Note 3 - Loans and Allowance for Loan Losses - Components of Loan Portfolio (Details) - USD ($)	9 Months Ended
	Sep. 30, 2017	Dec. 31, 2016
Loans	$ 2,554,272,000	$ 2,378,620,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	7.40%
Commercial Portfolio Segment [Member]
Loans	$ 2,214,822,000	$ 2,065,347,000
Percent of portfolio	86.70%	86.80%
Period increase (decrease)	7.20%
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 776,563,000	$ 713,903,000
Percent of portfolio	30.40%	30.00%
Period increase (decrease)	8.80%
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 28,575,000	$ 34,828,000
Percent of portfolio	1.10%	1.50%
Period increase (decrease)	(18.00%)
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 485,347,000	$ 450,464,000
Percent of portfolio	19.00%	18.90%
Period increase (decrease)	7.70%
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 805,167,000	$ 748,269,000
Percent of portfolio	31.50%	31.50%
Period increase (decrease)	7.60%
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 119,170,000	$ 117,883,000
Percent of portfolio	4.70%	4.90%
Period increase (decrease)	1.10%
Retail Portfolio Segment [Member]
Loans	$ 339,450,000	$ 313,273,000
Percent of portfolio	13.30%	13.20%
Period increase (decrease)	8.40%
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 103,376,000	$ 118,047,000
Percent of portfolio	4.00%	5.00%
Period increase (decrease)	(12.40%)
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 236,074,000	$ 195,226,000
Percent of portfolio	9.30%	8.20%
Period increase (decrease)	20.90%
Originated Loan [Member]
Loans	$ 2,133,766,000	$ 1,884,548,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	13.20%
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 1,922,998,000	$ 1,728,898,000
Percent of portfolio	90.10%	91.70%
Period increase (decrease)	11.20%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 710,699,000	$ 636,771,000
Percent of portfolio	33.30%	33.80%
Period increase (decrease)	11.60%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 21,272,000	$ 26,519,000
Percent of portfolio	1.00%	1.40%
Period increase (decrease)	(19.80%)
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 411,367,000	$ 363,509,000
Percent of portfolio	19.30%	19.30%
Period increase (decrease)	13.20%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 721,304,000	$ 652,054,000
Percent of portfolio	33.80%	34.60%
Period increase (decrease)	10.60%
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 58,356,000	$ 50,045,000
Percent of portfolio	2.70%	2.60%
Period increase (decrease)	16.60%
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 210,768,000	$ 155,650,000
Percent of portfolio	9.90%	8.30%
Period increase (decrease)	35.40%
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 69,325,000	$ 69,831,000
Percent of portfolio	3.30%	3.70%
Period increase (decrease)	(0.70%)
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 141,443,000	$ 85,819,000
Percent of portfolio	6.60%	4.60%
Period increase (decrease)	64.80%
Acquired Loan [Member]
Loans	$ 420,506,000	$ 494,072,000
Percent of portfolio	100.00%	100.00%
Period increase (decrease)	(14.90%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans	$ 291,824,000	$ 336,449,000
Percent of portfolio	69.40%	68.10%
Period increase (decrease)	(13.30%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	$ 65,864,000	$ 77,132,000
Percent of portfolio	15.70%	15.60%
Period increase (decrease)	(14.60%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	$ 7,303,000	$ 8,309,000
Percent of portfolio	1.70%	1.70%
Period increase (decrease)	(12.10%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	$ 73,980,000	$ 86,955,000
Percent of portfolio	17.60%	17.60%
Period increase (decrease)	(14.90%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	$ 83,863,000	$ 96,215,000
Percent of portfolio	19.90%	19.50%
Period increase (decrease)	(12.80%)
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	$ 60,814,000	$ 67,838,000
Percent of portfolio	14.50%	13.70%
Period increase (decrease)	(10.40%)
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans	$ 128,682,000	$ 157,623,000
Percent of portfolio	30.60%	31.90%
Period increase (decrease)	(18.40%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	$ 34,051,000	$ 48,216,000
Percent of portfolio	8.10%	9.80%
Period increase (decrease)	(29.40%)
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	$ 94,631,000	$ 109,407,000
Percent of portfolio	22.50%	22.10%
Period increase (decrease)	(13.50%)