Note 3 - Fair Value of Financial Instruments - Assets and Liabilities Measured at Fair Value on a Recurring and Nonrecurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Inputs, Level 1 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Assets measured on a recurring basis
Fair Value, Inputs, Level 1 [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 1 [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 1 [Member] | Impaired Loans [Member] | Commercial Portfolio Segment [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 1 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets measured on a recurring basis
Fair Value, Inputs, Level 1 [Member] | Other Real Estate Owned [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 2 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Assets measured on a recurring basis	10,636	8,965
Fair Value, Inputs, Level 2 [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 2 [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 2 [Member] | Impaired Loans [Member] | Commercial Portfolio Segment [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 2 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets measured on a recurring basis	94,224	82,686
Fair Value, Inputs, Level 2 [Member] | Other Real Estate Owned [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Assets measured on a nonrecurring basis
Fair Value, Inputs, Level 3 [Member] | US Government-sponsored Enterprises Debt Securities [Member]
Assets measured on a recurring basis
Fair Value, Inputs, Level 3 [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Owner Occupied [Member]
Assets measured on a nonrecurring basis	3,843
Fair Value, Inputs, Level 3 [Member] | Impaired Loans [Member] | Commercial Real Estate Portfolio Segment [Member] | Commercial Real Estate Nonowner Occupied [Member]
Assets measured on a nonrecurring basis	2,147	2,473
Fair Value, Inputs, Level 3 [Member] | Impaired Loans [Member] | Commercial Portfolio Segment [Member]
Assets measured on a nonrecurring basis	298	3,779
Fair Value, Inputs, Level 3 [Member] | Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Assets measured on a recurring basis
Fair Value, Inputs, Level 3 [Member] | Other Real Estate Owned [Member] | Commercial Real Estate Portfolio Segment [Member] | Construction Loans [Member]
Assets measured on a nonrecurring basis	$ 1,147	$ 1,147