Share capital - Authorized unlimited common shares, no par value (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended	12 Months Ended
	May 31, 2021	Feb. 28, 2021	May 31, 2020	Feb. 29, 2020	May 31, 2021	Nov. 30, 2020
Class of Stock [Line Items]
Beginning balance, Number of shares		144,137,850			144,137,850
Ending balance, Number of shares	144,446,485				144,446,485	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	232,000	76,635	63,110	19,514	308,635	3,297,588
Exercise of options, Ascribed value					$ 642	$ 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	144,446,485				144,446,485	144,137,850
Ending balance, Ascribed value	$ 180,388				$ 180,388	$ 179,746