Note H - Fair Value of Financial Instruments - Reconciliation of Beginning and Ending Balances for Derivative and Warrant Liability Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Balance as of beginning of period	$ 1,845	$ 7,709
Adjustment to fair value	(424)	9,741
Balance as of end of period	$ 1,421	$ 17,450