Note 13 - Stock Option Plan (Details) - Tax Benefits and Intrinsic Value Related to Stock Options Exercised - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Tax Benefits and Intrinsic Value Related to Stock Options Exercised [Abstract]
Tax benefits related to stock options exercised	$ 17	$ 21	$ 29
Intrinsic value of stock options exercised	$ 234	$ 148	$ 161

Tax Benefits and Intrinsic Value Related to Stock Options Exercised [Abstract]

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- Definition

Amount of deferred tax expense from write-off of the deferred tax asset related to deductible stock options at exercise.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 20
-Section 55
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=65896087&loc=d3e11283-113907

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- Definition

Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (d)(2)
-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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