Commitments and Contingencies - Liability for future environmental expenditures (Details) - USD ($)	3 Months Ended	12 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Sep. 30, 2020	Jun. 30, 2020
Commitments and Contingencies
Beginning Balance	$ 1,037,000
Charges to income		$ 1,100,000
Remedial and investigatory spending	15,806
Ending Balance	1,021,194	1,037,000
Current, included in Other Liabilities			$ 867,194	$ 514,000
Long-term environmental			154,000	523,000
Total liability	$ 1,021,194	$ 1,037,000	$ 1,021,194	$ 1,037,000