Note 3 - Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Details) - USD ($)	Mar. 31, 2018	Dec. 31, 2017
Loans	$ 2,551,204,000	$ 2,558,552,000
Originated Loan [Member]
Past due loans	3,061,000	2,451,000
Current loans	2,188,790,000	2,167,506,000
Loans	2,191,851,000	2,169,957,000
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member]
Past due loans	2,148,000	3,479,000
Current loans	357,205,000	385,116,000
Loans	359,353,000	388,595,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member]
Loans	2,193,029,000	2,203,568,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	739,805,000	753,764,000
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	31,438,000	29,873,000
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	531,152,000	526,328,000
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	794,206,000	791,685,000
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	96,428,000	101,918,000
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	2,530,000	1,457,000
Current loans	1,944,436,000	1,932,771,000
Loans	1,946,966,000	1,934,228,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	2,279,000	178,000
Current loans	672,909,000	680,627,000
Loans	675,188,000	680,805,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	35,000
Current loans	25,514,000	23,647,000
Loans	25,514,000	23,682,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	251,000	1,244,000
Current loans	468,526,000	454,821,000
Loans	468,777,000	456,065,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Current loans	715,725,000	708,824,000
Loans	715,725,000	708,824,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	0	0
Current loans	61,762,000	64,852,000
Loans	61,762,000	64,852,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	548,000	1,181,000
Current loans	245,515,000	268,159,000
Loans	246,063,000	269,340,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Past due loans	113,000	154,000
Current loans	64,504,000	72,805,000
Loans	64,617,000	72,959,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	14,000
Current loans	5,924,000	6,177,000
Loans	5,924,000	6,191,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	399,000	905,000
Current loans	61,976,000	69,358,000
Loans	62,375,000	70,263,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Current loans	78,481,000	82,861,000
Loans	78,481,000	82,861,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	36,000	108,000
Current loans	34,630,000	36,958,000
Loans	34,666,000	37,066,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member]
Loans	358,175,000	354,984,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	93,179,000	100,425,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	264,996,000	254,559,000
Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	531,000	994,000
Current loans	244,354,000	234,735,000
Loans	244,885,000	235,729,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Past due loans	65,000	744,000
Current loans	65,539,000	68,931,000
Loans	65,604,000	69,675,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	466,000	250,000
Current loans	178,815,000	165,804,000
Loans	179,281,000	166,054,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	1,600,000	2,298,000
Current loans	111,690,000	116,957,000
Loans	113,290,000	119,255,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Past due loans	249,000	614,000
Current loans	27,326,000	30,136,000
Loans	27,575,000	30,750,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	1,351,000	1,684,000
Current loans	84,364,000	86,821,000
Loans	85,715,000	88,505,000
Loans past due 90 days or more still accruing interest	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Originated Loan [Member]
Past due loans	1,415,000	647,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	835,000	1,786,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	1,350,000	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	1,350,000	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	27,000	688,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	40,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	14,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	0	634,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	27,000	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	65,000	647,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Past due loans	65,000	647,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	0	0
Financing Receivables, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	808,000	1,098,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Past due loans	163,000	408,000
Financing Receivables, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	645,000	690,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Originated Loan [Member]
Past due loans	1,175,000	11,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	431,000	385,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	929,000	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	929,000	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	156,000	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	156,000	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	0	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	246,000	11,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Past due loans	0	11,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	246,000	0
Financing Receivables, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	275,000	385,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Past due loans	44,000	52,000
Financing Receivables, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	231,000	333,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Originated Loan [Member]
Past due loans	471,000	1,793,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	882,000	1,308,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	251,000	1,457,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	178,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	35,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	251,000	1,244,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	365,000	493,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Past due loans	113,000	114,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	243,000	271,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	9,000	108,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	220,000	336,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Past due loans	0	86,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	220,000	250,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	517,000	815,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Past due loans	42,000	154,000
Financing Receivables, Equal to Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	$ 475,000	$ 661,000