Supplemental Financial Statement Information, Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Sep. 30, 2019
Income Statement Related Disclosures [Abstract]
Interest income	$ (0.1)	$ (0.2)
Interest income on restricted cash	0.0	(5.8)
Interest income on restricted cash	0.4	(1.1)
Pension benefit other than service costs	0.5	(0.7)
Acquisition foreign currency loss/(gain)	(2.2)	(9.0)
Gain on sale of assets	(1.0)	0.0
Transition services agreement income	0.3	0.0
Other	(0.1)	(0.1)
Total Other items, net	0.0	$ (16.9)
Inventories
Raw materials and supplies	73.7		$ 70.5
Work in process	92.3		103.7
Finished products	269.8		295.1
Total inventories	435.8		469.3
Other Current Assets
Miscellaneous receivables	15.4		16.5
Due from Spectrum	13.0		7.6
Prepaid expenses	91.0		71.3
Value added tax collectible from customers	32.3		23.1
Other	11.3		58.6
Total other current assets	163.0		177.1
Property, Plant and Equipment
Land	9.7		9.6
Buildings	121.5		119.9
Machinery and equipment	834.8		823.0
Capital leases	45.7		50.4
Construction in progress	31.9		25.8
Total gross property	1,043.6		1,028.7
Accumulated depreciation	(685.9)		(666.7)
Total property, plant and equipment, net	357.7		362.0
Other Current Liabilities
Accrued advertising, sales promotion and allowances	26.7		11.8
Accrued trade allowances	59.8		53.1
Accrued salaries, vacations and incentive compensation	29.8		59.2
Accrued interest expense	55.9		37.4
Due to Spectrum	4.4		2.6
Accrued acquisition and integration costs	6.1		7.9
Restructuring reserve			9.8
Income taxes payable	43.3		23.4
Other	122.2		128.4
Total other current liabilities	355.1		333.6
Other Liabilities
Pensions and other retirement benefits	107.0		109.0
Deferred compensation	28.6		28.1
Restructuring reserve	4.5		0.0
Mandatory transition tax	16.7		16.7
Other non-current liabilities	49.4		50.8
Total other liabilities	$ 206.2		$ 204.6