Revenue - Contract Balances (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Sep. 30, 2022	Sep. 30, 2023
Revenue from Contract with Customer [Abstract]
Contract assets	$ 88,351	$ 60,621
Contract liabilities	(79,857)	(279,796)
Net contract asset (liability)	8,494	(219,175)
Revenue recognized related to contract liabilities	2,500	70,500
Retention amounts included in accounts receivable	$ 6,900	7,400
Retained amount expected to be collected in the next twelve months		7,200
Retained amount expected to be collected		$ 200