Discontinued Operations - Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest and other financing (income) expense	$ (4.6)	$ 17.3	$ 27.4	$ 51.2
Income tax expense	22.9	13.2	14.2	32.6
(Loss) income from discontinued operations	(2.9)	58.4	1,246.4	169.6
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net revenues	0.0	696.2	1,174.4	1,953.4
Cost of sales	0.0	548.5	924.2	1,532.5
Gross profit	0.0	147.7	250.2	420.9
Selling, general and administrative expenses	0.0	78.0	125.0	225.7
Net legacy and separation-related expenses	5.6	0.2	26.2	0.5
Equity and other income, net	0.0	(7.8)	(14.2)	(28.6)
Operating (loss) income from discontinued operations	(5.6)	77.3	113.2	223.3
Net pension and other postretirement plan expense	0.0	0.1	0.1	0.1
Net interest and other financing (income) expense	(0.7)	1.2	4.3	2.7
Gain on sale of discontinued operations (a)	(0.8)	0.0	(1,571.6)	0.0
(Loss) income before income taxes - discontinued operations	(4.1)	76.0	1,680.4	220.5
Income tax expense	(1.2)	17.6	434.0	50.9
(Loss) income from discontinued operations	(2.9)	$ 58.4	1,246.4	$ 169.6
Currency translation adjustment loss	30.7
Tax impact on gain on sale of discontinued operations	$ 0.2		420.4
Tax impact on gain on sale of discontinued operations, current			327.8
Tax impact on gain on sale of discontinued operations, deferred			$ 92.6