Revenue - Contract Balances (Details) - USD ($)	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
Change In Contract With Customer, Assets [Roll Forward]
Contract assets - Beginning balance	$ 12,874,000	$ 11,997,000
Additional revenue recognized over-time	46,747,000	64,384,000
Less amounts billed to the customers	(49,449,000)	(63,507,000)
Contract assets - Ending balance	10,172,000	12,874,000
Change In Contract With Customer, Liability [Roll Forward]
Contract liabilities (included within Accrued liabilities) - Beginning balance	(236,000)	(636,000)
Payments received in advance of performance obligations	(1,691,000)	(829,000)
Performance obligations satisfied	1,120,000	1,229,000
Contract liabilities (included within Accrued liabilities) - Ending balance	(807,000)	(236,000)
Impairment loss on contract assets	$ 0	$ 0