Note 1 - Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares	Dec. 31, 2013 USD ($) shares
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Number of Operating Segments	1
Number of Reportable Segments	1
Trading Securities	$ 0	$ 0	$ 0
Other than Temporary Impairment Losses, Investments	0	0	$ 0
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	9,400,000	9,400,000
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 285,000	$ 506,000
Net Deferred Loan Costs Percent of Average Loans Outstanding	0.03%	0.05%
Interest Receivable Percent of Average Loans Outstanding	0.30%	0.30%
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage	$ 715,000	$ 380,000
Mortgage Banking Revenues Percent of Total Revenue	1.60%	1.10%	1.60%
Servicing Asset at Fair Value, Amount	$ 691,000	$ 694,000
Mortgage Loans Serviced for Others	200,000,000	206,000,000
Cash Reserve Deposit Required and Made	$ 18,000,000	$ 20,500,000
Treasury Stock, Shares, Acquired (in Shares) | shares	0	0
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent	85.00%
Stock Issued During Period, Shares, Employee Stock Purchase Plans (in Shares) | shares	6,329	6,894	8,893
Adjustments to Additional Paid in Capital, Share-based Compensation, Employee Stock Purchase Program, Requisite Service Period Recognition	$ 31,000	$ 32,000	$ 36,000
Employee Stock Option [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in Shares) | shares	0	0	22,049
Loans Receivable [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Interest Receivable	$ 2,900,000	$ 3,100,000
Minimum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Finite-Lived Intangible Asset, Useful Life	7 years
Minimum [Member] | Furniture and Fixtures [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	2 years
Minimum [Member] | Building and Building Improvements [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	10 years
Maximum [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Finite-Lived Intangible Asset, Useful Life	10 years
Maximum [Member] | Furniture and Fixtures [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	7 years
Maximum [Member] | Building and Building Improvements [Member]
Note 1 - Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	40 years