Note 3 - Loans and Allowance for Loan Losses - Loans Modified as Troubled Debt Restructurings (Details)	3 Months Ended
	Mar. 31, 2018 USD ($)	Mar. 31, 2017 USD ($)
Originated Loan [Member]
Number of Contracts	8	4
Pre- Modification Recorded Principal Balance	$ 4,022,000	$ 328,000
Post- Modification Recorded Principal Balance	$ 4,000,000	$ 329,000
Acquired Loan [Member]
Number of Contracts	9	4
Pre- Modification Recorded Principal Balance	$ 1,715,000	$ 94,000
Post- Modification Recorded Principal Balance	$ 1,716,000	$ 95,000
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Number of Contracts	7	0
Pre- Modification Recorded Principal Balance	$ 3,972,000	$ 0
Post- Modification Recorded Principal Balance	$ 3,950,000	$ 0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Number of Contracts	3	0
Pre- Modification Recorded Principal Balance	$ 107,000	$ 0
Post- Modification Recorded Principal Balance	$ 96,000	$ 0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Number of Contracts	0	0
Pre- Modification Recorded Principal Balance	$ 0	$ 0
Post- Modification Recorded Principal Balance	$ 0	$ 0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Owner Occupied Loan [Member]
Number of Contracts	4	0
Pre- Modification Recorded Principal Balance	$ 3,865,000	$ 0
Post- Modification Recorded Principal Balance	$ 3,854,000	$ 0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Number of Contracts	0	0
Pre- Modification Recorded Principal Balance	$ 0	$ 0
Post- Modification Recorded Principal Balance	$ 0	$ 0
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Number of Contracts	0	0
Pre- Modification Recorded Principal Balance	$ 0	$ 0
Post- Modification Recorded Principal Balance	$ 0	$ 0
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Number of Contracts	3	1
Pre- Modification Recorded Principal Balance	$ 1,597,000	$ 31,000
Post- Modification Recorded Principal Balance	$ 1,597,000	$ 31,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Number of Contracts	0	1
Pre- Modification Recorded Principal Balance	$ 0	$ 31,000
Post- Modification Recorded Principal Balance	$ 0	$ 31,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Vacant Land and Land Development and Residential Construction Loan [Member]
Number of Contracts	0	0
Pre- Modification Recorded Principal Balance	$ 0	$ 0
Post- Modification Recorded Principal Balance	$ 0	$ 0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Owner Occupied Loan [Member]
Number of Contracts	3	0
Pre- Modification Recorded Principal Balance	$ 1,597,000	$ 0
Post- Modification Recorded Principal Balance	$ 1,597,000	$ 0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Number of Contracts	0	0
Pre- Modification Recorded Principal Balance	$ 0	$ 0
Post- Modification Recorded Principal Balance	$ 0	$ 0
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Number of Contracts	0	0
Pre- Modification Recorded Principal Balance	$ 0	$ 0
Post- Modification Recorded Principal Balance	$ 0	$ 0
Retail Portfolio Segment [Member] | Originated Loan [Member]
Number of Contracts	1	4
Pre- Modification Recorded Principal Balance	$ 50,000	$ 328,000
Post- Modification Recorded Principal Balance	$ 50,000	$ 329,000
Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Number of Contracts	1	4
Pre- Modification Recorded Principal Balance	$ 50,000	$ 328,000
Post- Modification Recorded Principal Balance	$ 50,000	$ 329,000
Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Number of Contracts	0	0
Pre- Modification Recorded Principal Balance	$ 0	$ 0
Post- Modification Recorded Principal Balance	$ 0	$ 0
Retail Portfolio Segment [Member] | Acquired Loan [Member]
Number of Contracts	6	3
Pre- Modification Recorded Principal Balance	$ 118,000	$ 63,000
Post- Modification Recorded Principal Balance	$ 119,000	$ 64,000
Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Number of Contracts	6	2
Pre- Modification Recorded Principal Balance	$ 118,000	$ 6,000
Post- Modification Recorded Principal Balance	$ 119,000	$ 7,000
Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Number of Contracts	0	1
Pre- Modification Recorded Principal Balance	$ 0	$ 57,000
Post- Modification Recorded Principal Balance	$ 0	$ 57,000