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, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Balance	$ (49,340)	$ (44,291)	$ (49,683)	$ (34,642)	$ (49,683)	$ (19,184)
Total other comprehensive income (loss), net of tax	1,738	1,105	51	(111)	2,894	(10,018)
Adoption of ASU 2018-02						(11,355)
Balance	(48,960)	(49,340)	(44,291)	(40,429)	(48,960)	(40,429)
Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member]
Balance			(63,887)		(63,887)	(46,584)
Other comprehensive loss, net of tax, before reclassifications
Amounts reclassified from accumulated other comprehensive income (loss), net of tax, to other, net, on the condensed consolidated statements of comprehensive loss					1,827	1,648
Total other comprehensive income (loss), net of tax					1,827	(9,707)
Adoption of ASU 2018-02						(11,355)
Balance	(62,060)			(56,291)	(62,060)	(56,291)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance			753		753	101
Other comprehensive loss, net of tax, before reclassifications					1,067	(311)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax, to other, net, on the condensed consolidated statements of comprehensive loss
Total other comprehensive income (loss), net of tax					1,067	(311)
Adoption of ASU 2018-02
Balance	1,820			(210)	1,820	(210)
AOCI Attributable to Parent [Member]
Balance	(61,978)	(63,083)	(63,134)	(56,390)	(63,134)	(46,483)
Other comprehensive loss, net of tax, before reclassifications					1,067	(311)
Amounts reclassified from accumulated other comprehensive income (loss), net of tax, to other, net, on the condensed consolidated statements of comprehensive loss					1,827	1,648
Total other comprehensive income (loss), net of tax	1,738	1,105	51		2,894	(10,018)
Adoption of ASU 2018-02						(11,355)
Balance	$ (60,240)	$ (61,978)	$ (63,083)	$ (56,501)	$ (60,240)	$ (56,501)