Share capital (Narrative) (Details) $ / shares in Units, $ in Thousands	1 Months Ended	3 Months Ended				6 Months Ended				12 Months Ended
	Apr. 20, 2018 USD ($) $ / shares shares	May 31, 2019 USD ($) $ / shares shares	Feb. 28, 2019 USD ($)	May 31, 2018 USD ($) shares	Feb. 28, 2018 USD ($)	May 31, 2019 USD ($) $ / shares shares	May 31, 2019 USD ($) $ / shares $ / shares shares	May 31, 2018 USD ($) $ / shares shares	May 31, 2018 USD ($) $ / shares	Nov. 30, 2018 USD ($) shares	May 31, 2019 $ / shares
Stock options granted, weighted average exericse price | $ / shares							$ 2.96		$ 1.04
Stock options granted, weighted average exercise price | $ / shares						$ 1.08		$ 0.37
Stock-based compensation		$ 664	$ 1,939	$ 151	$ 922
Non-vested stock options outstanding | shares		11,129,781				11,129,781	11,129,781
Weighted average exercise price options outstanding | $ / shares		$ 0.95				$ 0.95	$ 0.95
Aggregate intrinsic value, vested options		$ 17,600		5,900		$ 17,600	$ 17,600	$ 5,900	$ 5,900
Aggregate intrinsic value, options exercised						$ 300		100
Stock Issued During Period, Value, New Issues				28,750
Legal Fees	$ 1,800
Proceeds from Issuance of Common Stock	26,900
Common Stock [Member]
Stock-based compensation		$ 0	$ 0	0	$ 0
Stock Issued During Period, Value, New Issues	$ 28,700			$ 28,750						$ 28,750
Stock Issued During Period, Shares, New Issues | shares	24,784,482			24,784,482						24,784,482
Shares Issued, Price Per Share | $ / shares	$ 1.16
Non-Vested Options [Member]
Non-vested stock options outstanding | shares		1,841,672				1,841,672	1,841,672
Weighted average exercise price options outstanding | $ / shares											$ 1.79
Number of DSU's [Member]
Common stock committed for issuance | shares		11,927				11,927	11,927
Class of Warrant or Right, Number of Securities Called by Warrants or Rights | shares		1,988				1,988	1,988
Stock Compensation Plan [Member]
Stock-based compensation						$ 660		$ 490
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period | shares										412,501
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period | shares										225,000
Approximationss [Member] | Non-Vested Options [Member]
Stock option expense						$ 900
New Employees [Member]
Stock options granted | shares						2,527,500		2,125,000
Directors, Employees and Services Providers [Member]
Stock-based compensation						$ 1,940		$ 580