Note 1 - Nature of Operations (Details Textual) - USD ($)	6 Months Ended	12 Months Ended
	Jan. 31, 2019	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2014	Dec. 05, 2018	Oct. 31, 2018	Oct. 03, 2018	Jan. 31, 2018
Revenue from Contract with Customer, Including Assessed Tax	$ 0	$ 0	$ 0	$ 0	$ 0
Stock Issued During Period, Value, New Issues	15,990,962
Working Capital	22,300,000
Cash and Cash Equivalents, at Carrying Value, Ending Balance	3,990,524	6,926,523							$ 3,639,646
Short-term Investments, Total	18,026,455
Long-term Debt, Gross	20,000,000	20,000,000				$ 20,000,000
Long-term Debt, Current Maturities, Total		$ 10,000,000					$ 15,000,000
Entity Incorporation, Date of Incorporation	May 16, 2003
Equity Financing [Member]
Stock Issued During Period, Shares, New Issues	12,613,049
Shares Issued, Price Per Share	$ 1.60							$ 1.60
Stock Issued During Period, Value, New Issues	$ 20,200,000
Proceeds from Stock Options and Warrants Exercised	$ 2,600,000