Income Taxes - Summary of Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2024	Jun. 30, 2023
Deferred tax assets:
Pensions	$ 33.1	$ 39.8
Postretirement provisions	14.4	20.0
Non-equity compensation	9.6	16.0
Net operating loss carryforwards	8.5	22.5
Tax credit carryforwards	2.0	1.2
Operating lease liabilities	8.9	10.0
Other	20.1	22.3
Gross deferred tax assets	96.6	131.8
Valuation allowances	(2.4)	(13.6)
Total deferred tax assets	94.2	118.2
Deferred tax liabilities:
Depreciation	219.6	237.6
Intangible assets	3.2	5.8
Inventories	28.2	27.4
Operating lease right-of-use assets	7.0	8.0
Other	2.8	3.1
Total deferred tax liabilities	260.8	281.9
Deferred tax liabilities, net	$ 166.6	$ 163.7