Share capital - Authorized unlimited common shares, no par value (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended						9 Months Ended	12 Months Ended
	Aug. 31, 2021	May 31, 2021	Feb. 28, 2021	Aug. 31, 2020	May 31, 2020	Feb. 29, 2020	Aug. 31, 2021	Nov. 30, 2020
Class of Stock [Line Items]
Unlimited common shares authorized							Unlimited	Unlimited
Common Stock, No Par Value	$ 0						$ 0	$ 0
Beginning balance, Number of shares			144,137,850				144,137,850
Ending balance, Number of shares	144,451,485						144,451,485	144,137,850
Share capital
Class of Stock [Line Items]
Beginning balance, Number of shares			144,137,850			140,427,761	144,137,850	140,427,761
Beginning balance, Ascribed value			$ 179,746			$ 177,971	$ 179,746	$ 177,971
Exercise of options, Number of shares	5,000	232,000	76,635	2,055,919	63,110	19,514	313,635	3,297,588
Exercise of options, Ascribed value							$ 646	$ 1,133
Restricted share units, Number of shares					200,000	212,501		412,501
Restricted share units, Ascribed value								$ 642
Ending balance, Number of shares	144,451,485						144,451,485	144,137,850
Ending balance, Ascribed value	$ 180,392						$ 180,392	$ 179,746