Note 12 - Capital Stock - Summary of Stock Options Outstanding and Exercisable (Details) - $ / shares	6 Months Ended
	Jan. 31, 2020	Oct. 31, 2019	Jul. 31, 2019
Options Outstanding Outstanding (in shares)	10,286,625	10,346,000	15,738,350
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 1.25	$ 1.25	$ 1.30
Options Outstanding Weighted Average Remaining Contractual Term (Year)	3 years 324 days
Options Exercisable (in shares)	7,852,334
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.31
Options Exercisable Weighted Average Remaining Contractual Term (Year)	2 years 197 days
Exercise Price Range 1 [Member]
Range of Exercise Prices, Lower Limit (in dollars per share)	$ 0.91
Range of Exercise Prices, Upper Limit (in dollars per share)	$ 0.99
Options Outstanding Outstanding (in shares)	4,227,625
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 0.94
Options Outstanding Weighted Average Remaining Contractual Term (Year)	6 years 40 days
Options Exercisable (in shares)	2,309,334
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 0.94
Options Exercisable Weighted Average Remaining Contractual Term (Year)	3 years 109 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)	3,572,500
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 1.22
Options Outstanding Weighted Average Remaining Contractual Term (Year)	1 year 335 days
Options Exercisable (in shares)	3,531,250
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.22
Options Exercisable Weighted Average Remaining Contractual Term (Year)	1 year 324 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)	$ 3.75
Options Outstanding Outstanding (in shares)	2,486,500
Options Outstanding Weighted Average Exercise Price (in dollars per share)	$ 1.84
Options Outstanding Weighted Average Remaining Contractual Term (Year)	2 years 346 days
Options Exercisable (in shares)	2,011,750
Options Exercisable Weighted Average Exercise Price (in dollars per share)	$ 1.91
Options Exercisable Weighted Average Remaining Contractual Term (Year)	2 years 302 days