Note 19 - Unaudited Supplementary Data - Selected Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Nov. 30, 2020	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Nov. 30, 2019	Aug. 31, 2019	May 31, 2019	Feb. 28, 2019	Nov. 30, 2020	Nov. 30, 2019	Nov. 30, 2018
Loss from operations	$ (7,973)	$ (10,895)	$ (8,087)	$ (6,282)	$ (7,520)	$ (7,216)	$ (6,413)	$ (5,663)	$ (33,237)	$ (26,812)	$ (27,291)
Net loss	$ (7,000)	$ (12,736)	$ (7,233)	$ (6,595)	$ (7,867)	$ (8,056)	$ (5,515)	$ (6,323)	$ (33,564)	$ (27,761)	$ (112,765)
Net loss per common share, basic and diluted (in dollars per share)	$ (0.02)	$ (0.04)	$ (0.02)	$ (0.02)	$ (0.02)	$ (0.02)	$ (0.02)	$ (0.02)	$ (0.10)	$ (0.09)	$ (0.35)