Share capital - Additional information (Details) $ / shares in Units, $ in Thousands			3 Months Ended				6 Months Ended				12 Months Ended
	Apr. 16, 2020 shares	Feb. 29, 2020 shares	May 31, 2020 USD ($) $ / shares shares	Feb. 29, 2020 USD ($)	May 31, 2019 USD ($)	Feb. 28, 2019 USD ($)	May 31, 2020 USD ($) $ / shares $ / shares shares	May 31, 2020 USD ($) $ / shares shares	May 31, 2019 USD ($) $ / shares	May 31, 2019 USD ($) $ / shares shares	Nov. 30, 2019 USD ($)	Nov. 30, 2018 shares
Stock options granted, weighted average exercise price | $ / shares							$ 2.93		$ 2.96
Stock options granted, weighted average fair value | $ / shares								$ 0.96		$ 1.08
Stock-based compensation | $			$ (770)	$ (1,196)	$ (664)	$ (1,939)
Non-vested stock options outstanding			11,118,933				11,118,933	11,118,933
Weighted average exercise price options outstanding | $ / shares			$ 1.25				$ 1.25	$ 1.25
Aggregate intrinsic value, vested options | $			$ 8,300		$ 17,600		$ 8,300	$ 8,300	$ 17,600	$ 17,600
Aggregate intrinsic value, options exercised | $								180		$ 300
Stock option expense not yet recognized | $			$ 710				$ 710	$ 710
Period for recognition of stock compensation expense								2 years
Minimum [Member]
Vesting period										2 years
Nonvested Options [Member]
Non-vested stock options outstanding			1,453,338				1,453,338	1,453,338
Weighted average exercise price options outstanding | $ / shares			$ 2.15				$ 2.15	$ 2.15
Number of DSU's [Member]
Common stock committed for issuance			11,927				11,927	11,927
Class of Warrant or Right, Number of Securities Called by Warrants or Rights			1,988				1,988	1,988
Stock Compensation Plan [Member]
Stock-based compensation | $								$ 390		$ 660
RSUs [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period	200,000	212,501
Granted units								200,000				225,000
New Employees [Member]
Stock options granted								2,325,000		2,527,500
Directors, Employees and Services Providers [Member]
Stock-based compensation | $								$ 1,580			$ 1,940