Note 13 - Capital Stock - Warrants Outstanding and Exercisable (Details) - $ / shares	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Weighted Average Exercise Price (in dollars per share)	$ 2.03	$ 1.94	$ 1.97	$ 1.78
Number of Warrants Outstanding (in shares)	7,721,981	19,443,910	30,923,489	19,676,560
Weighted Average Remaining Contractual Life (Year)	266 days
Warrants 1 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.25
Number of Warrants Outstanding (in shares)	150,000
Weighted Average Remaining Contractual Life (Year)	146 days
Expiry Date	Dec. 23, 2020
Warrants 2 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.50
Number of Warrants Outstanding (in shares)	150,000
Weighted Average Remaining Contractual Life (Year)	146 days
Expiry Date	Dec. 23, 2020
Warrants 3 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 2.05
Number of Warrants Outstanding (in shares)	7,063,253
Weighted Average Remaining Contractual Life (Year)	244 days
Expiry Date	Apr. 03, 2021
Warrants 4 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 2.30
Number of Warrants Outstanding (in shares)	308,728
Weighted Average Remaining Contractual Life (Year)	2 years 7 days
Expiry Date	Aug. 09, 2022
Warrants 5 [Member]
Weighted Average Exercise Price (in dollars per share)	$ 1.64
Number of Warrants Outstanding (in shares)	50,000
Weighted Average Remaining Contractual Life (Year)	2 years 292 days
Expiry Date	May 21, 2023