Supplemental Financial Statement Information, Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Sep. 30, 2020
Income Statement Related Disclosures [Abstract]
Interest income	$ (0.2)	$ (0.1)	$ (0.3)	$ (0.2)
Foreign currency exchange loss	0.5	5.5	1.8	5.1
Pension benefit other than service costs	(0.5)	(0.5)	(1.0)	(1.0)
Acquisition foreign currency loss	0.0	0.0	0.0	2.2
Transition services agreement income	0.0	(0.1)	0.0	(0.4)
Other	0.1	0.3	0.2	(0.6)
Total Other items, net	(0.1)	$ 5.1	0.7	$ 5.1
Inventories
Raw materials and supplies	122.3		122.3		$ 85.2
Work in process	164.9		164.9		148.7
Finished products	312.8		312.8		277.4
Total inventories	600.0		600.0		511.3
Other Current Assets
Miscellaneous receivables	23.8		23.8		15.8
Due from Spectrum	13.7		13.7		30.6
Prepaid expenses	106.5		106.5		76.5
Value added tax collectible from customers	28.8		28.8		20.4
Other	12.9		12.9		14.5
Total other current assets	185.7		185.7		157.8
Property, Plant and Equipment
Land	15.7		15.7		8.9
Buildings	124.9		124.9		121.9
Machinery and equipment	841.5		841.5		821.4
Capital leases	52.7		52.7		51.4
Construction in progress	45.6		45.6		39.3
Total gross property	1,080.4		1,080.4		1,042.9
Accumulated depreciation	(716.8)		(716.8)		(690.8)
Total property, plant and equipment, net	363.6		363.6		352.1
Other Current Liabilities
Accrued advertising, sales promotion and allowances	14.1		14.1		12.1
Accrued trade allowances	44.7		44.7		45.4
Accrued salaries, vacations and incentive compensation	46.2		46.2		68.1
Accrued interest expense	17.5		17.5		36.9
Accrued redemption premium	0.0		0.0		55.9
Restructuring reserve					9.4
Income taxes payable	38.0		38.0		30.2
Other	122.5		122.5		150.7
Total other current liabilities	289.3		289.3		408.7
Other Liabilities
Pensions and other retirement benefits	86.3		86.3		89.9
Deferred compensation	24.4		24.4		26.8
Mandatory transition tax	16.7		16.7		16.7
Other non-current liabilities	74.2		74.2		78.2
Total other liabilities	$ 201.6		$ 201.6		$ 211.6