Share capital - Stock options outstanding (Details)	6 Months Ended
	May 31, 2021 $ / shares shares
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Number of outstanding options | shares	11,123,316
Weighted average years to expiry	3 years 5 months 15 days
Weighted average exercise price options outstanding	$ 2.03
Number of exercisable options | shares	7,946,979
Weighted average exercise price exercisable	$ 1.97
Number of unvested options | shares	3,176,337
$0.58 to $1.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price lower range limit	$ 0.58
Exercise price upper range limit	$ 1.00
Number of outstanding options | shares	1,440,000
Weighted average years to expiry	1 year 1 month 2 days
Weighted average exercise price options outstanding	$ 0.73
Number of exercisable options | shares	1,440,000
Weighted average exercise price exercisable	$ 0.73
Number of unvested options | shares	0
$1.01 to $1.50
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price lower range limit	$ 1.01
Exercise price upper range limit	$ 1.50
Number of outstanding options | shares	75,000
Weighted average years to expiry	1 year 6 months 21 days
Weighted average exercise price options outstanding	$ 1.22
Number of exercisable options | shares	75,000
Weighted average exercise price exercisable	$ 1.22
Number of unvested options | shares	0
$1.50 to $2.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price lower range limit	$ 1.50
Exercise price upper range limit	$ 2.00
Number of outstanding options | shares	865,000
Weighted average years to expiry	3 years 5 months 23 days
Weighted average exercise price options outstanding	$ 1.96
Number of exercisable options | shares	865,000
Weighted average exercise price exercisable	$ 1.96
Number of unvested options | shares	0
$2.01 to $2.50
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price lower range limit	$ 2.01
Exercise price upper range limit	$ 2.50
Number of outstanding options | shares	8,705,816
Weighted average years to expiry	3 years 10 months 13 days
Weighted average exercise price options outstanding	$ 2.25
Number of exercisable options | shares	5,529,479
Weighted average exercise price exercisable	$ 2.29
Number of unvested options | shares	3,176,337
$2.51 to $3.00
Share-based Payment Arrangement, Option, Exercise Price Range [Line Items]
Exercise price lower range limit	$ 2.51
Exercise price upper range limit	$ 3.00
Number of outstanding options | shares	37,500
Weighted average years to expiry	2 years 11 months 19 days
Weighted average exercise price options outstanding	$ 2.82
Number of exercisable options | shares	37,500
Weighted average exercise price exercisable	$ 2.82
Number of unvested options | shares	0