Note 4 - Loans and Allowance for Loan Losses - Loans Modified as Troubled Debt Restructurings (Details)	12 Months Ended
	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)
Originated Loan [Member]
Number of Contracts	20	18
Pre- Modification Recorded Principal Balance	$ 5,636,000	$ 2,512,000
Post- Modification Recorded Principal Balance	$ 5,697,000	$ 3,288,000
Acquired Loan [Member]
Number of Contracts	14	11
Pre- Modification Recorded Principal Balance	$ 824,000	$ 1,067,000
Post- Modification Recorded Principal Balance	$ 827,000	$ 1,068,000
Commercial Portfolio Segment [Member] | Originated Loan [Member]
Number of Contracts	12	14
Pre- Modification Recorded Principal Balance	$ 4,966,000	$ 2,239,000
Post- Modification Recorded Principal Balance	$ 5,026,000	$ 3,008,000
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Commercial and Industrial [Member]
Number of Contracts	8	8
Pre- Modification Recorded Principal Balance	$ 3,771,000	$ 1,445,000
Post- Modification Recorded Principal Balance	$ 3,831,000	$ 2,103,000
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	1
Pre- Modification Recorded Principal Balance	$ 1,195,000	$ 167,000
Post- Modification Recorded Principal Balance	$ 1,195,000	$ 167,000
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Number of Contracts	0	1
Pre- Modification Recorded Principal Balance	$ 0	$ 462,000
Post- Modification Recorded Principal Balance	$ 0	$ 462,000
Commercial Portfolio Segment [Member] | Originated Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Number of Contracts	0	4
Pre- Modification Recorded Principal Balance	$ 0	$ 165,000
Post- Modification Recorded Principal Balance	$ 0	$ 276,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member]
Number of Contracts	3	6
Pre- Modification Recorded Principal Balance	$ 432,000	$ 955,000
Post- Modification Recorded Principal Balance	$ 432,000	$ 955,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Commercial and Industrial [Member]
Number of Contracts	2	0
Pre- Modification Recorded Principal Balance	$ 399,000	$ 0
Post- Modification Recorded Principal Balance	$ 399,000	$ 0
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	1	3
Pre- Modification Recorded Principal Balance	$ 33,000	$ 739,000
Post- Modification Recorded Principal Balance	$ 33,000	$ 739,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Non Owner Occupied Loan [Member]
Number of Contracts	0	2
Pre- Modification Recorded Principal Balance	$ 0	$ 209,000
Post- Modification Recorded Principal Balance	$ 0	$ 209,000
Commercial Portfolio Segment [Member] | Acquired Loan [Member] | Real Estate Multi Family and Residential Rental Loan [Member]
Number of Contracts	0	1
Pre- Modification Recorded Principal Balance	$ 0	$ 7,000
Post- Modification Recorded Principal Balance	$ 0	$ 7,000
Retail Portfolio Segment [Member] | Originated Loan [Member]
Number of Contracts	8	4
Pre- Modification Recorded Principal Balance	$ 670,000	$ 273,000
Post- Modification Recorded Principal Balance	$ 671,000	$ 280,000
Retail Portfolio Segment [Member] | Originated Loan [Member] | Home Equity and Other [Member]
Number of Contracts	8	3
Pre- Modification Recorded Principal Balance	$ 670,000	$ 240,000
Post- Modification Recorded Principal Balance	$ 671,000	$ 240,000
Retail Portfolio Segment [Member] | Originated Loan [Member] | One to Four Family Mortgages [Member]
Number of Contracts	0	1
Pre- Modification Recorded Principal Balance	$ 0	$ 33,000
Post- Modification Recorded Principal Balance	$ 0	$ 40,000
Retail Portfolio Segment [Member] | Acquired Loan [Member]
Number of Contracts	11	5
Pre- Modification Recorded Principal Balance	$ 392,000	$ 112,000
Post- Modification Recorded Principal Balance	$ 395,000	$ 113,000
Retail Portfolio Segment [Member] | Acquired Loan [Member] | Home Equity and Other [Member]
Number of Contracts	7	4
Pre- Modification Recorded Principal Balance	$ 192,000	$ 93,000
Post- Modification Recorded Principal Balance	$ 195,000	$ 94,000
Retail Portfolio Segment [Member] | Acquired Loan [Member] | One to Four Family Mortgages [Member]
Number of Contracts	4	1
Pre- Modification Recorded Principal Balance	$ 200,000	$ 19,000
Post- Modification Recorded Principal Balance	$ 200,000	$ 19,000