Segments - Restructuring and Related Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Segment Reporting [Line Items]
Total Restructuring and related costs	$ 14.4	$ 8.0	$ 76.8	$ 45.9
Restructuring costs	14.4	8.0	76.8	45.9
Corporate
Segment Reporting [Line Items]
Total Restructuring and related costs	14.4	8.0	76.8	45.9
Other restructuring related costs \| Corporate
Segment Reporting [Line Items]
Total Restructuring and related costs	0.0	0.0	0.0	(0.3)
Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServicesSold \| Corporate \| US Operating Efficiency Project
Segment Reporting [Line Items]
Total Restructuring and related costs	3.8	0.0	14.9	0.0
Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServicesSold \| Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment
Segment Reporting [Line Items]
Restructuring costs	3.7	2.9	35.0	21.0
Location, Statement of Income, Balance [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense \| Corporate
Segment Reporting [Line Items]
Total Restructuring and related costs	6.9	3.4	26.9	12.0
Location, Statement of Income, Balance [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense \| IT enablement
Segment Reporting [Line Items]
Restructuring costs	0.0	1.7	0.0	13.2
Location, Statement of Income, Balance [Axis]: us-gaap:SellingGeneralAndAdministrativeExpense \| IT enablement \| Corporate
Segment Reporting [Line Items]
Total Restructuring and related costs	$ 0.0	$ 1.7	$ 0.0	$ 13.2