Schedule of short term investments (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	May 31, 2021	Aug. 31, 2020
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short term investment, amortized cost	$ 60,948	$ 66,804
Gross unrealized gains	0	0
Gross unrealized loss	(23)	(61)
Short term investment, fair value	60,925	66,743
Commercial Paper [Member]
SEC Schedule, 12-15, Insurance Companies, Summary of Investments, Other than Investments in Related Parties [Line Items]
Short term investment, amortized cost	60,948	66,804
Gross unrealized gains	0	0
Gross unrealized loss	(23)	(61)
Short term investment, fair value	$ 60,925	$ 66,743