Pension and Other Postretirement Benefits - Schedule of Amounts in Other Comprehensive Loss that are Expected to be Recognized as Components of Net Periodic Benefit Cost (Details) $ in Millions	Jun. 30, 2020 USD ($)
Amounts in other comprehensive loss that are expected to recognized as components of net periodic benefit cost in the next fiscal year
Amortization of prior service cost (benefit)	$ (1.8)
Amortization of net actuarial loss	20.9
Amortization of accumulated other comprehensive loss (gain)	19.1
Pension Benefits
Amounts in other comprehensive loss that are expected to recognized as components of net periodic benefit cost in the next fiscal year
Amortization of prior service cost (benefit)	2.1
Amortization of net actuarial loss	17.3
Amortization of accumulated other comprehensive loss (gain)	19.4
Other Benefits
Amounts in other comprehensive loss that are expected to recognized as components of net periodic benefit cost in the next fiscal year
Amortization of prior service cost (benefit)	(3.9)
Amortization of net actuarial loss	3.6
Amortization of accumulated other comprehensive loss (gain)	$ (0.3)