,353,000	$ 388,595,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(7.50%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 246,063,000	$ 269,340,000
Percent of portfolio	68.50%	69.30%
Period increase (decrease)	(8.60%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 64,617,000	$ 72,959,000
Percent of portfolio	18.00%	18.80%
Period increase (decrease)	(11.40%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 5,924,000	$ 6,191,000
Percent of portfolio	1.60%	1.60%
Period increase (decrease)	(4.30%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 62,375,000	$ 70,263,000
Percent of portfolio	17.50%	18.10%
Period increase (decrease)	(11.20%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 78,481,000	$ 82,861,000
Percent of portfolio	21.80%	21.30%
Period increase (decrease)	(5.30%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 34,666,000	$ 37,066,000
Percent of portfolio	9.60%	9.50%
Period increase (decrease)	(6.50%)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 113,290,000	$ 119,255,000
Percent of portfolio	31.50%	30.70%
Period increase (decrease)	(5.00%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 27,575,000	$ 30,750,000
Percent of portfolio	7.70%	7.90%
Period increase (decrease)	(10.30%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 85,715,000	$ 88,505,000
Percent of portfolio	23.80%	22.80%
Period increase (decrease)	(3.20%)