Note 19 - Unaudited Supplementary Data - Selected Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Nov. 30, 2017	Aug. 31, 2017	May 31, 2017	Feb. 28, 2017	Nov. 30, 2016	Aug. 31, 2016	May 31, 2016	Feb. 29, 2016	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2015
Loss from operations	$ (8,753)	$ (8,423)	$ (7,558)	$ (8,963)	$ (6,804)	$ (6,422)	$ (7,391)	$ (9,530)	$ (33,697)	$ (30,147)	$ (31,696)
Net loss	$ (10,018)	$ (10,393)	$ (8,462)	$ (10,143)	$ (7,350)	$ (7,381)	$ (9,138)	$ (9,977)	$ (39,016)	$ (33,846)	$ (31,952)
Basic and diluted (in dollars per share)	$ (0.03)	$ (0.03)	$ (0.03)	$ (0.03)	$ (0.02)	$ (0.02)	$ (0.03)	$ (0.03)	$ (0.12)	$ (0.11)	$ (0.10)