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Note 3 - Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Details) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Past due loans	$ 2,792,000	$ 1,884,000
Current loans	2,898,751,000	2,854,783,000
Loans	2,901,543,000	2,856,667,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member]
Past due loans	1,640,000	325,000
Current loans	2,470,690,000	2,441,219,000
Loans	2,472,330,000	2,441,544,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans	702,000	0
Current loans	872,977,000	846,551,000
Loans	873,679,000	846,551,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	525,000	191,000
Current loans	62,383,000	55,928,000
Loans	62,908,000	56,119,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	232,000	134,000
Current loans	578,997,000	578,869,000
Loans	579,229,000	579,003,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Past due loans	0	0
Current loans	823,366,000	835,346,000
Loans	823,366,000	835,346,000
Loans past due 90 days or more still accruing interest	0	0
Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	181,000	0
Current loans	132,967,000	124,525,000
Loans	133,148,000	124,525,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member]
Past due loans	1,152,000	1,559,000
Current loans	428,061,000	413,564,000
Loans	429,213,000	415,123,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans	257,000	256,000
Current loans	72,618,000	75,118,000
Loans	72,875,000	75,374,000
Loans past due 90 days or more still accruing interest	0	0
Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans	895,000	1,303,000
Current loans	355,443,000	338,446,000
Loans	356,338,000	339,749,000
Loans past due 90 days or more still accruing interest	0	0
Financial Asset, 30 to 59 Days Past Due [Member]
Past due loans	1,472,000	1,107,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans	786,000	191,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans	123,000	0
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	482,000	191,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [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] | 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] | Real Estate Multi Family and Residential Rental Loan [Member]
Past due loans	181,000	0
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member]
Past due loans	686,000	916,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans	172,000	171,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans	514,000	745,000
Financial Asset, 60 to 89 Days Past Due [Member]
Past due loans	606,000	94,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans	579,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans	579,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [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] | Real Estate Owner Occupied Loan [Member]
Past due loans	0	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [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] | 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]
Past due loans	27,000	94,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans	27,000	65,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans	0	29,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due loans	714,000	683,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans	275,000	134,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [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] | Vacant Land and Land Development and Residential Construction Loan [Member]
Past due loans	43,000	0
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Past due loans	232,000	134,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [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] | 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]
Past due loans	439,000	549,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans	58,000	20,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans	$ 381,000	$ 529,000

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