Note 4 - Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Details) - USD ($)	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Loans	$ 2,856,667,000	$ 2,753,085,000
Originated Loan [Member]
Past due loans	482,000	658,000
Current loans	2,614,243,000	2,451,788,000
Loans	2,614,725,000	2,452,446,000	$ 2,169,957,000
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member]
Past due loans	1,402,000	3,125,000
Current loans	240,540,000	297,514,000
Loans	241,942,000	300,639,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member]
Loans	2,441,544,000	2,360,106,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	846,551,000	822,723,000
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	56,119,000	44,885,000
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	579,003,000	548,619,000
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	835,346,000	816,282,000
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	124,525,000	127,597,000
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	134,000	186,000
Current loans	2,271,283,000	2,151,812,000
Loans	2,271,417,000	2,151,998,000	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	0	186,000
Current loans	799,421,000	768,512,000
Loans	799,421,000	768,698,000
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	0
Current loans	52,097,000	39,950,000
Loans	52,097,000	39,950,000
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	134,000	0
Current loans	542,427,000	500,188,000
Loans	542,561,000	500,188,000
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	776,994,000	745,127,000
Loans	776,994,000	745,127,000
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	100,344,000	98,035,000
Loans	100,344,000	98,035,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	191,000	1,147,000
Current loans	169,936,000	206,961,000
Loans	170,127,000	208,108,000
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	0	8,000
Current loans	47,130,000	54,017,000
Loans	47,130,000	54,025,000
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	191,000	19,000
Current loans	3,831,000	4,916,000
Loans	4,022,000	4,935,000
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	0	1,058,000
Current loans	36,442,000	47,373,000
Loans	36,442,000	48,431,000
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	62,000
Current loans	58,352,000	71,093,000
Loans	58,352,000	71,155,000
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	0	0
Current loans	24,181,000	29,562,000
Loans	24,181,000	29,562,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member]
Loans	415,123,000	392,979,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	75,374,000	85,439,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	339,749,000	307,540,000
Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	348,000	472,000
Current loans	342,960,000	299,976,000
Loans	343,308,000	300,448,000	$ 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	157,000	44,000
Current loans	60,903,000	64,979,000
Loans	61,060,000	65,023,000
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	191,000	428,000
Current loans	282,057,000	234,997,000
Loans	282,248,000	235,425,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	1,211,000	1,978,000
Current loans	70,604,000	90,553,000
Loans	71,815,000	92,531,000
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	99,000	198,000
Current loans	14,215,000	20,218,000
Loans	14,314,000	20,416,000
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	1,112,000	1,780,000
Current loans	56,389,000	70,335,000
Loans	57,501,000	72,115,000
Loans past due 90 days or more still accruing interest	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Originated Loan [Member]
Past due loans	168,000	521,000
Financial Asset, 30 to 59 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	939,000	1,185,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	0	186,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	186,000
Financial Asset, 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
Financial Asset, 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
Financial Asset, 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
Financial Asset, 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
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	191,000	197,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	8,000
Financial Asset, 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	191,000	19,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	0	108,000
Financial Asset, 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	62,000
Financial Asset, 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	0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	168,000	335,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Past due loans	107,000	44,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	61,000	291,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	748,000	988,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Past due loans	64,000	167,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	684,000	821,000
Financial Asset, 60 to 89 Days Past Due [Member] | Originated Loan [Member]
Past due loans	50,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	44,000	1,328,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	0
Financial Asset, 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
Financial Asset, 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
Financial Asset, 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
Financial Asset, 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
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	0	950,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	0
Financial Asset, 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
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	0	950,000
Financial Asset, 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
Financial Asset, 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
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	50,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Past due loans	50,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	44,000	378,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Past due loans	15,000	31,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	29,000	347,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Originated Loan [Member]
Past due loans	264,000	137,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	419,000	612,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	134,000	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	0
Financial Asset, Equal to or 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	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	134,000	0
Financial Asset, Equal to or 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
Financial Asset, Equal to or 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
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Past due loans	0	0
Financial Asset, Equal to or 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
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	0	0
Financial Asset, Equal to or 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
Financial Asset, Equal to or 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	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	130,000	137,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Past due loans	0	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	130,000	137,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	419,000	612,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Past due loans	20,000	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Past due loans	$ 399,000	$ 612,000