Note 13 - Capital Stock - Schedule of Outstanding Stock Options (Details) - $ / shares	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Balance, number of stock options (in shares)	15,738,350	14,911,625	12,260,500
Balance, Weighted Average Exercise Price (in dollars per share)	$ 1.30	$ 1.41	$ 1.33
Granted, number of stock options (in shares)	6,163,900	2,006,350	4,083,000
Granted, Weighted Average Exercise Price (in dollars per share)	$ 0.95	$ 0.97	$ 1.40
Exercised, number of stock options (in shares)		(259,625)	(1,365,625)
Exercised Options, Weighted Average Exercise Price (in dollars per share)		$ 1.12	$ 0.70
Cancelled/Forfeited, number of stock options (in shares)	(179,344)	(910,000)	(66,250)
Cancelled/Forfeited, Weighted Average Exercise Price (in dollars per share)	$ 1.02	$ 2.41	$ 1.24
Expired, number of stock options (in shares)	(6,208,156)	(10,000)
Expired, Weighted Average Exercise Price (in dollars per share)	$ 1.39	$ 1.50
Balance, number of stock options (in shares)	15,514,750	15,738,350	14,911,625
Balance, Weighted Average Exercise Price (in dollars per share)	$ 1.13	$ 1.30	$ 1.41