Commitments and Contingencies - Leases and Asset Retirement Obligations Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Loss Contingencies [Line Items]
Lease option to extend length (in years)	5 years
Operating lease expenses	$ 2,200,000	$ 1,800,000
ARO liability	$ 2,049,000	2,022,000
Risk-free rate, minimum	0.06%
Risk-free rate, maximum	1.73%
Accretion expense	$ 47,600	31,900	$ 54,200
Minimum
Loss Contingencies [Line Items]
Operating lease, remaining lease term	7 months 6 days
Maximum
Loss Contingencies [Line Items]
Operating lease, remaining lease term	13 years 4 months 24 days
Property in Alhambra, California
Loss Contingencies [Line Items]
ARO liability	$ 2,000,000	$ 2,000,000