Pension and Other Postretirement Benefits - Schedule of Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Millions	12 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2015
Pension Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 20.5	$ 31.2	$ 32.2
Interest cost	50.3	58.0	54.1
Expected return on plan assets	(65.1)	(66.1)	(68.8)
Amortization of net loss	37.8	27.4	16.7
Amortization of prior service cost (benefit)	1.8	0.4	0.3
Curtailment loss (gain)	0.5	0.0	0.0
Net periodic benefit costs	45.8	50.9	34.5
Other Benefits
Defined Benefit Plan Disclosure [Line Items]
Service cost	3.6	3.3	4.4
Interest cost	9.2	10.4	11.8
Expected return on plan assets	(6.9)	(7.0)	(6.6)
Amortization of net loss	3.2	2.7	2.0
Amortization of prior service cost (benefit)	(6.5)	(6.5)	0.0
Curtailment loss (gain)	0.0	0.0	(1.6)
Net periodic benefit costs	$ 2.6	$ 2.9	$ 10.0