Income Taxes - Summary of Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2022	Jun. 30, 2021
Deferred tax assets:
Pensions	$ 43.2	$ 51.5
Postretirement provisions	26.9	30.5
Net operating loss carryforwards	44.5	38.7
Tax credit carryforwards	17.0	26.0
Operating lease liability	10.5	8.9
Other	36.8	38.7
Gross deferred tax assets	178.9	194.3
Valuation allowances	(21.3)	(25.2)
Total deferred tax assets	157.6	169.1
Deferred tax liabilities:
Depreciation	(262.9)	(271.3)
Intangible assets	(5.2)	(6.1)
Inventories	(28.9)	(30.6)
Operating lease right-of-use asset	(8.3)	(6.6)
Other	(9.0)	(6.0)
Total deferred tax liabilities	(314.3)	(320.6)
Deferred tax liabilities, net	$ (156.7)	$ (151.5)