Revenue - Contract Balances (Details) - USD ($)	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2019
Change In Contract With Customer, Assets [Roll Forward]
Contract assets - Beginning balance, October 1, 2019	$ 10,349,000	$ 10,349,000
Additional revenue recognized over-time		17,446,000
Less amounts billed to the customers		(17,294,000)
Contract assets - Ending balance, December 31, 2019	10,501,000	10,501,000
Change In Contract With Customer, Liability [Roll Forward]
Contract liabilities (included within Accrued liabilities) - Beginning balance, October 1, 2019	(382,000)
Payments received in advance of performance obligations	0
Performance obligations satisfied	382,000
Contract liabilities (included within Accrued liabilities) - Ending balance, December 31, 2019	0	$ 0
Impairment loss on contract assets	$ 0