Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2023	Sep. 30, 2022
Deferred tax assets
Non-U.S. net operating loss carryforwards	$ 1.1	$ 0.7
State net operating loss carryforwards	8.2	17.5
Employee benefit obligations	34.6	43.6
Compensation accruals	17.9	22.8
Credit carryforwards	0.3	12.3
Operating lease liabilities	95.2	99.6
Outside Basis Difference	0.0	99.1
Other	12.4	23.0
Valuation allowances	(3.0)	(33.3)
Net deferred tax assets	166.7	285.3
Deferred tax liabilities
Goodwill and other intangibles	19.1	18.7
Property, plant and equipment	134.7	131.6
Operating lease assets	68.1	74.5
Other	0.3	0.0
Total deferred tax liabilities	222.2	224.8
Total net deferred tax (liabilities) assets (f)		$ 60.5
Total net deferred tax (liabilities) assets (f)	(55.5)
Expiration Years 2039 Through 2042 | Foreign Tax Authority
Deferred tax liabilities
Operating loss carryforwards	3.9
Expiration Years 2023 Through 2034 | State and Local Jurisdiction
Deferred tax liabilities
Operating loss carryforwards	$ 154.9