Revenue - Contract Balances (Details) $ in Thousands	12 Months Ended
	Sep. 30, 2019 USD ($)
Change In Contract With Customer, Assets [Roll Forward]
Contract assets - Beginning balance, October 1, 2018	$ 0
Additional revenue recognized over-time	62,499
Less amounts billed to the customers	(62,290)
Contract assets - Ending balance, September 30, 2019	10,349
Change In Contract With Customer, Liability [Roll Forward]
Payments received in advance of performance obligations	(2,000)
Performance obligations satisfied	1,618
Contract liabilities (included within Accrued liabilities) - Ending balance, September 30, 2019	$ (382)