Pension and Other Postretirement Benefits - Schedule of Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2017
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 9.2	$ 9.5	$ 20.5
Interest cost	53.0	52.1	50.3
Expected return on plan assets	(64.9)	(65.9)	(65.1)
Amortization of net loss	10.4	13.5	37.8
Amortization of prior service cost (benefit)	2.1	2.1	1.8
Curtailment loss	0.0	0.0	0.5
Net periodic benefit costs	9.8	11.3	45.8
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	2.3	2.6	3.6
Interest cost	10.1	9.5	9.2
Expected return on plan assets	(7.0)	(6.9)	(6.9)
Amortization of net loss	1.6	2.9	3.2
Amortization of prior service cost (benefit)	(5.2)	(5.2)	(6.5)
Curtailment loss	0.0	0.0	0.0
Net periodic benefit costs	$ 1.8	$ 2.9	$ 2.6