Segments - Schedule of Segment Reporting Information, by Segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Net sales	$ 556.4	$ 374.4	$ 1,128.3	$ 947.7
Segment Profit	194.2	168.5	469.7	446.8
Research and development expense	(8.7)	(5.4)	(14.2)	(10.7)
Amortization of intangible assets	(12.5)	(2.8)	(15.7)	(5.6)
Acquisition and integration costs	95.4	19.4
Other items, net	(2.4)	(0.9)	(0.3)	(2.2)
(Loss)/earnings before income taxes	(74.0)	17.8	16.0	136.8
Operating Segments
Segment Reporting Information [Line Items]
Segment Profit	125.1	89.8	295.8	262.1
Segment Reconciling Items
Segment Reporting Information [Line Items]
General corporate and other expenses	(29.7)	(24.7)	(48.4)	(46.3)
Global marketing expense	(6.4)	(5.2)	(9.5)	(8.4)
Research and development expense	(8.7)	(5.4)	(14.2)	(10.7)
Amortization of intangible assets	(12.5)	(2.8)	(15.7)	(5.6)
Acquisition and integration costs	95.4	19.4	131.9	25.1
Interest and other financing items	(44.0)	(13.6)	(59.8)	(27.0)
Americas
Segment Reporting Information [Line Items]
Net sales	381.6	224.1	755.1	597.2
Americas \| Operating Segments
Segment Reporting Information [Line Items]
Net sales	381.6	224.1	755.1	597.2
Segment Profit	88.7	55.7	204.8	178.8
International
Segment Reporting Information [Line Items]
Net sales	174.8	150.3	373.2	350.5
International \| Operating Segments
Segment Reporting Information [Line Items]
Net sales	174.8	150.3	373.2	350.5
Segment Profit	36.4	34.1	91.0	83.3
Selling, General and Administrative Expenses
Segment Reporting Information [Line Items]
Global marketing expense	(2.2)	(1.3)	(3.4)	(1.8)
Acquisition and integration costs			131.9	25.1
Selling, General and Administrative Expenses \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Acquisition and integration costs	29.1	(16.5)	48.0	22.2
Advertising and Sales Promotion Expense
Segment Reporting Information [Line Items]
Global marketing expense	(4.2)	(3.9)	(6.1)	(6.6)
Cost of products sold
Segment Reporting Information [Line Items]
Acquisition and integration costs	31.7		27.2
Interest Expense
Segment Reporting Information [Line Items]
Interest and other financing items	33.2	$ 2.9	65.6	$ 2.9
Acquisition-related Costs
Segment Reporting Information [Line Items]
Acquisition and integration costs	$ 1.4		$ 13.4

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The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

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Aggregate revenue less cost of goods and services sold or operating expenses directly attributable to the revenue generation activity.

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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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Expenditures for planning and executing the conception, pricing, promotion, and distribution of ideas, goods, and services. Costs of public relations and corporate promotions are typically considered to be marketing costs.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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