Note G - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock based compensation expense	$ 385	$ 1,057	$ 2,034	$ 3,664
Research and Development Expense [Member]
Stock based compensation expense	157	400	748	1,196
General and Administrative Expense [Member]
Stock based compensation expense	228	657	866	2,468
Severance Expense [Member]
Stock based compensation expense			$ 420

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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