Revenue - Contract Balances (Details) - USD ($)	12 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Change In Contract With Customer, Assets [Roll Forward]
Contract assets - Beginning balance	$ 10,172,000	$ 12,874,000
Additional revenue recognized over-time	40,265,000	46,747,000
Less amounts billed to the customers	(40,346,000)	(49,449,000)
Contract assets - Ending balance	10,091,000	10,172,000
Change In Contract With Customer, Liability [Roll Forward]
Contract liabilities (included within Accrued liabilities) - Beginning balance	(807,000)	(236,000)
Payments received in advance of performance obligations	(2,242,000)	(1,691,000)
Performance obligations satisfied	1,899,000	1,120,000
Contract liabilities (included within Accrued liabilities) - Ending balance	(1,150,000)	(807,000)
Impairment loss on contract assets	$ 0	$ 0