Note 3 - Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Details) - USD ($)	Mar. 31, 2019	Dec. 31, 2018
Loans	$ 2,799,639,000	$ 2,753,085,000
Originated Loan [Member]
Past due loans	587,000	658,000
Current loans	2,510,449,000	2,451,788,000
Loans	2,511,036,000	2,452,446,000
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member]
Past due loans	2,024,000	3,125,000
Current loans	286,579,000	297,514,000
Loans	288,603,000	300,639,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member]
Loans	2,400,198,000	2,360,106,000
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans	839,207,000	822,723,000
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans	45,892,000	44,885,000
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans	551,518,000	548,619,000
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans	835,678,000	816,282,000
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans	127,903,000	127,597,000
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	6,000	186,000
Current loans	2,198,707,000	2,151,812,000
Loans	2,198,713,000	2,151,998,000
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	6,000	186,000
Current loans	786,699,000	768,512,000
Loans	786,705,000	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	41,179,000	39,950,000
Loans	41,179,000	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	0	0
Current loans	503,988,000	500,188,000
Loans	503,988,000	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	767,318,000	745,127,000
Loans	767,318,000	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	99,523,000	98,035,000
Loans	99,523,000	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	581,000	1,147,000
Current loans	200,904,000	206,961,000
Loans	201,485,000	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	359,000	8,000
Current loans	52,143,000	54,017,000
Loans	52,502,000	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	0	19,000
Current loans	4,713,000	4,916,000
Loans	4,713,000	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	133,000	1,058,000
Current loans	47,397,000	47,373,000
Loans	47,530,000	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	89,000	62,000
Current loans	68,271,000	71,093,000
Loans	68,360,000	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	28,380,000	29,562,000
Loans	28,380,000	29,562,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member]
Loans	399,441,000	392,979,000
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans	83,127,000	85,439,000
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans	316,314,000	307,540,000
Retail Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	581,000	472,000
Current loans	311,742,000	299,976,000
Loans	312,323,000	300,448,000
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	30,000	44,000
Current loans	64,739,000	64,979,000
Loans	64,769,000	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	551,000	428,000
Current loans	247,003,000	234,997,000
Loans	247,554,000	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	1,443,000	1,978,000
Current loans	85,675,000	90,553,000
Loans	87,118,000	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	153,000	198,000
Current loans	18,205,000	20,218,000
Loans	18,358,000	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	1,290,000	1,780,000
Current loans	67,470,000	70,335,000
Loans	68,760,000	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	439,000	521,000
Financial Asset, 30 to 59 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	1,001,000	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	493,000	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	359,000	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	0	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	106,000	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	28,000	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	439,000	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	13,000	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	426,000	291,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	508,000	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	107,000	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	401,000	821,000
Financial Asset, 60 to 89 Days Past Due [Member] | Originated Loan [Member]
Past due loans	23,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	193,000	1,328,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	6,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Past due loans	6,000	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	17,000	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	17,000	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	193,000	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	1,000	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	192,000	347,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Originated Loan [Member]
Past due loans	125,000	137,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Acquired Loan [Member]
Past due loans	830,000	612,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Originated Loan [Member]
Past due loans	0	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	0	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	88,000	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	27,000	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	61,000	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	125,000	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	125,000	137,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Acquired Loan [Member]
Past due loans	742,000	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	45,000	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	$ 697,000	$ 612,000