Note F - Earnings Per Share - Computation of Basic and Diluted Net Income (Loss) per Share (Details) - USD ($) $ / shares in Units, $ 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
Net income (loss)	$ (35,430)	$ (8,780)	$ (11,366)	$ (10,474)	$ (8,568)	$ (3,732)	$ 8,034	$ 2,120	$ (66,049)	$ (2,146)	$ 73,951
Basic (in shares)									19,982,363	19,646,646	19,097,355
Effect of dilutive options and restricted stock units (in shares)									0	0	1,042,000
Diluted (in shares)									19,982,363	19,646,646	20,139,105
Basic (in dollars per share)	$ (1.76)	$ (0.44)	$ (0.57)	$ (0.53)	$ (0.43)	$ (0.19)	$ 0.41	$ 0.11	$ (3.31)	$ (0.11)	$ 3.87
Diluted (in dollars per share)	$ (1.76)	$ (0.44)	$ (0.57)	$ (0.53)	$ (0.43)	$ (0.19)	$ 0.40	$ 0.11	$ (3.31)	$ (0.11)	$ 3.67