Note 8 - Fair Value Measurements - Assets Measured at Fair Value on Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Securities available for sale	$ 251,438	$ 271,172
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale	100,541	112,649
Agency Collateralized Mortgage Obligations [Member]
Securities available for sale	22,662	15,323
US Government Agencies Debt Securities [Member]
Securities available for sale	68,996	69,028
Municipal Notes [Member]
Securities available for sale	59,239	74,172
Fair Value, Measurements, Recurring [Member]
Securities available for sale	251,438	271,172
Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale	100,541	112,649
Fair Value, Measurements, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale	22,662	15,323
Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale	68,996	69,028
Fair Value, Measurements, Recurring [Member] | Municipal Notes [Member]
Securities available for sale	59,239	74,172
Fair Value, Measurements, Nonrecurring [Member]
Impaired loans	3,142	3,371
Loans held for sale	2,056	2,630
Foreclosed real estate	3,391	3,971
Fair Value, Measurements, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans	2,223	2,872
Foreclosed real estate	282	443
Fair Value, Measurements, Nonrecurring [Member] | Land Segment [Member]
Impaired loans	333
Fair Value, Measurements, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans	259	401
Foreclosed real estate	3,109	3,528
Fair Value, Measurements, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans	243	38
Fair Value, Measurements, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans	76	60
Fair Value, Measurements, Nonrecurring [Member] | Other Consumer Segment [Member]
Impaired loans	8
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Recurring [Member] | Municipal Notes [Member]
Securities available for sale
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Impaired loans
Loans held for sale
Foreclosed real estate
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans
Foreclosed real estate
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Land Segment [Member]
Impaired loans
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans
Foreclosed real estate
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans
Fair Value, Inputs, Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Consumer Segment [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member]
Securities available for sale	251,438	271,172
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale	100,541	112,649
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale	22,662	15,323
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale	68,996	69,028
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Recurring [Member] | Municipal Notes [Member]
Securities available for sale	59,239	74,172
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Impaired loans
Loans held for sale	2,056	2,630
Foreclosed real estate
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans
Foreclosed real estate
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Land Segment [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans
Foreclosed real estate
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans
Fair Value, Inputs, Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Consumer Segment [Member]
Impaired loans
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Agency Collateralized Mortgage Obligations [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | US Government Agencies Debt Securities [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Recurring [Member] | Municipal Notes [Member]
Securities available for sale
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Impaired loans	3,142	3,371
Loans held for sale
Foreclosed real estate	3,391	3,971
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Residential Mortgage Segment [Member]
Impaired loans	2,223	2,872
Foreclosed real estate	282	443
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Land Segment [Member]
Impaired loans	333
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Commercial Real Estate Segment [Member]
Impaired loans	259	401
Foreclosed real estate	3,109	3,528
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Commercial Business Segment [Member]
Impaired loans	243	38
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Home Equity and Second Mortgage [Member]
Impaired loans	76	$ 60
Fair Value, Inputs, Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member] | Other Consumer Segment [Member]
Impaired loans	$ 8