Significant Accounting Policies - Plant, equipment and depreciation (Details) - USD ($) $ in Thousands	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Line Items]
Land and land improvements	$ 289,686	$ 321,331
Buildings and building equipment	1,578,701	1,575,464
Machinery and equipment	3,218,639	3,167,885
Construction in progress	128,227	122,068
Total	$ 5,215,253	$ 5,186,748
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
Building Equipment
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