Segment Reporting (Details) (USD $)	3 Months Ended				9 Months Ended
	Apr. 30, 2014		Apr. 30, 2013		Apr. 30, 2014		Apr. 30, 2013		Jul. 31, 2013
United States [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	$ 19,721,145		$ 21,754,001		$ 61,328,509		$ 67,732,966
Gross Long-Lived Assets	30,456,300				30,456,300				29,508,055
Foreign Countries [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	11,782,754	[1]	10,464,922	[1]	34,001,953	[1]	37,459,208	[1]
Gross Long-Lived Assets	5,312,273				5,312,273				5,183,885
Peru [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	5,500,000		3,100,000		13,900,000		8,800,000
Brazil [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	3,500,000		3,700,000		10,100,000		11,500,000
Chile [Member]
Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Line Items]
Revenue	$ 2,300,000		$ 2,300,000		$ 7,000,000		$ 8,100,000

[1] Significant foreign revenues included revenues in Peru ($5.5 million and $3.1 million for the three months ended April 30, 2014 and 2013, respectively, and $13.9 million and $8.8 million for the nine months ended April 30, 2014 and 2013, respectively), Brazil ($3.5 million and $3.7 million for the three months ended April 30, 2014 and 2013, respectively, and $10.1 million and $11.5 million for the nine months ended April 30, 2014 and 2013, respectively) and Chile ($2.3 million for the three months ended April 30, 2014 and 2013, and $7.0 million and $8.1 million for the nine months ended April 30, 2014 and 2013, respectively).