Leases - Summary of Supplemental Balance Sheet Information Related to Leases (Details) - USD ($) $ in Millions	Mar. 31, 2024	Sep. 30, 2023
Supplementary Information Balance Sheets [Abstract]
Operating lease right-of-use asset	$ 598.7	$ 648.5
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other noncurrent assets	Other noncurrent assets
Current operating lease liabilities	$ 191.1	$ 202.4
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Other current liabilities	Other current liabilities
Noncurrent operating lease liabilities	$ 455.3	$ 499.7
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other noncurrent liabilities	Other noncurrent liabilities
Total operating lease liabilities	$ 646.4	$ 702.1
Property, plant and equipment	465.1	400.6
Accumulated depreciation	(74.9)	(105.3)
Property, plant and equipment, net	390.2	295.3
Current finance lease liabilities	$ 27.5	$ 62.9
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Current portion of debt	Current portion of debt
Noncurrent finance lease liabilities	$ 492.6	$ 409.7
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt due after one year	Long-term debt due after one year
Total finance lease liabilities	$ 520.1	$ 472.6