Discontinued Operations - Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net interest and other financing expenses	$ 18.7	$ 17.0
Income tax (benefit) expense	(20.1)	10.1
Income from discontinued operations	54.9	52.8
Discontinued Operations, Held-for-sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net revenues	705.8	619.0
Cost of sales	556.6	488.1
Gross profit	149.2	130.9
Selling, general and administrative expenses	72.3	74.1
Net legacy and separation-related expense	6.2	0.0
Equity and other income, net	(9.2)	(12.2)
Operating income from discontinued operations	79.9	69.0
Net pension and other postretirement plan expense	0.1	0.0
Net interest and other financing expenses	2.3	0.7
Income from discontinued operations before income taxes	77.5	68.3
Income tax (benefit) expense	22.6	15.5
Income from discontinued operations	$ 54.9	$ 52.8