Note O - Income Taxes - Reconciliation of the U.S. Federal Income Tax Rate (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Expected taxes at statutory rate									$ (10,791)	$ (2,053)	$ 29,584
Non-deductible/non-taxable items									962	1,020	1,212
Foreign rate differences									590	(1,043)	(11,656)
Foreign permanent differences									(671)	(1,067)	416
Increase (decrease) in valuation allowance									25,736	0	(1,700)
Share-based compensation									607	(1,325)	(10,348)
Changes in tax rates									0	(103)	2,768
Transition tax adjustment, net of foreign tax credits										(1,777)	5,067
Research and development credits									(1,616)	(2,022)	(2,821)
Uncertain tax positions									0	0	(1,616)
Foreign other									27	514	0
Other, net									(182)	224	(331)
Income tax (benefit) expense	$ 22,267	$ (1,940)	$ (3,191)	$ (2,474)	$ (3,638)	$ (5,294)	$ 2,296	$ (996)	$ 14,662	$ (7,632)	$ 10,575