Note 2 - Summary of Significant Accounting Policies - Summary of Basic and Diluted Net Income Per Share Calculations (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	12 Months Ended
Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015
Basic shares (in shares)									6,149,192	6,137,704
Dilutive shares (in shares)									272,550	175,550
Diluted shares (in shares)									6,421,742	6,313,254
Net income	$ (105)	$ 550	$ 462	$ 317	$ 441	$ 544	$ 774	$ 836	$ 1,224	$ 2,595
Basic net income per share (in dollars per share)	$ (0.02)	$ 0.09	$ 0.08	$ 0.05	$ 0.07	$ 0.09	$ 0.13	$ 0.14	$ 0.20	$ 0.42
Diluted net income per share (in dollars per share)	$ (0.02)	$ 0.09	$ 0.07	$ 0.05	$ 0.07	$ 0.09	$ 0.12	$ 0.13	$ 0.19	$ 0.41

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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