Note 7 - Fair Value Measurement - Fair Value of Financial Assets and Liabililties Measure on Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
US Government Agencies Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	$ 13,858	$ 17,019
US Government Agencies Debt Securities [Member]
Securities available-for-sale	13,858	17,019
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	21,578	18,190
Mortgage-backed Securities, Issued by US Government Sponsored Enterprises [Member]
Securities available-for-sale	21,578	18,190
Corporate Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	2,500
Corporate Debt Securities [Member]
Securities available-for-sale	2,500
US States and Political Subdivisions Debt Securities [Member] | Fair Value, Inputs, Level 1 [Member]
Securities available-for-sale	16,562	17,335
US States and Political Subdivisions Debt Securities [Member]
Securities available-for-sale	16,562	17,335
Securities available-for-sale	$ 54,498	$ 52,544