Note 8 - Retail Loans by Credit Quality (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	$ 779,671	$ 733,078
Total Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	144,982	138,074
Performing Financial Instruments [Member] | Total Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	143,755	136,964
Nonperforming Financial Instruments [Member] | Total Retail Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	1,227	1,110
Retail Portfolio Segment [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	6,955	6,680
Retail Portfolio Segment [Member] | Family Residential Mortgages [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	63,681	55,818
Retail Portfolio Segment [Member] | Home Equity Loans and Lines [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	74,346	75,576
Retail Portfolio Segment [Member] | Performing Financial Instruments [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	6,851	6,595
Retail Portfolio Segment [Member] | Performing Financial Instruments [Member] | Family Residential Mortgages [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	62,704	54,936
Retail Portfolio Segment [Member] | Performing Financial Instruments [Member] | Home Equity Loans and Lines [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	74,200	75,433
Retail Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | Consumer Loans [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	104	85
Retail Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | Family Residential Mortgages [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	977	882
Retail Portfolio Segment [Member] | Nonperforming Financial Instruments [Member] | Home Equity Loans and Lines [Member]
Financing Receivable Recorded Investment [Line Items]
Loans and leases receivable	$ 146	$ 143