Note I - Income Taxes (Details Textual) - USD ($) $ in Thousands	3 Months Ended
	Sep. 30, 2019	Sep. 30, 2018
Effective Income Tax Rate Reconciliation, Percent, Total	21.30%	20.60%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent	21.00%
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	$ 0
Domestic Tax Authority [Member]
Open Tax Year	2016 2017 2018 2019
State and Local Jurisdiction [Member]
Open Tax Year	2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019
Foreign Tax Authority [Member] | Swiss Federal Tax Administration (FTA) [Member]
Open Tax Year	2018 2019