Long-Term Debt Long-Term Debt (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015	Jul. 31, 2015
Gross interest expense	$ 10,900	$ 13,800	$ 21,500	$ 27,400
Long-term Debt	695,535	635,935	695,535	635,935	$ 816,830
Amortization of deferred financing costs	200	400	500	700
Interest costs incurred, capitalized	0	0	0	0
Industrial Development Bonds [Member]
Long-term Debt	$ 0	$ 215,000	$ 0	$ 215,000	$ 0