Supplemental Financial Statement Information, Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Sep. 30, 2020
Income Statement Related Disclosures [Abstract]
Interest income	$ (0.2)	$ (0.2)	$ (0.5)	$ (0.4)
Foreign currency exchange (gain)/loss	(0.9)	2.9	0.9	8.0
Pension benefit other than service costs	(0.6)	(0.5)	(1.6)	(1.5)
Acquisition foreign currency loss	0.0	0.0	0.0	2.2
Transition services agreement income	0.0	(0.4)	0.0	(0.8)
Other	0.2	(1.1)	0.4	(1.7)
Total Other items, net	(1.5)	$ 0.7	(0.8)	$ 5.8
Inventories
Raw materials and supplies	145.6		145.6		$ 85.2
Work in process	200.9		200.9		148.7
Finished products	344.6		344.6		277.4
Total inventories	691.1		691.1		511.3
Other Current Assets
Miscellaneous receivables	21.9		21.9		15.8
Due from Spectrum	13.5		13.5		30.6
Prepaid expenses	105.0		105.0		76.5
Value added tax collectible from customers	29.6		29.6		20.4
Other	13.1		13.1		14.5
Total other current assets	183.1		183.1		157.8
Property, Plant and Equipment
Land	15.8		15.8		8.9
Buildings	125.0		125.0		121.9
Machinery and equipment	855.8		855.8		821.4
Capital leases	52.8		52.8		51.4
Construction in progress	49.7		49.7		39.3
Total gross property	1,099.1		1,099.1		1,042.9
Accumulated depreciation	(726.5)		(726.5)		(690.8)
Total property, plant and equipment, net	372.6		372.6		352.1
Other Current Liabilities
Accrued advertising, sales promotion and allowances	18.3		18.3		12.1
Accrued trade allowances	48.1		48.1		45.4
Accrued salaries, vacations and incentive compensation	52.7		52.7		68.1
Accrued interest expense	11.8		11.8		36.9
Accrued redemption premium	0.0		0.0		55.9
Restructuring reserve	6.6		6.6		9.4
Income taxes payable	16.2		16.2		30.2
Other	136.7		136.7		150.7
Total other current liabilities	290.4		290.4		408.7
Other Liabilities
Pensions and other retirement benefits	84.1		84.1		89.9
Deferred compensation	22.8		22.8		26.8
Mandatory transition tax	16.7		16.7		16.7
Other non-current liabilities	70.9		70.9		78.2
Total other liabilities	$ 194.5		$ 194.5		$ 211.6