Note K - Derivatives and Hedging (Details Textual) € in Millions	6 Months Ended	12 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 EUR (€)
Gain (Loss) on Cash Flow Hedge Ineffectiveness, Net, Total	$ 0		$ 189,000
Accumulated Other Comprehensive Income (Loss) Cumulative Cash Flow Hedges, Gain (Loss)	328,000	$ 328,000	646,000
Deferred Tax Assets, Derivative Instruments	76,000	76,000	232,000
Prepaid Expenses and Other Current Assets [Member]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	55,000	55,000
Other Noncurrent Assets [Member]
Cash Flow Hedge Derivative Instrument Assets at Fair Value	46,000	46,000
Accrued Liabilities [Member]
Cash Flow Hedge Derivative Instrument Liabilities at Fair Value	101,000	101,000
Reclassification out of Accumulated Other Comprehensive Income [Member]
Foreign Currency Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months	(321,000)	(321,000)
Cash Flow Hedging [Member]
Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax		(1,400,000)	(320,000)
Derivative Instruments, Loss Reclassified from Accumulated OCI into Income, Effective Portion		900,000	430,000
Derivative Instruments, Gain Reclassified from Accumulated OCI into Income, Effective Portion		2,600,000	$ 685,000
Foreign Exchange Contract [Member]
Derivative, Notional Amount	34,400,000	34,400,000		€ 29
Foreign Exchange Contract [Member] | Cash Flow Hedging [Member]
Derivative, Notional Amount	$ 34,400,000	$ 34,400,000		€ 29