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Note 14 - Segment Information, Geographical Data and Major Customers - Entity Wide Major Customer (Details) - Customer Concentration Risk [Member] - Revenue Benchmark [Member]	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Chevron Corporation [Member]
Concentration Risk, Percentage	14.30%	13.00%	15.00%
Saudi Aramco [Member]
Concentration Risk, Percentage	11.50%

X

- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Publisher FASB
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-Section 50
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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