Note N - Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Balance	$ 143,114	$ 144,118	$ 146,950	$ 145,547
Net current period other comprehensive income (loss)	40	(67)	(784)	394
Balance	142,367	145,751	142,367	145,751
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	(1,996)		(1,209)
Other comprehensive income (loss) before reclassifications	26		(797)
Losses (gains) reclassified from accumulated other comprehensive income (loss)	(1)		36
Net current period other comprehensive income (loss)	25		(761)
Balance	(1,971)		(1,971)
Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member]
Balance	(20)
Other comprehensive income (loss) before reclassifications	13		(16)
Losses (gains) reclassified from accumulated other comprehensive income (loss)	7		16
Net current period other comprehensive income (loss)	20
Balance
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance	(399)		(409)
Other comprehensive income (loss) before reclassifications
Losses (gains) reclassified from accumulated other comprehensive income (loss)	5		15
Net current period other comprehensive income (loss)	5		15
Balance	(394)		(394)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	(283)		(256)
Other comprehensive income (loss) before reclassifications	(10)		(38)
Losses (gains) reclassified from accumulated other comprehensive income (loss)
Net current period other comprehensive income (loss)	(10)		(38)
Balance	(293)		(293)
AOCI Attributable to Parent [Member]
Balance	(2,698)	(1,391)	(1,874)	(1,852)
Other comprehensive income (loss) before reclassifications	29		(851)
Losses (gains) reclassified from accumulated other comprehensive income (loss)	11		67
Net current period other comprehensive income (loss)	40	(67)	(784)	394
Balance	$ (2,658)	$ (1,458)	$ (2,658)	$ (1,458)