Note 6 - Dividends (Details Textual) - USD ($)	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Payments of Ordinary Dividends, Common Stock	$ 817,000	$ 811,000
Line Of Credit Facility Dividend Restrictions Percentage Of Net Income Limit	25.00%
Paid Quarterly [Member]
Common Stock, Dividends, Per Share, Declared	$ 0.025	$ 0.025

Line of credit facility dividend restrictions percentage of net income limit.

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- Definition

Aggregate dividends declared during the period for each share of common stock outstanding.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.3-04)
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

+ Details

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- Definition

Amount of cash outflow in the form of ordinary dividends to common shareholders of the parent entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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