Note H - Income Taxes (Details Textual) - USD ($)	3 Months Ended			6 Months Ended	9 Months Ended		12 Months Ended
	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Jun. 30, 2018
Effective Income Tax Rate Reconciliation, Percent, Total	18.90%		21.10%		20.10%	69.40%
Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent					21.00%		28.06%
Income Tax Expense (Benefit), Continuing Operations, Discrete Tax Items Due to Tax Act, Amount, Total			$ 3,300,000			$ 3,300,000
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Transition Tax Liability			$ 1,800,000			1,800,000
Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount						775,000
Income Tax Expense (Benefit), Continuing Operations, Adjustment of Deferred Tax (Asset) Liability						$ 664,000
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount		$ 0		$ 0
State and Local Jurisdiction [Member]
Open Tax Year					2007 2008 2009 2015 2016 2017 2018
Domestic Tax Authority [Member]
Open Tax Year					2016 2017 2018
Foreign Tax Authority [Member] | Swiss Federal Tax Administration (FTA) [Member]
Open Tax Year					2015 2016 2017 2018