For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Note 8 - Segment Reporting (Details Textual)	3 Months Ended		6 Months Ended		12 Months Ended
Note 8 - Segment Reporting (Details Textual)	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Number of Reportable Segments			2
Geographic Concentration Risk [Member] \| Sales Revenue, Net [Member] \| UNITED STATES
Concentration Risk, Percentage	73.00%	73.00%	72.00%	72.00%
Geographic Concentration Risk [Member] \| Net Assets, Geographic Area [Member] \| UNITED STATES
Concentration Risk, Percentage			85.00%		85.00%