Supplemental Financial Statement Information, Supplemental Balance Sheet Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018	Sep. 30, 2018
Income Statement Related Disclosures [Abstract]
Interest income	$ (0.7)	$ (0.3)	$ (1.0)	$ (0.8)
Interest income on restricted cash	0.0	0.0	(5.8)	0.0
Interest income on restricted cash	3.8	2.9	2.7	7.0
Pension benefit other than service costs	(0.7)	(1.7)	(1.4)	(3.4)
Acquisition foreign currency gains	0.0	0.0	(9.0)	0.0
Settlement of acquired business hedging contracts	1.5	0.0	1.5	0.0
Transition services agreement income	(0.1)	0.0	(0.1)	0.0
Other	0.0	0.0	0.0	(0.6)
Total Other items, net	3.8	$ 0.9	(13.1)	$ 2.2
Inventories
Raw materials and supplies	89.3		89.3		$ 40.0
Work in process	130.2		130.2		86.5
Finished products	271.6		271.6		196.6
Total inventories	491.1		491.1		323.1
Other Current Assets
Miscellaneous receivables	26.5		26.5		9.9
Prepaid expenses	99.4		99.4		52.2
Value added tax collectible from customers	19.1		19.1		20.8
Other	8.6		8.6		12.6
Total other current assets	153.6		153.6		95.5
Property, Plant and Equipment
Land	9.8		9.8		4.5
Buildings	171.0		171.0		110.8
Machinery and equipment	762.9		762.9		696.2
Capital leases	50.8		50.8		0.0
Construction in progress	22.3		22.3		12.1
Total gross property	1,016.8		1,016.8		823.6
Accumulated depreciation	(653.1)		(653.1)		(656.9)
Total property, plant and equipment, net	363.7		363.7		166.7
Other Current Liabilities
Accrued advertising, sales promotion and allowances	10.2		10.2		16.5
Accrued trade allowances	57.2		57.2		39.4
Accrued salaries, vacations and incentive compensation	40.1		40.1		48.8
Accrued interest expense	34.3		34.3		27.1
Accrued related party amount	34.7		34.7		0.0
Income taxes payable	24.0		24.0		23.4
Other	115.1		115.1		115.8
Total other current liabilities	315.6		315.6		271.0
Other Liabilities
Pensions and other retirement benefits	68.1		68.1		70.2
Deferred compensation	27.1		27.1		29.0
Mandatory transition tax	33.1		33.1		33.1
Deferred tax liability	248.2		248.2		19.3
Other non-current liabilities	47.2		47.2		44.7
Total other liabilities	$ 423.7		$ 423.7		$ 196.3