Note N - Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Balance	$ 146,250	$ 144,457	$ 146,950	$ 145,547
Net current period other comprehensive income	(181)	146	(824)	461
Balance	143,114	144,119	143,114	144,119
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	(1,873)		(1,209)
Other comprehensive income (loss) before reclassifications	(161)		(823)
Losses (gains) reclassified from accumulated other comprehensive income	38		37
Net current period other comprehensive income	(123)		(786)
Balance	(1,996)		(1,996)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Balance
Other comprehensive income (loss) before reclassifications	(29)		(29)
Losses (gains) reclassified from accumulated other comprehensive income	9		9
Net current period other comprehensive income	(20)		(20)
Balance	(20)		(20)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(404)		(409)
Other comprehensive income (loss) before reclassifications
Losses (gains) reclassified from accumulated other comprehensive income	5		10
Net current period other comprehensive income	5		10
Balance	(399)		(399)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	(240)		(256)
Other comprehensive income (loss) before reclassifications	(43)		(28)
Losses (gains) reclassified from accumulated other comprehensive income
Net current period other comprehensive income	(43)		(28)
Balance	(283)		(283)
AOCI Attributable to Parent [Member]
Balance	(2,517)	(1,537)	(1,874)	(1,852)
Other comprehensive income (loss) before reclassifications	(233)		(880)
Losses (gains) reclassified from accumulated other comprehensive income	52		56
Net current period other comprehensive income	(181)	146	(824)	461
Balance	$ (2,698)	$ (1,391)	$ (2,698)	$ (1,391)