Revenue - Contract Balances (Details) - USD ($)	9 Months Ended	12 Months Ended
	Jun. 30, 2023	Sep. 30, 2022
Change In Contract With Customer, Assets [Roll Forward]
Contract assets - Beginning balance	$ 10,172,000
Additional revenue recognized over-time	28,955,000
Less amounts billed to the customers	(30,108,000)
Contract assets - Ending balance	9,019,000	$ 10,172,000
Change In Contract With Customer, Liability [Roll Forward]
Contract liabilities (included within Accrued liabilities) - Beginning balance	(807,000)
Payments received in advance of performance obligations	(1,531,000)
Performance obligations satisfied	1,435,000
Contract liabilities (included within Accrued liabilities) - Ending balance	(903,000)	(807,000)
Impairment loss on contract assets	$ 0	$ 0