Note N - Net Loss Per Share - Summary of Computation of Basic and Diluted Net Loss and Net Loss Per Share (Details) - USD ($)
$ / shares in Units, $ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2016
Sep. 30, 2016
Jun. 30, 2016
Mar. 31, 2016
Dec. 31, 2015
Sep. 30, 2015
Jun. 30, 2015
Mar. 31, 2015
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Net loss - basic and diluted $ (9,936) $ (13,414) $ 9,768 $ (2,934) $ (9,203) $ (9,744) $ (29,743) $ (5,974) $ (16,516) $ (54,664) $ (24,455)
Weighted-average number of common shares - basic and diluted (in shares)                 14,597,053 7,368,681 2,381,041
Net loss per share - basic and diluted (in dollars per share)                 $ (1.13) $ (7.42) $ (10.27)