Summary of Significant Accounting Policies Adopted Accounting Policies (Details) - USD ($)	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019	Oct. 01, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI, Current Period, Tax			$ 0.2
Selling and administrative expenses	$ 887,000,000.0	$ 820,400,000	941,000,000.0
Cares Act	21.7
Operating Lease, Liability	73,300,000
Cumulative Effect on Retained Earnings, Net of Tax		300,000
Acquisition-related intangible asset amortization	(108,600,000)	(109,000,000.0)	(122,400,000)
Stockholders' Equity Attributable to Parent	(1,879.7)	(1,726,100,000)	(4.9)
Retained Earnings (Accumulated Deficit)	2,315.9	2,132,200,000
Deferred Tax Assets, Valuation Allowance	53,000,000.0	50,800,000
Inventory, Finished Goods, Net of Reserves	153.7	167,600,000
Inventory, Work in Process, Net of Reserves	53.3	48,400,000
Inventory, Raw Materials, Net of Reserves	112.4	136,000,000.0
Inventory, Net	319.4	352,000,000.0
Deferred Tax Assets, Valuation Allowance	53,000,000.0	50,800,000
Operating Lease, Liability	73,300,000
Reclassification from AOCI, Current Period, Tax			0.2
Selling, General and Administrative Expenses [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Selling and administrative expenses		$ 820,400,000	818,600,000
Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating Lease, Liability				$ 85,800,000
Operating Lease, Liability				$ 85,800,000
Retained Earnings [Member] | Accounting Standards Update 2016-02 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Stockholders' Equity Attributable to Parent			$ (5,400,000)
Retained Earnings [Member] | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reclassification from AOCI, Current Period, Tax	800,000
Stockholders' Equity Attributable to Parent	2,200,000
Reclassification from AOCI, Current Period, Tax	$ 800,000
Minimum [Member]
Finite-Lived Intangible Asset, Useful Life	1 year
Minimum [Member] | Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Asset, Useful Life	3 years
Maximum [Member]
Finite-Lived Intangible Asset, Useful Life	20 years
Maximum [Member] | Computer Software, Intangible Asset [Member]
Finite-Lived Intangible Asset, Useful Life	5 years