Segment Information Geographic Information (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jul. 31, 2018	Apr. 30, 2018	Jan. 31, 2018	Oct. 31, 2017	Jul. 31, 2017	Apr. 30, 2017	Jan. 31, 2017	Oct. 31, 2016	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 211,637	$ 844,491	$ 734,575	$ 220,850	$ 209,124	$ 794,631	$ 725,198	$ 178,265	$ 2,011,553	$ 1,907,218	$ 1,601,286
Property, Plant and Equipment, Net	1,627,219				1,714,154				1,627,219	1,714,154
Canadian [Member]
Segment Reporting Information [Line Items]
Revenues									321,000	257,800
Property, Plant and Equipment, Net	316,800				338,800				316,800	338,800
Geographic Distribution, Foreign [Member]
Segment Reporting Information [Line Items]
Revenues									401,230	328,942	66,570
Property, Plant and Equipment, Net	417,050				453,933				417,050	453,933
Geographic Distribution, Domestic [Member]
Segment Reporting Information [Line Items]
Revenues									1,610,323	1,578,276	$ 1,534,716
Property, Plant and Equipment, Net	$ 1,210,169				$ 1,260,220				$ 1,210,169	$ 1,260,220