Note K - Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Loss By Component (Details) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Balance	$ (42,559)	$ (54,423)	$ (53,123)	$ (49,340)	$ (44,291)	$ (49,683)	$ (53,123)	$ (49,683)
Total other comprehensive (loss) income, net of tax	(390)	856	278	1,738	1,105	51	744	2,894
Balance	(38,387)	(42,559)	(54,423)	(48,960)	(49,340)	(44,291)	(38,387)	(48,960)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance			(68,544)			(63,887)	(68,544)	(63,887)
Other comprehensive income (loss), net of tax, before reclassifications							0	0
Amounts reclassified from accumulated other comprehensive income (loss), net of tax, to other, net, on the condensed consolidated statements of comprehensive loss							2,457	1,827
Total other comprehensive (loss) income, net of tax							2,457	1,827
Balance	(66,087)			(62,060)			(66,087)	(62,060)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance			2,933			753	2,933	753
Other comprehensive income (loss), net of tax, before reclassifications							(1,713)	1,067
Amounts reclassified from accumulated other comprehensive income (loss), net of tax, to other, net, on the condensed consolidated statements of comprehensive loss							0	0
Total other comprehensive (loss) income, net of tax							(1,713)	1,067
Balance	1,220			1,820			1,220	1,820
AOCI Attributable to Parent [Member]
Balance	(64,477)	(65,333)	(65,611)	(61,978)	(63,083)	(63,134)	(65,611)	(63,134)
Other comprehensive income (loss), net of tax, before reclassifications							(1,713)	1,067
Amounts reclassified from accumulated other comprehensive income (loss), net of tax, to other, net, on the condensed consolidated statements of comprehensive loss							2,457	1,827
Total other comprehensive (loss) income, net of tax	(390)	856	278	1,738	1,105	51	744	2,894
Balance	$ (64,867)	$ (64,477)	$ (65,333)	$ (60,240)	$ (61,978)	$ (63,083)	$ (64,867)	$ (60,240)