Long-Term Debt Long-Term Debt (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2016	Apr. 30, 2015	Apr. 30, 2016	Apr. 30, 2015	Jul. 31, 2015
Gross interest expense	$ 10,400	$ 13,700	$ 31,900	$ 41,100
Long-term Debt	629,178	636,749	629,178	636,749	$ 816,830
Amortization of deferred financing costs	200	400	700	1,100
Interest costs incurred, capitalized	0	0	0	0
Industrial Development Bonds [Member]
Long-term Debt	$ 0	$ 215,000	$ 0	$ 215,000	$ 0