Note 12 - Capital Stock - Summary of Stock Options Outstanding and Exercisable (Details) - $ / shares	3 Months Ended
	Oct. 31, 2020	Jul. 31, 2020
Options Outstanding Outstanding (in shares)	14,171,250	15,514,750
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 1.10	$ 1.13
Options Outstanding Weighted Average Remaining Contractual Term (Year)	5 years 321 days
Options Exercisable (in shares)	8,092,534
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.21
Options Exercisable Weighted Average Remaining Contractual Term (Year)	3 years 105 days
Exercise Price Range 1 [Member]
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 0.80
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 0.99
Options Outstanding Outstanding (in shares)	8,141,000
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 0.92
Options Outstanding Weighted Average Remaining Contractual Term (Year)	7 years 138 days
Options Exercisable (in shares)	3,487,284
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 0.93
Options Exercisable Weighted Average Remaining Contractual Term (Year)	4 years 281 days
Exercise Price Range 2 [Member]
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 1
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 1.49
Options Outstanding Outstanding (in shares)	3,900,000
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 1.19
Options Outstanding Weighted Average Remaining Contractual Term (Year)	4 years 211 days
Options Exercisable (in shares)	2,475,000
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.25
Options Exercisable Weighted Average Remaining Contractual Term (Year)	1 year 306 days
Exercise Price Range 3 [Member]
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 1.50
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 2.81
Options Outstanding Outstanding (in shares)	2,130,250
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 1.64
Options Outstanding Weighted Average Remaining Contractual Term (Year)	2 years 204 days
Options Exercisable (in shares)	2,130,250
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.64
Options Exercisable Weighted Average Remaining Contractual Term (Year)	2 years 204 days