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, 2022	May 31, 2022	Feb. 28, 2022	Aug. 31, 2021	May 31, 2021	Feb. 28, 2021	Aug. 31, 2022	Nov. 30, 2021
Class of Stock [Line Items]
Unlimited common shares authorized							Unlimited	Unlimited
Common Stock, No Par Value	$ 0						$ 0	$ 0
Joint venture contribution			$ 51
Share capital
Class of Stock [Line Items]
Beginning balance, Number of shares			145,009,811				145,009,811
Beginning balance, Ascribed value			$ 180,820				$ 180,820
Exercise of options, Number of shares		50,000	31,674	5,000	232,000	76,635	81,674
Exercise of options, Ascribed value							$ 76
Restricted share units, Number of shares	244,216	110,000	391,332				745,548
Restricted share units, Ascribed value							$ 998
Joint venture equity contribution (note 3(b)), Number of shares			31,469				31,469
Joint venture contribution	$ 51		$ 51				$ 51
Ending balance, Number of shares	145,868,502						145,868,502	145,009,811
Ending balance, Ascribed value	$ 181,945						$ 181,945	$ 180,820