Note 3 - Loans and Allowance for Loan Losses - Age Analysis of Past Due Loans (Details) - USD ($)		Mar. 31, 2021	Dec. 31, 2020
Past due loans		$ 2,118,000	$ 3,041,000
Current loans		3,362,252,000	3,190,429,000
Loans		3,364,370,000	3,193,470,000
Loans past due 90 days or more still accruing interest		0	0
Commercial Portfolio Segment [Member]
Past due loans		1,182,000	1,074,000
Current loans		2,966,033,000	2,792,888,000
Loans		2,967,215,000	2,793,962,000
Loans past due 90 days or more still accruing interest		0	0
Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans		762,000	433,000
Current loans		1,283,745,000	1,144,990,000
Loans	[1]	1,284,507,000	1,145,423,000
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	0
Current loans		58,738,000	55,055,000
Loans		58,738,000	55,055,000
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		420,000	618,000
Current loans		543,922,000	529,335,000
Loans		544,342,000	529,953,000
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	23,000
Current loans		932,334,000	917,413,000
Loans		932,334,000	917,436,000
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		147,294,000	146,095,000
Loans		147,294,000	146,095,000
Loans past due 90 days or more still accruing interest		0	0
Retail Portfolio Segment [Member]
Past due loans		936,000	1,967,000
Current loans		396,219,000	397,541,000
Loans		397,155,000	399,508,000
Loans past due 90 days or more still accruing interest		0	0
Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans		157,000	231,000
Current loans		59,154,000	61,389,000
Loans		59,311,000	61,620,000
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		779,000	1,736,000
Current loans		337,065,000	336,152,000
Loans		337,844,000	337,888,000
Loans past due 90 days or more still accruing interest		0	0
Financial Asset, 30 to 59 Days Past Due [Member]
Past due loans		1,270,000	1,520,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans		593,000	261,000
Financial Asset, 30 to 59 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans		593,000	261,000
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	0
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		677,000	1,259,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans		112,000	112,000
Financial Asset, 30 to 59 Days Past Due [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans		565,000	1,147,000
Financial Asset, 60 to 89 Days Past Due [Member]
Past due loans		138,000	681,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans		137,000	369,000
Financial Asset, 60 to 89 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans		0	172,000
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		137,000	197,000
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		1,000	312,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans		0	65,000
Financial Asset, 60 to 89 Days Past Due [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Past due loans		1,000	247,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member]
Past due loans		710,000	840,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Past due loans		452,000	444,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Past due loans		169,000	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		283,000	421,000
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	23,000
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		258,000	396,000
Financial Asset, Equal to or Greater than 90 Days Past Due [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Past due loans		45,000	54,000
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		$ 213,000	$ 342,000

[1] Includes $455 million and $365 million in loans originated under the Paycheck Protection Program for March 31, 2021 and December 31, 2020, respectively.