Employee Benefit Plans - Investments of the Plan Measured at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 1,938.2	$ 1,879.6	$ 1,854.4
Commingled trusts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	501.6	679.5
Commingled trusts | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Commingled trusts | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	501.6	679.5
Commingled trusts | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Government securities
Defined Benefit Plan Disclosure [Line Items]
Plan assets	532.4	490.4
Government securities | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Government securities | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	532.4	490.4
Government securities | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Corporate and municipal bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	783.6	695.4
Corporate and municipal bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Corporate and municipal bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	783.6	695.4
Corporate and municipal bonds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Mortgage-backed security bonds
Defined Benefit Plan Disclosure [Line Items]
Plan assets	15.7	3.9
Mortgage-backed security bonds | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Mortgage-backed security bonds | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	15.7	3.9
Mortgage-backed security bonds | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Total pension asset investments
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1,833.3	1,869.2
Total pension asset investments | Level 1
Defined Benefit Plan Disclosure [Line Items]
Plan assets	0.0	0.0
Total pension asset investments | Level 2
Defined Benefit Plan Disclosure [Line Items]
Plan assets	1,833.3	1,869.2
Total pension asset investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 0.0	$ 0.0