Share capital - Stock options outstanding (Details)	6 Months Ended
	May 31, 2020 $ / shares shares
Number of outstanding options | shares	11,118,933
Weighted average years to expiry	2 years 7 months 24 days
Weighted average exercise price options outstanding	$ 1.25
Number of exercisable options | shares	9,715,595
Weighted average exercise price exercisable	$ 2.43
Number of unvested options | shares	1,403,338
Range 1 [Member]
Exercise price lower range limit	$ 0.32
Exercise price upper range limit	$ 0.50
Number of outstanding options | shares	3,901,433
Weighted average years to expiry	9 months 22 days
Weighted average exercise price options outstanding	$ 0.40
Number of exercisable options | shares	3,901,433
Weighted average exercise price exercisable	$ 0.81
Number of unvested options | shares	0
Range 2 [Member]
Exercise price lower range limit	$ 0.51
Exercise price upper range limit	$ 1.00
Number of outstanding options | shares	1,845,000
Weighted average years to expiry	2 years 5 months 23 days
Weighted average exercise price options outstanding	$ 0.73
Number of exercisable options | shares	1,845,000
Weighted average exercise price exercisable	$ 2.48
Number of unvested options | shares	0
Range 3 [Member]
Exercise price lower range limit	$ 1.01
Exercise price upper range limit	$ 1.50
Number of outstanding options | shares	225,000
Weighted average years to expiry	2 years 10 months 13 days
Weighted average exercise price options outstanding	$ 1.29
Number of exercisable options | shares	175,000
Weighted average exercise price exercisable	$ 2.83
Number of unvested options | shares	50,000
Range 4 [Member]
Exercise price lower range limit	$ 1.51
Exercise price upper range limit	$ 2.00
Number of outstanding options | shares	915,000
Weighted average years to expiry	4 years 4 months 28 days
Weighted average exercise price options outstanding	$ 1.72
Number of exercisable options | shares	898,333
Weighted average exercise price exercisable	$ 4.43
Number of unvested options | shares	16,667
Range 5 [Member]
Exercise price lower range limit	$ 2.01
Exercise price upper range limit	$ 2.54
Number of outstanding options | shares	4,232,500
Weighted average years to expiry	4 years 11 days
Weighted average exercise price options outstanding	$ 2.17
Number of exercisable options | shares	2,895,829
Weighted average exercise price exercisable	$ 3.92
Number of unvested options | shares	1,336,671