Property, Plant and Equipment, net - Narrative (Details) $ in Millions	12 Months Ended
	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($) facility	Jun. 30, 2019 USD ($)
Property, Plant and Equipment [Line Items]
Depreciation	$ 104.7	$ 111.0	$ 108.1
Capitalized software amortization expense	12.0	$ 5.3	$ 6.1
Facility Closing
Property, Plant and Equipment [Line Items]
Number of power production facilities closed | facility		2
Facility Closing | Property, Plant and Equipment
Property, Plant and Equipment [Line Items]
Impairment charges	$ 8.2	$ 31.4