Revenue - Contract Balances (Details) - USD ($)	6 Months Ended		12 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Sep. 30, 2023	Sep. 30, 2022
Change In Contract With Customer, Assets [Roll Forward]
Contract assets - Beginning balance	$ 10,091,000	$ 10,172,000	$ 10,172,000
Additional revenue recognized over-time	19,250,000	20,230,000
Less amounts billed to the customers	(19,365,000)	(19,766,000)
Contract assets - Ending balance	9,976,000	10,636,000	10,091,000
Change In Contract With Customer, Liability [Roll Forward]
Contract liabilities (included within Accrued liabilities) - Beginning balance	(1,150,000)	(807,000)	(807,000)
Payments received in advance of performance obligations	(1,830,000)	(1,428,000)
Performance obligations satisfied	1,581,000	1,019,000
Contract liabilities (included within Accrued liabilities) - Ending balance	(1,399,000)	(1,216,000)	(1,150,000)
Accounts receivable		$ 17,395,000		$ 16,515,000
Impairment loss on contract assets	$ 0		$ 0