Note M - Segment Information (Details Textual) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2019	Jun. 30, 2019	Jun. 30, 2018
Number of Reportable Segments		2
Revenue from Contract with Customer, Including Assessed Tax		$ 138,290	$ 132,437
Non-US [Member]
Revenue from Contract with Customer, Including Assessed Tax		71,290	66,955
UNITED STATES
Revenue from Contract with Customer, Including Assessed Tax		$ 67,000	$ 65,482
Products Manufactured by NAIE [Member] \| Non-US [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Concentration Risk, Percentage		78.00%	81.00%
Products Manufactured by NAIE [Member] \| UNITED STATES
Revenue from Contract with Customer, Including Assessed Tax	$ 0		$ 0

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
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6351-108592

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13531-108611

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=118260190&loc=d3e13537-108611

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

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