Note 4 - Loans and Allowance for Loan Losses - Nonperforming Loans (Details) - USD ($)	Dec. 31, 2018	Dec. 31, 2017
Originated Loan [Member]
Loans past due 90 days or more still accruing interest	$ 0	$ 0
Originated Loan [Member] | Commercial Portfolio Segment [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Retail Portfolio Segment [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans past due 90 days or more still accruing interest	0	0
Originated Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Retail Portfolio Segment [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Loans past due 90 days or more still accruing interest	0	0
Acquired Loan [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Loans past due 90 days or more still accruing interest	0	0
Nonperforming Financial Instruments [Member]
Total nonperforming loans	4,140,000	7,143,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member]
Total nonperforming loans	1,107,000	3,898,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Commercial and Industrial [Member]
Total nonperforming loans	16,000	1,444,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Total nonperforming loans	0	35,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Real Estate Owner Occupied Loan [Member]
Total nonperforming loans	950,000	2,241,000
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Real Estate Non Owner Occupied Loan [Member]
Total nonperforming loans	0	0
Nonperforming Financial Instruments [Member] | Commercial Portfolio Segment [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Total nonperforming loans	141,000	178,000
Nonperforming Financial Instruments [Member] | Retail Portfolio Segment [Member]
Total nonperforming loans	3,033,000	3,245,000
Nonperforming Financial Instruments [Member] | Retail Portfolio Segment [Member] | Home Equity and Other [Member]
Total nonperforming loans	454,000	577,000
Nonperforming Financial Instruments [Member] | Retail Portfolio Segment [Member] | One to Four Family Mortgages [Member]
Total nonperforming loans	2,579,000	2,668,000
Nonperforming Financial Instruments [Member] | Originated Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Nonaccrual loans	803,000	3,672,000
Total nonperforming loans	803,000	3,672,000
Nonperforming Financial Instruments [Member] | Acquired Loan [Member]
Loans past due 90 days or more still accruing interest	0	0
Nonaccrual loans	3,337,000	3,471,000
Total nonperforming loans	$ 3,337,000	$ 3,471,000