Employee Benefit Plans - Investments of the Plan Measured at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2024
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 1,985.2	$ 1,938.2	$ 1,879.6
Commingled trusts
Defined Benefit Plan Disclosure [Line Items]
Plan assets	534.2	501.6
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	534.2	501.6
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	536.3	532.4
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	536.3	532.4
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	854.4	783.6
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	854.4	783.6
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	38.6	15.7
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	38.6	15.7
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	1,963.5	1,833.3
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	1,963.5	1,833.3
Total pension asset investments | Level 3
Defined Benefit Plan Disclosure [Line Items]
Plan assets	$ 0.0	$ 0.0