Pension and Other Postretirement Benefits - Schedule of Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Settlement charge	$ 11.4	$ 0.0	$ 0.0
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	9.6	9.9	9.2
Interest cost	39.4	46.9	53.0
Expected return on plan assets	(56.5)	(62.2)	(64.9)
Amortization of net loss	15.3	15.5	10.4
Amortization of prior service cost (benefit)	2.1	2.1	2.1
Settlement charge	11.4	0.0	0.0
Net periodic benefit costs	21.3	12.2	9.8
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.7	2.6	2.3
Interest cost	7.7	9.0	10.1
Expected return on plan assets	(6.8)	(7.1)	(7.0)
Amortization of net loss	3.6	2.5	1.6
Amortization of prior service cost (benefit)	(3.9)	(3.9)	(5.2)
Settlement charge	0.0	0.0	0.0
Net periodic benefit costs	$ 3.3	$ 3.1	$ 1.8