Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Loans	$ 2,636,856,000	$ 2,558,552,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	3.10%
Commercial Portfolio Segment [Member]
Loans	$ 2,261,970,000	$ 2,203,568,000
Percent of portfolio	85.80%	86.10%
Period increase (decrease)	2.70%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 776,995,000	$ 753,764,000
Percent of portfolio	29.50%	29.40%
Period increase (decrease)	3.10%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 37,868,000	$ 29,873,000
Percent of portfolio	1.50%	1.20%
Period increase (decrease)	26.80%
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 533,075,000	$ 526,328,000
Percent of portfolio	20.20%	20.60%
Period increase (decrease)	1.30%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 818,376,000	$ 791,685,000
Percent of portfolio	31.00%	30.90%
Period increase (decrease)	3.40%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 95,656,000	$ 101,918,000
Percent of portfolio	3.60%	4.00%
Period increase (decrease)	(6.10%)
Retail Portfolio Segment [Member]
Loans	$ 374,886,000	$ 354,984,000
Percent of portfolio	14.20%	13.90%
Period increase (decrease)	5.60%
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 91,229,000	$ 100,425,000
Percent of portfolio	3.50%	3.90%
Period increase (decrease)	(9.20%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 283,657,000	$ 254,559,000
Percent of portfolio	10.70%	10.00%
Period increase (decrease)	11.40%
Originated Loan [Member]
Loans	$ 2,296,204,000	$ 2,169,957,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	5.80%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 2,027,193,000	$ 1,934,228,000
Percent of portfolio	88.30%	89.10%
Period increase (decrease)	4.80%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 712,138,000	$ 680,805,000
Percent of portfolio	31.00%	31.30%
Period increase (decrease)	4.60%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 32,031,000	$ 23,682,000
Percent of portfolio	1.40%	1.10%
Period increase (decrease)	35.30%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 477,696,000	$ 456,065,000
Percent of portfolio	20.80%	21.00%
Period increase (decrease)	4.70%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 743,102,000	$ 708,824,000
Percent of portfolio	32.40%	32.70%
Period increase (decrease)	4.80%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 62,226,000	$ 64,852,000
Percent of portfolio	2.70%	3.00%
Period increase (decrease)	(4.00%)
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 269,011,000	$ 235,729,000
Percent of portfolio	11.70%	10.90%
Period increase (decrease)	14.10%
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 66,683,000	$ 69,675,000
Percent of portfolio	2.90%	3.20%
Period increase (decrease)	(4.30%)
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 202,328,000	$ 166,054,000
Percent of portfolio	8.80%	7.70%
Period increase (decrease)	21.80%
Acquired Loan [Member]
Loans	$ 340,652,000	$ 388,595,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(12.30%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 234,777,000	$ 269,340,000
Percent of portfolio	68.90%	69.30%
Period increase (decrease)	(12.80%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 64,857,000	$ 72,959,000
Percent of portfolio	19.00%	18.80%
Period increase (decrease)	(11.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 5,837,000	$ 6,191,000
Percent of portfolio	1.70%	1.60%
Period increase (decrease)	(5.70%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 55,379,000	$ 70,263,000
Percent of portfolio	16.30%	18.10%
Period increase (decrease)	(21.20%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 75,274,000	$ 82,861,000
Percent of portfolio	22.10%	21.30%
Period increase (decrease)	(9.20%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 33,430,000	$ 37,066,000
Percent of portfolio	9.80%	9.50%
Period increase (decrease)	(9.80%)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 105,875,000	$ 119,255,000
Percent of portfolio	31.10%	30.70%
Period increase (decrease)	(11.20%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 24,546,000	$ 30,750,000
Percent of portfolio	7.20%	7.90%
Period increase (decrease)	(20.20%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 81,329,000	$ 88,505,000
Percent of portfolio	23.90%	22.80%
Period increase (decrease)	(8.10%)