Note K - Business Segments and Foreign Operations - Geographic Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Net Sales	$ 246,838	$ 302,663
Long-lived assets	76,724	75,016
Reportable Geographical Components [Member] | UNITED STATES
Net Sales	83,771	132,467
Long-lived assets	41,996	41,233
Reportable Geographical Components [Member] | NETHERLANDS
Net Sales	39,501	31,521
Long-lived assets	12,659	13,186
Reportable Geographical Components [Member] | CHINA
Net Sales	26,354	28,772
Reportable Geographical Components [Member] | BELGIUM
Long-lived assets	8,363	8,595
Reportable Geographical Components [Member] | AUSTRIA
Net Sales	12,552	10,464
Reportable Geographical Components [Member] | SWITZERLAND
Long-lived assets	6,804	6,810
Reportable Geographical Components [Member] | AUSTRALIA
Net Sales	12,438	12,463
Reportable Geographical Components [Member] | ITALY
Net Sales	11,802	12,755
Long-lived assets	1,697	1,894
Reportable Geographical Components [Member] | Other Countries [Member]
Net Sales	54,756	63,346
Long-lived assets	5,205	3,298
Reportable Geographical Components [Member] | CANADA
Net Sales	$ 5,664	$ 10,875