Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	12 Months Ended						156 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2004	Dec. 31, 2000	Dec. 31, 1997	Dec. 31, 2016	Dec. 31, 2013
Number of Operating Segments	1
Number of Reportable Segments	1
Federal Home Loan Bank Stock and Federal Reserve Bank Stock	$ 9,800	$ 9,400					$ 9,800
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 301	$ 285					$ 301
Net Deferred Loan Costs, Percent of Average Loans Outstanding	0.03%	0.30%					0.03%
Interest Receivable, Percent of Average Loans Outstanding	0.30%	0.30%					0.30%
Loans Receivable Held-for-sale, Net, Not Part of Disposal Group, Mortgage	$ 1,700	$ 715					$ 1,700
Mortgage Banking Revenues, Percent of Total Revenue	1.60%	1.60%	1.10%
Servicing Asset at Fair Value, Amount	$ 731	$ 691					731
Mortgage Loans Serviced for Others	202,000	200,000					202,000
Cash Reserve Deposit Required and Made	$ 18,000	$ 18,000					$ 18,000
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	6,631	6,329	6,894
Adjustments to Additional Paid in Capital, Share-based Compensation, Employee Stock Purchase Program, Requisite Service Period Recognition	$ 32	$ 31	$ 32
Trading Securities		0	0					$ 0
Other than Temporary Impairment Losses, Investments	0	0	$ 0
Servicing Asset at Amortized Cost, Other than Temporary Impairments	$ 0	$ 0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number	0	0	0				0
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross	0	0	0	40,049	54,000	450,000	0
Treasury Stock, Shares, Acquired	0	0
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	7 years
Minimum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment, Useful Life	2 years
Minimum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life	10 years
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	10 years
Maximum [Member] | Furniture and Fixtures [Member]
Property, Plant and Equipment, Useful Life	7 years
Maximum [Member] | Building and Building Improvements [Member]
Property, Plant and Equipment, Useful Life	40 years
Loans Receivable [Member]
Interest Receivable	$ 2,800	$ 2,900					$ 2,800