Revenue - Contract Balances (Details) - USD ($)	6 Months Ended	12 Months Ended
	Mar. 31, 2022	Sep. 30, 2021
Change In Contract With Customer, Assets [Roll Forward]
Contract assets - Beginning balance	$ 12,874,000
Additional revenue recognized over-time	27,375,000
Less amounts billed to the customers	(27,136,000)
Contract assets - Ending balance	13,113,000	$ 12,874,000
Change In Contract With Customer, Liability [Roll Forward]
Contract liabilities (included within Accrued liabilities) - Beginning balance	(236,000)
Payments received in advance of performance obligations	(1,209,000)
Performance obligations satisfied	1,169,000
Contract liabilities (included within Accrued liabilities) - Ending balance	(276,000)	(236,000)
Impairment loss on contract assets	$ 0	$ 0