Property plant and equipment - Narrative (Details)		9 Months Ended
	Feb. 20, 2020 USD ($)	Jun. 30, 2020 USD ($) $ / ft²
Property, Plant and Equipment [Abstract]
Sale Lease back Transaction Price	$ 13,200,000
Proceeds from sale of leasebacks	$ 12,800,000
Sale and Leaseback Transaction, Gain (Loss), Net		$ 300,000
Sale And Lease Back Transaction, Lease Term		15 years
Sale Leaseback Transaction, Base Monthly Rent Per Unit | $ / ft²		0.75
Sale Leaseback Transaction, Base Monthly Rent		$ 77,500
Sale Leaseback Transaction, Percentage Of Increase On Lease Rent		3.00%
Additional operating lease right use of assets		$ 10,800,000
Additional Operating Lease, Liability		$ 10,800,000