Nature of Business and Summary of Significant Accounting Policies - Intangible Assets (Details) - USD ($)	3 Months Ended		12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Jun. 30, 2023
Intangible assets
Amortization expense	$ 84,000	$ 90,000
Changes in intangible assets
Carrying value	13,848,000		$ 13,848,000
Accumulated amortization	(9,993,000)		(9,909,000)
Net book value	3,855,000		$ 3,939,000
Future amortization expense
2024	336,000
2025	315,000
2026	297,000
2027	283,000
2028	$ 269,000
Weighted average remaining period	15 years 3 months 18 days		15 years 6 months
Customer relationships
Changes in intangible assets
Carrying value	$ 9,800,000		$ 9,800,000
Accumulated amortization	(9,335,000)		(9,302,000)
Net book value	465,000		498,000
Trade name
Changes in intangible assets
Carrying value	4,048,000		4,048,000
Accumulated amortization	(658,000)		(607,000)
Net book value	$ 3,390,000		$ 3,441,000