Note 3 - Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Details) - USD ($)		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Past due loans		$ 3,041,000	$ 1,884,000
Current loans		3,213,317,000	2,854,783,000
Loans		3,216,358,000	2,856,667,000	$ 2,753,085,000
Loans past due 90 days or more still accruing interest		0	0
Commercial Portfolio Segment [Member]
Past due loans		1,074,000	325,000
Current loans		2,792,888,000	2,441,219,000
Loans		2,793,962,000	2,441,544,000	2,360,106,000
Loans past due 90 days or more still accruing interest		0	0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans		433,000	0
Current loans		1,144,990,000	846,551,000
Loans	[1]	1,145,423,000	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		0	191,000
Current loans		55,055,000	55,928,000
Loans		55,055,000	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		618,000	134,000
Current loans		529,335,000	578,869,000
Loans		529,953,000	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		23,000	0
Current loans		917,413,000	835,346,000
Loans		917,436,000	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		0	0
Current loans		146,095,000	124,525,000
Loans		146,095,000	124,525,000
Loans past due 90 days or more still accruing interest		0	0
Retail Portfolio Segment [Member]
Past due loans		1,967,000	1,559,000
Current loans		420,429,000	413,564,000
Loans		422,396,000	415,123,000	$ 392,979,000
Loans past due 90 days or more still accruing interest		0	0
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans		231,000	256,000
Current loans		61,389,000	75,118,000
Loans		61,620,000	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		1,736,000	1,303,000
Current loans		359,040,000	338,446,000
Loans		360,776,000	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		1,520,000	1,107,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans		261,000	191,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans		261,000	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		0	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		0	0
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member]
Past due loans		1,259,000	916,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans		112,000	171,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans		1,147,000	745,000
Financial Asset, 60 to 89 Days Past Due [Member]
Past due loans		681,000	94,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans		369,000	0
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans		172,000	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		197,000	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		312,000	94,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans		65,000	65,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans		247,000	29,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due loans		840,000	683,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans		444,000	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		0	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		421,000	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		23,000	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		396,000	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		54,000	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		$ 342,000	$ 529,000

[1] For December 31, 2020, includes $365 million in loans originated under the Paycheck Protection Program.