Revenue Recognition (Tables)

3 Months Ended

Dec. 31, 2024

Revenue from Contract with Customer [Abstract]

Schedule of Revenues Disaggregated by Revenue Sources

The following tables present the Company’s revenues disaggregated by revenue sources:

	Three months ended
	December 31, 2024		December 31, 2023
	(in millions)
Cost reimbursable	$	1,505.7	$	1,617.2
Guaranteed maximum price	1,527.4		1,414.9
Fixed-price	981.1		867.8
Total revenue	$	4,014.2	$	3,899.9

	Three months ended
	December 31, 2024		December 31, 2023
	(in millions)
Americas	$	3,112.1	$	3,038.9
Europe, Middle East, India, Africa	537.0		495.4
Asia-Australia-Pacific	365.1		365.6
Total revenue	$	4,014.2	$	3,899.9

Schedule of Net Accounts Receivable

Net accounts receivable consisted of the following:

	December 31, 2024		September 30, 2024
	(in millions)
Billed	$	2,039.9	$	2,184.9
Contract retentions	696.4		696.3
Total accounts receivable—gross	2,736.3		2,881.2
Allowance for doubtful accounts and credit losses	(87.3)		(87.9)
Total accounts receivable—net	$	2,649.0	$	2,793.3