Significant Accounting Policies - Plant, equipment and depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Property, Plant and Equipment [Line Items]
Land and land improvements	$ 281,040	$ 289,686
Buildings and building equipment	1,567,130	1,578,701
Machinery and equipment	3,223,585	3,218,639
Construction in progress	114,975	128,227
Total	$ 5,186,730	$ 5,215,253
Buildings
Property, Plant and Equipment [Line Items]
Useful life (in years)	40 years
Land Improvements
Property, Plant and Equipment [Line Items]
Useful life (in years)	15 years
Machinery and Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	7 years
Machinery and Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	10 years
Vehicles and Office Equipment | Minimum
Property, Plant and Equipment [Line Items]
Useful life (in years)	3 years
Vehicles and Office Equipment | Maximum
Property, Plant and Equipment [Line Items]
Useful life (in years)	8 years